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Potential of Spent Tea Leaves as Adsorbent for Treatment of Tannery Wastewater
Abstract:
Spent Tea Leaves, a natural adsorbent, have been successfully used for the treatment of tannery wastewater. Characterization of spent tea leaves was carried out made by Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Batch mode tests were performed to evaluate the influences of various experimental parameters like adsorbent dose, contact time and pH. Tea waste is capable of removing appreciable amount of pollutants (BOD, COD, Cr and Pb) from the tannery wastewater. It was found that different initial concentration of pollutants reached equilibrium at different times. The optimum adsorbent dose for BOD and COD removal was found at 5 gm/l and pH were 5-6 and 9-10 respectively. The optimal conditions for Cr removal were 14 gm/l with pH 8-10 whereas for Pb removal these were 11 gm/l with pH 8-10.Adsorption behavior was found to follow Freundlich and Langmuir isotherms.

Keywords: Tanning, BOD, COD, Heavy metals, Spent Tea Leaves, Adsorption, Batch Process
Introduction:
Tanning industry considered as one of the highly polluting industries in Bangladesh and this has an adverse impact on the environment. It uses raw hides and skins which are by product of meat industry. R.P. Shaha in 1940s established the first tannery of Bangladesh at Narayanganj. Then it was shifted to Hazaribagh area in Dhaka city and at the end of 1990, the leather industry got importance by foreign investmentADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Howlader”, “given” : “Subrata”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “January”, “issued” : { “date-parts” : “2016” }, “title” : “Leather industry of Bangladesh Department of Research”, “type” : “report”, “volume” : “2016” }, “uris” : “http://www.mendeley.com/documents/?uuid=771e34be-3991-44ef-8f86-9621b9b431c5” } , “mendeley” : { “formattedCitation” : “1”, “plainTextFormattedCitation” : “1”, “previouslyFormattedCitation” : “(Howlader, 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }1. There are reportedly around 220 tanneries in Bangladesh but only 113 tanneries are in effective operationADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/S0011-9164(04)00193-6”, “ISSN” : “01440322”, “abstract” : “The Government of Bangladesh has indentified the leather sector as one with considerable growth and investment potential ranked fifth in the export earning sector. Currently Bangladesh produces and exports quality bovine and ovine, caprine (buffalo and cow; sheep and goat) leathers that have a good international reputation for fine textured skins. However, the entire leather sector meets only 0.5% of the worldu2019s leather trade worth US$75 billion. There are about 113 tanneries in Bangladesh that produce 180 million square feet of hides and skins per year. In addition there are about 30 modern shoe manufacturing plants engaged in the production of high-quality footwear, with over 2500 smaller footwear manufacturers also present in the sector. There are around 100 small-to-medium leather goods manufacturers, and a small number of niche larger manufacturers. The sector directly employs approximately 558 000 people. Most of the tanneries do not have proper effluent plants and generate 20 000m3 tannery effluent and 232 tonnes solid waste per day. Tannery liquid and solid wastes are a potential pollutant but also have a potential value. Specific technologies to convert wastes are required. These vary from crude and simple to highly sophisticated and complex. A proposed new leather park is expected to bring a clear transformation to the leather industry with a marked increase in production, product diversification and new product lines with increased sustainability of the sector. Sustainable and cleaner production will be a key issue for the development without placing burdens on the environment.”, “author” : { “dropping-particle” : “”, “family” : “Paul”, “given” : “H L”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Antunes”, “given” : “A P M”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Covington”, “given” : “A D”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Evans”, “given” : “P”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Phillips”, “given” : “P S”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “SLTC Journal”, “id” : “ITEM-1”, “issue” : “January”, “issued” : { “date-parts” : “2013” }, “page” : “25-32”, “title” : “Bangladeshi Leather Industry : An Overview of Recent Sustainable Developments”, “type” : “article-journal”, “volume” : “97” }, “uris” : “http://www.mendeley.com/documents/?uuid=71d0f1af-b959-4ed0-a113-8299c267ee32” } , “mendeley” : { “formattedCitation” : “2”, “plainTextFormattedCitation” : “2”, “previouslyFormattedCitation” : “(Paul, Antunes, Covington, Evans, & Phillips, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }2. These running tanneries do not have proper effluent treatment plant as well as solid waste management system and they produce 20,000m3 of tannery effluent and 232 tons of solid waste per dayADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “SUMMARY: An extensive project has been authorized by Bangladesh Government to relocate tannery industries from Hazaribagh to Savar over 200 acres of land including the installation of modern technology based CETP (Common Effluent Treatment Plant) and SPGS (Sludge Power Generation System) constructed integrally with CETP capable of generating power of 5MW/hour. Minimization, optimization and ease of handling of sludge and management of solid waste generated from adjacent tannery area are the core challenges accepted in constructing the SPGS. Activated with a mixer fuel capacity of 250 ton/day, coal design amount of 50.00 ton/day can generate 5.46 MW/hour electricity from 200 ton/day sludge (using design mixing ratio as 20.00% and 80.00% ,supplied amount of steam 28.20 ton/hour). 1 The concentration of impurities in Solid waste from dumping site of CETP was analyzed in the Department of Glass and Ceramic Engineering, BUET. From analysis it is observed that the percentage of existing analytes are Cl: 65.9977 %, Na:17.6190 %, Ca : 4.7198 %, Si: 3.3834 %, S:2.3050 %, K: 2.0332 %, Fe:1.6465 %, Al: 0.7830 %, Mg: 0.2817 %, Ti: 0.2870 %, P: 0.2373%, Cr: 0.1531 %, Sr: 0.0532 %. The TCLP (Toxicity Characteristics Leaching Procedure) analysis performed in the laboratory of Civil Engineering Department, BUET determines which of the contaminants identified by the United States Environmental Protection Agency (EPA) are present in the leachate and their concentrations. The chromium concentration was found 1.16mg/kg in the TCLP test. The EPA guideline value for chromium is 5.0mg/kg is the TCLP test to dispose in landfills. Hence the solid waste of Savar tannery estate can be considered as disposable in the landfills in the consideration of chromium concentration present in the solid waste of Savar Tannery Estate.”, “author” : { “dropping-particle” : “”, “family” : “Debnath”, “given” : “K”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Delwar Hossain”, “given” : “DR”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “A Jalil”, “given” : “DR M”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Proceedings Sardinia Margherita di Pula”, “id” : “ITEM-1”, “issue” : “October 2017”, “issued” : { “date-parts” : “2017” }, “title” : “Solid Waste Management of Tannery Industrial Estate Dhaka”, “type” : “article-journal” }, “uris” : “http://www.mendeley.com/documents/?uuid=3d5ee46f-ed53-406d-8400-696bddce2f37” } , “mendeley” : { “formattedCitation” : “3”, “plainTextFormattedCitation” : “3”, “previouslyFormattedCitation” : “(Debnath, Delwar Hossain, & A Jalil, 2017)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }3. Water is an important medium in leather processing and nearly 40-45 L water/kg raw hide or skin is needed for leather processingADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISBN” : “0022-4456”, “ISSN” : “00224456”, “abstract” : “Leather industry, like paper and textile industries, consumes large quantities of water. Such excessive usage, resulting from adoption of traditional processing methods and equipments, lead to acute water availability and eftluent treatment problems. Presently, about 30 billion litres of water is being used by this industry annually. A systematic study made at CLRI to reduce the excessive usage and further minimise water consumption in leather processing through optimisation and recycle and reuse strategies. The role of newer equipments, such as the hide processor and the compartmental drum in minimising water usage in leather processing has also been studied extensively. Most of the protocols standardised at CLRI were implemented at select tanneries in India and Sri Lanka, which resulted in better water management in the leather processing industry. The results of such detailed studies have been incorporated in the paper. Introduction”, “author” : { “dropping-particle” : “”, “family” : “Sundar”, “given” : “V. J.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ramesh”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Rao”, “given” : “P. S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Saravanan”, “given” : “P.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Sridharnath”, “given” : “B.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Muralidharan”, “given” : “C.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Scientific and Industrial Research”, “id” : “ITEM-1”, “issue” : “6”, “issued” : { “date-parts” : “2001” }, “page” : “443-450”, “title” : “Water management in leather industry”, “type” : “article-journal”, “volume” : “60” }, “uris” : “http://www.mendeley.com/documents/?uuid=0757e97d-3ead-4caa-a767-62c81c410963” } , “mendeley” : { “formattedCitation” : “4”, “plainTextFormattedCitation” : “4”, “previouslyFormattedCitation” : “(Sundar et al., 2001)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }4. These tannery effluents are typically high in organic and inorganic pollutants which cause serious environmental pollution if discharged without treatment. The major components of the effluent include sulphide, chloride, heavy metals such as chromium, volatile organic compounds, large quantities of solid waste (e.g. flashings), suspended solids like animal hair etc. Chemicals like salts, acids, alkalis, tannins, dyes, fatliquors, etc., which used in leather processing are not fixed completely by the raw hides or skins and the unfixed chemicals release in the effluent as waste. These wastewater from tanneries are discharged into streams which drain into ponds, canals and other water bodies, thereby polluting the surface and ground water sources and cultivable landsADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Thambavani”, “given” : “D Sarala”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Prathipa”, “given” : “V”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “2011” }, “title” : “Physico-chemical characteristics of leather tannery effluent- current scenario in Dindigul town (Tamil Nadu), India”, “type” : “article-journal” }, “uris” : “http://www.mendeley.com/documents/?uuid=4804e325-eb75-4c72-8d87-894e5c8a0272” } , “mendeley” : { “formattedCitation” : “5”, “plainTextFormattedCitation” : “5”, “previouslyFormattedCitation” : “(Thambavani & Prathipa, 2011)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }5.

