Jiang Yong, Wu Gaoying, Pu Ying, Wang Yue, Chu Na, Zeng Raymond Jianxiong, Zhang Xudong, Zhu Xiangdong, Liang Peng
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Chinese Academy of Sciences Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
Proc Natl Acad Sci U S A. 2024 Oct 8;121(41):e2408205121. doi: 10.1073/pnas.2408205121. Epub 2024 Oct 3.
Acidic CO electrolysis, enhanced by the introduction of alkali cations, presents a strategic approach for improving carbon efficiency compared to processes conducted in neutral and alkaline environments. However, a significant challenge arises from the dissolution of both organic acids and alkali cations in a strongly acidic feed stream, resulting in a considerable energy penalty for downstream separation. In this study, we investigate the feasibility of using flow-electrode capacitive deionization (FCDI) technology to separate organic acids and recover alkali cations from a strongly acidic feed stream (pH ~ 1). We show that organic acids, such as formic acid and acetic acid, are retained in molecular form in the separation chamber, achieving a rejection rate of over 90% under all conditions. Alkali cations, such as K and Cs, migrate to the cathode chamber in ionic form, with their removal and recovery significantly influenced by their concentration and the pH of the feed stream, but responding differently to the types and concentrations of organic acids. The energy consumption for the removal and recovery of K is 4 to 8 times higher than for Cs, and the charge efficiency is significantly influenced by the types of organic acid products and alkali cations. We conduct a series of electrochemical measurements and analyze the impedance spectroscopy, identifying that hindered mass transfer governed the electrode process. Our findings underscore the potential of FCDI as an advanced downstream separation technology for acidic electrocatalysis processes.
与在中性和碱性环境中进行的过程相比，通过引入碱金属阳离子增强的酸性CO电解是提高碳效率的一种战略方法。然而，在强酸性进料流中有机酸和碱金属阳离子的溶解带来了重大挑战，导致下游分离的能量消耗相当大。在本研究中，我们研究了使用流动电极电容去离子化（FCDI）技术从强酸性进料流（pH ~ 1）中分离有机酸并回收碱金属阳离子的可行性。我们表明，甲酸和乙酸等有机酸以分子形式保留在分离室中，在所有条件下的截留率均超过90%。K和Cs等碱金属阳离子以离子形式迁移到阴极室，它们的去除和回收受到其浓度和进料流pH值的显著影响，但对有机酸的类型和浓度有不同的反应。去除和回收K的能量消耗比Cs高4至8倍，电荷效率受到有机酸盐产物和碱金属阳离子类型的显著影响。我们进行了一系列电化学测量并分析了阻抗谱，确定传质受阻控制了电极过程。我们的研究结果强调了FCDI作为酸性电催化过程先进下游分离技术的潜力。
