Solvent-Free CO Capture Using Membrane Capacitive Deionization.

Capture of CO, originating from both fossil fuels, such as coal combustion, and from renewables, such as biogas, appears to be one of the greatest technological challenges of this century. In this study, we show that membrane capacitive deionization (MCDI) can be used to capture CO as bicarbonate and carbonate ions produced from the reaction of CO with water. This novel approach allows capturing CO at room temperature and atmospheric pressure without the use of chemicals. In this process, the adsorption and desorption of bicarbonate ions from the deionized water solution drive the CO(g) absorption-desorption from the gas phase. In this work, the effects of the current density and the CO partial pressure were studied. We found that between 55 and 75% of the electrical charge of the capacitive electrodes can be directly used to absorb CO gas. The energy requirement of such a system was found to be ≈40 kJ mol at 15% CO and could be further improved by reducing the ohmic and non-ohmic energy losses of the MCDI cell.