Chemically Activated Carbon from Bagasse and the Removal of Chromium from Aqueous Solution with Activated Carbon
Keywords:
Activated carbon, chemical activation, chromium removal, adsorptionAbstract
Highly porous activated carbon was prepared from sugar-mill bagasse by chemical activation with phosphoric acid in a tubular furnace. Effects of preparation conditions including, chemical-to-precursor ratio, time and temperature of activation on the porous properties of activated carbon were investigated. The maximum in BET surface area of 1,574 m2/g of carbon was achieved with a chemical weight ratio of 1 : 1, and time and temperature of 120 min and 400 oC, respectively. The potential use of the prepared activated carbon for the removal of chromium (VI) from potassium dichromate solution was studied. Maximum removal efficiency of chromium (~82%) by adsorption at 30 oC occurred at pH 2.5, where the oxyanion HCrO4- was the dominant adsorbed species. The adsorption capacity of chromium was favored by an increase in the adsorption temperature over the range of 30 - 40 oC. Langmuir type of adsorption isotherm was found to fit the adsorption of chromium by activated carbon reasonably well. The adsorption kinetics of chromium from solution can be best described by the second-order rate model, with the value of the rate constant being 11 x 10-5 g/mg-min.
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