Gao Jianan, Ma Qingquan, Wang Zhiwei, Rittmann Bruce E, Zhang Wen
Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, US.
State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, Tongji Advanced Membrane Technology Center, School of Environmental Science and Engineering, Tongji University, Shanghai, China.
Nat Commun. 2024 Sep 30;15(1):8455. doi: 10.1038/s41467-024-52830-4.
Electrosynthesis, a viable path to decarbonize the chemical industry, has been harnessed to generate valuable chemicals under ambient conditions. Here, we present a membrane-free flow electrolyzer for paired electrocatalytic upcycling of nitrate (NO) and chloride (Cl) to ammonia (NH) and chlorine (Cl) gases by utilizing waste streams as substitutes for traditional electrolytes. The electrolyzer concurrently couples electrosynthesis and gaseous-product separation, which minimizes the undesired redox reaction between NH and Cl and thus prevents products loss. Using a three-stacked-modules electrolyzer system, we efficiently processed a reverse osmosis retentate waste stream. This yielded high concentrations of (NH)SO (83.8 mM) and NaClO (243.4 mM) at an electrical cost of 7.1 kWh per kilogram of solid products, while residual NH/NH (0.3 mM), NO (0.2 mM), and Cl/HClO/ClO (0.1 mM) pollutants in the waste stream could meet the wastewater discharge regulations for nitrogen- and chlorine-species. This study underscores the value of pairing appropriate half-reactions, utilizing waste streams to replace traditional electrolytes, and merging product synthesis with separation to refine electrosynthesis platforms.
电合成是化学工业脱碳的一条可行途径，已被用于在环境条件下生成有价值的化学品。在此，我们展示了一种无膜流动电解槽，通过利用废物流替代传统电解质，将硝酸盐（NO）和氯化物（Cl）成对电催化升级循环为氨（NH）和氯气（Cl）。该电解槽同时将电合成和气态产物分离结合在一起，最大限度地减少了NH和Cl之间不希望发生的氧化还原反应，从而防止了产物损失。使用一个三层模块电解槽系统，我们有效地处理了反渗透浓缩液废物流。这产生了高浓度的（NH）SO（83.8 mM）和NaClO（243.4 mM），每千克固体产物的电耗为7.1千瓦时，而废物流中残留的NH/NH（0.3 mM）、NO（0.2 mM）和Cl/HClO/ClO（0.1 mM）污染物可符合氮和氯物种的废水排放规定。这项研究强调了配对合适的半反应、利用废物流替代传统电解质以及将产物合成与分离相结合以优化电合成平台的价值。
