Catalytic ozonation of p-chlorobenzoic acid over MCM-41 and Fe loaded MCM-41

Mesoporous MCM-41 and Fe loaded MCM-41 (Fe/MCM-41), which were prepared by hydrothermal and dipping method respectively, were applied as heterogeneous catalysts for the ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution. MCM-41 and Fe/MCM-41 were characterized by low and wide angle XRD, atomic absorption spectrometer (AAS) and N2 adsorption–desorption techniques. Due to the synergetic effect, Fe/MCM-41/O3 process significantly improves p-CBA and total organic carbon (TOC) removal efficiency compared to ozonation alone. Under the experimental condition, TOC removal efficiency of Fe/MCM-41/O3 process is over 94.5% at 60 min oxidation time, only 61.5% by MCM-41/O3 process, 62.3% by O3 alone process. Fe/MCM-41/O3 process follows apparent first-order kinetics, while ozonation alone, MCM-41/O3 and Fe2O3/O3 processes follow apparent second-order kinetics. The presence of tert-butanol (TBA) in the Fe/MCM-41/O3 process indicated that the oxidation mechanism of p-CBA occurs via OH in the liquid bulk. Fe/MCM-41 is a promising catalyst for the ozonation process of p-CBA.

► Fe/MCM-41 was used as a heterogeneous catalyst in ozonation process. ► The presence of Fe/MCM-41 obviously improved TOC removal compared that of MCM-41. ► There was a synergetic effect between O3 and catalyst adsorption in Fe/MCM-41/O3. ► Fe/MCM-41 is a promising catalyst for ozonation of p-CBA in aqueous solution.