Tea(Camellia sinensis) is one of the popular drinks in Bangladesh and tea industry produces 2% of world production and exports 3% of world export ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Sabur”, “given” : “S A”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Molla”, “given” : “M M U”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Azad”, “given” : “M A K”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “2000” }, “page” : “77-90”, “title” : “Tea Industry in Bangladesh : Marketing System and Price Behaviour”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=414c04a3-ff8e-42eb-bdc6-8c6edd9d0aee”, “http://www.mendeley.com/documents/?uuid=e6714304-6ef2-4cc6-a307-3f7c1b1e3772” } , “mendeley” : { “formattedCitation” : “6”, “plainTextFormattedCitation” : “6”, “previouslyFormattedCitation” : “(S. A. Sabur, Molla, & Azad, 2000)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }6.At present, the country has 172 commercial tea estates, including many of the world’s largest working plantations and provides direct employment to about one lakh twenty thousand poor people, 50% of whom are womenADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Ahammed”, “given” : “Kazi Muzafar”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “June”, “issued” : { “date-parts” : “2012” }, “title” : “Investment for Sustainable Development of Bangladesh Tea Industry – An Empirical Study”, “type” : “report”, “volume” : “682347” }, “uris” : “http://www.mendeley.com/documents/?uuid=74b5adc7-d22e-422c-ab69-6ac212924541”, “http://www.mendeley.com/documents/?uuid=9b8f406f-755c-4bde-bfdb-137e1d973df4” } , “mendeley” : { “formattedCitation” : “7”, “plainTextFormattedCitation” : “7”, “previouslyFormattedCitation” : “(Ahammed, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }7. Bangladesh Tea Industry established at 1840 on the slopes of the hills in Chittagong and the first commercial tea garden was established in 1857 at Mulnichera in Sylhet ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Nasir”, “given” : “Tasnuba”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Shamsuddoha”, “given” : “Mohammad”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2011” }, “page” : “68-73”, “title” : “Tea Productions , Consumptions and Exports : Bangladesh”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=680328f0-8871-4a0c-9e1d-aa813adbcdda” } , “mendeley” : { “formattedCitation” : “8”, “plainTextFormattedCitation” : “8”, “previouslyFormattedCitation” : “(Nasir & Shamsuddoha, 2011)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }8.The growth of tea production is now 1% per year where as consumption of tea is increasing at 3.5% per yearADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Khan”, “given” : “A.Q”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Biswas”, “given” : “A”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Saha”, “given” : “A.k”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Motalib”, “given” : “M.A”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Tea J. Bangladesh,”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2012” }, “page” : “17-26”, “title” : “SOIL PROPERTIES OF LALMAI HILL, SHALBAN BIHAR AND NILACHAL HILL OF GREATER COMILLA DISTRICT AND ITS SUITABILITY FOR TEA PLANTATION”, “type” : “article-journal”, “volume” : “41” }, “uris” : “http://www.mendeley.com/documents/?uuid=fabe7570-3055-428b-9a64-1553df5dc7b6”, “http://www.mendeley.com/documents/?uuid=390fd5f6-4b08-49e8-b833-7658fbbd362c” } , “mendeley” : { “formattedCitation” : “9”, “plainTextFormattedCitation” : “9”, “previouslyFormattedCitation” : “(Khan, Biswas, Saha, & Motalib, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }9. The annual per capita consumption of tea in Bangladesh is 0.390 kg in 2013ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “URL” : “http://www.helgilibrary.com/indicators/tea-consumption-per-capita/bangladesh/”, “author” : { “dropping-particle” : “”, “family” : “Helgilibrary”, “given” : “”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “2013” }, “title” : “Tea Consumption Per Capita in Bangladesh”, “type” : “webpage” }, “uris” : “http://www.mendeley.com/documents/?uuid=29a68d73-a9f7-4ad1-b00f-894dfb76668b” } , “mendeley” : { “formattedCitation” : “10”, “plainTextFormattedCitation” : “10”, “previouslyFormattedCitation” : “(Helgilibrary, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }10.Once the tea has been brewed, the spent tea becomes a waste that must be disposed of. Like other wastes, tea wastes represent an unused resource and pose increasing disposal problems. After water, tea is the most widely-consumed beverage in the world. With great production and consumption, large quantities of tea wastes (from the Cafe, Cafeteria, or tea –processing factory) are usually discarded into the environment without any treatmentADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Waste water contamination is ever increasing problem which the whole world is now facing. Industrialization and globalization has led to production and disposal of large amount of heavy metals in the environment. The tremendous increase in use of heavy metals over the past decades has inevitably resulted in an increase flux of metallic substances in the aquatic environment. Heavy metals are major pollutants in marine, ground, industrial and even treated wastewaters. Mining activities, agricultural runoff, domestic and industrial effluents are mainly responsible for the increase of the metals released into the environment. Tea waste has been utilized in agricultural field to enhance the production under heavy metal stress. After water, tea is the most widely consumed beverage in the world With great production and consumption large quantities of tea wastes( From the Caff,Cafeteria,or tea u2013processing factory) are usually discarded into the environment without any treatment. The main objectives of the review is to determine the effectiveness and feasibility of some low cost agricultural waste material (Tea waste, coconut husk and coconut shell) in the process of heavy”, “author” : { “dropping-particle” : “”, “family” : “Nandal”, “given” : “Meenakshi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Hood”, “given” : “Rajni”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Dhania”, “given” : “Geeta”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Current Engineering and Technology”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2014” }, “page” : “1-5”, “title” : “Tea Wastes as a Sorbent for Removal of Heavy Metals from wastewater”, “type” : “article-journal”, “volume” : “4” }, “uris” : “http://www.mendeley.com/documents/?uuid=5159c7a9-1db1-4191-b650-bd661fa59a87” } , “mendeley” : { “formattedCitation” : “11”, “plainTextFormattedCitation” : “11”, “previouslyFormattedCitation” : “(Nandal, Hood, & Dhania, 2014)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }11.In last few years, a vast number of publications have been dedicated to the treatment of industrial wastewater by using adsorption techniques with different low-cost materials. Tea waste as well as other low cost adsorbents is also gaining grounds due to its potential of treatment wastewater. Insoluble cell walls of tea leaves are largely made up of cellulose and hemicelluloses, lignin, condensed tannins and structural proteins ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Wang”, “given” : “Shaobin”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Soudi”, “given” : “Mehdi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Li”, “given” : “Li”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Zhu”, “given” : “Z.H”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Hazardous Materials”, “id” : “ITEM-1”, “issue” : “1-3”, “issued” : { “date-parts” : “2006” }, “page” : “243-251”, “title” : “Coal ash conversion into effective adsorbents for removal of heavy metals and dyes from wastewater”, “type” : “article-journal”, “volume” : “133” }, “uris” : “http://www.mendeley.com/documents/?uuid=e3bcd9c3-d24e-42d9-a1e2-bb99e709bb01” } , “mendeley” : { “formattedCitation” : “12”, “plainTextFormattedCitation” : “12”, “previouslyFormattedCitation” : “(Wang, Soudi, Li, & Zhu, 2006)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }12.So tea waste has a good potential to treat the wastewater due to its functional groups. Azo dyes from wastewater ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.3303/CET1332004”, “ISBN” : “9788895608235”, “ISSN” : “19749791”, “abstract” : “Spent tea leaves (STL), a solid waste that is available in large amounts worldwide, was investigated as a potential low-cost adsorbent for the removal of two azo dyes, Reactive Green 19 (RG19) and Reactive Violet 5 (RV5), from contaminated waters. Preliminary experiments conducted on untreated STL showed that this material exhibited very low removal efficiencies (<10 %). By contrast, thermal activation of STL (200 to 400 Cu00b0 for up to 2 h) resulted in a significant increase in dye adsorption. After thermal exposure of STL to 300 Cu00b0 for 1 hour, removal efficiencies of 98.8 % and 72.8 % were observed, respectively, for RG19 and RV5. Characterization of the adsorbent by TG/DTA and FTIR measurements showed that structural and chemical changes occurred in the lignocellulosic material which were probably responsible for the enhancement in adsorption capacity. These results strongly support the use of activated STL as a low-cost alternative to conventional adsorbents. Copyright u00a9 2013, AIDIC Servizi S.r.l.”, “author” : { “dropping-particle” : “”, “family” : “Zuorro”, “given” : “Antonio”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Lavecchia”, “given” : “Roberto”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Medici”, “given” : “Franco”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Piga”, “given” : “Luigi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Chemical Engineering Transactions”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2013” }, “page” : “19-24”, “title” : “Spent tea leaves as a potential low-cost adsorbent for the removal of azo dyes from wastewater”, “type” : “article-journal”, “volume” : “32” }, “uris” : “http://www.mendeley.com/documents/?uuid=1f34a4a5-d9d8-4d09-9ec1-3a928adebde0”, “http://www.mendeley.com/documents/?uuid=71de0466-79e2-49bc-8507-69eda6598d5e” } , “mendeley” : { “formattedCitation” : “13”, “plainTextFormattedCitation” : “13”, “previouslyFormattedCitation” : “(Zuorro, Lavecchia, Medici, & Piga, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }13, heavy metal (Cu2, Ni2 and Zn2) from synthetic wastewater ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Thakur”, “given” : “Lokendra Singh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Parmar”, “given” : “Mukesh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Chemical and Physical Sciences”, “id” : “ITEM-1”, “issue” : “6”, “issued” : { “date-parts” : “2013” }, “page” : “6-19”, “title” : “Adsorption of Heavy Metal from Synthetic Waste Water by Tea Waste Adsorbent”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=fc916006-3e71-4fe3-bca3-d9531b5e8311” } , “mendeley” : { “formattedCitation” : “14”, “plainTextFormattedCitation” : “14”, “previouslyFormattedCitation” : “(Lokendra Singh Thakur & Parmar, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }14, lead ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.2134/jeq2009.0114”, “ISSN” : “1684u20135315”, “abstract” : “An adsorbent was prepared using spent tea leaf and was used to remove lead (Pb) from solution. The Pb removal by the spent tea leaf adsorbent depended on pretreatment of spent tea leaf, adsorption contact time and adsorbent dosage. The optimum pretreatment conditions were confirmed to be that tea leaf was ground to 0.28-0.45 mm in diameter and then drenched in 0.3 M NaOH for 12 h. Adsorption kinetic study showed that the adsorption of Pb onto the spent tea leaf followed the pseudo-second-order model. The adsorption was time dependent and adsorbent dosage dependent. The optimum contact time was 8 h.”, “author” : { “dropping-particle” : “”, “family” : “Lavecchia”, “given” : “Roberto”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pugliese”, “given” : “Alessio”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Zuorro”, “given” : “Antonio”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “African Journal of Biotechnology”, “id” : “ITEM-1”, “issue” : “10”, “issued” : { “date-parts” : “2009” }, “page” : “2212-2217”, “title” : “Removal of lead from aqueous solutions by spent tea leaf”, “type” : “article-journal”, “volume” : “8” }, “uris” : “http://www.mendeley.com/documents/?uuid=71113549-f2a0-418b-97b2-f550fd843dd7” } , “mendeley” : { “formattedCitation” : “15”, “plainTextFormattedCitation” : “15”, “previouslyFormattedCitation” : “(Lavecchia, Pugliese, & Zuorro, 2009)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }15, crystal violet from textile dyeing ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.7763/IPCBEE.”, “ISBN” : “2134328568”, “ISSN” : “2010-4618”, “PMID” : “8568690”, “abstract” : “Textile dyeing is considered as one of the large water consuming industries and produces large volumes of (color) wastewater in dyeing and finishing process. The effluents of such industry poses a serious environmental problem as it causes harm to the biota of receptor water. In this study, it is intended to conduct an experimental attempt to estimate the breakpoint and exhaustion times for a fixed-bed column packed with the low-cost and household waste product of Spent Tea Leaves (STL) while adsorbing Crystal Violet (CV) basic type of dyes. For optimizing the experimental conditions, the initial concentration of CV (10u201330) mg l-1, height of adsorbent bed (10u201320) cm and flow rate (5u201315) mlmin-1 were investigated. Fourier transform infrared (FT-IR) spectroscopy and thermal analysis (TGA) of the raw material were also studied.”, “author” : { “dropping-particle” : “”, “family” : “Sulyman”, “given” : “Mohamed”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “2014 5th International Conference on Environmental Science and Technology”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2014” }, “page” : “110-118”, “title” : “Fixed-bed Column Packed with Low-Cost Spent Tea Leaves for the Removal of Crystal Violet from Aqueous Solution”, “type” : “article-journal”, “volume” : “69” }, “uris” : “http://www.mendeley.com/documents/?uuid=4680182d-60c0-4a58-8b1d-c6b4c73628c6”, “http://www.mendeley.com/documents/?uuid=1339955d-4b7d-49b4-8094-296b2344e241” } , “mendeley” : { “formattedCitation” : “16”, “plainTextFormattedCitation” : “16”, “previouslyFormattedCitation” : “(Sulyman, 2014)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }16, CO2 adsorption ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISSN” : “18234690”, “abstract” : “In this study, spent tea leaves are used as raw material to produce activated carbon (AC). Characterization of used tea leaves-derived AC is studied as low-cost adsorbents to capture carbon dioxide (COu2082) which has been a major contributing factor in relation to global warming. Effects of parameters such as activation sequence, activating chemical agents, ratio of activating agent to tea leaves, activation temperature and heating rate during AC production and its potential to adsorb COu2082 are investigated. The characterization of the spent tea leaves derived AC was analysed using Thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET). For an effective COu2082 adsorption to occur, properties such as large surface area, considerable amount of micropores and suitable pore width are desired. From this study, the total surface area of the ACs produced varied from 311 to 1044 mu00b2/g and total pore volume is ranged from 0.18 to 0.59 cmu00b3/g respectively. Chemically activated sample using H 3 PO 4 at a ratio of 2:1 (CAP2) generated the highest micropore volume of 0.59 cmu00b3/g and surface area of 1044 mu00b2/g, making it the most optimum parameters in this study. Changes in activation temperature and activation sequence have the most extensive effect on the properties of the AC.”, “author” : { “dropping-particle” : “”, “family” : “Menon”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Singh”, “given” : “J.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Doshi”, “given” : “V.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Lim”, “given” : “Xiao Y.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Engineering Science and Technology”, “id” : “ITEM-1”, “issue” : “Special Issue 2”, “issued” : { “date-parts” : “2015” }, “page” : “50-61”, “title” : “Investigation on spent tea leaves derived activated carbon for CO2adsorption”, “type” : “article-journal”, “volume” : “10” }, “uris” : “http://www.mendeley.com/documents/?uuid=b723edff-9869-4338-b839-915dc8a7015c”, “http://www.mendeley.com/documents/?uuid=f675fa64-29c0-49ff-b494-bc72a7034e1f” } , “mendeley” : { “formattedCitation” : “17”, “plainTextFormattedCitation” : “17”, “previouslyFormattedCitation” : “(Menon, Singh, Doshi, & Lim, 2015)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }17, reactive dyes from textile wastewater ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISSN” : “18234690”, “abstract” : “In this study, spent tea leaves are used as raw material to produce activated carbon (AC). Characterization of used tea leaves-derived AC is studied as low-cost adsorbents to capture carbon dioxide (COu2082) which has been a major contributing factor in relation to global warming. Effects of parameters such as activation sequence, activating chemical agents, ratio of activating agent to tea leaves, activation temperature and heating rate during AC production and its potential to adsorb COu2082 are investigated. The characterization of the spent tea leaves derived AC was analysed using Thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET). For an effective COu2082 adsorption to occur, properties such as large surface area, considerable amount of micropores and suitable pore width are desired. From this study, the total surface area of the ACs produced varied from 311 to 1044 mu00b2/g and total pore volume is ranged from 0.18 to 0.59 cmu00b3/g respectively. Chemically activated sample using H 3 PO 4 at a ratio of 2:1 (CAP2) generated the highest micropore volume of 0.59 cmu00b3/g and surface area of 1044 mu00b2/g, making it the most optimum parameters in this study. Changes in activation temperature and activation sequence have the most extensive effect on the properties of the AC.”, “author” : { “dropping-particle” : “”, “family” : “Menon”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Singh”, “given” : “J.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Doshi”, “given” : “V.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Lim”, “given” : “Xiao Y.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Engineering Science and Technology”, “id” : “ITEM-1”, “issue” : “Special Issue 2”, “issued” : { “date-parts” : “2015” }, “page” : “50-61”, “title” : “Investigation on spent tea leaves derived activated carbon for CO2adsorption”, “type” : “article-journal”, “volume” : “10” }, “uris” : “http://www.mendeley.com/documents/?uuid=f675fa64-29c0-49ff-b494-bc72a7034e1f”, “http://www.mendeley.com/documents/?uuid=b723edff-9869-4338-b839-915dc8a7015c” } , “mendeley” : { “formattedCitation” : “17”, “plainTextFormattedCitation” : “17”, “previouslyFormattedCitation” : “(Menon et al., 2015)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }17, Cu (II) and Ni (II) from synthetic wastewater ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Aslan”, “given” : “Sukru”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Yildiz”, “given” : “Sayiter”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ozturk”, “given” : “Mustafa”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Polat”, “given” : “Ayben”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “European Scientific Journal”, “id” : “ITEM-1”, “issue” : “July”, “issued” : { “date-parts” : “2016” }, “page” : “269-275”, “title” : “Adsorption Of Heavy Metals Onto Waste Tea”, “type” : “article-journal”, “volume” : “7881” }, “uris” : “http://www.mendeley.com/documents/?uuid=0c12ae90-6a3a-47ef-ac75-a52667f3c5a4” } , “mendeley” : { “formattedCitation” : “18”, “plainTextFormattedCitation” : “18”, “previouslyFormattedCitation” : “(Aslan, Yildiz, Ozturk, & Polat, 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }18 and Cr (VI) ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.17485/ijst/2007/v1i1/29209”, “author” : { “dropping-particle” : “”, “family” : “Dhanakumar”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Solaraj”, “given” : “G.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Mohanraj”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pattabhi”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Science and Technology”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2007” }, “page” : “1-6”, “title” : “Removal of Cr (VI) from aqueous solution by adsorption Using cooked tea dust.”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=872ab890-9120-4b58-933f-072cf3fb9b21” } , “mendeley” : { “formattedCitation” : “19”, “manualFormatting” : “19”, “plainTextFormattedCitation” : “19”, “previouslyFormattedCitation” : “(Dhanakumar, Solaraj, Mohanraj, & Pattabhi, 2007)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }19-ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISSN” : “0971457X”, “abstract” : “Adsorption of Cr (VI) from aqueous solutions on tea wastes and coconut husk has been studied. The effect of experimental parameters like contact time, adsorbent dosage, initial metal ions concentration and pH has been investigated. The percentage removal of chromium ions increases with the increase in contact time and dosage of adsorbent. Adsorption of Cr (VI) shows maximum adsorption capacity of 34.25 mg/g and 21.59 mg/g with tea waste and coconut husk respectively at pH 2. The removal of Cr (VI) increases with the increase in adsorbent dosage, the optimum dosage being 8 mg/L. The percentage removal of Cr in tea waste and coconut husk is found to be 86% and 82% respectively. Adsorption data have been modelled with the Freundlich and Langmuir adsorption isotherms and various first order kinetic equations. These isotherms are found to be applicable. The various kinetic models used are Natarajan-Khalaf equation, Lagergren equation, Bhattacharya and Venkobachar equation, and the Intra-particle diffusion model. An excellent fit is obtained by the Lagergren equation. Thus, adsorbents prepared from tea waste and coconut husk could be used for the removal of Cr (VI) from aqueous solutions.”, “author” : { “dropping-particle” : “”, “family” : “Dave”, “given” : “Pragnesh N.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pandey”, “given” : “Nishtha”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Thomas”, “given” : “Hannah”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Chemical Technology”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2012” }, “page” : “111-117”, “title” : “Adsorption of Cr(VI) from aqueous solutions on tea waste and coconut husk”, “type” : “article-journal”, “volume” : “19” }, “uris” : “http://www.mendeley.com/documents/?uuid=4f0a57ef-8a3d-4b66-897e-3406843895ac”, “http://www.mendeley.com/documents/?uuid=d14eab1d-b0f9-42a7-be32-78a2cf31c9aa” } , “mendeley” : { “formattedCitation” : “20”, “manualFormatting” : “22”, “plainTextFormattedCitation” : “20”, “previouslyFormattedCitation” : “(Dave, Pandey, & Thomas, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }22 were treated by the tea waste as adsorbent.

