The highly efficient cocatalyst of molybdenum powder enhancing low-cost and stable electro-Fenton system for organic contaminants degradation at wide pH range

To conquer the challenges in conventional electro-Fenton (EF) such as catalyst deactivation and expensive modified cathode material, commercial molybdenum powder (Mo) is firstly applied as co-catalyst in GACSS (the cathode fabricated by granular active carbon wrapped with stainless steel mesh) EF process for organic contaminants degradation. The intermittent energy saving system is proved to enhance the co-catalytic performance, without external O2 aeration, extra catalyst addition and pH adjusting. Optimal parameters are 50 mA applied current, 0.15 g/L Mo and 10 min on-10 min off power frequency in intermittent Mo-GACSS system, where 94.03% Rhodamine B (RhB) removal and 0.0467 min−1 degradation rate constant in 60 min is remarkable than other systems. Electron spin resonance (ESR) and quenching experiment confirm the major dominant radicals are superoxide radical (·O2−) and singlet oxygen (1O2), which originate from Fe2+ catalyzing and active site on Mo surface. Furthermore, the long-term consecutive experiments and characterization analysis are investigated to prove the stability of Mo-GACSS system. Various contaminants removal and electric energy consumption evaluation confirm the superiority of wide application and cost-effectiveness. The study combines co-catalyst Mo and low-cost GACSS to provide new perspective in practical organic wastewater treatment to reduce energy consumption.