Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
Laboratório de Eletroquímica Ambiental e Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Norte, Lagoa Nova, Natal, RN, 59072-900, Brazil.
Environ Sci Pollut Res Int. 2021 May;28(19):23833-23848. doi: 10.1007/s11356-020-11421-8. Epub 2020 Nov 11.
One of the main challenges of electrochemical Fenton-based processes is the treatment of organic pollutants at near-neutral pH. As a potential approach to this problem, this work addresses the use of a low content of soluble chelated metal catalyst, formed between Fe(III) and ethylenediamine-N,N'-disuccinic (EDDS) acid (1:1), to degrade the herbicide triclopyr in 0.050 M NaSO solutions at pH 7.0 by photoelectro-Fenton with UVA light or sunlight (PEF and SPEF, respectively). Comparison with electro-Fenton treatments revealed the crucial role of the photo-Fenton-like reaction, since this promoted the production of soluble Fe(II) that enhanced the pesticide removal. Hydroxyl radicals formed at the anode surface and in the bulk were the main oxidants. A boron-doped diamond (BDD) anode yielded a greater mineralization than an IrO-based one, at the expense of reduced cost-effectiveness. The effect of catalyst concentration and current density on the performance of PEF with BDD was examined. The PEF trials in 0.25 mM NaSO + 0.35 mM NaCl medium showed a large influence of generated active chlorine as oxidant, being IrO more suitable than RuO and BDD. In SPEF with BDD, the higher light intensity from solar photons accelerated the removal of the catalyst and triclopyr, with small effect on mineralization. A plausible route for the herbicide degradation by Fe(III)-EDDS-catalyzed PEF and SPEF is finally proposed based on detected byproducts: three heteroaromatic and four linear N-aliphatic compounds, formamide, and tartronic and oxamic acids.
电化学芬顿法的主要挑战之一是在近中性 pH 条件下处理有机污染物。作为解决该问题的一种潜在方法，本工作采用低含量的可溶性螯合金属催化剂，即三价铁（Fe(III)）与乙二胺-N,N'-二琥珀酸（EDDS）酸（1:1）形成的催化剂，在 pH 7.0 的 0.050 M NaSO 溶液中，通过光电芬顿法（UVA 光，PEF）或阳光（SPEF）处理降解除草剂三氯吡。与电芬顿处理相比，该研究揭示了类芬顿光反应的关键作用，因为它促进了可溶性 Fe(II)的生成，从而增强了农药的去除。在阳极表面和本体中形成的羟基自由基是主要的氧化剂。与基于 IrO 的阳极相比，掺硼金刚石（BDD）阳极的矿化程度更高，但成本效益降低。考察了催化剂浓度和电流密度对 BDD 光电芬顿性能的影响。在 0.25 mM NaSO + 0.35 mM NaCl 介质中进行的 PEF 试验表明，作为氧化剂的活性氯的生成具有很大的影响，IrO 比 RuO 和 BDD 更适合。在 BDD 光电芬顿法（SPEF）中，太阳光子产生的更高光强度加速了催化剂和三氯吡的去除，对矿化的影响较小。最后，根据检测到的副产物，提出了 Fe(III)-EDDS 催化的光电芬顿和阳光芬顿降解除草剂的可能途径：三种杂芳族和四种直链 N-脂肪族化合物、甲酰胺、酒石酸和氨基乙二酸。
