|Alternative Title||Toxicity directed transformation characteristics of UV-filter Benzophenone-4 in chloramination (photo-induction) disinfection process|
|Place of Conferral||北京|
|Keyword||Bp-4,氯胺消毒,氯胺-光联处理,转化机理,急性毒性 Bp-4, Chloramination, Uv-induced Chloramination, Transformation Mechanism, Acute Toxicity|
The 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4) is the most widely used UV filter all over the world. It has been frequently found in natural environment and living organisms. The potential environmental and health risk should not be neglected. Disinfection is an essential unit in water treatment process. Chlorine is the most commonly used disinfectant at present due to its low cost, high efficiency, and convinent operation. In order to eliminate the formation of trihalomethanes, haloroacetic acids and other disinfection by-products, chloramination, UV and some other new disinfection tecniques have been applied as surrogate disinfection methods. However, the transformation characteristics and toxicity varirtion trend of BP-4 during chloramination and UV treatment are not clear. Therefore, this study selected BP-4 as target, the transformation characteristics of BP-4 and the change of the acute toxicity during chloramination (post-UV) were explored. The influence of pH values, dosages of chloramine, and coexistence of bromide or iodide ions, were respectively investigated as well. The main conclusions were as below:
(1) The transformation characteristics and toxicity variation of BP-4 during chloramination treatment were studied. With the help of high performance liquid chromatography-high resolution mass spectrometry, 23 major products were identified. among them, 19 products contained N elements and 9 contained Cl elements, 8 pairs of isomers were found. Based on the organic chemistry reaction principles and isotope labeling experiments, the transformation pathways of BP-4 chloramination were proposed. It was found that, with the increase of pH, the degradation degree and rate of BP-4 increased, and the toxicity increased gradually. With the increasing dosages of chloramine, the degree and rate of BP-4 degradation increased, while the toxicity first increased and then decreased, with the toxicity peak appeared at the dosage of 5 molar equivalent to BP-4. It was speculated that two quinones P13 and P13' were possible toxic products by analyzing the correlation between the products relative content and toxicity. In the presence of bromide and iodide ions, 4 bromine-containing products and 5 iodine-containing products were produced.
(2) The transformation characteristics and toxicity variation of BP-4 during chloramination-UV were studied. It was found that BP-4 could not be degraded by UV irradiation, while the intermediates of BP-4 formed in chloramination could be converted rapidly under UV irradiation. Ten products have been identified in chloramination-UV treatment system. As for the reaction solution of BP-4 and chloramine, further UV irradiation would lead to a rapid increase in toxicity. With the increase of pH and doasage of chloramine, the acute toxicity increased gradually. It was speculated that P2 and P5 were the main toxic products by correlation analysis between the relative content and toxicity. In the presence of bromide and iodide ions, the toxicity and the rate of toxicity increasing trend were reduced.
|杨帆. 毒性效应引导的二苯甲酮类紫外防晒剂BP-4氯胺-紫外转化机制研究[D]. 北京. 中国科学院生态环境研究中心,2018.|
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