Testing Viability of Solid Amine-Based Adsorption Methods for Carbon Scrubbing on Space Habitats

The purpose of this research is to test the viability of solid guanidinium-based sorbents for carbon scrubbing in space habitats. Carbon scrubbing is critical to use in space habitats like the International Space Station (ISS) to ensure CO₂ levels do not rise to dangerous levels for habitation. Carbon capture, where CO₂ is selectively absorbed or adsorbed from the air into a material, is the preferred method for carbon scrubbing and is currently employed aboard the ISS. This process currently relies on 5A zeolite molecular sieves, which selectively adsorb CO₂. Previous research on solid guanidinium sorbents demonstrate it is an effective sorbent for selectively filtering CO₂. As a sorbent, guanidinium sorbents are highly selective, have high reusability, have low desorption temperatures, and are resistant to negative effects caused by humidity. These properties make guanidinium a possible alternative to zeolite sorbents.

To prove the viability of guanidinium as an effective sorbent for carbon scrubbing, the sorption capacity of synthesized guanidinium sorbents was compared to 5A zeolite molecular sieves at varying concentrations of CO₂. Two solid guanidinium sorbents will be synthesized. One using guanidinium carbonate and another using guanidinium isophthalate. Each sorbent was composed of 15wt% of the guanidinium crystal, with the rest being activated carbon. Their sorption capacities were then tested by placing each sorbent inside of an adsorption column system and running CO₂ through. The difference in concentration across the column over time was used to determine the amount of CO₂ captured per mass of sorbent. Each sorbent was run through 10 adsorption-desorption cycles inside the adsorption column. The sorption capacity of each material was used to determine its effectiveness, with higher capacities showing a greater potential for CO₂ scrubbing.