Project 1

In this project, a student researcher will evaluate the separation performance of supported carbonates in removing CO2 and releasing water vapor near ambient conditions essential for supporting life. Over the last decade researchers have found that anion exchange polymers embedded with carbonate anions bind with CO2 to form bicarbonate. This is commonly encountered across all carbonate systems found in biological and geologic realms. The bicarbonate anion can revert to the carbonate species with temperatures above 120 ⁰C or extremely low partial pressures of CO2 (~ 1 Pa). However, when the trapped CO2 as bicarbonate is hydrated with water or water vapor, it destabilizes, releasing CO2 leaving behind a hydroxide, thus enabling the moisture swing. For the reverse, as the material binds CO2, water is released back to the vapor phase. The student will examine how combinations of the different separation drivers (T, pressure, water vapor activity and an electric field) can influence the amount and rates of CO2 and water vapor transfer to inform separation processes that may prove useful in controlling ambient atmospheres in space exploration missions, both for scrubbing CO2 from human habitat and enhancing CO2 for photosynthetic habitats. Further, these phenomena will be examined across a suite of material families, including the polymer anion exchange resins, membranes and carbonate salts suspended in porous solids. In this project, a student researcher will evaluate the separation performance of supported carbonates in removing CO2 and releasing water vapor near ambient conditions essential for supporting life. Over the last decade researchers have found that anion exchange polymers embedded with carbonate anions bind with CO2 to form bicarbonate. This is commonly encountered across all carbonate systems found in biological and geologic realms. The bicarbonate anion can revert to the carbonate species with temperatures above 120 ⁰C or extremely low partial pressures of CO2 (~ 1 Pa). However, when the trapped CO2 as bicarbonate is hydrated with water or water vapor, it destabilizes, releasing CO2 leaving behind a hydroxide, thus enabling the moisture swing. For the reverse, as the material binds CO2, water is released back to the vapor phase. The student will examine how combinations of the different separation drivers (T, pressure, water vapor activity and an electric field) can influence the amount and rates of CO2 and water vapor transfer to inform separation processes that may prove useful in controlling ambient atmospheres in space exploration missions, both for scrubbing CO2 from human habitat and enhancing CO2 for photosynthetic habitats. Further, these phenomena will be examined across a suite of material families, including the polymer anion exchange resins, membranes and carbonate salts suspended in porous solids.

The student will operate open-flow gas-solid experiments where step changes in gas composition, temperature or an applied electric field will induce a change in sorption on the solid. Gravimetric, calorimetric, gas detection and electrical impedance measurements can be conducted on the solid (and outlet gas) materials while undergoing a step change, revealing the coupled yet counter effects of CO2 sorption / H2O desorption. To carry out this work, either myself or a graduate student will train the undergraduate in the use of our custom thermogravimetric, calorimetric, evolved gas analyzer, and also be trained to use a larger scale system that can measure changes in gas composition due to an applied electric field. For the later measurement, filmbased materials are required to accommodate an application of electrodes. The student will also learn how to impregnate salts or prescribed concentrations onto porous surfaces and perform quantitative ion exchange procedures to get the polymeric anion exchange materials into a CO2 reactive state. Execution of the experiment requires skill development in instrument calibration (mass, temperature, flow, composition), plotting and comparing time series trends, processing signals in order to integrate cumulative changes, then fitting experimental data to extract important parameters like rate constants.

The major outcomes of the work is data supporting separation co-drivers like electric fields, heat, and the use of water that will also result in the release of water vapor to enhance the rates of CO2 separation from ambient environments. The data will be tabulated and visualized for dissemination in to presentations, and potentially publication if of satisfactory quality.