Flow-electrode capacitive separation of organic acid products and recovery of alkali cations after acidic CO2 electrolysis

• 成果类型: Article
• 署名作者: Jiang, Yong; Wu, Gaoying; Pu, Ying; Wang, Yue; Chu, Na; Zeng, Raymond Jianxiong; Zhang, Xudong; Zhu, Xiangdong; Liang, Peng
• 署名单位: Fujian Agriculture & Forestry University; Chinese Academy of Sciences; Chengdu Institute of Biology, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Vanderbilt University; Chinese Academy of Sciences; Nanjing Institute of Soil Science, CAS; Tsinghua University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13008
• DOI: 10.1073/pnas.2408205121
• 发表日期: 2024-10-03
• 关键词: deionization; desalination; reduction; removal

摘要

Acidic CO2 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 similar to 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.