Investigation into Catalytic Oxidation and Its Mechanism of As(III) in Alkaline System

A method of aerial oxidation of As(Ⅲ) in alkaline system was investigated using potassium permanganate as catalyst.The influence of several variables such as solution pH value,total arsenic concentration,air flow,reaction temperature and reaction time on As(Ⅲ) oxidation efficiency was determined.The properties of reactive products were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM) and chemical phase analysis.Results show that the potassium permanganate has characteristics of supper-metering oxidizing arsenic.The As(Ⅲ) could be effectively oxidized when As/Mn mole ratio reaches 21∶1.The solution pH value would influence the oxidation results significantly by altering products properties.The oxidation rate of As(Ⅲ) would decrease with the increase of the total arsenic concentration in the solutions.However,the oxidation rate of As(Ⅲ) could increase remarkably with the increase of air flow or system temperature.