Abstract
Mn(II) ions in alkaline aqueous solution containing dioctyl sulfosuccinate (AOT) were successfully oxidized under sonication to form brown precipitate. The formed products were found to be Mn_3O_4 by XRD analyses, regardless of calcination. The oxidation of Mn(II) ions was thought to be promoted by sonochemically generated oxidizing agent, such as hydrogen peroxide or effective stirring. In conventional precipitation method, Mn_2O_3 and Mn_3O_4 were formed in the absence and presence of AOT, respectively. We evaluated their catalytic properties for ozone decomposition under high humidity at 5 degree C. The activities of sonochemically prepared Mn_3O_4 were higher than that of Ma_2O_3 by precipitation method, and almost same as that of Mn_3O_4 by precipitation method. It is known that Mn_3O_4 could easily adsorb oxygen atoms and store them up to the composition of Mn_3O_<4.26>. The reason why sonochemically prepared catalyst maintained its activity might be that the adsorbed oxygen atoms constantly desorbed even at low temperature.
