这项工作的目的是开发一种电化学技术，用于高效降解水环境中的持久性有机污染物。此外，本研究还旨在探索PFOS、PMS和电极之间的电子转移途径，弄清ROSs的产生机制，阐明PFOS吸附和降解的关键反应位点。本文制备了新型D-Ce/Sb
2
O
3
电极以补偿金属离子的浸出缺陷，并采用D-Ce/Sb
2
O
3
电极的EO-PMS工艺有效降解PFOS。使用不同的淬灭反应、ESR捕获方法和ROS定量分析来证明不同ROS的主要贡献。密度泛函理论 (DFT) 计算支持关键活性中心、电极上的 PMS 吸附行为、电子转移以及自由基生成途径。基于不同的支持电解质、循环试验、各种有机物的降解性能和脱氟性能的结果，证实了D-Ce/Sb
2
O
3
电极通过EO-PMS工艺从水环境中去除PFOS的稳定性和可行性。
Fig. 1. (a) The fabrication procedure of the D-Ce/Sb2O3; (b,c) SEM images of the Ce/Sb2O3; (d-f) SEM images of the D-Ce/Sb2O3; (g) The size distribution of particle on the surface of the D-Ce/Sb2O3; EDS mapping images of (h1-6) the D-Ce/Sb2O3 (C, N, O, Sb, Ce, and Si) and (i1-6) the Ce/Sb2O3 (C, N, O, Sb, and Ce).
Fig. 2. Effects of (a) different electrodes on the PFOS degradation and (b) TOC changes; Effects of various (c) current densities on the PFOS degradation and (d) TOC changes. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
Fig. 3. (a) Effects of different current densities on the PFOS degradation and the corresponding (b) TOC changes; (c) Energy consumption conditions in EO process; (d) LSV curves of the D-Ce/Sb2O3 electrode in electrolytes with PMS and without the PMS. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
Fig. 4. Effects of various scavengers on the PFOS degradation: (a) MeOH, (b) TBA, (c) BQ, and (d) FFA; (e) kinetic rates vs. scavenger concentration; (f) degradation performance of the PFOS under different scavengers. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
Fig. 5. (a) the EPR spectra in different conditions and (b) the quantitative concentration of reactive oxygen species. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
Fig. 6. (a) Degradation properties of the PFOS with the addition of various atmosphere and (b) the corresponding TOC changes; Effects of (c) initial pH, (d) anions, (e) cations, and (f) natural organic matter. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
Fig. 7. Optimal configurations and the corresponding difference charge densities of the PMS adsorbed on the (a) Sb2O3, (b) Ce/Sb2O3, and (c) D-Ce/Sb2O3; (d) Bond length and adsorption energy of the PMS adsorbed on various surface configurations; Optimal configurations and the corresponding difference charge densities of the PFOS adsorbed on the (e) Ce/Sb2O3, and (f) D-Ce/Sb2O3.
Fig. 8. (a) The schematic diagram of the PMS adsorption, decomposition, and reactive oxygen species generation on the surface of the D-Ce/Sb2O3; (b) Electron transfer pathways for the PFOS degradation; (c) Proposal mechanism of the PFOS degradation in the EO process with the PMS activation.
Fig. 9. (a) The changes of the PMS concentration during EO process; (b) Effects of different water matrices on the PFOS degradation and (c) the corresponding TOC changes; (d) Degradation properties of various organic pollutants via the EO process and (e) the corresponding TOC changes; (f) Reusability tests and (g) the corresponding TOC changes; (h) The leaching properties of metal ions during the EO process; (i) Mass balance of fluorine element with time. Conditions: current density = 10 mA cm−2; Initial PMS concentration = 5 mM; Initial PFOS concentration = 10 mg L−1; T = 28 °C.
在这项工作中，硅藻土和Ce共修饰的Sb
2
O
3
被合成为电化学中的阳极电极，该电极在PMS活化和PFOS降解方面表现出优异的催化性能。电解和PMS活化的结合可以显着提高PFOS的降解性能，在初始PMS浓度为5 mM、电流密度为10
mA·cm
-2
、动力学速率常数为0.117 min
-1
的条件下，PFOS可在30 min内完全去除。各种自由基清除剂的猝灭实验、自由基定量测试和EPR光谱表明•OH和电子是PFOS高效降解的原因。DFT计算表明，在势能差的驱动下，电子可以从PFOS的HOMO快速转移到PMS的LUMO。该技术稳定性高，离子浸出量小，对各种有机微污染物降解效率高。最后, EO-PMS工艺可用于水环境中持久性有机污染物的净化和修复。
Meng Li, et al., Efficient decomposition of perfluorooctane sulfonate by electrochemical activation of peroxymonosulfate in aqueous solution: Efficacy, reaction mechanism, active sites, and application potential, Water Research, 2022,
https://doi.org/10.1016/j.watres.2022.118778
