Department of Chemical Engineering, Bharati Vidyapeeth (Deemed to be University) College of Engineering, Dhankawadi, Pune 411043, India.
Department of Chemical Engineering, Bharati Vidyapeeth (Deemed to be University) College of Engineering, Dhankawadi, Pune 411043, India.
Ultrason Sonochem. 2021 Jan;70:105310. doi: 10.1016/j.ultsonch.2020.105310. Epub 2020 Aug 14.
The present study has investigated the degradation of thiamethoxam using ultrasound cavitation (US) operated at a frequency of 20 kHz and its combination with intensifying additives viz. hydrogen peroxide, Fenton and photo-Fenton reagent. At the outset, the performance of US (20 kHz) has been maximised by the optimization of process parameters. Highest rate of degradation of thiamethoxam was observed at the optimum ultrasonic power density of 0.22 W/mL, thiamethoxam concentration of 10 ppm and the pH of 2. The established optimum values of operating parameters were used further in case of combined treatment approaches. The effect of concentration of HO on the rate of degradation of thiamethoxam in the case of US + HO process has confirmed the existence of optimum concentration of HO with the ratio of thiamethoxam: HO as 1:10. US + Fenton process indicated the optimal molar ratio of FeSO·7HO:HO as 1:15. The combined processes of US + HO US + Fenton and US + photo-Fenton have resulted in the extent of degradation of 20.47 ± 0.61%, 34.41 ± 1.03% and 85.17 ± 2.56% respectively after 45 min. of operation. These combined processes lead to the synergistic index of 2.04 ± 0.06, 2.26 ± 0.07 and 2.42 ± 0.07 in case of US + HO, US + Fenton and US + photo-Fenton processes respectively over only US/stirring treatment with the additive. Additionally, the extent of mineralization and the energy efficiency of individual and combined processes have been compared. US + photo-Fenton process has been found to be the best strategy for effective degradation of thiamethoxam with a significant intensification benefit. The by-products formed during the ultrasonic degradation of thiamethoxam have been identified by using LC-MS/MS analysis.
本研究考察了超声空化（US）在 20 kHz 频率下对噻虫嗪的降解及其与强化添加剂（如过氧化氢、芬顿和光芬顿试剂）的组合作用。首先，通过优化工艺参数来最大化 US（20 kHz）的性能。在最佳超声功率密度为 0.22 W/mL、噻虫嗪浓度为 10 ppm 和 pH 值为 2 的条件下，观察到噻虫嗪的最高降解速率。在联合处理方法中，进一步使用已建立的最佳操作参数值。在 US+HO 工艺中，HO 浓度对噻虫嗪降解速率的影响证实了 HO 的最佳浓度的存在，噻虫嗪与 HO 的比例为 1:10。US+Fenton 工艺表明，FeSO·7HO:HO 的最佳摩尔比为 1:15。US+HO、US+Fenton 和 US+photo-Fenton 的联合工艺在 45 分钟后分别导致 20.47±0.61%、34.41±1.03%和 85.17±2.56%的降解程度。这些联合工艺导致 US+HO、US+Fenton 和 US+photo-Fenton 工艺的协同指数分别为 2.04±0.06、2.26±0.07 和 2.42±0.07，而仅 US/搅拌处理与添加剂相比。此外，还比较了各工艺及联合工艺的矿化程度和能量效率。发现 US+photo-Fenton 工艺是有效降解噻虫嗪的最佳策略，具有显著的强化效益。噻虫嗪超声降解过程中形成的副产物通过 LC-MS/MS 分析进行了鉴定。
