Department of Environmental and Sustainable Engineering, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, United States.
College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, 257 Fuller Road, Albany, New York 12203, United States.
Environ Sci Technol. 2021 Jun 1;55(11):7674-7680. doi: 10.1021/acs.est.1c01703. Epub 2021 May 10.
Ammonia (NH) recovery from used water (previously wastewater) is highly desirable to depart from fossil fuel-dependent NH production and curb nitrogen emission to the environment. Electrochemical NH recovery is promising since it can simply convert aqueous NH to gaseous NH using cathodic reactions (OH generation). However, the use of a separated electrode and membrane imposes high resistances to the cathodic reaction and NH transfer. This study examined an activated carbon (AC)-based membrane electrode functionalized with nickel to electrochemically recover NH from synthetic anaerobic centrate. The membrane electrode was fabricated using nickel-adsorbed AC powder and a polyvinylidene fluoride (PVDF) binder, and the PVDF membrane layer was formed at the electrode surface by phase inversion. The NH-N recovery flux of 50.3 ± 0.4 gNH-N/m/d was produced at 17.1 A/m with a recovery solution at pH 7, and NH-N fluxes and energy consumptions were improved as the recovery solution became acidic (62.2 ± 2.1 gNH-N/m/d with 16.0 ± 1.6 kWh/kgNH-N at pH 2). Increasing PVDF loadings did not impact the electrochemical performances of the Ni/AC-PVDF electrode, but slightly lower (7%) NH-N fluxes were obtained with higher PVDF loadings. Ni dissolution (3.7-6.0% loss) was affected by the recovery solution pH, but it did not impact the performances over the cycles.
从用过的水中（以前是废水）回收氨（NH）是非常理想的，可以摆脱对化石燃料依赖的 NH 生产，并减少氮向环境的排放。电化学 NH 回收很有前景，因为它可以通过阴极反应（OH 生成）简单地将水中的 NH 转化为气态 NH。然而，使用分离的电极和膜会对阴极反应和 NH 转移造成高电阻。本研究考察了一种基于活性炭（AC）的膜电极，该电极功能化有镍，用于从合成厌氧浓缩物中电化学回收 NH。膜电极是使用吸附有镍的 AC 粉末和聚偏二氟乙烯（PVDF）粘结剂制造的，并且 PVDF 膜层是通过相转化在电极表面形成的。在 pH 7 的回收溶液中，以 17.1 A/m 的电流密度可产生 50.3 ± 0.4 gNH-N/m/d 的 NH-N 回收通量，并且随着回收溶液变得更酸性（pH 2 时，62.2 ± 2.1 gNH-N/m/d 和 16.0 ± 1.6 kWh/kgNH-N），NH-N 通量和能耗得到提高。增加 PVDF 负载对 Ni/AC-PVDF 电极的电化学性能没有影响，但在更高的 PVDF 负载下，NH-N 通量略低（低 7%）。Ni 的溶解（损失 3.7-6.0%）受回收溶液 pH 的影响，但在循环过程中不会影响性能。
