College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
Sci Total Environ. 2019 May 1;663:453-464. doi: 10.1016/j.scitotenv.2019.01.190. Epub 2019 Jan 16.
On account of high oxidation ability of sulfate radical-based advanced oxidation processes (AOPs), the eco-friendly catalysts for peroxymonosulfate (PMS) activation have received considerable attentions. Previous studies mainly focused on Cobalt-based catalyst due to its high activation efficiency, such as CoO/MnO and FeCo-layered double hydroxide (LDH), whereas Cobalt-based catalyst usually has serious risk to environment. To avoid this risk, MnFe-LDH was primarily synthesized in this research by simple co-precipitation and subsequently utilized as an effective catalyst for peroxymonosulfate (PMS) activation to degrade organic pollutants. The experimental results demonstrated that MnFe-LDH with a lower dosage (0.20 g/L) could efficiently activate PMS to achieve 97.56% removal of target organic pollutants Acid Orange 7 (AO7). The AO7 degradation process followed the pseudo-first-order kinetic well with an activation energy of 21.32 kJ/mol. The intrinsic influencing mechanism was also investigated. The quenching experiment and electron spin resonance (ESR) indicated that sulfate and hydroxyl radicals were produced by the effective activation of PMS by MnFe-LDH, resulting in a high rate of decolorization. The possible AO7 removal pathway in the constructed MnFe-LDH/PMS system was presented on the basis of UV-vis spectrum analysis and GC-MS, which suggested that the AO7 degradation was firstly initiated by breaking azo linkages, then generated phenyl and naphthalene intermediates and finally presented as ring-opening products. This effective MnFe-LDH/PMS system showed great application potential in the purification of wastewater contaminated by refractory organic pollutants.
由于硫酸根自由基基高级氧化工艺（AOPs）具有高氧化能力，因此用于过一硫酸盐（PMS）活化的环保型催化剂受到了相当多的关注。先前的研究主要集中在钴基催化剂上，因为其具有较高的活化效率，例如 CoO/MnO 和 FeCo 层状双氢氧化物（LDH），但是钴基催化剂通常对环境有严重的风险。为了避免这种风险，本研究主要通过简单的共沉淀法合成了 MnFe-LDH，并将其用作过一硫酸盐（PMS）活化的有效催化剂来降解有机污染物。实验结果表明，MnFe-LDH 的用量较低（0.20 g/L）时，可以有效地活化 PMS，使目标有机污染物酸性橙 7（AO7）的去除率达到 97.56%。AO7 的降解过程符合准一级动力学，其活化能为 21.32 kJ/mol。还研究了内在的影响机制。淬灭实验和电子自旋共振（ESR）表明，MnFe-LDH 有效活化 PMS 产生了硫酸根和羟基自由基，从而导致高脱色率。根据紫外可见光谱分析和 GC-MS，提出了在构建的 MnFe-LDH/PMS 体系中可能的 AO7 去除途径，表明 AO7 的降解首先是通过打破偶氮键开始的，然后生成苯和萘中间体，最后呈现出开环产物。这种有效的 MnFe-LDH/PMS 体系在净化含有难降解有机污染物的废水方面显示出巨大的应用潜力。
