Dissolution Of MnO2 Research Articles

Leaching of MnO2 with mixed non‐aqueous solvent dimethyl sulfoxide–sulfur dioxide

AbstractElectrolytic manganese dioxide is dissolved in the mixed non‐aqueous solvent dimethyl sulfoxide–sulfur dioxide (DMSO–SO2) to form manganese disulfate as a final product. Sulfur dioxide does not change the oxidation state of the metal cations in DMSO–SO2 solvent. However, oxidation of sulfur(IV) to sulfur(VI) is possible. The complete MnO2 dissolution occurs in 50 min at a stirring speed of 650 rpm, pH 1, 0.2% solids concentration, 35 × 44 mesh particle size, and 36°C. IR and FTIR evidence has been presented in favor of the formation of SO, S2O, (CH3)2S+ as intermediate species for the proposed mechanism. In the mixed non‐aqueous solvent system the kinetics of leaching is controlled by a mass transport process. The equation 1–⅔α–(1–α)2/3 = kt fits the experimental data very well. This is further supported by scanning electron micrographs, which show a product layer formation on the surface of the MnO2 particle, and by the dependence of k on 1/r.