Electrochemical recovery of LiOH from used CO2 adsorbents

Abstract

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.