Confinement and characterization of deep eutectic solvent based on choline chloride:alcohol into nanoporous silica for CO2 capture

Biodegradable nanocomposite adsorbents based on nanoporous silica (NS) and deep eutectic solvents (DESs) mixture of choline chloride:glycerol (ChCl:Gly) and choline chloride:ethylene glycol (ChCl:EG) were synthesized and the ability to adsorb carbon dioxide (CO2) has been studied. All DESs were prepared in mole ratio 1:2 and 10 w/w% were confined into nanoporous silica through sol gel method. The physicochemical properties of the prepared adsorbents have been characterized using Fourier transform infrared attenuated total reflectance (FTIR-ATR) and surface analyzer ASAP 2020. The presence of ChCl:Gly and ChCl:EG in the NS can be detected with the presence sp3 hybridized CH stretching and CH2 bending peaks. Specific surface areas of the NS were significantly reduced with confinement of DESs due to the transformation of micropores to mesopores. The ability of adsorbent to adsorb CO2 was evaluated using isothermal CO2 adsorption by Micromeritic ASAP 2020. ChCl:Gly/NS showed higher CO2 adsorption capacity compared to ChCl:EG/NS which are 20.1 mgCO2/gadsorbent and 18.8 mgCO2/gadsorbent, respectively.