Among the conventional treatment technologies, adsorption process is found to be the most effective and economical method because of its simplicity, highly efficient, sludge free and low investment of both the initial costs and land ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Waste water contamination is ever increasing problem which the whole world is now facing. Industrialization and globalization has led to production and disposal of large amount of heavy metals in the environment. The tremendous increase in use of heavy metals over the past decades has inevitably resulted in an increase flux of metallic substances in the aquatic environment. Heavy metals are major pollutants in marine, ground, industrial and even treated wastewaters. Mining activities, agricultural runoff, domestic and industrial effluents are mainly responsible for the increase of the metals released into the environment. Tea waste has been utilized in agricultural field to enhance the production under heavy metal stress. After water, tea is the most widely consumed beverage in the world With great production and consumption large quantities of tea wastes( From the Caff,Cafeteria,or tea u2013processing factory) are usually discarded into the environment without any treatment. The main objectives of the review is to determine the effectiveness and feasibility of some low cost agricultural waste material (Tea waste, coconut husk and coconut shell) in the process of heavy”, “author” : { “dropping-particle” : “”, “family” : “Nandal”, “given” : “Meenakshi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Hood”, “given” : “Rajni”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Dhania”, “given” : “Geeta”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Current Engineering and Technology”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2014” }, “page” : “1-5”, “title” : “Tea Wastes as a Sorbent for Removal of Heavy Metals from wastewater”, “type” : “article-journal”, “volume” : “4” }, “uris” : “http://www.mendeley.com/documents/?uuid=5159c7a9-1db1-4191-b650-bd661fa59a87” } , “mendeley” : { “formattedCitation” : “11”, “manualFormatting” : “11”, “plainTextFormattedCitation” : “11”, “previouslyFormattedCitation” : “(Nandal et al., 2014)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }11,ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISSN” : “2277-2502”, “abstract” : “apid globalization leads us on the way to industrialization. Pollution of water by organic and inorganic chemicals is of serious environmental concern. Sugar industry is one of the biggest consumer of water, and can also introduce serious pollutant to the environment. Chemical as well as biological treatments to these waste waters are in practice since long. Powdered Activated Carbon (PAC) prepared from wood and nutshell charcoal with specific surface area of 5602.352 cm2/gm and particle size 44 u03bc m and Granular Activated Carbon (GAC) prepared from wood and nutshell charcoal with specific surface area of 10.50 cm2/gm and particle size 1.08 mm are used as adsorbents to the combined waste water of Sugar mill at room temperature. The different dosage of PAC and GAC is kept in contact for 24 hours and analyzed before and after treatment. The results of COD removal follow the Freundlich and Langmuir adsorption isotherm. Among PAC and GAC -PAC removes 62.26% of COD at the dose of 20gm/L further at the dose of 30 gm/L its 66.04%, whereas GAC removes 62.26% of COD at the dose of 20gm/L and found exhausted for higher dosages. It proves that rates of adsorption increases with with the reduction in particle size.”, “author” : { “dropping-particle” : “”, “family” : “Lakdawala”, “given” : “M M”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Lakdawala”, “given” : “J M”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Reseach Journal of Recent Sciences”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2013” }, “page” : “90-97”, “title” : “Comparative Study of Effect of PAC and GAC on Removal of COD Contributing Component of Sugar Industry waste water”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=729364c8-99b6-4f0a-ae90-fdbc60e3ef5f” } , “mendeley” : { “formattedCitation” : “21”, “manualFormatting” : “13”, “plainTextFormattedCitation” : “21”, “previouslyFormattedCitation” : “(Lakdawala & Lakdawala, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }13. Attempts have been made to develop low-cost alternative adsorbents which may be classified in two ways either (i) on basis of their availability, i.e., (a) natural materials(wood, peat, coal, lignite etc.), (b) industrial/agricultural/domestic wastes or by-products (slag, sludge, fly ash, bagasse flyash, red mud etc.), and (c) synthesized products; or (ii) depending on their nature, i.e., (a) inorganic and (b)organic materialADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1007/978-94-007-3916-1”, “ISBN” : “978-94-007-3915-4”, “abstract” : “Emerging contaminants are chemicals recently discovered in natural streams as a result of human and industrial activities. Most of them have no regulatory standard and can potentially cause deleterious effects in aquatic life at environmentally relevant concentrations. The conventional wastewater treatment plants (WWTPs) are not always effective for the removal of these huge classes of pollutants and so further water treatments are necessary. This chapter has the aim to study the adsorption process in the removal of emerging compounds. Firstly, a brief description of adsorption mechanism is given and then the study of conventional and non-conventional adsorbents for the removal of emerging compounds is reviewed with the comparison between them.”, “author” : { “dropping-particle” : “”, “family” : “Grassi”, “given” : “Mariangela”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Kaykioglu”, “given” : “Gul”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Belgiorno”, “given” : “Vincenzo”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “2012” }, “page” : “15-38”, “title” : “Emerging Compounds Removal from Wastewater”, “type” : “article-journal” }, “uris” : “http://www.mendeley.com/documents/?uuid=2cb6243c-866a-4954-8bc5-388fe37de588” } , “mendeley” : { “formattedCitation” : “22”, “plainTextFormattedCitation” : “22”, “previouslyFormattedCitation” : “(Grassi, Kaykioglu, & Belgiorno, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }22. Little information is available in Bangladesh on the use of tea spent waste in treating tannery wastewater. For this reason, this study is taken to evaluate the possible use of this tea waste as a bio-adsorbent for tannery effluent. In this study, batch adsorption process was performed to establish adsorption isotherms and adsorption capacity of the spent tea leaves as the adsorbent for removal of BOD, COD, Cr and Pb from tannery wastewater. The batch mode was selected for its simplicity ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Water used in industries creates a wastewater that has a potential hazard for our environment because of introducing various contaminants such as heavy metals into soil and water resources. There are atleast 20 metals which cannot be degraded or destroyed. In this study, removal of Chromium (VI) from the industrial effluent has been investigated by using activated waste tea (AWT) as a useful natural adsorbent. The study was performed using batch experiments with chemical industry effluent having Cr(VI) in higher concentration. The adsorption experiments were carried out under different conditions of solution pH and AWT dose. The results indicated that the AWT has good removal efficiency. About 88% and 98% Cr removal was achieved by using 0.5 gm and 2 gm adsorbent for wastewater initial concentration of 250 mg/l. The adsorption process reached equilibrium within 40 minutes of the contact time with maximum adsorption at neutral pH. The equilibrium data were fitted to Langmuir and Freundlich isotherms. The adsorption behaviour followed both Langmuir and Freundlich isotherm model. Higher sorption capacity of this sorbent indicates that the waste tea can be used for the treatment of effluent containing Cr(VI).”, “author” : { “dropping-particle” : “”, “family” : “Bhavsar”, “given” : “Khushboo”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Patel”, “given” : “Payal”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Science and Research (IJSR) ISSN (Online Impact Factor”, “id” : “ITEM-1”, “issue” : “7”, “issued” : { “date-parts” : “2014” }, “page” : “2319-7064”, “title” : “Efficiency Evaluation of Tea Waste for Adsorption of Hexavalent Chromium from Industrial Effluent”, “type” : “article-journal”, “volume” : “3” }, “uris” : “http://www.mendeley.com/documents/?uuid=e5bf8b60-e59c-4094-a94e-c5b25141c38f” } , “mendeley” : { “formattedCitation” : “23”, “plainTextFormattedCitation” : “23”, “previouslyFormattedCitation” : “(Bhavsar & Patel, 2014)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }23.

