Department of Ecohydrology and Biogeochemistry, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587 Berlin, Germany; Department of Geosciences, Environmental Mineralogy and Chemistry, Eberhard Karls University of Tübingen, Schnarrenbergstr. 94-96, 72076 Tübingen, Germany.
Department of Ecohydrology and Biogeochemistry, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587 Berlin, Germany; Department of Geosciences, Environmental Mineralogy and Chemistry, Eberhard Karls University of Tübingen, Schnarrenbergstr. 94-96, 72076 Tübingen, Germany.
Water Res. 2024 Nov 1;265:122267. doi: 10.1016/j.watres.2024.122267. Epub 2024 Aug 13.
Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal.
芬顿样过程使用过硫酸盐进行氧化水处理和污染物去除，可以通过添加氧化还原活性生物炭来增强，这加速了 Fe(III)还原为 Fe(II)，并增加了与有机污染物反应的反应性物质的产量。然而，关于生物炭/Fe(III)/过硫酸盐系统中形成非自由基或自由基物种的现有数据不一致，这限制了对处理效率和在不同水基质中适用性的评估。基于竞争动力学计算，我们使用不同的清除剂和探针化合物来系统地评估在有机物存在下氯对生物炭/Fe(III)/过硫酸盐系统中主要反应性物质形成的影响，以研究模型化合物 N,N-二乙基-间甲苯甲酰胺 (DEET)在 pH 2.5 下的转化。我们表明，先前认为，将甲基苯基亚砜 (PMSO) 转化为甲基苯磺酸 (PMSO) 不能作为 Fe(IV)的可靠指标，因为硫酸根自由基也会诱导 PMSO 的形成。尽管不能完全排除 Fe(IV)的形成，但在纯水中，已鉴定出生物炭/Fe(III)/过硫酸盐系统中的主要反应性物质是硫酸根自由基。在溶解有机物存在下，低浓度的氯离子 (0.1 mM) 可能将主要的反应性物质转变为羟基自由基。在采矿影响的酸性地表水存在的高浓度氯离子 (1 mM) 导致形成另一种反应性物质，可能是 Cl，并有效地降解 DEET。为了调整该氧化过程的应用，必须将水基质视为形成反应性物质和去除污染物的决定性因素。
