Reduction Kinetics of Chromium(VI) by S(-II) in Alkalescent Aqueous Media

Batch experiments were performed to study the reaction kinetics of chromium(VI) and S(-II) in alkalescent aqueous media with high reactant concentrations. Effects of stirring rate, pH, initial Cr(VI) concentration, temperature and inert substance concentration on Cr(VI) reduction were experimentally investigated. Apparent reaction kinetics were obtained. The apparent activation energy(E_a) of the reaction was ca. 30.9 kJ · mol⁻¹ at temperature range of 303-333 K and the reaction showed positive salt effect in the low inert substance concentration media of 0.025–0.25 mol/L, suggesting that the actual reactants might be HCrO₄⁻ and HS⁻.