Determination of removal efficiency of hexavalent chromium from aqueous solutions and tannery wastewater using kaolinite

Abstract

The discharge of effluents containing chromium (VI) generated by tannery industry reveals serious toxicological and aesthetical problems in the environment. In this study, the use of kaolinite as an adsorbent was evaluated in the tannery wastewater treatment. The sorption of Cr(VI) from aqueous solution and tannery wastewater was conducted by a batch technique. Furthermore, systematic zeta potential experiments have been performed to be able to understand the adsorption mechanism and process. Consequently, zeta potential of kaolinite was not dramatically varied with the solid concentration, but pH altered the zeta potential of the suspensions. After the investigation of variation of zeta potential for kaolinite suspensions, isoelectric point was determined at about pH 2.15. For adsorption process, increase in pH was resulted the adsorption in the direction of decrease, and increase in temperature and ionic strength was not changed significantly the adsorption of hexavalent chromium. The results indicate that kaolinite could be employed as a low cost adsorbent for removals of Cr(VI) from aqueous solutions including industrial wastewaters.