College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha 410082, PR China.
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, PR China; Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, PR China.
Water Res. 2023 Mar 1;231:119659. doi: 10.1016/j.watres.2023.119659. Epub 2023 Jan 24.
Residual flotation reagents in mineral processing wastewater can trigger severe ecological threats to the local groundwater if they are discharged without treatment. Metal-free biochar-induced persulfate-advanced oxidation processes (KCBC/PS) were used in this study to elucidate the degradation of aniline aerofloat (AAF) - a typical flotation reagent. In KCBC/PS system, AAF can be removed at low doses of catalyst (KCBC, 0.05 g/L) and oxidant (PS, 0.3 mM) additions with high efficiency. The analysis revealed the dominance of O among the identified reactive oxygen species (ROS), which achieved deeper mineralization for the AAF degradation in the KCBC/PS system. The role of the electron transfer mechanism was equally important; the importance was corroborated by the chemical quenching experiments, electron spin resonance (ESR) detection, probe experiments, and electrochemical analysis. It benefited from the electron transfer mechanism in the KCBC/PS system and exhibited a wide pH adaptation (3.5-11) and high resistance to inorganic anions for real mining wastewater treatment. Combined with theoretical calculations and other analyses, the carbonyl group was deemed to be the active site of the non-radical pathway of biochar, while the site of the conversion of SO to superoxide radicals by biochar activation represented a defect. These findings revealed a synergistic effect of multiple active sites on PS activation in biochar-based materials. Moreover, the intermediate degradation products of AAF from mass spectrometry indicated a possible pathway through the density functional theory (DFT) method, which was effective in reducing the environmental toxicity of pollutants for the first time according to the T.E.S.T software and seed germination experiments. Overall, our study proposed a novel modification strategy for cost-effective and environmentally friendly biochar-based catalysts, while also deepening our understanding of the mechanism of activation of persulfate by metal-free carbon-based materials.
如果未经处理就排放，选矿废水中残留的浮选药剂会对当地地下水造成严重的生态威胁。本研究采用无金属生物炭诱导过硫酸盐高级氧化工艺（KCBC/PS）来阐明一种典型浮选药剂——苯胺浮选剂（AAF）的降解过程。在 KCBC/PS 体系中，催化剂（KCBC，0.05 g/L）和氧化剂（PS，0.3 mM）的低剂量添加即可实现 AAF 的高效去除。分析表明，在 KCBC/PS 体系中，活性氧物种（ROS）中以 O 为主，这使得 AAF 降解的深度矿化程度更高。电子转移机制同样重要；通过化学猝灭实验、电子顺磁共振（ESR）检测、探针实验和电化学分析得到了验证。该体系得益于电子转移机制，在实际选矿废水处理中表现出较宽的 pH 适应范围（3.5-11）和对无机阴离子的高抗性。结合理论计算和其他分析，认为生物炭的非自由基途径的活性位点是羰基，而生物炭活化将 SO 转化为超氧自由基的位点则代表一个缺陷。这些发现揭示了生物炭基材料中多个活性位点对 PS 活化的协同作用。此外，通过质谱对 AAF 的中间降解产物进行分析，表明了一条可能的通过密度泛函理论（DFT）方法的途径，根据 T.E.S.T 软件和种子发芽实验，该方法首次有效地降低了污染物的环境毒性。总的来说，本研究提出了一种用于成本效益高和环境友好的生物炭基催化剂的新型改性策略，同时也加深了我们对无金属碳基材料活化过硫酸盐机制的理解。
