Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India.
Department of Civil Engineering, University of Calgary, ENF 262, 2500 University Drive NW, Calgary, T2N 1N4, Canada.
Chemosphere. 2023 Nov;341:140025. doi: 10.1016/j.chemosphere.2023.140025. Epub 2023 Sep 1.
The removal of three antibiotics i.e., metronidazole (MNZ), ciprofloxacin (CIP) and tetracycline (TET), from aqueous system via TiO photocatalysis under UV-A light was investigated. Photocatalyst(s) were prepared using sol-gel method under different calcination temperatures (400-800 °C) and water-alcohol ratio. The spherical shaped catalyst (mean particle size ∼ 61 nm) was characterized via FTIR, XRD, BET, SEM, Raman, XPS, UV-DRS, and Fluorometry, and point of zero charge was also determined (pH ∼ 6.6). Batch photo-catalytic degradation studies have shown complete degradation of MNZ, CIP and TET after 50, 75 and 20 min with a TOC removal of 37%, 44% and 31%, respectively. The activity of sol-gel prepared TiO was comparatively higher than commercially available pure anatase TiO nanoparticles due to lesser mean particle size. The ratio of water to alcohol in the preparation of TiO catalyst was found to have significant effect on antibiotic removal. Moreover, persulfate (PS) addition of 0.1 g/L amplified the pseudo-first-order removal-rate constant by 2.75, 3.3 and 1.6 times for MNZ, CIP and TET, respectively. The higher initial pH values (8 and 10) have shown the best removal efficiency for all antibiotics. Subsequently, central composite design (CCD) experiments were conducted under multi-antibiotic conditions. Near complete removal of all antibiotics were observed within 120 min. Scavenging studies revealed that hydroxyl and superoxide radicals play major roles in photo-catalytic degradation of MNZ, CIP and TET. During photocatalysis, MNZ degradation was initiated by hydroxylation reaction, CIP by piperazine ring opening by hydroxyl attack and TET by multiple hydroxylation process. Overall, TiO showed good efficiency at degrading multiple antibiotics and has the potential for practical application on a larger scale.
采用溶胶-凝胶法在不同煅烧温度（400-800°C）和水醇比下制备光催化剂。采用 FTIR、XRD、BET、SEM、拉曼、XPS、UV-DRS 和荧光法对球形催化剂（平均粒径约为 61nm）进行了表征，并测定了零电荷点（pH 约为 6.6）。批量光催化降解研究表明，MNZ、CIP 和 TET 在 50、75 和 20min 后完全降解，TOC 去除率分别为 37%、44%和 31%。由于平均粒径较小，溶胶-凝胶法制备的 TiO 的活性明显高于市售的纯锐钛矿 TiO 纳米粒子。在制备 TiO 催化剂时，水醇比发现对抗生素去除有显著影响。此外，添加 0.1g/L 的过硫酸盐（PS）将 MNZ、CIP 和 TET 的准一级去除速率常数分别提高了 2.75、3.3 和 1.6 倍。较高的初始 pH 值（8 和 10）对所有抗生素的去除效率最高。随后，在多抗生素条件下进行了中心复合设计（CCD）实验。所有抗生素在 120min 内几乎完全去除。清除研究表明，羟基自由基和超氧自由基在 MNZ、CIP 和 TET 的光催化降解中起主要作用。在光催化过程中，MNZ 的降解是由羟化反应引发的，CIP 是由羟基进攻哌嗪环开环引起的，TET 是由多次羟化过程引起的。总的来说，TiO 在降解多种抗生素方面表现出良好的效率，并有潜力在更大规模上实际应用。
