Catalytic Ozonation of Succinic Acid in Aqueous Solution by Co/Al_2O_3-EPM: Performance, Characteristics, and Reaction Mechanism

摘要

In this study, the high-reactive Co/Al_(2)O_(3)-EPM (prepared by electroless plating method) were used for catalytic ozonation. On account of the powerless degradation of small molecule acid by ozone alone, succinic acid (SA), a kind of small molecule acid, was selected as the simulated pollutant to evaluate the performance of Co/Al_(2)O_(3)-EPM in Co/Al_(2)O_(3)-EPM/O_(3) system. First, several key preparation parameters of Co/Al_(2)O_(3)-EPM and operational parameters in Co/Al_(2)O_(3)-EPM/O_(3) system for SA removal were optimized. The maximum SA removal (100%) and the total organic carbon (TOC) removal (66.9%) were obtained under the optimal conditions. Second, the superior performance of Co/Al_(2)O_(3)-EPM/O_(3) system for SA removal was confirmed by four control experiments (i.e., Co/Al_(2)O_(3)-EPM alone, O_(3) alone, Co/Al_(2)O_(3)-IM alone, and Co/Al_(2)O_(3)-IM/O_(3) systems). The conversion and mineralization of SA were investigated by high-performance liquid chromatography and TOC analyzer, respectively. The stability of different systems was evaluated by cobalt leaching in the effluent. Besides, X-ray diffraction, Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller were used to analyze the characteristics of Co/Al_(2)O_(3)-EPM and Co/Al_(2)O_(3)-IM (prepared via impregnation method). The results show that Co/Al_(2)O_(3)-EPM had a more uniform and dense cobalt film than Co/Al_(2)O_(3)-IM. In addition, in the Co/Al_(2)O_(3)-EPM/O_(3) system, quenching experiments were conducted, and the dynamic concentration of HO~(•) in the bulk solution was detected. Finally, a possible reaction mechanism for SA degradation in Co/Al_(2)O_(3)-EPM/O_(3) system was proposed. In brief, all results suggest that Co/Al_(2)O_(3)-EPM is a promising catalyst with high catalytic activity and strong stability for ozone decomposition.