Deep eutectic solvents for efficient capture of cyclohexane in volatile organic compounds: Thermodynamic and molecular mechanism

Abstract

Deep eutectic solvents (DESs) as promising green absorbents were first proposed to capture the condensable cyclohexane gas. Choline chloride-ethylene glycol (EG) (Ethaline) and choline chloride-urea (Reline) were prepared using choline chloride as the hydrogen-bond acceptor (HBA) and urea or EG as the hydrogen-bond donor (HBD). To explore the potential application of DESs in condensable gas capture, the COSMO-RS model was used to predict the solubility of cyclohexane in Ethaline and Reline. The thermodynamic properties, that is, Henry's constant and excess enthalpy, were estimated by correlating solubility data with Henry's law equation.Quantum chemical (QC) calculation was applied to understand the absorption mechanism at the molecular level. The results showed that the absorption performance of cyclohexane in Ethaline and Reline was dependent on the weak interaction between O of EG (or N of urea) and H of cyclohexane as well as the free volume effect of DESs.

Extraction of polycyclic aromatic hydrocarbons from fluid catalytic cracking diesel with ionic liquids

“…In this work, taking the separation of n‐hexadecane and 1‐methylnaphthalene in FCC diesel as an example, the theoretical feasibility of ILs as extractants was preliminarily explored by using the predictive COSMO‐RS model 30–33 . As shown in Figure 2, of 50 kinds of ILs initially screened, solvent capacities of some common ILs for 1‐methylnaphthalene at 298.15 K are higher than those of the benchmark solvents (e.g., Sulfolane, NMP, and DMF).…”

“…In this work, taking the separation of n-hexadecane and 1-methylnaphthalene in FCC diesel as an example, the theoretical feasibility of ILs as extractants was preliminarily explored by using the predictive COSMO-RS model. [30][31][32][33] As shown in Figure 2, of 50 kinds of ILs initially screened, solvent capacities of some common ILs for 1-methylnaphthalene at 298.15 K are higher than those of the benchmark solvents (e.g., Sulfolane, NMP, and DMF). Meanwhile, the selectivities of n-hexadecane to 1-methylnaphthalene are also higher than those of the benchmark solvents (noting that a higher selectivity corresponds to a lower IL amount).…”

Condensable Gases Capture with Ionic Liquids

“…Ordinarily, ILs are divided into hydrophobic and hydrophilic types, and some hydrophilic ILs have strong water absorption; 183−185 (3) The ideal solvent should have as low viscosity as possible to minimize the energy requirements of pumping and mixing and to ensure high mass transfer rate in the absorption process. The relevant studies have shown that the viscosity of IL containing 1 wt % water will be reduced by 50% compared to the completely dry IL; 186 (4) The idea solvents should be robust in terms of thermal decomposition and chemical corrosion by oxygen. Compared to glycol solvents, [EMIM][EtSO 4 ] can be treated/stripped by hot air (≤393.2 K) without chemical corrosion.…”

“…4 ] was further proven by 20 absorption−desorption cycles, indicating that ILs were a potential excellent absorbent for aromatic chlorides.…”

Bridging Machine Learning and Redlich–Kister Theory for Solid–Liquid Equilibria Prediction of Binary Eutectic Solvent Systems

“…Different from ionic liquids (ILs), that present excellent designability due to a huge number of possible cation–anion combinations, ESs can exhibit additional designability by tuning not only the HBA–HBD combination but also their mixing proportion. Bearing the virtues of ILs including nonflammability, high thermal and chemical stabilities, wide electrochemical window, and low volatility, − ESs also possess overwhelming advantages of low cost, simple preparation, and reasonable biodegradability. , These luring properties make ESs excellent solvent options for various chemical processes, such as extraction, − gas capture, − gas dehydration, , catalysis, etc. Nevertheless, despite the extensive efforts that have been made, most studies still rely on the experimental trial-and-error method for the selection of ES toward a specific application.…”