Systematic Screening of Deep Eutectic Solvents as Sustainable Separation Media Exemplified by the CO₂ Capture Process

Abstract

Although deep eutectic solvents (DESs) have attracted significant interest in various separation processes, rational methods guiding task-specific DES selection are still scarce. In this work, a systematic method for screening DESs as sustainable separation solvents is proposed and exemplified by the CO 2 capture application. To achieve a large screening space, experimentally reported DESs are collected exhaustively from literature; for the most studied choline chloride (ChCl) based DESs a correlation between their freezing point depression and COSMO-RS molecular descriptors of their hydrogen bond donors (HBDs) is established, which is applied to search a huge number of novel combinations of ChCl and HBD candidates for potential DESs. From the extended database combining experimental and potential DESs, promising CO 2 absorbents are screened by integrating (a) the freezing point constraint according to the operating requirement, (b) the estimation of environment, health, and safety (EHS) impacts using quantitative structure-activity relationships methods, and (c) the prediction of thermodynamic properties by COSMO-RS. The practical solvent performance of the top DES candidates is finally studied by experiments, identifying ChCl: ethylenecyanohydrin (at mole ratios of 1:2 and 1:3) as very attractive CO 2 absorbents.

Comprehensive Evaluation of a Deep Eutectic Solvent Based CO2 Capture Process through Experiment and Simulation

“…However, it is time-consuming, laborious, and costly to select the appropriate DES through experimental methods due to the many kinds of DESs. 16,17 As an a priori thermodynamic model irrespective of experimental data, the conductor-like screening models− segment activity coefficient (COSMO-SAC) 18 model has been widely used to predict macroscopic properties by combining quantum chemistry with statistical mechanics. The COSMO-SAC model describes the surface electric field density of polarized material molecules and shows a very promising a priori predictive ability.…”

Computer-aided solvent screening for the fractionation of wet microalgae biomass

“…In order to obtain the OGS for the whole DESs, the scores for the HBA and HBD were averaged weighted by their molar fractions. VEGA models were recently applied for a screening of DESs by Song et al 99 and are a reasonable choice given the number of solvent candidates. However, recent studies regarding the toxicity of DESs suggest, that the toxicity of the DES might be higher than that of its single components.…”

Carbon Dioxide Solubility in Nonionic Deep Eutectic Solvents Containing Phenolic Alcohols

“…CO 2 capture is one application that can benefit from DES. Existing studies have demonstrated the potential of DES for CO 2 capture ( Krishnan et al, 2020 ; Song et al, 2020 ; Wazeer et al, 2021a ; Wazeer et al, 2021b ). However, most studies investigating CO 2 capture in DES proposed using ionic DES, which has the same drawbacks as those related to IL, especially in terms of hygroscopicity.…”

“…The conductor-like screening model for realistic solvation (COSMO-RS) is a predictive thermodynamic model based on quantum mechanics and statistical thermodynamics ( Klamt, 1995 ; Klamt et al, 1998 ; Eckert and Klamt, 2002 ). COSMO-RS successfully provides qualitative predictions for screening IL and ionic DES for gas capture applications ( Völkl et al, 2012 ; Song et al, 2020 ; Liu et al, 2021 ; Qin et al, 2021 ).…”