HEXAVALENT CHROMIUM ADSORPTION KINETICS AND EQUILIBRIUM IN A NATURAL SOIL

A laboratory investigation of reactions between hexavaleat chromium, Cr(VI), and a natural soil was conducted to evaluate factors that influence sorption and reduction of Cr(VI) in the soil. Results of batch experiments indicated that adsorption and reduction are the major processes that control the fate of chromium (VI) in the soil. Chromium (VI) removal from solution increased with increasing solute concentration and with decreasing solution pH. Small amounts of magnetite, Fe3O4, contained in the soil caused steady reduction of Cr(VI) to Cr(lll). Competing oxyanions, especially phosphate (H2PO4-/HPO4), decreased Cr(VI) adsorption by direct competition for adsorption sites.