Removal of Chromium from Chromium(VI) Solutions by Adsorption and Reduction Using Immobilized Persimmon Gel

The removal of chromium(VI) from an aqueous solution using persimmon gel was examined. The amount of chromium(VI) removed was strongly affected by the pH of the solution, with all chromium(VI) being removed at pH 2 or lower. However, in a solution containing, 15 mg dry weight of immobilized persimmon gel, the amount of removed chromium(VI) decreased as the pH increased. A part of chromium(VI) was reduced another oxidation stage, mainly chromium(III), by immobilized persimmon gel. The amount of reduced chromium(III) in the solution was increased with decreasing the pH of the solution. As a result, the amount of total chromium removed was maximal at pH 2. The amount of chromium removed were affected by the chromium concentration and the amount of gel. The maximal amount of chromium removed by the column system was also discussed.