CO2-Dependent Nanoscale Organization in Bulk and Interfacial Carbon Dioxide Capture Liquids Elucidated Using X-Ray Scattering

Daniel Eduardo Morán, University of Texas at El Paso


The pressing need to control carbon dioxide emissions has propelled extensive research efforts employing a variety of approaches across the globe. In flue-gas recovery of CO2, the water-lean amine-based solvent N-(2-ethoxyethyl)-3-morpholinopropan-1-amine (2-EEMPA), has shown exceptional performance. Recent studies show that 2-EEMPA exhibits intermediate-range order (IRO), beyond the first nearest neighbor length scale, consisting of tetrameric clusters. In view of the need to find solutions for direct air capture (DAC) of CO2, this system may represent a critical linkage in a DAC strategy, yet structural insights on EEMPA’s behavior at solid surfaces are still lacking. To this end, we applied the technique Wide-Angle X-ray Scattering (WAXS) to study nanoscale intermediate and molecular short-range ordering of liquids in the bulk state Furthermore, the Teubner-Strey model yields insights into thermodynamic properties of compounds and their associated nanoscale features including domain size and intermolecular alignment and is used to analyze our results. The quartz crystal microbalance (QCM) is another useful tool we employed to determine the rate of mass absorption of CO2 onto EEMPA thin films. We will present WAXS results of 2-EEMPA structure as a function of carbon dioxide molar concentrations and temperature. A model consisting of Teubner-Strey and Gaussian peak parameters describes the changes in IRO clustering and short intermolecular structure. The changes in the peak positions, intensities, and widths provide information on the liquid’s structure, as well as variations in the amphiphilicity of phases in the sample. The combined use of x-ray scattering and QCM enables insights into CO2 transport and equilibrium structure properties of 2-EEMPA under bulk and interfacial conditions.

Subject Area

Physics|Chemical engineering|Physical chemistry

Recommended Citation

Morán, Daniel Eduardo, "CO2-Dependent Nanoscale Organization in Bulk and Interfacial Carbon Dioxide Capture Liquids Elucidated Using X-Ray Scattering" (2023). ETD Collection for University of Texas, El Paso. AAI30819818.