Fabrication of a low-cost cementitious catalytic membrane for p-chloronitrobenzene degradation using a hybrid ozonation-membrane filtration system

A new plate microfiltration membrane was fabricated using low-cost cement and quartz to catalyze dissolved ozone. The membrane was characterized using pore size analysis, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF). Through the characterization studies, multiple alkaline hydration products and metal oxides were observed in the membrane, which contained abundant hydroxyl groups. The membrane-catalyzed ozonation process successfully increased the degradation efficiency of p-chloronitrobenzene ( p-CNB) compared with the ozone-alone process in aqueous conditions under continuous flow. The ozone-membrane process decomposed 1.5. mg/L of dissolved ozone and increased the p-CNB removal by 50% with little adsorption. The results of electron paramagnetic resonance (EPR) and tert-butanol affection experiments confirmed that p-CNB degradation followed the mechanism of hydroxyl radical oxidation during the ozone-membrane process. The alkaline hydration products and metal oxides appeared on the surface of membrane pores possibly promoted the hydroxyl radical generation and enhanced the p-CNB degradation. The hybrid process was observed to maintain the ability of removal p-CNB efficiently in different water sources, and it also had the stability of long-time operation. The cementitious membrane was an efficacious catalyzer for p-CNB degradation by ozonation.