Carbon dioxide capture using resin-wafer electrodeionization

A resin-wafer electrodeionization (RW-EDI) apparatus for removing carbon dioxide from a gas stream, the apparatus comprising:

• a cathode;
• and
• an anode that is separated from the cathode by a plurality of porous solid ion exchange resin wafers arranged in a stack between the cathode and the anode, and comprising pairs of alternating basic and acidic wafers with a basic wafer and an acidic wafer in each pair, and a cation exchange membrane between the basic and acidic wafers of each pair;
• the cathode being adjacent to a basic wafer with a bipolar membrane therebetween, the anode being adjacent to an acidic wafer with a bipolar ion exchange membrane therebetween, and each pair of wafers being separated from any adjacent pair by a bipolar ion exchange membrane;
• each basic wafer comprising a porous basic ion exchange medium and each acidic wafer comprising a porous acidic ion exchange medium;
• each basic wafer being adapted to (a) introduce a CO2-containing gas into an aqueous fluid within the basic ion exchange medium to convert CO2 from the gas into bicarbonate ion, and (b) vent a CO2-depleted gas therefrom;
• in use, bicarbonate-containing fluid flows from the basic ion exchange medium into the acidic ion exchange medium in fluid communication therewith to convert bicarbonate ion into CO2 gas;
• each acidic wafer being adapted to vent CO2 gas generated in the acidic ion exchange medium thereof out of the apparatus;
• the cathode, wafers, cation exchange membranes, bipolar ion exchange membranes, and the anode together directing a net flow of protons through the wafers toward the cathode and a net flow of hydroxyl ions through the wafers toward the anode when an electric potential is applied across the cathode and anode, to thereby maintain a basic pH in each basic wafer portion and an acidic pH in each acidic wafer during capture and release of CO2 from the gas stream.