Efficient mineralization of aqueous antibiotics by simultaneous catalytic ozonation and photocatalysis using MgMnO3 as a bifunctional catalyst
Herein a novel coupling process of simultaneous catalytic ozonation and photocatalysis (SCOP) using a bifunctional catalyst for the antibiotics wastewater treatment was developed. MgMnO 3 , as the first example of bifunctional catalyst, was successfully prepared by a simple sol-gel method. In the MgMnO 3 -mediated SCOP process, the TOC removal of sulfamethoxazole, tetracycline, ciprofloxacin, and trimethoprim within 80 min reached 94.7 ± 0.9%, 88.4 ± 0.9%, 97.8 ± 1.0%, and 76.3 ± 0.9%, respectively, much higher than that in ozonation or photocatalysis (less than 20%). The first order kinetics reaction constant of TOC removal in the case of tetracycline degradation by SCOP is 2.58 × 10 −2 min −1 , which is 2.7, 23.0, and 6.2 times that by catalytic ozonation, photocatalysis, and photo ozonation, respectively. ESR spectra show that much more ·OH radicals are generated in SCOP than the sum in photocatalysis and catalytic ozonation processes, indicating the synergism between two processes and explaining the high mineralization efficiency in SCOP. Finally, eight intermediates were identified by LC-MS analysis and the initial degradation pathway of tetracycline in SCOP was proposed. Excellent treatment efficiency, high ozonation utilization (>93%) and low energy consumption (14.9 KJ/mg TOC) suggest that SCOP is a promising choice for antibiotics-containing wastewater treatment.
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