Simultaneously remove Phosphine, hydrogen sulfide and hydrogen Cyanide: Synergistic effect of micro-electrolysis and liquid-phase catalytic electrolysis

[Display omitted] •The synergistic effect of micro-electrolysis & liquid-phase catalytic electrolysis was proposed.•The sustainability and electrical conductivity of the electrochemical liquid-phase catalysis was enhanced.•Simultaneous removal PH3, H2S and HCN with high efficiency.•The synchronous purification mechanism was analyzed in detail. In this study, phosphine, hydrogen sulfide and hydrogen cyanide were efficiently removed in the three-dimensional electrochemical catalysis system. The effect of electrolysis conditions, micro-electrolysis & electrolysis system, and micro-electrolysis & liquid-phase catalytic electrolysis system on PH3, H2S and HCN removal was investigated. The mechanism of synergistic effect of electrolysis, micro-electrolysis and liquid-phase catalysis, as well as the catalytic oxidation pathway of PH3, H2S and HCN, were thoroughly analyzed. The results showed that the addition of Fe/C particle electrodes improved the removal efficiency and stability of PH3, H2S and HCN in both liquid-phase catalytic and electrolytic systems. The removal efficiency was increased as the external field voltage increased. The reaction products and free radicals of the PH3, H2S and HCN removal process were analyzed by XRD, GC, ion chromatography and ESR, etc., and PH3, H2S and HCN was eventually oxidized to PO43-, S, H2, CO2, N2 and NO3– by free radicals. By incorporating the micro-electrolysis effect into liquid-phase catalytic electrolysis system, the removal efficiencies of PH3, H2S and HCN removal rate can be maintained above 90% for nearly 800 min, eventually reaching 90%, 98%, 93.68% at 800 min. The system is regenerative and the removal efficiency of PH3, H2S and HCN after regeneration is about 80% of the original.