Moisture-Swing Polymer@Textile Composites for CO2 Capture

Quaternary ammonium-containing sorbents have significant potential in direct air capture (DAC) of CO₂. In DAC sorbents, the adsorption of CO₂ can be achieved at lower concentrations, which is advantageous in mitigating global warming caused by the excess of CO₂ already in the atmosphere. DAC could reduce emissions from nonstationary sources like transportation and agriculture where carbon capture technology would otherwise be difficult to implement.

This carbon capture in ambient air can occur through different mechanisms, for example, via a moisture-swing mechanism where the sorbent absorbs CO₂ at lower moisture levels and desorbs it at higher moisture levels.

The project investigated the modification of textiles into polymer@textile composite membranes with improved mechanical properties for long-term stability and DAC performance. This was done by immobilizing polymeric sorbents with quaternary ammonium groups into the textiles.

Membrane synthesis via free-radical polymerization was performed at various monomer concentrations with the textile submerged in the polymerization solution. Crosslinking agents were included to encourage modification of the textile. Modification was successful with a 15-20% degree of modification (DM%) quantified by mass difference and a clear increase in the stiffness of the material.

The stability was measured after washing the membranes and a conventional ion exchange process was performed to add −HCO₃ counterions, which are involved in the moisture-swing mechanism.

The CO₂ capture performance was tested in a closed system where the modified polymer@textiles composites showed moisture-swing activity that makes them a promising candidate for DAC.

Additionally, this work acts as a starting point to eventually use discarded textiles as a material in DAC membranes. Textile waste is a major source of pollution in the environment and new methods of textile reuse, especially for blended textiles which are otherwise difficult to separate and recycle, could help alleviate this problem. Green chemistry techniques such as using water as a solvent in membrane synthesis might also be investigated based on the findings of this work.