Effects of pH, Ionic Strength, Time and Temperature on the Sorption of Cd(Ⅱ) to Illite

The sorption of Cd(Ⅱ) on illite was studied as a function of pH, ionic strength, time and temperature under ambient conditions using batch technique. The results indicate that sorption of Cd(Ⅱ) on illite is strongly dependent on pH values and ionic strength. At low pH, the sorption is dominated by outer-sphere surface complexation and ion exchange on illite surfaces, whereas inner-sphere surface complexation is the main sorption mechanism at high pH. The adsorption of Cd(Ⅱ) on illite is found to follow pseudo-second-order kinetic model well. Sorption of Cd(Ⅱ) increase with increasing temperature and fit the Langmuir isotherm well.