Chemical Engineering Journal 149 (2009) 249–262 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Removal of lead(II) from wastewater by activated carbon developed from Tamarind wood by zinc chloride activation Jyotikusum Acharya a , J.N. Sahu b , C.R. Mohanty c , B.C. Meikap b,∗ a School of Energy and Environment Management, Rajib Gandhi Technical University (RGTU), Gandhinagar, Bhopal, Madhya Pradesh, India b Department of Chemical Engineering, Indian Institute of Technology (IIT), Kharagpur, P.O. Kharagpur Technology, Kharagpur, West Bengal 721302, India c State Pollution Control Board, Orissa, Bhubaneswar, India article info Article history: Received 19 August 2008 Received in revised form 13 October 2008 Accepted 30 October 2008 Keywords: Lead removal Activated carbon Chemical activation Zinc chloride Adsorption Wastewater treatment abstract In this work, the adsorption of lead(II) was studied on activated carbon prepared from Tamarind wood with zinc chloride activation. Adsorption studies were conducted in the range of 10–50 mg/l initial lead(II) concentration and at temperature in the range of 10–50 ◦ C. The experimental data were analyzed by the Freundlich isotherm and the Langmuir isotherm. Equilibrium data fitted well with the Langmuir model and Freundlich model with maximum adsorption capacity of 43.85mg/g. The rates of adsorption were found to confirm to pseudo-second-order kinetics with good correlation and the overall rate of lead(II) uptake was found to be controlled by pore diffusion, film diffusion and particle diffusion, throughout the entire adsorption period. Boyd plot confirmed that external mass transfer was the rate-limiting step in the sorption process. Different thermodynamic parameters, viz., H ◦ , S ◦ and G ◦ have also been evaluated and it has been found that the sorption was feasible, spontaneous and endothermic in nature. The results indicate that the Tamarind wood activated could be used to effectively adsorb lead(II) from aqueous solutions. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Lead is a heavy, soft, malleable, bluish gray metal. Its common ore is galena where it occurs in the form of sulphide. Most of the lead in the air comes as aerosols, fumes and sprays. It is very widely used in din storage batteries and the gasoline auto exhaust from gaso- line. Powder motor vehicle is the major source of atmospheric layer in the urban area. Other anthropogenic sources of lead include the combustion of coal, processing and manufacturing of lead prod- ucts and manufacturing of lead additives such as tetra ethyl lead (TEL) for gasoline. Some lead is also introduced in the atmospheric during incineration of refuse of lead containing pesticides. Lead is systemic poison causing anemia, kidney malfunction, tissue dam- age of brain and even death in extreme poison. Lead occurs as its sulphide, cerussite (PbCl 2 ) and galena. Lead is also present at 50 parts per million (ppm) in the earths crust. In sea water 5 parts per billion (ppb) lead is present. It is found in all living organism. Those it is distributed in food and in environment. A human body contains about 121 ppb, 96% in the bone. The concentration of lead ∗ Corresponding author. Tel.: +91 3222 283958 (O)/2283959 (R); fax: +91 3222 282250. E-mail addresses: bcmeikap@che.iitkgp.ernet.in, bcmeikap@iitkgp.ac.in (B.C. Meikap). increases with age and it may reach to a limit at 400 mg. It is not essential for mammals. Under specific condition lead is stimula- tory causing enhancing of protein synthesis, DNA synthesis and cell replication. Any metabolic disturbance resulting is an osteol- ysis will liberate lead from its skeletal storage. Lead is deposited mostly in bones and in some soft tissues. Lead is also retaining by mammals in lever, kidney, muscles, etc. About 800 mg of lead create toxicity in human beings. The removal Pb(II) from industrial efflu- ents is a major problem due to the difficulty in threating such waste waters by conventional treatment method. The presence of lead in waste water is dangerous to aquatic flora and fauna even in rel- atively low concentration and stringent environmental regulation attracts the attention of chemists and environmental engineers for its control. The major sources containing lead are the waste water from process industries engaged in lead acid battery, paints, oils, mental phosphate, fertilizer, electronic wood production and also combustion of fossil fuel, forest fires, mining activity, automobile emission, sewage waste water, sea spray, etc. are just few examples [1–3]. The industrial wastewaters are considered to be the main source of lead impurities. The presence of high levels of lead in the environment may cause long-term health risks to humans and ecosystems. It is there fore mandatory that their levels in drinking water, waste water and water used for agricultural and recreational purposes must be reduced to within the maximum allowable concentrations recom- 1385-8947/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.cej.2008.10.029