State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu, 610065, China; Sino-German Centre for Water and Health Research, Sichuan University, Chengdu, 610065, China.
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu, 610065, China.
Water Res. 2022 Jun 30;218:118412. doi: 10.1016/j.watres.2022.118412. Epub 2022 Apr 6.
Reduction of Fe(III) is the rate-limiting step of iron induced Fenton-like systems, such as the iron/peroxydisulfate system, reducing agents (RAs) were frequently employed as electron donors to directly reduce Fe(III) to further promote the formation of reactive oxygen species (ROS), mainly including hydroxyl radical (OH), sulfate radical (SO), and ferryl ion (Fe(IV)). However, the intrinsic distinctions among these ROS cause the substrate specific reactivity towards oxidation of diverse organic contaminants. In this study, various RAs (representative solid amorphous boron (A-Boron) and dissolved hydroxylamine (HA)) were added to enhance the Fe(III)/PDS system for investigating the substrate specific reactivity of ROS. It is demonstrated that RAs remarkably boost the Fe(III)/Fe(II) cycles to produce OH, SO, and Fe(IV) in the RAs/Fe(III)/PDS systems, based on the results of EPR analysis, quenching tests, and chemical probe analysis. Furthermore, the different yields of methyl phenyl sulfone (PMSO) indicate that the distribution of multiple oxidizing species changed with various factors (i.e., type and dosage of RAs added, solution pH, Fe(III) and PDS dosage). This work provides the possibility for the adjustment of oxidation selectivity of RAs/Fe(III)/PDS systems by regulating contribution of radicals and non-radical for oxidizing organic contaminants due to the substrate specific reactivity of OH, SO, and Fe(IV), moreover, the comparison of homogeneous and heterogeneous RAs provides assistance in the application of RAs for environmental remediation.
三价铁的还原是铁诱导类芬顿体系（如铁/过二硫酸盐体系）的限速步骤，还原剂（RAs）通常被用作电子供体，直接将三价铁还原，以进一步促进活性氧物质（ROS）的形成，主要包括羟基自由基（OH）、硫酸根自由基（SO）和高铁离子（Fe（IV））。然而，这些 ROS 的内在区别导致它们对不同有机污染物氧化的底物特异性反应性。在这项研究中，添加了各种 RAs（代表性的固体无定形硼（A-Boron）和溶解的羟胺（HA））来增强 Fe（III）/PDS 体系，以研究 ROS 的底物特异性反应性。结果表明，RAs 显著促进了 Fe（III）/Fe（II）循环，在 RAs/Fe（III）/PDS 体系中产生 OH、SO 和 Fe（IV），这是基于 EPR 分析、猝灭试验和化学探针分析的结果。此外，不同的甲基苯基亚砜（PMSO）产率表明，多种氧化物种的分布随各种因素（即添加的 RAs 的类型和剂量、溶液 pH 值、Fe（III）和 PDS 剂量）而变化。这项工作通过调节自由基和非自由基对有机污染物氧化的贡献，为调整 RAs/Fe（III）/PDS 体系的氧化选择性提供了可能性，这是由于 OH、SO 和 Fe（IV）的底物特异性反应性所致，此外，对均相和非均相 RAs 的比较为 RAs 在环境修复中的应用提供了帮助。
