School of Chemical Science and Engineering, Shanghai Key Lab of Chemical Assessment and Sustainability, Key Laboratory of Yangtze River Water Environment, Tongji University, Siping Road 1239, Shanghai 200092, P. R. China.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092, P. R. China.
Environ Sci Technol. 2021 May 4;55(9):6042-6051. doi: 10.1021/acs.est.0c08018. Epub 2021 Feb 22.
The regeneration rate of Fe from Fe dictates the performance of the electro-Fenton (EF) process, represented by the amount of produced hydroxyl radicals (·OH). Current strategies for the acceleration of Fe regeneration normally require additional chemical reagents, to vary the redox potential of Fe/Fe. Here, we report an attempt at using the intrinsic property of the electrode to our advantage, i.e., nitrogen-doped carbon aerogel (NDCA), as a reducing agent for the regeneration of Fe without using foreign reagents. Moreover, the pyrrolic N in NDCA provides unpaired electrons through the carbon framework to reduce Fe, while the graphitic and pyridinic N coordinate with Fe to form a C-O-Fe-N bond, facilitating electron transfer from both the external circuit and pyrrolic N to Fe. Our Fe/NDCA-EF system exhibits a 5.8 ± 0.3 times higher performance, in terms of the amount of generated ·OH, than a traditional Fenton system using the same Fe concentration. In the subsequent reaction, the Fe/NDCA-EF system demonstrates 100.0% removal of dimethyl phthalate, 3-chlorophenol, bisphenol A, and sulfamethoxazole with a low specific energy consumption of 0.17-0.36 kW·h·g. Furthermore, 90.1 ± 0.6% removal of dissolved organic carbon and 83.3 ± 0.9% removal of NH-N are achieved in the treatment of domestic sewage. The purpose of this work is to present a novel strategy for the regeneration of Fe in the EF process and also to elucidate the role of different N species of the carbonaceous electrode in contributing to the redox cycle of Fe/Fe.
从 Fe 到 Fe 的再生速率决定了电芬顿（EF）过程的性能，这表现为产生的羟基自由基（·OH）的数量。目前加速 Fe 再生的策略通常需要额外的化学试剂，以改变 Fe/Fe 的氧化还原电位。在这里，我们报告了尝试利用电极的固有特性来发挥优势，即氮掺杂碳气凝胶（NDCA）作为一种还原剂，无需使用外来试剂即可再生 Fe。此外，NDCA 中的吡咯 N 通过碳骨架提供未配对电子来还原 Fe，而石墨和吡啶 N 与 Fe 配位形成 C-O-Fe-N 键，促进来自外部电路和吡咯 N 的电子转移到 Fe。我们的 Fe/NDCA-EF 系统在生成·OH 的量方面表现出 5.8±0.3 倍的性能提升，优于使用相同 Fe 浓度的传统芬顿系统。在随后的反应中，Fe/NDCA-EF 系统以 0.17-0.36 kW·h·g 的低比能消耗实现了对邻苯二甲酸二甲酯、3-氯苯酚、双酚 A 和磺胺甲恶唑的 100.0%去除率。此外，在处理生活污水时，溶解有机碳的去除率为 90.1±0.6%，NH-N 的去除率为 83.3±0.9%。本工作的目的是提出一种在 EF 过程中再生 Fe 的新策略，并阐明碳电极中不同 N 物种在促进 Fe/Fe 氧化还原循环中的作用。
