Adsorption of cadmium(II) from aqueous solutions by an indigenous clay mineral

Abstract

Removal of cadmium, a priority pollutant, has been investigated by a locally available clay mineral, China clay. The removal depends on initial concentration of cadmium in solution and higher removal has been obtained in lower concentration ranges. The removal increased from 41.0 to 80.3% by decreasing the concentration of cadmium in solution from 2.0<img src='/image/spc_char/cross.gif' border=0>10^-4 to 0.5<img src='/image/spc_char/cross.gif' border=0>10^-4 M at 6.5 <i style="">p</i>H, 100 rpm and 0.01 M NaClO₄ ionic strength. The <i style="">p</i>H of the solution plays an important role in the removal of cadmium. Rate of the removal was calculated by Lagergren’s model and was found to be 5.10<img src='/image/spc_char/cross.gif' border=0>10^-2 min^-1 in optimum conditions. The process of removal proceeds with intraparticle diffusion and the value of the coefficient of intraparticle diffusion was found to be 3.25<img src='/image/spc_char/cross.gif' border=0>10^-10 cm²s^-1. The parameters can be used for designing a plant for treatment of Cd(II) rich water and wastewater economically.