Materials and Methods:
Sample Collection
Tannery effluents were collected from Hazaribagh tanning area, Dhaka, during the time from November 2016 to January 2017. Pre-washed plastic bottles were used for sample collection. Study locations :
Sample S1: Drain near ILET main gate
Sample S2: A Tannery outlet
Sample S3: Drain backside of ILET
Preparation of the adsorbent
Black tea leaves as adsorbent were used for the treatment of tannery effluent. The tea waste was collected from restaurants, hotels, teashops and offices, etc. Soluble and colored components were removed from tea waste by repeating washing with boiling water until virtually colorless and finally washed with distilled water and oven dried for 6-8 h at 1050CADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Thakur”, “given” : “Lokender. Singh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Parmar”, “given” : “Mukesh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Chemical and physical Science”, “id” : “ITEM-1”, “issue” : “Nov-Dec”, “issued” : { “date-parts” : “2013” }, “page” : “6-19”, “title” : “Adsorption of Heavy Metal ( Cu2 + , Ni2 + and Zn2 + ) from Synthetic Waste Water by Tea Waste Adsorbent Adsorption of Heavy Metal ( Cu 2 + , Ni 2 + and Zn 2 + ) from Synthetic Waste Water by …”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=2179c334-ee1c-41c6-b8c4-37b4be93ff3e” } , “mendeley” : { “formattedCitation” : “24”, “plainTextFormattedCitation” : “24”, “previouslyFormattedCitation” : “(Lokender. Singh Thakur & Parmar, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }24. Tea waste is a cheap material which is easily available in our country. So its utilization in wastewater treatment particularly in tannery wastewater would be convenient.

122872513335

Figure 1: SEM images of Spent Tea
Figure 1 shows the Scanning electron microscope (SEM) image of STL which was used to examine the surface morphologies. The surface of STL was found smooth with uniform wide microporous structure.

542925130175
Figure 2: FTIR spectra of Spent Tea Leave (STP)
Each specific chemical bond often shows a unique energy absorption band in FTIR analysis and it has been used as a useful tool to identify the presence of certain functional groups of the bio adsorbent 6. The FTIR spectrum of STL is shown in Figure 2. The surface contains various functional groups. The distinct broad and elongated ‘U’ shape peak around 3311.3 cm-1 in the spectrum indicates the oxygen hydrogen (bonded- OH, hydroxyl) group and confirms the presence of alcohols and polyphenols in cellulose and lignin. Spectrums 2919 cm-1 and 2851.4 cm-1 assigning the -CH stretching mode for aliphatic and 1622.8 cm-1 corresponds to C=O group. C-O stretching in alcohols can be due to the peak of 1032.1 – 1151.6 cm-1.

57150140970
Figure3: TGA of Spent tea leave
The TGA profile shows (Fig. 3) typical weight loss pattern for the adsorbent and complete degradation of adsorbent starts around 2900C and by 5500 C the degradation is complete. The first stage corresponds to decomposition of lignocellulosic materials and the second corresponds to complete decomposition ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.4236/aces.2016.64046”, “ISSN” : “2160-0392”, “abstract” : “In this study adsorptive removal of Pb(II) and Cu(II) from aqueous solution by using environmental friendly natural polymers present in exhausted tea leaves has been studied. The biosorbent was modified with dimethylamine to introduce N-functional groups on the surface of adsorbent. The modified adsorbent was characterized by elemental analysis, zeta potential analysis, SEM, DRFTIR, XRD and TG/DTA analysis to conform the modification. Adsorption capacity of the adsorbent was determined as the function of pH of the solution, initial concentration of the solution and contact time. The adsorption experiments were performed using batch experiments. The maximum adsorption capacities of the adsorbent were found to be 91.68 and 71.20 mg/g for Pb(II) and Cu(II), respectively. To minimize the process cost, regeneration of the biosorbent and recovery of metal ions was explored by desorption study. The results indicate that the adsorbent holds great potential for the sequestration of Pb(II) and Cu(II) from their aqueous solution. Hence the modified exhausted tea leaves (MTL) have been investigated as a new cost effective and efficient biosorbent for removal of Pb(II) and Cu(II) from their aqueous solution.”, “author” : { “dropping-particle” : “”, “family” : “Shrestha”, “given” : “Bindra”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Kour”, “given” : “Jagjit”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ghimire”, “given” : “Kedar Nath”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Advances in Chemical Engineering and Science”, “id” : “ITEM-1”, “issue” : “04”, “issued” : { “date-parts” : “2016” }, “page” : “525-540”, “title” : “Adsorptive Removal of Heavy Metals from Aqueous Solution with Environmental Friendly Materialu2014Exhausted Tea Leaves”, “type” : “article-journal”, “volume” : “06” }, “uris” : “http://www.mendeley.com/documents/?uuid=864bb7e3-1db7-46fc-83cd-0faf75a1b8d5” } , “mendeley” : { “formattedCitation” : “25”, “plainTextFormattedCitation” : “25”, “previouslyFormattedCitation” : “(Shrestha, Kour, & Ghimire, 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }25. In the range between 40- 900 C the weight loss is purely due to removal of moisture.

Experimental procedure
The experiment was performed in a batch mode process selected for its simplicityADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Water used in industries creates a wastewater that has a potential hazard for our environment because of introducing various contaminants such as heavy metals into soil and water resources. There are atleast 20 metals which cannot be degraded or destroyed. In this study, removal of Chromium (VI) from the industrial effluent has been investigated by using activated waste tea (AWT) as a useful natural adsorbent. The study was performed using batch experiments with chemical industry effluent having Cr(VI) in higher concentration. The adsorption experiments were carried out under different conditions of solution pH and AWT dose. The results indicated that the AWT has good removal efficiency. About 88% and 98% Cr removal was achieved by using 0.5 gm and 2 gm adsorbent for wastewater initial concentration of 250 mg/l. The adsorption process reached equilibrium within 40 minutes of the contact time with maximum adsorption at neutral pH. The equilibrium data were fitted to Langmuir and Freundlich isotherms. The adsorption behaviour followed both Langmuir and Freundlich isotherm model. Higher sorption capacity of this sorbent indicates that the waste tea can be used for the treatment of effluent containing Cr(VI).”, “author” : { “dropping-particle” : “”, “family” : “Bhavsar”, “given” : “Khushboo”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Patel”, “given” : “Payal”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Science and Research (IJSR) ISSN (Online Impact Factor”, “id” : “ITEM-1”, “issue” : “7”, “issued” : { “date-parts” : “2014” }, “page” : “2319-7064”, “title” : “Efficiency Evaluation of Tea Waste for Adsorption of Hexavalent Chromium from Industrial Effluent”, “type” : “article-journal”, “volume” : “3” }, “uris” : “http://www.mendeley.com/documents/?uuid=e5bf8b60-e59c-4094-a94e-c5b25141c38f” } , “mendeley” : { “formattedCitation” : “23”, “plainTextFormattedCitation” : “23”, “previouslyFormattedCitation” : “(Bhavsar & Patel, 2014)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }23. At the end of predetermined time, the suspension was filtered and the remaining concentration of BOD5, COD and heavy metals (Cr and Pb) value in the aqueous phase were determined. The effect of various controlling parameters such as contact time, pH, and adsorbent dose of tea waste were studied.

Adsorbent dose effect was carried out with 250 ml of tannery sample in each different conical flask with different adsorbent dose (03 to 20 gm/l). Then, all the flasks were kept inside the stirrer at 100 rpm for 60 minutes and finally, the flasks were withdrawn from the stirrer and filtered for BOD, COD, Cr and Pb determination. Effect of contact time was conducted by agitating 250 ml sample for the different time period 30 to180 min with best adsorbent dose.
After the predetermined time intervals, the samples were filtered and then analyzed. pH effect was performed taking the best adsorbent dose and contact time. Dilute NaOH/HCL solution was used to vary the pH of the working solution. The samples were agitated for specific time, filtered and then BOD, COD, Cr and Pb were analyzed. Finally, adsorption was investigated according to the adsorption isotherms.

Glassware and Apparatus used
All glassware’s used were of Borosil / Ranken. The instrument and apparatus used in the experiment were listed below the Table-1.

Table-1: List of Used Instrument
Instrument Brand Function
pH meter Hanna To measure pH
Digital Weight Balance ViBRA AJ To measure weight
Whatman filter paper no. 40 To filter the sample
Automatic Stirrer LovibondTo stir the sample mixture
BOD Incubator Sanyo To incubate the test sample
COD Digester HACH To digest the sample mixture
Portable SpectophotometerHACH DR/2010 Absorbance
AAS Shimadzu AA-6800 Absorbance
Oven — To dry the sample
Results and Discussion
The tannery effluent sample was characterized by the parameters of pH, COD, BOD, EC and Cr (Table 2).

Table-2: Characteristics of Sample
Parameter Unit S1 S2 S3 Tannery Effluent STD
(ECR-97) ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “DoE”, “given” : “”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Bangladesh Department of Environment, Ministry of Environment and Forest, Government of the People’s Republic of Bangladesh”, “id” : “ITEM-1”, “issued” : { “date-parts” : “1997” }, “number-of-pages” : “179-227”, “title” : “The Environment Conservation Rules, 1997”, “type” : “report” }, “uris” : “http://www.mendeley.com/documents/?uuid=3562cd3b-ba42-481d-b832-4ada25285a70” } , “mendeley” : { “formattedCitation” : “26”, “plainTextFormattedCitation” : “26”, “previouslyFormattedCitation” : “(DoE, 1997)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }26
pH — 6.5 8.2 6.2 6-9
BOD mg/l 1,700 12,600 2,100 100
COD mg/l 2,490 21,060 3,200 —
Cr mg/l 10.35 616.770 15.40 02
Pb mg/l 0.24 0.142 0.11 —
BOD Removal
Effect of Adsorbent Dose on BOD removal:
250 ml of Tannery effluent was treated with the different amount of doses (03 to 20 gm/l) of tea waste adsorbent.

