Copper modifies ceramic membrane for catalytic air oxidation of humic acid at low temperatures

Refractory organic contaminants such as humic acid (HA) are challenging for conventional water or wastewater treatment processes. The integration of ceramic membrane (CM) separation and low-temperature (<100 °C) catalytic air oxidation technology (LTCAO) could be a simple approach for the elimination of organic pollutants with low energy and chemical consumption. This study tested this proposal using a series of batch treatment experiments on the fabricated CM@Cu, and multiple analytical procedures were applied to disclose the catalytical mechanism and the degradation pathway of HA. The results showed that Cu nanoparticles dispersed uniformly on the membrane surface and in the membrane pores, and they provided adequate active sites for catalytic oxidation of HA. A degradation efficiency of 89 % was achieved in 60 min, and the CM@Cu sustained a 95 % elimination rate of HA throughout the multi-cycle operation. The energy used in LTCAO was derived from ambient heat, which activated O₂ on the catalyst surface to form •O₂^- and •OH and generated oxygen vacancy via hopping conduction inside CM@Cu. The reactive oxygen species degraded or even mineralized HA. This work provided a new and green way of combining catalytic CM with LTCAO for organic wastewater treatment.