Tsai Shao-Wei, Cuong Dinh Viet, Hou Chia-Hung
Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4. Roosevelt Rd., Taipei 10617, Taiwan.
Faculty of Environmental Engineering, Hanoi University of Civil Engineering, 55 Giai Phong, Hai Ba Trung, Hanoi 100000, Vietnam.
Water Res. 2022 Aug 1;221:118786. doi: 10.1016/j.watres.2022.118786. Epub 2022 Jun 22.
Currently, intercalation materials such as Prussian blue analogs have attracted considerable attention in water treatment applications due to their excellent size-based selectivity toward cations. This study aimed to explore the feasibility of using a nickel hexacyanoferrate (NiHCF) electrode for selective NH capture from effluent from a municipal wastewater treatment plant. To assess the competitive intercalation between NH and other common cations (Na, Ca), a NiHCF//activated carbon (AC) hybrid capacitive deionization (CDI) cell was established to treat mixed-salt solutions. The results of cyclic voltammetry (CV) analysis showed a higher current response of the NiHCF electrode toward NH ions than toward Na and Ca ions. In a single-salt solution with NH, the optimized operating voltage of the hybrid CDI cell was 0.8 V, with a higher salt adsorption capacity (51.2 mg/g) than those obtained at other voltages (0.1, 0.4, 1.2 V). In a multisalt solution containing NH, Na, and Ca ions, the selectivity coefficients of NH/Ca and NH/Na were 9.5 and 4.9, respectively. The feasibility of selective NH capture using the NiHCF electrode in a hybrid CDI cell was demonstrated by treating the effluent from a municipal wastewater treatment plant (WWTP). The intercalation preference of the NiHCF electrode with the WWTP effluent was NH>K>Na>Ca>Mg, and NH showed the highest salt adsorption capacity among the cations during consecutive cycles. Our results revealed that cations with smaller hydrated radii and lower (de)hydration energies were more favorably intercalated by the NiHCF electrode. The results provide important knowledge regarding the use of intercalation-type electrodes for selective nutrient removal and recovery from wastewater.
目前，诸如普鲁士蓝类似物之类的插层材料因其对阳离子具有出色的基于尺寸的选择性而在水处理应用中备受关注。本研究旨在探索使用镍铁氰化物（NiHCF）电极从城市污水处理厂的流出物中选择性捕获NH的可行性。为了评估NH与其他常见阳离子（Na、Ca）之间的竞争性插层，建立了一个NiHCF//活性炭（AC）混合电容去离子化（CDI）电池来处理混合盐溶液。循环伏安法（CV）分析结果表明，NiHCF电极对NH离子的电流响应高于对Na和Ca离子的电流响应。在含有NH的单盐溶液中，混合CDI电池的优化工作电压为0.8 V，其盐吸附容量（51.2 mg/g）高于在其他电压（0.1、0.4、1.2 V）下获得的容量。在含有NH、Na和Ca离子的多盐溶液中，NH/Ca和NH/Na的选择性系数分别为9.5和4.9。通过处理城市污水处理厂（WWTP）的流出物，证明了在混合CDI电池中使用NiHCF电极选择性捕获NH的可行性。NiHCF电极对WWTP流出物的插层偏好为NH>K>Na>Ca>Mg，并且在连续循环中，NH在阳离子中表现出最高的盐吸附容量。我们的结果表明，水合半径较小且（去）水合能较低的阳离子更容易被NiHCF电极插层。这些结果为使用插层型电极从废水中选择性去除和回收营养物质提供了重要知识。
