Upcycling wastewater nitrate into ammonia fertilizer via concurrent electrocatalysis and membrane extraction
Upcycling wastewater nitrate into ammonia fertilizer via concurrent electrocatalysis and membrane extraction
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DOI：
10.1016/j.cej.2022.140959
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发表时间：
2022-12
影响因子：
15.1
通讯作者：
Ning Shi;Jianan Gao;Kai Li;Yifan Li;Wen Zhang;Qipeng Yang;Bo Jiang
中科院分区：
文献类型：
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作者：
Ning Shi;Jianan Gao;Kai Li;Yifan Li;Wen Zhang;Qipeng Yang;Bo Jiang
电催化将废水中的硝酸盐(NO3-−)转化为有价值的氨基肥料，已被认为是一种替代生物脱氮或工业氨生产工艺的绿色、有吸引力的替代方法。本文研究了一种新颖高效的电解槽，该电解槽由多孔活性铁镍(FeNi)合金阴极和中空纤维膜萃取单元组成，实现了NO3-−的电化学还原和同时循环为硫酸铵盐((NH4)2SO4)。阴极和阳极的电化学半反应耦合，使NO3-−还原为氨和原位酸碱产物，从而促进NH3的膜剥离。结果表明，在阴极电流密度为30 mA·cm−2的条件下，对含1 50mMNO3−的合成废水电解14h后，NO3−的去除效率可达99%，氨氮选择性为98%，法拉第效率为93%，总氨氮回收率为97%。氨回收通量和比能耗分别达到2050g-(NH4)2SO4·m−2·d−1和11kWh·kg−1-(NH4)2SO4，超过了许多已报道的工艺。直接电子转移是NO3-−电化学还原为氨的主要机理。界面反应热力学和界面反应动力学分析表明，热激活FeNi合金表面的NiFe2O4(3+1+1)-Ni位对NO3-−电化学反应生成氨具有较高的反应活性和专一性。最终，本研究的目的是促进污水处理中氮素养分的可持续回收和氨氮的合成。
Electrocatalytic upcycling of nitrate (NO3−) in wastewater into the valuable ammonium-based fertilizer has been considered as a green and appealing alternative to biological nitrogen removal or the industrial ammonia (NH3) production processes. This work investigated an innovative and energy-efficient electrolysis flow-through cell consisting of a porous activated iron nickel (FeNi) alloy cathode and a hollow polypropylene fiber membrane extraction unit to realize the electrochemical NO3−reduction and simultaneous upcycling to ammonium sulphate salts ((NH4)2SO4). Cathodic and anodic electrochemical half-reactions were coupled to enable NO3−reduction to ammonia and in-situ acid/base productions to promote the membrane stripping of NH3. Our results show that after electrolysis operation for 14 h for a synthetic wastewater containing 150 mM NO3−under a cathodic current density of 30 mA·cm−2, 99 % of NO3−removal efficiency, 98 % of ammonia selectivity, 93 % of Faradic efficiency and 97 % of total ammonia nitrogen (TAN) recovery were achieved respectively. A NH3recovery flux and a specific energy consumption reached 2050 g-(NH4)2SO4·m−2·d−1and 11 kWh·kg−1-(NH4)2SO4, respectively, which outcompetes many reported processes. Direct electron transfer was the main mechanisms of electrochemical NO3−reduction to ammonia. Interfacial reaction thermodynamics and kinetics analysis of key intermediates (e.g., *NO3, *NO2, and *NO) shows that the NiFe2O4(3 1 1)-Ni site on the thermally activated FeNi alloy surface exhibited higher reactivity and specificity toward electrochemical NO3−reduction to ammonia over nitrogen (N2) or hydrogen (H2) generation. Ultimately, this study aims to promote sustainable nitrogen nutrient recovery and ammonia fertilizer synthesis from wastewater treatment.