Abstract
Anodic oxidation of reduced phosphorus forms - hypophosphorous and phosphorous acids is an attractive approach from both fundamental science and applied applications (purification and phosphorus recycling). The aim of this research is to investigate the anodic oxidation of phosphorous acid under galvanostatic conditions and to comprehensively evaluate the influence of key parameters on the process efficiency and reaction mechanism. Electrochemical property of phosphorous acid was carried out by recording cyclic voltammetry using a Potentiostat/galvanostat Electrochemical Workstation Corrtest Instruments and electrolysis under galvanostatic condition. The influence of the current density, electrolyte concentration, and temperature on the current efficiency of phosphorous acid oxidation has been studied. The obtained results show that the two distinct anodic peaks observed at a potential of approximately +0,7 V and a potential of approximately +0,95 V upon the addition of H3PO3) can be confidently assigned to the stepwise electro-oxidation of phosphorous acid. The results demonstrate that under electrolysis conditions, the anodic oxidation of phosphorous acid yields phosphate ions. Based on the electrochemical data, it was hypothesized that the formed lead oxide layer exhibits an electrocatalytic effect toward this process, significantly enhancing the anodic currents. The practical significance of this work lies in the scientific substantiation and selection of optimal process parameters for the anodic oxidation of phosphorous acid. Replacing expensive noble metals with a lead anode— which is both cost-effective and corrosion-resistant in sulfuric acid media - ensures a high current efficiency for the target product. Based on the obtained scientific results, the proposed electrochemical method for purifying thermal phosphoric acid was tested at the «NDFZ» LLP production facility.