アルベンダゾールとメトロニダゾールの光触媒オゾン化反応における各種紫外線照射の重要な役割を検討した。統合化と相乗的反応機構の解明

Scrutinizing the vital role of various ultraviolet irradiations on the comparative photocatalytic ozonation of albendazole and metronidazole: Integration and synergistic reactions mechanism.

• Mehrangiz Fathinia
• Alireza Khataee
• Behrouz Vahid
• Sang Woo Joo

抄録

ここでは、TiOナノ粒子をゾル-ゲルディップコート法を用いてセラミック表面に固定化し、走査型電子顕微鏡(SEM)と原子間力顕微鏡(AFM)で確認した。次に、調製したセラミックプレートを含むセミバッチ反応器を用いて、各種紫外線を照射し、光触媒オゾン法によるアルベンダゾール(ALZ)及びメトロニダゾール(MTZ)医薬品の分解を行った。UV-A、UV-B、UV-C照射と同一操作条件で光触媒オゾン化工程、光オゾン化工程、光触媒オゾン化工程を比較するための対照実験を行った。その結果、UV-A/TiO/OがALZ及びMTZの分解において最も効率的であることが明らかになった。本研究では、UV-A/TiO/Oプロセスを含む様々なプロセスにおいて、溶存オゾン濃度,酸素濃度及び過酸化水素濃度をモニタリングすることにより、MTZ及びALZの分解を調べた。その結果、ALZの分解は、MTZに比べてバルク溶液中のオゾンの直接的な攻撃を受けにくい性質のため、MTZよりも低いことが明らかになった。さらに、光触媒-オゾン化の正確なメカニズムを調べるために、正孔(h)や活性酸素消去剤、オゾン溶解度向上剤としての様々な化合物を反応バルクに添加した。最終的に、光触媒-オゾン化過程で生成した医薬品の分解中間体をガスクロマトグラフィー-質量分析法(GC-MS)により認識することに成功し、それぞれの場合の原因となる活性酸素を考慮した汚染物質の分解経路の可能性を示唆した。

Herein, TiO nanoparticles were immobilized on the ceramic surface using the sol-gel dip-coating method, which confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Then, a semi-batch reactor containing the prepared ceramic plates, which irradiated by the various UV lights was used for the degradation of the albendazole (ALZ) and metronidazole (MTZ) pharmaceuticals by the photocatalytic ozonation process. The control experiments were performed to compare the photocatalysis, ozonation, photo-ozonation and photocatalytic ozonation processes under the same operational conditions with the UV-A, UV-B and UV-C irradiations. The synergistic effect of photocatalysis and ozonation was observed; moreover, the results revealed that the UV-A/TiO/O had the highest efficiency for the ALZ and MTZ degradation owing to the synergistic heterogeneous reactions (SHRs), which led to more reactive oxygen species (ROS). The MTZ and ALZ degradation were probed by monitoring the dissolved ozone, oxygen and hydrogen peroxide concentrations during the various processes including the UV-A/TiO/O process. The obtained results disclose that the ALZ degradation is lower than the MTZ due to its resistant nature with more direct attacks of the ozone in the bulk solution compared to the MTZ. Furthermore, the various compounds as the holes (h) and ROS scavengers or ozone solubility enhancers were added to the reaction bulk to investigate the exact mechanism of the photocatalytic-ozonation. Eventually, the degradation intermediates of the pharmaceuticals generated in the photocatalytic-ozonation process were successfully recognized by the Gas chromatography-mass spectrometry (GC-MS) and the possible degradation paths were suggested for the degradation of pollutants considering the responsible ROS in each case.

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