190500
Figure 4: Effect of adsorbent dose on BOD removal
The samples were agitated for 60 min, filtered and then analysed. The effect of adsorbent doses on BOD removal by spent tea leaves (STL) was presented in Fig 4. As illustrated in the Figure, the highest percentage of BOD removal were found 81.76%, 91.35% and 84.76% at dose of 05 gm/l for the sample of S1, S2 and S3 respectively and whose initial concentration were 1700 mg/l, 12,600 mg/l and 2100 mg/l respectively. After dose 05 gm/l, further increase in adsorbent dose does not affect the BOD removal considerably. The decrease in uptake might be due to the larger surface area at higher dose which remained free or uncovered which leads to lower specific uptakeADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1155/2010/987620”, “ISSN” : “09734945”, “abstract” : “The composite of wastewater treatment was carried out using activated charcoal as adsorbent to remove COD, BOD, color in which various parameters like adsorbent dose, contact duration, temperature and agitator speed were considered. The adsorbent behavior can be explained on the basis of Freundlich and Langmuir adsorption isotherm model. Maximum removal (87.6, 81.0 and 90.0%) of COD, BOD and color respectively was found at adsorbent dosage of 11 g/L. Also, the textile mill wastewater was treated with different doses of coagulants like alum, ferric sulphate and ferrous sulphate at constant contact duration (4 hours) and room temperature (300 K). Percentage reduction (maximum) corresponds to 80.2, 74.0 and 84.9% was obtained for removal of COD, BOD and color respectively.”, “author” : { “dropping-particle” : “”, “family” : “Patel”, “given” : “Himanshu”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Vashi”, “given” : “R. T.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “E-Journal of Chemistry”, “id” : “ITEM-1”, “issue” : “4”, “issued” : { “date-parts” : “2010” }, “page” : “1468-1476”, “title” : “Treatment of textile wastewater by adsorption and coagulation”, “type” : “article-journal”, “volume” : “7” }, “uris” : “http://www.mendeley.com/documents/?uuid=96dbb30d-0ae4-4d3d-aa87-b6d0b37c0b52” } , “mendeley” : { “formattedCitation” : “27”, “plainTextFormattedCitation” : “27”, “previouslyFormattedCitation” : “(Patel ; Vashi, 2010)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }27. Thus 05 gm/l is found to be optimum dose.

19050164465Effect of Contact time on BOD removal:
Figure 5: Effect of contact time on BOD removal
In order to find out the equilibrium contact time, experiments were carried with best adsorbent dose (5gm/l) for different time period (30-180 minutes). After the predetermined time intervals, the samples were filtered and then analyzed. From Fig.5, it is observed that after certain contact time BOD remains almost constant. This may be due to the attainment of equilibrium between the adsorbent and adsorbate. 60 min, 150 min and 150min are found optimum contact time for sample S1, S2 and S3 respectively. It is evident from the results that the contact time required to attain equilibrium is dependent on the initial concentration of the pollutants. For the same concentration, the percentage removal of pollutants increases with increase of contact time till equilibrium is attained.

Effect of pH on BOD removal:
190502540
Figure 6: Effect of pH on BOD removal
Adsorption experiments were performed at different pH values (3, 5, 6, 8, 9 and 10). Fig 6 shows the effect of pH on percentage removal BOD. For sample S1, at pH 6, the BOD removal was 85.29%, which then decreased as the pH increased. The same trends were observed for sample S2 and S3. About 92.7 % and 88.1% BOD were removed for Sample S2 and S3 respectively at pH 6. This can be explained on the basis that at low and high pH, the adsorption centers or active sites are altered as well as leaching out of lignin and other organic constituents of the adsorbents which leads to lower adsorption of BODADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Inamdar”, “given” : “S.S”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Industrial Pollution Control”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2006” }, “title” : “BOD REDUCTION USING LOW COST ADSORBENTS”, “type” : “article-journal” }, “uris” : “http://www.mendeley.com/documents/?uuid=c34118ad-70c3-45b8-84c8-6882b1b8680e” } , “mendeley” : { “formattedCitation” : “28”, “plainTextFormattedCitation” : “28”, “previouslyFormattedCitation” : “(Inamdar, 2006)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }28.

COD Removal
Effect of Adsorbent Dose on COD removal:
635170815
Figure 7: Effect of adsorbent dose on COD removal
Figure 7 shows the effect of adsorbent dose on COD removal with varying adsorbent amount and 60 min contact time. For sample S1, adsorbent dose was taken of 05 to 20gm/l while 03 to 17 gm/l dose was taken for Sample S2 and S3. The result shows that optimum dosage of adsorbents for COD was 05 gm/l for the samples. About 79.12, 89.65 and 83.44 % removal was achieved for Sample S1, S2 and S3 respectively.

Effect of Contact Time (min) on COD removal:
76298475
Figure 8: Effect of contact time on COD removal
The effect of contact time (min) on the adsorption capacity of spent tea leaves and hence COD concentration reduction from tannery wastewater was shown in Fig.8. Here, experiments were carried with adding best adsorbent dose (5gm/l) for different time period (30-180 minutes). The result obtained shows that maximum COD removal occurred at time of 60 min for S1 and S3 which were 79.12 and 83.44 % of removal respectively. There were no significant changes after these times due to the attainment of equilibrium between the adsorbent and adsorbateADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Kulkarni”, “given” : “Sunil J”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “10”, “issued” : { “date-parts” : “2013” }, “page” : “1836-1839”, “title” : “Removal of Organic Matter From Domestic Waste Water By Adsorption”, “type” : “article-journal”, “volume” : “2” }, “uris” : “http://www.mendeley.com/documents/?uuid=dbce4eb2-8bf5-4e1d-8819-dbb570fe7ee7” } , “mendeley” : { “formattedCitation” : “29”, “plainTextFormattedCitation” : “29”, “previouslyFormattedCitation” : “(Kulkarni, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }29. Hence 60 min is found to be optimum contact time for sample S1 and S3 respectively. For sample S2, percentage of removal is increasing with time and so far 94.45 % removal was achieved at contact time of 180 min. Among the three samples, S2 has the highest initial COD concentration (21,060 mg/l). For this reason, it needs more time to attain equilibrium.

Effect of pH on COD removal:
1905073177
Figure 9: Effect of pH on percentage COD removal.

Effect of pH on COD removal by spent tea leaves shown in Fig.9. For all the three samples, the optimum pH was observed to be 9-10 for adsorption purpose. The reason for the better adsorption of COD of tannery wastewater observed at higher pH attributed to the co-precipitation of the organic matters and the other chemicals with the colloidal Cr(OH)3 responsible for COD. At lower pH, Cr(OH)3 formation was not sufficient for coagulationADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Sabur”, “given” : “M. A.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Rahman”, “given” : “M. M.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Safiullah”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Scientific Research”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2013” }, “page” : “143-150”, “title” : “Treatment of Tannery Effluent by Locally Available Commercial Grade Lime”, “type” : “article-journal”, “volume” : “5” }, “uris” : “http://www.mendeley.com/documents/?uuid=2730bc9a-5fdd-42f3-aafd-336032f62a7c” } , “mendeley” : { “formattedCitation” : “30”, “plainTextFormattedCitation” : “30”, “previouslyFormattedCitation” : “(M. A. Sabur, Rahman, ; Safiullah, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }30.

