School of Mechanical Science and Engineering, Northeast Petroleum University, Daqing, Heilongjiang, 163318, China.
School of Civil Engineering and Architecture, Northeast Petroleum University, Daqing, Heilongjiang, 163318, China.
Environ Res. 2024 Dec 15;263(Pt 1):120020. doi: 10.1016/j.envres.2024.120020. Epub 2024 Sep 16.
The low yield of hydrogen peroxide, narrow pH application range, and secondary pollution due to iron sludge precipitation are the major drawbacks of the electro-Fenton (EF) process. Metal-free electro-Fenton technology based on carbonaceous materials is a promising green pollutant degradation technology. Activated carbon cathodes enriched with carbonyl functional groups were prepared using a two-step annealing method for the degradation of phenol pollutants. The OH in the activation process of HO were identified using the EPR test technique. The action mechanism of carbonyl groups on HO activation was investigated in conjunction with density functional theory (DFT) calculations. The EPR tests demonstrated that the modified activated carbon could promote the in-situ activation of HO to OH. And the results of material analysis and DFT showed that C=O could facilitate the activation of hydrogen peroxide through the electron transfer mechanism as an electron-donating group. Electrochemical tests showed that both the oxygen reduction activity and 2eORR selectivity of the modified activated carbons were significantly improved. Compared with the original activated carbon cathode and EF, the degradation efficiency of phenol in the ACNH-1000/GF cathode was increased by 58.10% and 45.61%, respectively. Compared with EF, ACNH-1000/GF metal-free electro-Fenton effectively expands the pH application range, and is proven to be less affected by solution initial pH, while avoiding secondary pollution. The metal-free electro-Fenton system can save more than a quarter of the cost of EF system. This study has a deep understanding of the reaction mechanism of the carbonyl modified activated carbon, and provides valuable insights for the design of metal-free catalysts, so as to promote its application in the degradation of organic pollutants.
过氧化氢产率低、pH 应用范围窄以及铁污泥沉淀导致的二次污染是电芬顿（EF）过程的主要缺点。基于碳材料的无金属电芬顿技术是一种很有前途的绿色污染物降解技术。采用两步退火法制备了富含羰基官能团的活性炭阴极，用于降解苯酚污染物。使用 EPR 测试技术鉴定了 HO 中的 OH。结合密度泛函理论（DFT）计算，研究了羰基基团对 HO 活化的作用机制。EPR 测试表明，改性活性炭可以促进 HO 的原位活化生成 OH。并且材料分析和 DFT 的结果表明，C=O 可以通过电子转移机制作为供电子基团促进过氧化氢的活化。电化学测试表明，改性活性炭的氧还原活性和 2eORR 选择性均得到显著提高。与原始活性炭阴极和 EF 相比，ACNH-1000/GF 阴极对苯酚的降解效率分别提高了 58.10%和 45.61%。与 EF 相比，ACNH-1000/GF 无金属电芬顿有效地扩展了 pH 应用范围，并且被证明受溶液初始 pH 的影响较小，同时避免了二次污染。无金属电芬顿系统可以节省 EF 系统成本的四分之一以上。本研究深入了解了羰基改性活性炭的反应机制，为无金属催化剂的设计提供了有价值的见解，从而促进了其在有机污染物降解中的应用。
