Yichang Atmospheric Pollution Prevention and Control Administrative Center, Yichang 435000, China.
Department of Environmental Science, School of Resources and Environmental Science, Wuhan University, Wuhan 430079, China.
Molecules. 2022 Mar 30;27(7):2248. doi: 10.3390/molecules27072248.
The Fe(III)-S(IV) system used for advanced oxidation processes (AOPs) at acidic pH has just been proposed and demonstrated valid for very few contaminants in the last several years. In this work, we investigated the effect of ultraviolet A (UVA) radiation on the degradation efficiency of the Fe(III)/S(IV) system at near-neutral pH. Paracetamol (PARA) was selected as a model contaminant. The influencing factors, such as initial pH and Fe(III)/S(IV) molar ratio on chemical kinetics, and the mechanism of PARA degradation are investigated, with an emphasis on the determination of dominant oxidant species. Our results show that irradiation enhances the PARA degradation by accelerating the decrease of pH to acidic levels, and the optimal pH for the degradation of PARA in the Fe(III)/S(IV)/O system was around 4.0. At near-neutral pH, more than 60% of PARA was decomposed within 40 min under irradiation, whereas no significant degradation of PARA was observed using Fe(III)/S(IV) at pH 7.0 without irradiation. Mechanism investigation revealed that sulfate radical (SO) is the main oxidant species generated and responsible for the PARA degradation under these conditions. This finding may have promising implications in developing a new degradation process for dealing with wastewater at near-neutral pH by the Fe(III)/S(IV)/O system under UVA irradiation.
Fe(III)-S(IV) 体系在酸性 pH 下用于高级氧化工艺 (AOPs) 仅在过去几年中被提出并证明对少数污染物有效。在这项工作中，我们研究了近中性 pH 下 UVA 辐射对 Fe(III)/S(IV)体系降解效率的影响。选择扑热息痛 (PARA) 作为模型污染物。研究了初始 pH 值和 Fe(III)/S(IV)摩尔比对化学动力学的影响，以及 PARA 降解的机制，重点是确定主要氧化剂种类。我们的结果表明，辐照通过加速 pH 值降低到酸性水平来增强 PARA 的降解，Fe(III)/S(IV)/O 体系中 PARA 降解的最佳 pH 值约为 4.0。在近中性 pH 值下，在辐照下，PARA 在 40 分钟内分解超过 60%，而在 pH 值为 7.0 且没有辐照的情况下，Fe(III)/S(IV) 对 PARA 没有明显的降解。机理研究表明，在这些条件下，硫酸根自由基 (SO) 是主要的氧化剂种类，负责 PARA 的降解。这一发现可能对开发一种新的降解工艺具有重要意义，即在 UVA 辐照下，通过 Fe(III)/S(IV)/O 体系在近中性 pH 值下处理废水。
