In-situ electrochemical upcycling ammonia from wastewater-level nitrate with a natural hematite electrode: Regulation, performance, and application

Electrochemical reduction of nitrate (NO3-RR) to ammonia (NH4+/NH3) offers promising prospects for NO3- treatment. However, this process still suffers from NH4+ causing secondary pollution and catalyst deactivation in high-concentration NO3- wastewater. Herein, a high-performance system comprising a...

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Veröffentlicht in:Applied catalysis. B, Environmental Environmental, 2024-12, Vol.359, p.124467, Article 124467
Hauptverfasser: Wu, Xing, Song, Zhenhui, Liu, Zhigong, Tang, Xi, Yao, Fubing, Zhao, Feiping, Min, Xiaobo, Tang, Chong-Jian
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Sprache:eng
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Zusammenfassung:Electrochemical reduction of nitrate (NO3-RR) to ammonia (NH4+/NH3) offers promising prospects for NO3- treatment. However, this process still suffers from NH4+ causing secondary pollution and catalyst deactivation in high-concentration NO3- wastewater. Herein, a high-performance system comprising a hematite (α-Fe2O3) electrode and a water-resistant membrane achieved 97.6 % NO3- removal and 81.6 % NH4+ as (NH4)2SO4in situ recovery at wastewater-level NO3-. The system exhibited an energy consumption of 62.2 kWh·KgNH3−1 and a Faradaic efficiency of 85.9 %. In-situ spectroscopy and electrochemical measurements revealed that α-Fe2O3 acted as both an electron transfer mediator for reducing NO3- to NO2- and an active center for NH3 formation via NO2-/Fe(Ⅱ) redox. Density functional theory calculations identified *HNO3 to *NO2 as potential-determining step of NO3-RR. Natural hematite-based system exhibited 74.8 % total inorganic nitrogen removal and 77.1 % NH4+ recovery for actual photovoltaic wastewater. This study provides insights into the development of electrochemical systems for resourcefully treating NO3--containing wastewater. [Display omitted] •The electrochemical reduction of NO3- to NH4+ and in situ upcycling system was constructed by natural hematite.•The system achieved 97.6 % NO3- removal and 81.6 % NH4+ recovery from wastewater-level NO3-.•The NH4+ selectivity production was realized via coupling electron transfer and NO2-/Fe2+ redox.•83.1 % total inorganic nitrogen removal and 80 % NH4+ recovery was achieved for real photovoltaic wastewater.
ISSN:0926-3373
DOI:10.1016/j.apcatb.2024.124467