Electrospun Poly(vinyl alcohol)–<scp>l</scp>-Arginine Nanofiber Composites for Direct Air Capture of CO<sub>2</sub>
Mani Modayil Korah, Salma Ly, Thiago Stangherlin Barbosa, Richard Nile, Kailong Jin, Klaus S. Lackner, Matthew Green
Abstract
The low concentration of CO2 in the atmosphere makes its capture (i.e., direct air capture or DAC) challenging. By incorporating the amino acid l-arginine (l-Arg) into a poly(vinyl alcohol) (PVA) nanofiber support structure, we created porous substrates with very high surface areas of l-Arg available for CO2 sorption. The bio-inspired PVA–Arg nanofiber composites are flexible and show excellent DAC performance compared to that of bulk l-Arg. The nanofiber composites are fabricated from an electrospinning process using an aqueous polymer solution. After obtaining the nanofiber mats, they are physically cross-linked to improve resistance to water. Increasing l-Arg loading to 50 wt % (with respect to PVA) improves sorption performance; however, loadings above 50 wt % decrease the performance due to a reduction in porosity of the nanofiber composite. High ambient humidity levels improve sorption performance significantly. The best performing nanofiber composite collected 542 μmol of CO2 per gram of the composite during 2 h of exposure to ambient, high-humidity (100% RH) air that had a CO2 concentration of 400–450 ppm.