Electrochemical recovery of LiOH from used CO₂ adsorbents

In recent years, there have been growing interest in indoor air quality, and large efforts have been devoted to controlling the concentration of CO₂ below a certain level. Lithium hydroxide (LiOH) is the most widely used material for CO₂ capture due to its large adsorption capacity and fast kinetics; however, steep increase in the cost of lithium is endangering the economic feasibility of CO₂ adsorbents comprised of LiOH. In order to resolve this problem, we herein propose an electrochemical system for selective recovery of LiOH from used CO₂ adsorbents. Electrocatalytic water splitting electrodes separated by a cation exchange membrane enable selective migration of lithium ions from the oxygen-evolving feed chamber to hydrogen-evolving recovery chamber, and this leads to one-step production of LiOH solution. Electrochemical behaviors of the system, including the time-dependent quantities of the active chemical species during the operation, are discussed by experimental and theoretical investigations, and the strategy to maximize the energy efficiency of our system is suggested.