# Experimental and predictive analysis of deep eutectic solvent gel membranes for efficient CO2 separation

## TL;DR

This paper explores using deep eutectic solvent gel membranes as a cost-effective and safe alternative to ionic liquids for separating CO2 from gas mixtures.

## Contribution

The study introduces a novel DES-gel membrane fabrication method and evaluates its CO2 separation performance using experimental and predictive methods.

## Key findings

- DES-gel membranes achieved high CO2 permeability of 138.98 Barrer for pure gas and 93.17 Barrer for mixed gas.
- DES-gel membranes outperformed other DES-supported liquid membranes in CO2 separation efficiency.
- DFT calculations confirmed strong interactions between DES and CO2 molecules.

## Abstract

The capture of Carbon Dioxide (CO2) is very relevant nowadays as global warming hits its peak. The separation of CO2 using membranes has received wide recognition by researchers because of its energy efficiency. Various Ionic Liquid supported membranes have been proven effective in this regard; however, their higher cost and toxicity are limitations, which opens possibilities for Deep Eutectic Solvents (DES). This work explains how DES gel membrane fabrication separates CO2 from CO2/CH4 mixtures. DES, composed of choline chloride and glycerol, is mixed with Pebax1657 polymer, and Polyvinylidene fluoride sheets are used as supports for casting. Fourier transform infrared spectroscopy has been used to confirm the synthesis of DES. X-ray Diffraction and Scanning Electron Microscopy analysis were used to analyse the membrane structure and cross-section. The physicochemical properties of DES are measured at a temperature range from 293.15 to 343.15 K. Pure and mixed gas permeabilities of CO2 and CH4 with increased pressure have been calculated. The highest permeability values obtained for pure and mixed gas CO2 were 138.98 Barrer and 93.17 Barrer, respectively. Density Functional Theory (DFT) is also applied to predict the interaction energy between DES and gas molecules. The efficacy of the DES-gel membrane was evaluated against other DES-supported liquid Membranes, revealing that DES may serve as a viable substitute for hazardous and costly ionic liquids.

The online version contains supplementary material available at 10.1038/s41598-025-14520-z.