A novel green and safe dearsenization of white phosphorus by selective electrocatalytic oxidation

Abstract

Arsenic, as one of the main impurities in white phosphorus, is a kind of highly toxic element which limits the application of high-purity white phosphorus. In this study, electrocatalytic oxidation method was first applied to remove arsenic from white phosphorus. The novel technology of dearsenization was considered as a green and safe process. The effects of the type and concentration of electrolyte, current, stirring speed, temperature and reaction time on the arsenic removal were studied. Arsenic in white phosphorus could be reduced from 450 to 10 mg/L under the following conditions: 0.3 mol/L potassium iodide aqueous solution, 190 mA, 800 r/min and 318 K. 85% food grade phosphoric acid with 2.83 mg/L arsenic concentration, can be obtained from purified white phosphorus. The yield of purified white phosphorus was 94%. The electrolyte was recycled without any generation of pollutants in the reaction system. The reaction of arsenic removal was calculated as a first order reaction. Electrocatalytic oxidation was controllable by current intensity.