Chromium (Cr) removal
Effect of Adsorbent Dose on Cr removal:
2270859131
Figure 10: Effect of adsorbent dose on Cr removal
The results for adsorptive removal of Cr with respect to adsorbent dose are shown in Fig. 10 Over the range 5 to 20 gm/l and 60 min contact time. The percentage removal of Cr is seen to increase sharply with adsorbent dose. The maximum removal of Cr for Sample S1, S2 and S3 are 91.79, 78.6 and 88.64% respectively at dose of 14 gm/l. At higher dose of adsorbent, the number of adsorption sites or surface area increases thus results in higher percentage of metal remover. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.cej.2007.01.016”, “ISBN” : “1385-8947”, “ISSN” : “13858947”, “abstract” : “Adsorption of copper and lead ions onto tea waste from aqueous solutions was studied to enable comparison with alternative commonly available absorbents. Batch experiments were conducted to determine the factors affecting adsorption and kinetics of the process. Fixed bed column experiments were performed to study practical applicability and breakthrough curves were obtained. Tea waste is capable of binding appreciable amounts of Pb and Cu from aqueous solutions. The adsorption capacity was highest at solution pH range 5-6. The adsorbent to solution ratio and the metal ion concentration in the solution affect the degree of metal ion removal. The equilibrium data were satisfactorily fitted to Langmuir and Freundlich isotherms. Highest metal uptake of 48 and 65 mg/g were observed for Cu and Pb, respectively. Pb showed higher affinity and adsorption rate compared to Cu under all the experimental conditions. Kinetic studies revealed that Pb and Cu uptake was fast with 90% or more of the adsorption occurring within first 15-20 min of contact time. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.999. Increase in the total adsorption capacity was observed when both Cu and Pb ions are present in the solution. Higher adsorption rate and the capacity were observed for smaller adsorbent particles. Tea waste is a better adsorbent compared to number of alternative low cost adsorbents reported in literature. u00a9 2007 Elsevier B.V. All rights reserved.”, “author” : { “dropping-particle” : “”, “family” : “Amarasinghe”, “given” : “B. M W P K”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Williams”, “given” : “R. A.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Chemical Engineering Journal”, “id” : “ITEM-1”, “issue” : “1-3”, “issued” : { “date-parts” : “2007” }, “page” : “299-309”, “title” : “Tea waste as a low cost adsorbent for the removal of Cu and Pb from wastewater”, “type” : “article-journal”, “volume” : “132” }, “uris” : “http://www.mendeley.com/documents/?uuid=b89f0b12-ade4-41ac-97b8-a89d3a18cd73” } , “mendeley” : { “formattedCitation” : “31”, “plainTextFormattedCitation” : “31”, “previouslyFormattedCitation” : “(Amarasinghe ; Williams, 2007)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }31. So, optimum adsorbent dose is found to be 14 gm/l. Previous study has reported that bonded -OH on the surface of tea waste formed complexation with several chemical specious of Chromium (e.g. Cr(OH)6 and Cr(OH)3) ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.18178/ijesd.2017.8.4.959”, “ISSN” : “20100264”, “author” : { “dropping-particle” : “”, “family” : “Amir”, “given” : “Amnorzahira”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Rahim”, “given” : “Raja Noraisar Raja Abd”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Abdul-Talib”, “given” : “Suhaimi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Journal of Environmental Science and Development”, “id” : “ITEM-1”, “issue” : “4”, “issued” : { “date-parts” : “2017” }, “page” : “260-263”, “title” : “Removal of Chromium Hexavalent Using Agriculture Waste”, “type” : “article-journal”, “volume” : “8” }, “uris” : “http://www.mendeley.com/documents/?uuid=58c3f27b-d066-4c56-b835-d8be4818c236” } , “mendeley” : { “formattedCitation” : “32”, “plainTextFormattedCitation” : “32”, “previouslyFormattedCitation” : “(Amir, Rahim, ; Abdul-Talib, 2017)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }32.
Effect of Contact time (min) on Cr removal:
-10211110033
Figure 11: Effect of contact time on Cr removal
Performance of waste tea on the adsorption of Cr at best adsorption dose (14 gm/l) and for different time intervals (30-150min) shown in Fig. 11. From figure, it is shown that adsorption increased with time and the highest percentage of removals are observed at 60 min, 150 min and 60 min for the sample S1, S2 and S3 which are corresponded to 91.79, 85.40 and 88.64 % and their initial Cr concentration were 10.35, 616.77 and 15.4 gm/l respectively. Then the rate slowed down gradually until it attained equilibrium beyond which there was no significant increase in the rate of removal. This shows that the equilibrium time is dependent on initial concentration because at low solute concentrations the adsorption sites adsorbed the available Cr more quickly
ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISSN” : “0971457X”, “abstract” : “The ability of sawdust carbon to remove chromium from aqueous solution by adsorption was investigated according to equilibrium and kinetics. The extent of removal of Cr(VI) is dependent on concentration, pH and temperature of the solution. With an initial concentration of 100 mg/L and at 60u00b0C and pH 2.5, the removal was found to be 49.8 mg/g. The intra-particle diffusion of Cr(VI) through pores in the adsorbent was sbown to be the main rate limiting step. The higher uptake at pH 2.5 was attributed to chemical reduction of Cr(VI) to Cr(III) coupled with physico-chemical adsorption of Cr(VI) species. The Langmuir and Freundlich adsorption isotherms were used to represent the experimental data. The Langmuir and Freundlich constants were calculated at different temperatures and the adsorption capacity for Cr(VI) increases with temperature. The method was applied on synthetic wastewaters. Treatment of the exhausted carbon with 0.1 M NaOH removed only 87.2% of the adsorbed chromium, suggesting that the binding to the carbon involved strong chemisorption forces.”, “author” : { “dropping-particle” : “”, “family” : “Raji”, “given” : “C.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Anirudhan”, “given” : “T. S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Chemical Technology”, “id” : “ITEM-1”, “issue” : “5”, “issued” : { “date-parts” : “1997” }, “page” : “228-236”, “title” : “Chromium(VI) adsorption by sawdust carbon: Kinetics and equilibrium”, “type” : “article-journal”, “volume” : “4” }, “uris” : “http://www.mendeley.com/documents/?uuid=30e1354b-488e-42e6-a7aa-edeeecd91a01” } , “mendeley” : { “formattedCitation” : “33”, “plainTextFormattedCitation” : “33”, “previouslyFormattedCitation” : “(Raji ; Anirudhan, 1997)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }33.
Effect of pH on Cr removal:
1905069825
Figure 12: Effect of pH on Cr removal
The effect of pH on the Cr removal from wastewater is shown in Fig 12. For removal of metal ions from aqueous solution, pH has an important role due to its responsibility for protonation of metal binding sites ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “abstract” : “Biosorption is potentially an attractive technology for treatment of waste water for retaining heavy metals from dilute solutions. Several researches in environmental biotechnology have shown that many biosorbents present in our environment have the capacity to remove heavy metals from solutions. This paper presents the result of studies carried out on sorption of nickel ions from aqueous solutions by waste tea (Camellia sinensis) powder as a low cost sorbent. The biosorption experiments were performed under various conditions such as different initial metal concentrations, pH and reaction time. Different concentration of nickel solution reached equilibrium at different times. About 0.2g of waste tea powder was found to be enough to remove 98% of 10g/L nickel ion concentration from 30ml metal solution. The optimum pH was found to be 5. The pseudo first order, pseudo second order, Elovich, intraparticle diffusion and parabolic diffusion models were used to describe the kinetic data. The data were best fitted with pseudo second order kinetic model for nickel. The experimental adsorption also reasonably fitted well the Langmuir and Freundlich isotherm”, “author” : { “dropping-particle” : “”, “family” : “Aikpokpodion”, “given” : “PE”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ipinmoroti”, “given” : “RR”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Omotoso”, “given” : “SM”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Soil Nature”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2010” }, “page” : “7-16”, “title” : “Evaluation of Camellia sinensis (Tea) biomass in nickel contaminated waste water treatment”, “type” : “article-journal”, “volume” : “4” }, “uris” : “http://www.mendeley.com/documents/?uuid=732d975f-745c-4f86-8500-9e2500ba9bb0” } , “mendeley” : { “formattedCitation” : “34”, “plainTextFormattedCitation” : “34”, “previouslyFormattedCitation” : “(Aikpokpodion, Ipinmoroti, ; Omotoso, 2010)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }34. This study was conducted at a constant adsorbent dose of 14 gm/l and different agitation period of 60 min, 150 min and 60 min for sample S1, sample S2 and sample S3 respectively. The highest % of Cr reductions were found at pH 10 for samples S1, S2 and S3 which were about 95.42%, 83.57% and 88.38% respectively. With increasing pH the percentage of Cr removal increases because of de-protonation of binding sites which makes different functional groups available for metal binding and vice-versa ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISBN” : “2006-9820”, “abstract” : “Duckweed was used to study adsorption of several metal ions (Fe2+,Cu2+, Zn2+ and Pb2+) from wastewater under different conditions .The dried leaves of duckweed were used at different adsorbent/metal ion ratios. The experimental conditions which includes, pH, contact time, initial concentration, and loading weight on the removal process were investigated. Bach adsorption was studied in a room temperature. The efficiency of adsorption depends on pH value, it increases with the increase of pH value at (2 to 8 ) in range time between 60 to 90 min. The most percentage of removal in the main way of loading weigh was 1.5 gm and 50 ml mixed metal ions solution at 50 ppm concentration of each metal ion. The study of isothermal showed that data was confirmed with temkin isotherm model. The removal order was found to be Pb2+; Zn2+; Cu2+; Fe2+. The potential of application for the treatment of solutions containing these heavy metals in multimetal solutions is indicated. The characterization (the infrared) for the surface of duckweed showed the presence of many function groups which can be binding with metal cations.”, “author” : { “dropping-particle” : “”, “family” : “Dhabab”, “given” : “Jameel M”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “June”, “issued” : { “date-parts” : “2011” }, “page” : “164-170”, “title” : “Removal of some heavy metal ions from their aqueous Solutions by duckweed”, “type” : “article-journal”, “volume” : “3” }, “uris” : “http://www.mendeley.com/documents/?uuid=fb220cce-a56e-4624-adea-d40afdb4ac6f” } , “mendeley” : { “formattedCitation” : “35”, “plainTextFormattedCitation” : “35”, “previouslyFormattedCitation” : “(Dhabab, 2011)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }35.

Lead (Pb) removal
Effect of Adsorbent Dose on Pb removal:
952557150
Figure 13: Effect of adsorbent dose on Pb removal
The results for adsorptive removal of Pb with respect to adsorbent dose are shown in Fig. 13 over the range 05 to 20 gm/l and 60 minutes contact time. The percentage removal of Pb is seen to increase with adsorbent dose. It is observed that there is a sharp increase in percentage removal with adsorbent dose for Pb. The maximum removal of Pb of Sample S1, S2 and S3 are 47.92, 56.2 and 66.36 percentages respectively at 11 gm/l dose amount of waste tea adsorbent. It is apparent that the percent removal of heavy metals increases rapidly with increase in the adsorbent dose due to the greater availability of the exchangeable sites or surface area. It is reported that among various functional groups of tea waste, the carboxyl group (C=O) plays an important role in binding Pb ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1002/elsc.200420066”, “ISBN” : “1618-0240”, “ISSN” : “16180240”, “abstract” : “In this paper, tea leaves were shown to be an effective, low-cost biosorbent. Removal of lead, iron, zinc and nickel from 20 mg/L metal solution by dried biomass of waste tea leaves amounted to 96, 91, 72 and 58%, respectively, at equilibrium, which followed Langmuir and Freundlich adsorption isotherms. Adsorption of metal was in the order of Pb ; Fe ; Zn ; Ni from 5-100 mg/L of metal solution. From a multi-metallic mixture, 92.5, 84 and 73.2% of lead, iron and zinc, respectively, were removed. Fourier transform infrared (FTIR) studies indicated that the carboxyl group was involved in the binding of lead and iron, whereas the amine group was involved in the binding of nickel and zinc. A flow through sorption column packed with dried biomass demonstrated a sorption capacity of 73 mg Pb/g of biomass, indicating its potential in cleaning metal containing wastewater. The metal laden biomass obtained could be disposed off by incineration.”, “author” : { “dropping-particle” : “”, “family” : “Ahluwalia”, “given” : “S. S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Goyal”, “given” : “D.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Engineering in Life Sciences”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2005” }, “page” : “158-162”, “title” : “Removal of heavy metals by waste tea leaves from aqueous solution”, “type” : “article-journal”, “volume” : “5” }, “uris” : “http://www.mendeley.com/documents/?uuid=dca67fd2-86e5-427d-ad43-6aa78099d7ea” } , “mendeley” : { “formattedCitation” : “36”, “plainTextFormattedCitation” : “36”, “previouslyFormattedCitation” : “(Ahluwalia ; Goyal, 2005)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }36 .

Effect of Contact time (min) on Pb removal:
1905047244
Figure 14:Effect of contact time on Pb removal
Figure 14 shows the effect of contact time on Pb removal efficiencies of waste tea adsorbent. Removal efficiency up to 150, 150 and 150 min. at maximum 70.42, 75.35 and 77.27 percentage for sample S1, S2 and S3 respectively. There was an increase rate of adsorption with increase in contact time. Increase in contact time increases the chances of interaction between adsorbate ions and adsorbent sites increasing the rate of adsorption. Equilibrium is attained after exhaustion of the active sites present in the adsorbents.

Effect of pH on Pb removal:
1905062815
Figure 15: Effect of pH on Pb removal
pH variation is one of the most important parameters controlling uptake of heavy metals from wastewater and aqueous solutions. Fig.15 shows the effect of pH on Pb removal efficiencies of waste tea adsorbent. The adsorption increases with increase of pH.At low pH, highly mobile H+ would compete with metal ions for the active binding sites. Hence at low pH all the binding sites may be protonated which tends to decrease the metal sorption on the surface of the adsorbent. As pH increases concentration of H+ ions decrease and positive charge density on the sorption sites also reduced which enhances the adsorption of metal ions to get optimum valueADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.4236/aces.2016.64046”, “ISSN” : “2160-0392”, “abstract” : “In this study adsorptive removal of Pb(II) and Cu(II) from aqueous solution by using environmental friendly natural polymers present in exhausted tea leaves has been studied. The biosorbent was modified with dimethylamine to introduce N-functional groups on the surface of adsorbent. The modified adsorbent was characterized by elemental analysis, zeta potential analysis, SEM, DRFTIR, XRD and TG/DTA analysis to conform the modification. Adsorption capacity of the adsorbent was determined as the function of pH of the solution, initial concentration of the solution and contact time. The adsorption experiments were performed using batch experiments. The maximum adsorption capacities of the adsorbent were found to be 91.68 and 71.20 mg/g for Pb(II) and Cu(II), respectively. To minimize the process cost, regeneration of the biosorbent and recovery of metal ions was explored by desorption study. The results indicate that the adsorbent holds great potential for the sequestration of Pb(II) and Cu(II) from their aqueous solution. Hence the modified exhausted tea leaves (MTL) have been investigated as a new cost effective and efficient biosorbent for removal of Pb(II) and Cu(II) from their aqueous solution.”, “author” : { “dropping-particle” : “”, “family” : “Shrestha”, “given” : “Bindra”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Kour”, “given” : “Jagjit”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ghimire”, “given” : “Kedar Nath”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Advances in Chemical Engineering and Science”, “id” : “ITEM-1”, “issue” : “04”, “issued” : { “date-parts” : “2016” }, “page” : “525-540”, “title” : “Adsorptive Removal of Heavy Metals from Aqueous Solution with Environmental Friendly Materialu2014Exhausted Tea Leaves”, “type” : “article-journal”, “volume” : “06” }, “uris” : “http://www.mendeley.com/documents/?uuid=864bb7e3-1db7-46fc-83cd-0faf75a1b8d5” } , “mendeley” : { “formattedCitation” : “25”, “manualFormatting” : “25”, “plainTextFormattedCitation” : “25”, “previouslyFormattedCitation” : “(Shrestha et al., 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }25,ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Shrestha”, “given” : “Bindra”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Homagai”, “given” : “P L”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pokhrel”, “given” : “M R”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ghimire”, “given” : “K N”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of nepal chemical society”, “id” : “ITEM-1”, “issue” : “Ii”, “issued” : { “date-parts” : “2012” }, “page” : “123-129”, “title” : “Exhausted Tea Leaves u2013 a low cost bioadsorbent for the removal of Lead ( II ) and Zinc ( II ) ions from their aqueous solution”, “type” : “article-journal”, “volume” : “30” }, “uris” : “http://www.mendeley.com/documents/?uuid=b3fecde9-e9d7-48d3-9326-216e83f0dd59”, “http://www.mendeley.com/documents/?uuid=202e9403-5765-4270-9e31-2f811c276126” } , “mendeley” : { “formattedCitation” : “37”, “manualFormatting” : “26”, “plainTextFormattedCitation” : “37”, “previouslyFormattedCitation” : “(Shrestha, Homagai, Pokhrel, ; Ghimire, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }26.A researcher also found the same trend by using rice straw for Pb removal from wastewater. Here at low pH, the surface functional groups, basically carboxylic groups (-COOH), of the bio-sorbent (rice straw) gets protonated by H+ ions leading to a net positive charge on the surface of the adsorbent which creates a repulsive force between cationic species of the metal (Pb2+) and the positively charged surface of the sorbent, which hinders the bio-sorption process. However, the small amount of removal achieved at low pH is due to protons H+ exchange with heavy metal ionADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Amer”, “given” : “Hayam”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issue” : “December”, “issued” : { “date-parts” : “2015” }, “number-of-pages” : “80-81”, “publisher” : “The American University in Cairo”, “title” : “REMOVAL OF LEAD FROM INDUSTRIAL WASTEWATER USING A LOW COST WASTE MATERIAL”, “type” : “thesis” }, “uris” : “http://www.mendeley.com/documents/?uuid=fef19785-d204-4305-bda8-0dc043783b48” } , “mendeley” : { “formattedCitation” : “38”, “plainTextFormattedCitation” : “38”, “previouslyFormattedCitation” : “(Amer, 2015)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }38.

