School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, People's Republic of China.
School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, People's Republic of China; Faculty of Biotechnology and Health, Wuyi University, Jiangmen 529020, People's Republic of China.
Sci Total Environ. 2020 Dec 20;749:142106. doi: 10.1016/j.scitotenv.2020.142106. Epub 2020 Sep 1.
Photochemical methods attracted much research interests for their high-efficiency and low secondary pollution. Decomposition of synthetic pyrethroids, the fourth major group of insecticides in use worldwide, was also of great significance due to their possible environmental risks. The photodegradation of deltamethrin, permethrin and dihaloacetylated heterocyclic pyrethroids in methanol/acetone = 9/1 (by volume) by a 400 W mercury lamp was examined. The t of tested pyrethroids was less than 25 min, except for cis-permethrin with a t of up to 50 min. The trans-isomer of permethrin and compound DCA-01 with a smaller t might be more susceptible to degradation than their cis-isomer. Besides, the photodegradation of pyrethroids was divided into twelve pathways including isomerization, ester hydrolysis, ester bond cleavage, CO bond cleavage, 3,3-dimethylacrylate formation, double bond break, C1-C3 bond cleavage in cyclopropyl, reductive dehalogenation, decarboxylation, nucleophilic reagents attack on lone pair electrons on oxygen atoms in the phenyl ether, cyano hydrolysis, and halogenated hydrocarbon hydrolysis. The ECOSAR program displayed that pyrethroids and most of their photodegradation products were toxic to fish, daphnid, green algae. Particularly, some photodegradation products were more harmful to aquatic organisms than their parents.
光化学方法因其高效和低二次污染而引起了广泛的研究兴趣。由于其可能存在环境风险，因此对合成拟除虫菊酯（世界上使用的第四大杀虫剂）的分解也具有重要意义。在 400W 汞灯下，用甲醇/丙酮（体积比为 9/1）研究了除虫菊酯、氯菊酯和二卤乙酰基杂环拟除虫菊酯的光降解。除顺式氯菊酯的 t 达到 50 分钟外，测试的拟除虫菊酯的 t 都小于 25 分钟。顺式异构体和较小 t 的化合物 DCA-01 的反式异构体可能更容易降解。此外，拟除虫菊酯的光降解分为 12 种途径，包括异构化、酯水解、酯键断裂、CO 键断裂、3,3-二甲基丙烯酸酯形成、双键断裂、环丙基中 C1-C3 键断裂、还原脱卤、脱羧、亲核试剂对苯醚中氧原子上孤对电子的攻击、氰基水解和卤代烃水解。ECOSAR 程序显示，拟除虫菊酯及其大部分光降解产物对鱼类、水蚤和绿藻有毒。特别是，一些光降解产物对水生生物的危害比其母体更大。
