Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Int J Environ Res Public Health. 2018 Feb 7;15(2):284. doi: 10.3390/ijerph15020284.
Taste- and odor-causing (T&O) compounds are a major concern in drinking water treatment plants due to their negative impacts on the safety and palatability of water supply. This study explored the degradation kinetics and radical chemistry of four often-detected T&O compounds, geosmin (GSM), 2-methylisoborneol (MIB), benzothiazole (BT), and 2-isobutyl-3-methoxypyrazine (IBMP), in the ultraviolet/chlorine (UV/chlorine) advanced oxidation process. All experiments were carried out in a 700 mL photoreactor and the process effectively degraded the investigated T&O compounds in a slightly acidic environment. The degradation of T&O decreased with increasing pH but slightly with decreasing chlorine dosage. When the pH increased from 6 to 8, the pseudo-first-order rate constants of GSM, MIB, BT, and IBMP dropped from 2.84 × 10, 2.29 × 10, 3.64 × 10, and 2.76 × 10 s to 3.77 × 10, 2.64 × 10, 6.48 × 10, and 6.40 × 10 s, respectively. Increasing the chlorine dosage slightly accelerated the degradation of the investigated T&O compounds, but excessive hypochlorous acid and hypochlorite scavenged the HO• radicals and reactive chlorine species (RCS). Generally, HO• primarily contributed to the degradation of all of the investigated T&O compounds as compared to RCS. The degradation by RCS was found to be structurally selective. RCS could not degrade GSM, but contributed to the degradation of MIB, BT, and IBMP. The results confirmed that the proposed oxidation process effectively degraded typical T&O compounds in aqueous phase.
嗅味（T&O）化合物是饮用水处理厂的主要关注点，因为它们会对供水的安全性和可接受性产生负面影响。本研究探讨了四种常见嗅味化合物（土臭素（GSM）、2-甲基异莰醇（MIB）、苯并噻唑（BT）和 2-异丁基-3-甲氧基吡嗪（IBMP））在紫外线/氯（UV/Cl）高级氧化过程中的降解动力学和自由基化学。所有实验均在 700mL 光反应器中进行，该过程在微酸性环境中有效降解了所研究的嗅味化合物。在略微酸性的环境中，T&O 的降解随 pH 值的增加而降低，但随氯剂量的减少而略有增加。当 pH 值从 6 增加到 8 时，GSM、MIB、BT 和 IBMP 的拟一级速率常数从 2.84×10、2.29×10、3.64×10 和 2.76×10 s 分别降至 3.77×10、2.64×10、6.48×10 和 6.40×10 s。增加氯剂量略微加速了所研究的 T&O 化合物的降解，但过量的次氯酸和次氯酸盐会捕获 HO•自由基和活性氯物种（RCS）。一般来说，与 RCS 相比，HO•主要有助于所有所研究的 T&O 化合物的降解。降解通过 RCS 发现是结构选择性的。RCS 不能降解 GSM，但有助于 MIB、BT 和 IBMP 的降解。结果证实，所提出的氧化过程有效地降解了水相中典型的 T&O 化合物。
