铁基亚硫酸盐(S(IV))活化已成为产生硫酸盐自由基(SO4·-)以降解污染物的新策略。然而,许多研究集中在溶解的铁诱导的均相活化过程,而结构Fe(III)的潜力尚不清楚。在这项研究中,五种铁(氢)氧化物土壤矿物(FeOx),包括水铁矿,schwertmannite,鳞茎岩,针铁矿和赤铁矿,已成功用作S(IV)活化的结构Fe(III)的来源。结果表明,Fe(III)结构的催化活性主要取决于FeOx的结晶度,而不是它们的比表面积和粒径,其中水铁矿和schwertmannite是最活跃的。此外,原位ATR-FTIR光谱和2D-COS分析表明,HSO3-最初通过单齿内球络合吸附在FeOx的FeO6八面体上,最终氧化为SO42-,然后通过外球络合重新吸附。在这个过程中,形成了强氧化性的SO4·-和·OH,用于降解污染物,通过自由基猝灭实验和电子自旋共振证实。此外,FeOx/S(IV)系统在回收测试方面表现出优越的适用性,真实水域和二十六种污染物降解。最终,提出了三种典型污染物的合理降解途径。这项研究强调了含Fe(III)的结构性土壤矿物在废水处理中用于S(IV)活化的可行性。
Iron-based sulfite (S(IV)) activation has emerged as a novel strategy to generate sulfate radicals (SO4•-) for contaminants degradation. However, numerous studies focused on dissolved iron-induced homogeneous activation processes while the potential of structural Fe(III) remains unclear. In this study, five iron (hydr)oxide soil minerals (FeOx) including ferrihydrite, schwertmannite, lepidocrocite, goethite and hematite, were successfully employed as sources of structural Fe(III) for S(IV) activation. Results showed that the catalytical ability of structural Fe(III) primarily depended on the crystallinity of FeOx instead of their specific surface area and particle size, with ferrihydrite and schwertmannite being the most active. Furthermore, in-situ ATR-FTIR spectroscopy and 2D-COS analysis revealed that HSO3- was initially adsorbed on FeO6 octahedrons of FeOx via monodentate inner-sphere complexation, ultimately oxidized into SO42- which was then re-adsorbed via outer-sphere complexation. During this process, strong oxidizing SO4•- and •OH were formed for pollutants degradation, confirmed by radical quenching experiments and electron spin resonance. Moreover, FeOx/S(IV) system exhibited superior applicability with respect to recycling test, real waters and twenty-six pollutants degradation. Eventually, plausible degradation pathways of three typical pollutants were proposed. This study highlights the feasibility of structural Fe(III)-containing soil minerals for S(IV) activation in wastewater treatment.