Adsorption and Reduction of Chromium(VI) on Activated Carbon

Abstract

By employing the aqueous potassium dichromate solution, whose Cr(VI) concentration being lOppm, the adsorption of Cr(VI) on activated carbon has been studied. The following conclusions were obtained by investigating the adsorption of Cr(VI) and Cr(III) as a function of pH and by determining the amount of total Cr and Cr(VI) eluted from activated carbon with either NaOH or HC1 solution. In the pH range from 4 to 6.5, Cr(VI) is readily adsorbed on activated carbon in the form of anionic species such as HCrO4- and CrO2-4(Fig.l, 2 and 5), while Cr2+ ion is scarcely adsorbed on activated carbon (Fig. 4). In acidic solution, Cr(VI) is easily reduced to Cr(VI) in the presence of activated carbon (Fig. 5). Adsorbed Cr(VI) on activated carbon was eluted quantitatively in the form of Cr(VI) by using NaOH solution, whose concentration being higher than 0.1 N, while 90% of it was eluted in the form of Cr(III) by using IN HC1 solution (Table 2). © 1977, The Chemical Society of Japan. All rights reserved.