Notice of RetractionOxidation of As(III) by Hydrous Manganese Oxide: Effect of Carbonate

The mobility of arsenic in aquatic environment is largely governed by its speciation and adsorption on the surfaces of minerals. Hydrous manganese oxide (HMO) plays an important role in redox transformation of arsenic in aquatic environment and is available for remedy of groundwater with high arsenic concentration. Carbonate is often present as major anion in groundwater and its influence on adsorption and transformation of arsenite (As(III)) on HMO is not understood well. This work studied the effect of carbonate on the adsorption and oxidation of As(III) on HMO. The results showed that oxidation of As(III) followed first-order kinetics. The reaction rate constant in the presence of carbonate (k1 = 0.365 h-1) was 2.4 times higher than that in the absence of carbonate (k1 = 0.152 h-1). Precipitation of manganese carbonate may be responsible for the enhanced oxidation of As(III) since adsorption of Mn(II) on HMO will decrease the number of active sites for As(III) oxidation. Precipitation of Mn(II) may also control the manganese pollution by suppressing Mn(II) release.