Eco-friendly CO2 adsorption by activated-nano-clay montmorillonite promoted with deep eutectic solvent

In this work, an innovative and environmentally friendly adsorbent for CO2 capture is synthesized by Choline Chloride-Urea (ChCl: U) functionalization of the acid-activated montmorillonite (MMT) for the first time. The surface area enhancement was achieved by acid activation at 3 Molarity, which resulted in 7.1 and 10.9 times increase in the specific area and pore volume, respectively. In fact, the highest reported value of the surface area of montmorillonite has been achieved. The characterization was carried out by FTIR, BET, XRD, and SEM to ensure the qualification of the modified acid-activated and then impregnated with the solvent. The optimum condition for the input variable was 30 oC, 9 bar, and 50% of the solvent to MMT, where the response was 252 mg/g. The evaluation of the heterogeneous and mono-multilayer adsorption indicated the experimental data well-fitted to the Hill isotherm model with n higher than 1, indicating the desirability of the adsorbent (n was also 1.59 for the Freundlich isotherm model). The Elovich kinetic model was observed to be in the best agreement with the experimental data. Eight cycles of adsorption-desorption results indicated an excellent reversible adsorbent with low-temperature regeneration (90oC) is attained.