Efficient degradation of para-chlorobenzoic acid in water by catalytic ozonation with La-Ce-MCM-41

La-Ce-MCM-41 was directly synthesized by a hydrothermal method and applied as heterogeneous catalyst for the ozonation process of para chlorobenzoic-acid (pCBA). La3+ and Ce3+ were successfully incorporated into the framework of MCM-41 and the formation of degradation products (p-chlorophenol, p-dihydroxybenzene, maleic acid and oxalic acid) were monitored qualitatively using gas chromatography-mass spectrometer and high performance liquid chromatography. Due to the synergy of bimetal and the fast degradation of accumulated intermediates, total organic carbon (TOC) removal efficiency was significantly improved (92 %) in La-Ce-MCM-41/O-3 process compared with ozonation (40 %) at identical reaction condition. The presence of tert-butanol (TBA) in La-Ce-MCM-41/O-3 process indicated that the oxidation of pCBA was mainly due to the function of hydroxyl radicals in the liquid bulk, and a plausible degradation pathway was proposed. TOC removal slightly decreased from 90 to 86 % after La-Ce-MCM-41 being re-utilized three times, which illustrated that La-Ce-MCM-41 was an efficient of promising catalyst for ozonation of pCBA.