Specific Adsorption of Chromium Species on Kaolinite Surface

Abstract

Specific adsorption of hydrolyzed chromium species on kaolinite surface was studied. Electrokinetic behavior of kaolinite particles in aqueous solutions in the presence of CrCl₃ showed that the hydrolyzed chromium species can adsorb on kaolinite surfaces and reverse its charge. This adsorption reached the maximum near the precipitation pH (ppt) of chromium hydroxide. The adsorption followed Langmuir isotherm and was irreversible. It might be resulted from hydrogen bonding between the hydrolyzed metal species and kaolinite surfaces. A novel chemical adsorption model was proposed between kaolinite surfaces and the hydrolyzed multivalent metal species.

Keywords:

• chromium salts
• hydrogen bond
• specific adsorption
• zeta potential

ACKNOWLEDGMENTS

The financial supports for this work from the Consejo Nacional de Ciencia y Tecnología (CONACyT) of Mexico under the grants nos. 48436-Y and 92506 are gratefully acknowledged. Also, F. Rao would like to thank the CONACyT for offering him the scholarship under the grant no. 213624 during his Ph.D. study.