Wafers Assist in the Capture of CO2 (not nilla wafers)

My research involving Ionic Liquids is tangentially related to carbon capture, so I’m always interested when new alternative methods for carbon capture arise.  Efficient carbon dioxide management is one of the most important means for escaping runaway climate change, and we have many sources spewing CO₂.  Seeing as how we are reluctant to give up our current methods of producing energy we must find technologies that work well with existing infrastructures.

For example, flue gases that are emitted from smokestacks of coal plants contain nitrogen, carbon dioxide, and water vapor in addition to a smaller percentage of particulate matter. Currently those gases can be treated via “scrubbing” to remove the carbon dioxide for use in other industrial applications or sequestration.  Scrubbing involves bubbling flue gas through an aqueous solution of amines, that in turn react with the CO₂ and trapping about 95% of it in the solution.  But in order to release the CO₂ and recover the amine solution, the carbon filled mixture must be heated under a vacuum – something that requires a lot of energy.

A new method, recently published in I&EC, relies on basic chemistry. Snyder et al realized that by playing with the a narrow range of pH’s, you can change the way CO₂ mixes with water.  If in a basic solution CO₂ can exist either as a bicarbonate ion whereas if acidic it will behave like a normal gas molecule.  Instead of dealing with jugs of acids and bases to tinker with the pH and capture and remove CO₂, they used an electrochemical device called a resin wafer electrodeionization (RW-EDI) that continuously controls the pH of the fluid. Using this system of water, phosphate buffer, an enzyme/catalyst, and a wafer at normal temperatures and pressures they were able to capture greater than 80% of the carbon dioxide from the flue gas.

This is just a proof of concept paper, so improvements are required before moving to an industrial scale, however it represents a unique approach to alleviating our carbon dioxide problem.