Kinetic and isothermal studies of cadmium sorption onto bentonite and zeolite
 
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1
Department of Soil Science, College of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
2
Department of Soil Science, College of Agriculture, Isfahan University of Technology, Isfahan 83156-8111, Iran
 
Int. Agrophys. 2010, 24(3): 253–259
 
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ABSTRACT
This study deals with the use of natural bentonite and zeolite for the removal of Cd(II) from aqueous solutions. Batch sorption experiments were carried out to investigate the sorption of Cd(II) to the sorbents with particular focus on sorption kinetics, the pH dependence of sorption, sorption capacity and isotherms. Percent removal of Cd(II) by the minerals increased with increasing pH, contact time and sorbent dose. Bentonite had a higher percent removal of Cd(II) in all chemical conditions compared to zeolite. Our data showed that the Koble-Corrigan models had a better fit (r2 0.99) as compared to the Langmuir model. Maximum sorption capacity calculated from the Langmuir model was 17.6 and 9.4 mg g-1 for bentonite and zeolite, respectively. Pseudo-second order kinetic model provided a perfect fit for the kinetic data of Cd(II) sorption onto both minerals. Based on the sorption and kinetic information obtained for Cd(II) removal by these minerals, it may be concluded that Iranian zeolite and especially bentonite are effective sorbents for Cd(II).
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