Adsorption Isotherms
Equilibrium studies that give the capacity of the adsorbent and adsorbate are described by adsorption isotherms, which is usually the ratio between the quantity adsorbed and that remained in solution at equilibrium at fixed temperature ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Brunauer”, “given” : “Stephen”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Emmett”, “given” : “P.H”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Teller”, “given” : “Edward”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of American Chemical Society”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “1938” }, “page” : “309-319”, “title” : “Adsorption of gases in multimolecular layers.”, “type” : “article-journal”, “volume” : “60” }, “uris” : “http://www.mendeley.com/documents/?uuid=505c0112-7b1e-43e0-a524-2e5aec845fc9” } , “mendeley” : { “formattedCitation” : “39”, “manualFormatting” : “28”, “plainTextFormattedCitation” : “39”, “previouslyFormattedCitation” : “(Brunauer, Emmett, ; Teller, 1938)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }28,ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.17485/ijst/2007/v1i1/29209”, “author” : { “dropping-particle” : “”, “family” : “Dhanakumar”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Solaraj”, “given” : “G.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Mohanraj”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pattabhi”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Science and Technology”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2007” }, “page” : “1-6”, “title” : “Removal of Cr (VI) from aqueous solution by adsorption Using cooked tea dust.”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=872ab890-9120-4b58-933f-072cf3fb9b21” } , “mendeley” : { “formattedCitation” : “19”, “manualFormatting” : “29”, “plainTextFormattedCitation” : “19”, “previouslyFormattedCitation” : “(Dhanakumar et al., 2007)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }29 Freundlich and Langmuir’s isotherms are the earliest and simplest known relationships describing the adsorption equation ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.17485/ijst/2007/v1i1/29209”, “author” : { “dropping-particle” : “”, “family” : “Dhanakumar”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Solaraj”, “given” : “G.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Mohanraj”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pattabhi”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Science and Technology”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2007” }, “page” : “1-6”, “title” : “Removal of Cr (VI) from aqueous solution by adsorption Using cooked tea dust.”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=872ab890-9120-4b58-933f-072cf3fb9b21” } , “mendeley” : { “formattedCitation” : “19”, “plainTextFormattedCitation” : “19”, “previouslyFormattedCitation” : “(Dhanakumar et al., 2007)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }19. Adsorption isotherm was an equilibrium plot of the solid phase (qe) versus liquid phase concentration (Ce). Freundlich model with linear plotted log qe versus log Ce shown in the following equation;
logqe = log Kf + 1/n log CeWhere, Kf is, roughly, an indicator of the adsorption capacity mg/g, Ce is the equilibrium concentration (mg/L) and 1/n is the adsorption intensity. A linear form of the Freundlich expression will yield the constants Kf and 1/n. Freundlich isotherm model assumes a non-ideal adsorption on heterogeneous surfaces in a multilayer coverage. It suggests that stronger binding sites are occupied first, followed by weaker binding sites. In other words, as the degree of site occupation increases, the binding strength decreases ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.5923/j.aac.20160601.03”, “abstract” : “Anionic layered double hydroxides (LDH) known to have high adsorption capacities and are easily synthesized in the laboratory. With nitrilotriacetate (NTA) anions inclusion as ligand, which is incorporated as interlayer anion in the LDH structure via ion-exchange or coprecipitation reaction, this inclusion would give the Zn-Al LDH material considerable potential as chelate for metal cation contaminants in the aqueous environment by changing the regular behavior of anion exchange to cationic exchanger or serpent. The characterization of the new sorbent is carried out by FTIR spectroscopy (FT-IR), powder x-ray diffraction and scanning electron microscope (SEM). The potential capacity of uptake of Ni(II) and Pb(II) at pH of 5 is attributed to the complex formation between metal ions and NTA in the interlayer of LDH as well as surface adsorption. This work aimed to investigate the kinetics of the sorption mechanism using batch technique at different temperature, pH and various metal concentrations. In addition to the kinetic study of adsorption isotherms and the interaction of adsorbent-adsorbate time as parameters, using a pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models. The results show better correspondence to a pseudo-second-order kinetics model with high correlation coefficients (R2= 0.997 for the initial concentrations). The model of Freundlich is appropriate to describe the experimental adsorption results with sorption capacities of 7.153, 6.807 mg/g for Ni(II) and Pb(II) respectively. These behaviors are attributed to the structural construction of the Zn-Al-NTA material. All these results have shown the high efficiency of Zn-Al-NTA adsorbent for the fast removal of Ni(II) and Pb(II) from aqueous solution.”, “author” : { “dropping-particle” : “”, “family” : “Jamhour”, “given” : “Rasheed M A Q”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ababneh”, “given” : “Taher S”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Al-rawashdeh”, “given” : “Albara I”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Advances in Analytical Chemistry”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2016” }, “page” : “17-33”, “title” : “Adsorption Isotherms and Kinetics of Ni ( II ) and Pb ( II ) Ions on New Layered Double Hydroxides-Nitrilotriacetate Composite in Aqueous Media”, “type” : “article-journal”, “volume” : “6” }, “uris” : “http://www.mendeley.com/documents/?uuid=ffe9f409-d835-4200-92f6-d53b7cce9756” } , “mendeley” : { “formattedCitation” : “40”, “plainTextFormattedCitation” : “40”, “previouslyFormattedCitation” : “(Jamhour, Ababneh, ; Al-rawashdeh, 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }40.Langmuir model with linear plotted1/qe versus 1/Ce shown in the following equation:

Where, qe is the equilibrium adsorbate concentration in solution; qmax is the maximum adsorption capacity (mg/g) which is determined from the slope; Ce is the equilibrium concentration (mg/L) and KL is Langmuir constant related to of the binding sites and determined from the intercept,(L/mg).The Langmuir isotherm model is valid for monolayer adsorption onto the surface containing a finite number of identical sorption sites. This model assumes that adsorbed molecules cannot move across the surface or interact with each other ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.5923/j.aac.20160601.03”, “abstract” : “Anionic layered double hydroxides (LDH) known to have high adsorption capacities and are easily synthesized in the laboratory. With nitrilotriacetate (NTA) anions inclusion as ligand, which is incorporated as interlayer anion in the LDH structure via ion-exchange or coprecipitation reaction, this inclusion would give the Zn-Al LDH material considerable potential as chelate for metal cation contaminants in the aqueous environment by changing the regular behavior of anion exchange to cationic exchanger or serpent. The characterization of the new sorbent is carried out by FTIR spectroscopy (FT-IR), powder x-ray diffraction and scanning electron microscope (SEM). The potential capacity of uptake of Ni(II) and Pb(II) at pH of 5 is attributed to the complex formation between metal ions and NTA in the interlayer of LDH as well as surface adsorption. This work aimed to investigate the kinetics of the sorption mechanism using batch technique at different temperature, pH and various metal concentrations. In addition to the kinetic study of adsorption isotherms and the interaction of adsorbent-adsorbate time as parameters, using a pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models. The results show better correspondence to a pseudo-second-order kinetics model with high correlation coefficients (R2= 0.997 for the initial concentrations). The model of Freundlich is appropriate to describe the experimental adsorption results with sorption capacities of 7.153, 6.807 mg/g for Ni(II) and Pb(II) respectively. These behaviors are attributed to the structural construction of the Zn-Al-NTA material. All these results have shown the high efficiency of Zn-Al-NTA adsorbent for the fast removal of Ni(II) and Pb(II) from aqueous solution.”, “author” : { “dropping-particle” : “”, “family” : “Jamhour”, “given” : “Rasheed M A Q”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Ababneh”, “given” : “Taher S”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Al-rawashdeh”, “given” : “Albara I”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Advances in Analytical Chemistry”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2016” }, “page” : “17-33”, “title” : “Adsorption Isotherms and Kinetics of Ni ( II ) and Pb ( II ) Ions on New Layered Double Hydroxides-Nitrilotriacetate Composite in Aqueous Media”, “type” : “article-journal”, “volume” : “6” }, “uris” : “http://www.mendeley.com/documents/?uuid=ffe9f409-d835-4200-92f6-d53b7cce9756” } , “mendeley” : { “formattedCitation” : “40”, “manualFormatting” : “30”, “plainTextFormattedCitation” : “40”, “previouslyFormattedCitation” : “(Jamhour et al., 2016)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }30, ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1155/2013/740847”, “ISBN” : “2090-9071”, “ISSN” : “20909063”, “abstract” : “Arsenic is a naturally occurring metalloid, which is widely distributed in nature and is regarded as the largest mass poisoning in history. The adsorption potential of Salvadora persica stem ash in a batch system for the removal of As(V) from wastewater was studied. Isotherm studies were carried out to evaluate the effect of contact time (20-240 min), pH (2-11), initial As concn. (50-500 u03bcg/L), and adsorbent dose on sorption efficiency. Maximum removal efficiency of 98.33 and 99.32% was obtained at pH 6, adsorbent dosage 3.5 g/L, initial As(V) concn. 500 u03bcg/L, and contact time 80 and 60 min for S. persica stem ash at 300u00b0 and 500u00b0, resp. Also, the adsorption equil. were analyzed by the Langmuir and Freundlich isotherm models. Such equil. showed that the adsorption data was well fitted with the Freundlich isotherm model for S. persica stem ash at both 300u00b0 and 500u00b0 (R2 =0.8983 and 0.9274, resp.). S. persica stem ash can be used effectively for As(V) removal from the aq. environment. on SciFinder(R)”, “author” : { “dropping-particle” : “”, “family” : “Kord Mostafapour”, “given” : “Ferdos”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Bazrafshan”, “given” : “Edris”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Farzadkia”, “given” : “Mahdi”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Amini”, “given” : “Samira”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Chemistry”, “id” : “ITEM-1”, “issue” : “Mcl”, “issued” : { “date-parts” : “2013” }, “title” : “Arsenic removal from aqueous solutions by salvadora persica stem ash”, “type” : “article-journal”, “volume” : “2013” }, “uris” : “http://www.mendeley.com/documents/?uuid=72baea3a-030e-45dd-b5c5-555ec05716db” } , “mendeley” : { “formattedCitation” : “41”, “manualFormatting” : “31”, “plainTextFormattedCitation” : “41”, “previouslyFormattedCitation” : “(Kord Mostafapour, Bazrafshan, Farzadkia, ; Amini, 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }31.

Adsorption Isotherms for BOD removal:
The results obtained from both Freundlich and Langmuir isotherms at initial concentration are shown in Table 3. For sample of Co 1,700 mg/l, R2 values are 0.937 and 0.828 for Freundlich and Langmuir respectively. The separation factor (RL) for Langmuir isotherm is 0.0008 <1 indicating favorable adsorption. For sample of Co 12,600 mg/l, R2 values are 0.800 and 0.857 for Freundlich and Langmuir respectively. The separation factor (RL) is less than one (0.0019). Figure 16 and 17 represents the Freundlich and Langmuir isotherms for 1,700 mg/l and 12,600 mg/l initial concentration of BOD respectively.

