Accelerating gas capture and conversion in aqueous systems

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Capturing and solubilizing gases from dilute gaseous mixtures is a pressing technological need. As increasing greenhouse gas concentrations magnify the severity of extreme weather events such as floods, direct air capture is becoming increasingly important. Traditional methods for gas capture (gas scrubbers) are becoming obsolete given the energy requirements. New methods are urgently needed to accelerate gas-liquid mass transfer. This research program will study fundamental physico-chemical interactions at interfaces to accelerate retention and conversion of gases in aqueous systems. This novel approach will investigate triple solid-liquid-gas boundaries through the decimation of bulky gas volumes into thin gas sheets held stably between a microtextured solid and an absorbing aqueous solution like potassium hydroxide. By creating these thin, stable gas sheets over large areas, two interfaces will be created - gas-solid and gas-liquid interfaces that can be systematically studied for enhancing mass transfer. These thin sheets require a combination of advances in materials (solids with manipulatable advancing and receding contact angles) as well as advances in interfacial texture engineering (micro and nano textures that can hold stable gas films over areas exceeding 5 cm2). Like a paper towel hastening the evaporation of water, gas mass transfer will be significantly enhanced by using thin sheets that have been precisely designed using a framework that incorporates timescales and length-scales of interfacial interactions. The embodiment of thin gas films, while good for scientific study, can be scaled up to continuous processing. A key property is "pinning" where the gas-liquid interface is arrested on the solid. Zooming in to the micron length scales, the first question that will be answered is the stability of the layer as a function of surface microtexture parameters. In the surface chemistry regime (molecular length-scales), rare-earth ceramics will be studied. These have been shown to have large variations in contact angle hysteresis which offers knobs to control the shape of the gas-liquid interface and arrest the interface which is key to advance these systems. Advancing and receding contact angles, which hold key to pinning interfaces, are of particular interest. With thin sheets that can be rapidly solubilized, this research program aims to have the widest impact in direct capture of CO2 from air. Knowledge from this research program can also be applied to scrubbing sour gases such as H2S and SO2 from flue gas emissions. Canadian industries such as oil and gas, food processing, cosmetics, and transportation will strongly benefit from these technological advancements. This research program will also train several HQP with the skills to respond to the growing climate urgency.