Adsorption and Reduction of Chromium(VI) on Activated Carbon'

Abstract

By employing the aqueous potassium dichromate solution, whose Cr 00 concentration being 10 ppm, the adsorption of Cr (V) on activated carbon has been studied. The following conclusions were obtained by investigating the adsorption of Cr (VI) and Cr 110 as a function of pH and by determining the amount of total Cr and Cr (VI) eluted from activated carbon with either NaOH or HCI solution. In the pH range from 4 to 6.5, Cr (1, ) is readily adsorbed on activated carbon in the form of anionic species such as HCr04- and Cr042- (Fig.1, 2 and 5), while Cr" ion is scarcely adsorbed on activated carbon (Fig.4). In acidic solution, Cr (VI) is easily reduced to Cr OE in the presence of activated carbon (Fig.5). Adsorbed Cr() on activated carbon was eluted quantitatively in the form of Cr (171) by using NaOH solution, whose concentration being higher than 0.1 N, while 90% of it was eluted in the form of Cr (111) by using 1 N HCl solution (Table 2).