Table 3: Isotherm Models for BOD removal using Spent Tea Leaves at different initial concentration of BOD
Co (mg/l) Freundlich Isotherm constants Langmuir Isotherm constants
Kf1/n R2 qmaxKL R2 RL
1,700 60.54 -23.36 0.937 -234.91 0.73 0.828 0.0008
12,600 42.03 -13.05 0.800 -40.26 0.04 0.857 0.0019

FreundlichLangmuir
Figure 16: Adsorption Isotherms for BOD removal at initial concentrations (Co) of1,700 mg/l

FreundlichLangmuir
Figure 17: Adsorption Isotherms for BOD removal at initial concentrations (Co) of12,600 mg/l
Adsorption Isotherms for COD removal:
The results obtained from both Freundlich and Langmuir isotherms are shown in Table 4. The regression coefficients (R2) of Freundlich isotherm are 0.902 and 0.861 for the initial concentration of 2,490 mg/l and
21,060 mg/l COD respectively whose are close to 1. The R2 values of Langmuir
isotherm are 0.926 and 0.857 for the initial concentration of 2,490 mg/l and 21,060 mg/l COD respectively. The separation factors (RL) for Langmuir isotherm of Co 2,490 mg/l and 21,060 mg/l are less than one which indicating favorable adsorption. Figure 18 and 19 represents the Freundlich and Langmuir isotherms for 2,490 and 21,060 mg/L Co respectively.

Table 4: Isotherm Models for COD removal using Spent Tea Leaves at different initial concentration of COD.

Co (mg/l) Freundlich Isotherm constants Langmuir Isotherm constants
Kf1/n R2 qmaxKL R2 RL
2,490 63.56 0.40 0.902 -316.29 0.55 0.926 0.0007
21,060 24.57 -6.97 0.861 -15.11 0.01 0.857 0.0036

FreundlichLangmuir
Figure 18: Adsorption Isotherms for COD removal at initial concentrations (Co) of2,490 mg/l
2857522226
-190541275
FreundlichLangmuir
Figure 19: Adsorption Isotherms for COD removal at initial concentrations (Co) of 21,060mg/l
Adsorption Isotherms for Cr removal:
From table 5 and figure 20 & 21, it can be observed that the Freundlich and Langmuir isotherms can be used to describe the adsorption data with the Freundlich having a better correlation. The regression coefficients (R2) of Freundlich isotherm are 0.884 and 0.943 for the initial concentration of 10.35 mg/l and 616.77 mg/l Cr respectively. The R2 values of Langmuir isotherm are 0.850 and 0.921 for the initial concentration 10.35 mg/l and 616.77 mg/l Cr respectively. The separation factors (RL) for Langmuir isotherm are greater than zero and less than one indicating that the Langmuir isotherm is favorable for describing the dynamics of Cr adsorption by STL.

Table 5: Isotherm Models for Cr removal using Spent Tea Leaves (STL) at different initial concentration of Cr
Co (mg/l) Freundlich Isotherm constants Langmuir Isotherm constants
Kf1/n R2 qmaxKL R2 RL
10.35 -0.78 0.85 0.884 6.1 0.09 0.850 0.521
616.77 -1.02 0.97 0.943 11.65 0.003 0.921 0.365

FreundlichLangmuir
Figure 20: Adsorption Isotherms for Cr removal at initial concentrations (Co) of10.35 mg/l
-2349591440
127079375
FreundlichLangmuir
Figure 21: Adsorption Isotherms for Cr removal at initial concentrations (Co) of616.77 mg/l
Adsorption Isotherms for Pb removal:
From the table 6 and figure 22 & 23, it can be observed that the R2 values for both the isotherms, Freundlich and Langmuir, are not close to one. Between them, Freundlich R2 value is higher than that of Langmuir R2 value. The separation factors (RL) for Langmuir isotherm of Co 0.24 mg/l and 0.142 mg/l are less than one which indicating favorable adsorption.

Table 6: Isotherm Models for Pb removal using Spent Tea Leaves at different initial concentration of PbCo (mg/l) Freundlich Isotherm constants Langmuir Isotherm constants
Kf1/n R2 qmaxKL R2 RL
0.24 -0.98 1.4 0.606 26.85 1.4 0.507 0.754
0.142 -1.13 0.69 0.737 3.73 30.43 0.620 0.188
1333500 69215152400
FreundlichLangmuir
Figure 22: Adsorption Isotherms for Pb removal at initial concentrations (Co) of0.24 mg/l
1905066040 55245-635
FreundlichLangmuir
Figure 23: Adsorption Isotherms for Pb removal at initial concentrations (Co) of0.142 mg/l
The effect of isotherm shape is discussed from the direction of the predicting whether and adsorption system is “favorable” or “unfavorable”. Hall et al (1966) proposed a dimensionless separation factor or equilibrium parameter, RL, as an essential feature of the Langmuir Isotherm to predict if an adsorption system is “favorable” or “unfavorable”, which is defined as ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.17485/ijst/2007/v1i1/29209”, “author” : { “dropping-particle” : “”, “family” : “Dhanakumar”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Solaraj”, “given” : “G.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Mohanraj”, “given” : “R.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Pattabhi”, “given” : “S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Indian Journal of Science and Technology”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2007” }, “page” : “1-6”, “title” : “Removal of Cr (VI) from aqueous solution by adsorption Using cooked tea dust.”, “type” : “article-journal”, “volume” : “1” }, “uris” : “http://www.mendeley.com/documents/?uuid=872ab890-9120-4b58-933f-072cf3fb9b21” } , “mendeley” : { “formattedCitation” : “19”, “plainTextFormattedCitation” : “19”, “previouslyFormattedCitation” : “(Dhanakumar et al., 2007)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }19:
RL = 1 / (1+bC0)
Where, C0= reference fluid-phase concentration of adsorbate (mg/l) (initial concentration)
b = Langmuir constant, (intercept, L/ mg)
The value of RL indicates the shape of the isotherm accordingly as shown in Table 7 below. For a single adsorption system, Co is usually the highest fluid-phase concentration encountered.

Table 7: Characteristics of adsorption Langmuir isotherm
Separation factor, RL Characteristics of adsorption Langmuir isotherm
RL> 1 Unfavorable
RL = 1 Linear
0 <RL< 1 Favorable
RL = 0 Irreversible
Table 8: Characteristics of adsorption Langmuir isotherm of the samples
Parameter C0 (mg/l) Separation factor, RL
BOD 1,700 0.0008
12,600 0.0019
COD 2,490 0.0007
21,060 0.0036
Cr 10.35 0.521
616.77 0.365
Pb0.24 0.754
0.142 0.188
All the values of separation factor (RL) for the present study (Table 8) are less than 1 which indicating the favorable isotherm shape.

3810090805a 9334590805b
Figure 24: SEM images of Spent Tea Leave Before (a) and after Treatment (b)
Scanning electron microscope (SEM) images of STL before and after treatment of tannery wastewater were shown in figure 24.It is used to examine the surface morphologies of the material. Gaps, slits or channels can be seen as well as get the useful information about the pore structure by SEM image ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.jaap.2013.07.008”, “ISBN” : “4562337427”, “ISSN” : “01652370”, “abstract” : “Tonnes of waste are generated during tea production in Turkey, one of the black tea producing countries in the world. These wastes are not used for any purposes throughout industrial sector. The objective of this study is to bring in economic value to waste materials by producing activated carbons from wastes of a tea plant and to characterize their physicochemical properties. Three types of activated carbons were produced by chemical activation using zinc chloride from tea industry wastes (TIW). Mesoporous structure and surface area rise as the ratio of ZnCl2/TIW increases. When the ratios of ZnCl2/TIW were selected as :1, 1:1, and 2:1, mesoporous activated carbons are found in the percentages of 10.9%, 39.9% and 77.7% with BET surface areas of 706, 1066 and 1141 m2g-1, respectively. The resultant activated carbons were characterized by analyses of proximate-ultimate, FT-IR, SEM, TGA, methylene blue-iodine numbers, and surface functional groups. u00a9 2013 Elsevier B.V. All rights reserved.”, “author” : { “dropping-particle” : “”, “family” : “Gundogdu”, “given” : “Ali”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Duran”, “given” : “Celal”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Senturk”, “given” : “H. Basri”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Soylak”, “given” : “Mustafa”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Imamoglu”, “given” : “Mustafa”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Onal”, “given” : “Yunus”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of Analytical and Applied Pyrolysis”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2013” }, “number-of-pages” : “249-259”, “publisher” : “Elsevier B.V.”, “title” : “Physicochemical characteristics of a novel activated carbon produced from tea industry waste”, “type” : “book”, “volume” : “104” }, “uris” : “http://www.mendeley.com/documents/?uuid=65440851-291b-47e9-83d8-fa4ca6f279de” } , “mendeley” : { “formattedCitation” : “42”, “plainTextFormattedCitation” : “42”, “previouslyFormattedCitation” : “(Gundogdu et al., 2013)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }42 . Before treatment, the surface of the STL was found smooth with uniform microporous structure (Fig 24a). After treatment the surface structures were destroyed and became saturated as shown in figure 24b.

Conclusion
The present study is done to find an alternative source of low cost adsorbent for the treatment of tannery wastewater. Since tea waste has some functional groups, it is an ideal material as adsorbent to treat the wastewater. Tannery effluent contains very high concentration of organic matter, solids, sulfates, sulfides, chromium, lead and other heavy metals. Discharging this effluent directly to the environment causes many environmental and health effects. The solution would be preventing the discharge
of wastewater directly into the environment. The conventional process of removing pollutants has many disadvantages like high investment and operational cost, not suitable for small scale industries. Adsorbent used in this work was spent tea leaves (STL) collected from local market. Batch test was conducted in sample S1 for determination of optimum conditions(adsorbent dose, contact time and pH).From the experience and result of sample S1, another two samples (S2 and S3) were performed and evaluated by the percentage removal of wastewater parameters (BOD, COD, Cr and Pb). The following conclusions are made according to the data found in this study:
Low cost adsorbents prepared from agricultural wastes (spent tea leaves) can be successfully used to treat tannery wastewater.

Maximum percentages of BOD and COD reduction in Sample S1 were 81.76% and 79.12% respectively whereas for Sample S2 these were 92.11% and 94.45% respectively and for Sample S3 these were 86.71% and 83.44% respectively.

Maximum percentages of Cr and Pb reduction in Sample S1 were 91.79% and 70.42% respectively whereas for Sample S2 these were 85.4% and 75.35% respectively and for Sample S3 these were 88.64% and 77.27% respectively.

The optimum adsorbent dose for BOD, COD, Cr and Pb were found at 05gm/l, 05 gm/l, 14 gm/l and 11 gm/l respectively.

The optimum pH range for BOD and COD reduction on spent tea leaves were 5-6 and 9-10 respectively.

The optimum pH range for Cr and Pb reduction on spent tea leaves was 8-10 respectively.

The contact time required to attain equilibrium is dependent of the initial concentrations of the pollutants. For the same concentration, the percentage removal of pollutants increases with increase of contact time till equilibrium is attained.

Both Langmuir and Freundlich isotherms were followed by the adsorption except for the lead (Pb) which had lower value of regression coefficient, R2.

Based on the results of this research, spent tea leaves (STL) can be considered as available, low cost, environmental friendly and effective adsorbent for the treatment of tannery waste water.

Authors Contributions
MNA and MASM carried out a major part of the literature review and drafted the manuscript. FA carried out literature review for selected sections. MNA conceived the study. MMR supervised the research project and helped to finalize the manuscript. All authors read and approved the final manuscript.

Acknowledgements
This research was supported by CASR Research Fund, BUET.
Competing interests
The authors declare that they have no competing interests.

Consent for publication
The authors confirm that the content of the manuscript has not been published, or submitted for publication elsewhere.

Ethical approval and consent to participate
Research and manuscript are original and unpublished. All authors read and approved the final manuscript.

Funding
This research was supported by CASR Research Fund, BUET.

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