Kinetics and thermodynamics of copper ions removal from wastewater by use of bentonite

Department of Chemistry, K. S. K. V. Kachchh University, Mundra Road, Bhuj-370 001, Gujarat, India E-mail : pragnesh7@yahoo.com Chemical Engineering Department, Institute of Technology, Nirma University of Science and Technology, Gandhinagar-Sarkhej Highway, Post : Chharodi, Ahmedabad-382 481, Gujarat, India Manuscript received 15 March 2011, accepted 16 December 2011 A study on the adsorption of copper from aqueous solutions on bentonite has been carried out with an aim to obtain information on treating effluents from metal finishing industries. The effect of various experimental parameters like contact time; dosage of bentonite; initial concentration of metal ions; pH etc. The percentage removal of metal ions increased with the decrease in initial concentration and increase in contact time, dosage of adsorbent and initial pH. Adsorption data were modeled with the :Freundlich and l,angmuir adsorption isotherms, various first order kinetic equations viz. Lagergren, Natarajan-Khalaf and Bhattacharya and Venkobachar equations and intra particle diffusion model. These isotherms, first order equations and models were found to be applicable. The kinetics of adsorption is found to be first order with intra particle diffusion as the rate determining step. Removal of metal ions using bentonite is found to be favorable and hence it could be used as an adsorbent for the treatment of effluents from metal finishing industries, especially for the removal of metal ions