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Percarbonate mediated advanced oxidation completely degrades recalcitrant pesticide imidacloprid: Role of reactive oxygen species and transformation products
Separation and Purification Technology ( IF 8.1 ) Pub Date : 2020-06-20 , DOI: 10.1016/j.seppur.2020.117269
Michael M. Sablas , Mark Daniel G. de Luna , Sergi Garcia-Segura , Chiu-Wen Chen , Chih-Feng Chen , Cheng-Di Dong

Pesticides are vital and indispensable especially in agricultural production. However, pesticide contamination is also a serious threat to human health and the environment. Imidacloprid (IMD), an archetypal neonicotinoid insecticide, is commonly used to protect a variety of crops worldwide. This study examined the destruction of IMD contaminant in wastewater via catalytic oxidation with sodium percarbonate (SPC). The process exemplified 100% removal at optimum condition. Rates of reaction were expressed in terms of the apparent rate constants (kapp) and were observed to satisfactorily follow pseudo-first-order kinetics. Inhibitory effects of humic acid and various coexisting ions on IMD degradation were examined and the trend was observed as follows: NO2 > PO43− > NH4+ > Cl > NO3. In addition, we elucidated the participation of OH (hydroxyl), O2 (superoxyl), and HO2 (perhydroxyl) radicals in the process by performing scavenging experiments for these reactive oxygen species. A likely IMD degradation pathway was proposed based on the intermediate species identified via gas chromatography/mass spectroscopy electron ionization procedure. Overall, the present study established SPC as a cleaner alternative to other oxidants for pesticide degradation as it is non-toxic, safe to handle, and produces by-products that inherently exist in the natural water matrix.



中文翻译:

过碳酸盐介导的高级氧化作用完全降解顽固性农药吡虫啉:活性氧和转化产物的作用

农药至关重要,必不可少,特别是在农业生产中。但是,农药污染也是对人类健康和环境的严重威胁。吡虫啉(IMD)是一种典型的新烟碱类杀虫剂,通常用于保护全世界的各种农作物。这项研究检查了过碳酸钠(SPC)催化氧化对废水中IMD污染物的破坏。该工艺例证了在最佳条件下100%去除的效果。反应速率以表观速率常数(k app)表示,并且观察到令人满意地遵循拟一级动力学。检查腐殖酸和IMD降解各种共存离子的抑制效果,观察趋势如下:NO 2 -> PO 4 3- > NH 4 + >氯- > NO 3 - 此外,我们阐明参与OH(羟基),Ô 2 -(superoxyl),和HO 2通过对这些活性氧物种进行清除实验,在过程中获得(全羟基)自由基。基于通过气相色谱/质谱电子电离程序鉴定的中间物质,提出了可能的IMD降解途径。总体而言,本研究确立了SPC作为农药降解过程中其他氧化剂的更清洁替代品,因为它无毒,操作安全并且会产生天然水基质中固有的副产物。

更新日期:2020-06-27
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