Benzotriazole (BTA) is widely used as a corrosion inhibitor of yellow metals, antifreezes, cutting fluids, and coating materials in various industries or even in domestic products. Because of its high polarity and low biodegradability, BTA is expected to be mobile in the aquatic environment. The reported removal of BTA ranges between 29% and 58% in wastewater treatment plant. In this study, the removal kinetics and degradation mechanisms of BTA during UV/chlorination process were investigated, especially focusing on UV-A/chlorination process. The experiment was performed with batch type photo reactor. The light intensity of UV lamps (UV-A, B, C) used were 3.3 – 4.3 mW/cm2. UHPLC- MS/MS was used for BTA analysis and UPLC-qTOF-MS was used for byproducts identification. The result showed that the removal rate of BTA was fast in the order of UV-C, UV-B, UV-A. UV-A/chlorination process showed a synergetic effect compared to UV-A photolysis and chlorination only processes. The synergetic effect is due to the OH radical generated in the UV/chlorination process. The kinetics followed the pseudo-first order kinetics. More chlorine dosage, faster removal rate was achieved. Alkaline pH increased the removal of BTA UV-A/chlorination process. Additionally, reaction byproducts during UV/chlorination process were identified (m/z 150.0307, 166.0252, 124.0147, 140.0071, 154.0245). Using the identified byproducts we proposed the degradation pathway of BTA during UV-A/chlorination process. Also, toxic profiles during UV-A/chlorination of BTA was investigated with Microtox bioassay. The ecotoxicity during UV-A/chlorination of BTA was decreased. As a result, it was confirmed that UV-A/Chlorination process was quite effective not only for BTA elimination, but also for ecotoxicity decrease.
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Degradation kinetics and byproducts pathway of 1H-benzotriazole during UV/chlorination process
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