Conductor-like Screening Model For Real Solvents Research Articles

Study of the ionic liquids’ electrochemical reduction using experimental and computational methods

Ionic liquids (ILs) as electrolytes have attracted attention because of their distinctive properties. Numerous studies on the electrochemical stability of the ILs have been published. However, a deep understanding of the parameters that affect the reduction stability is highly required. In this study, the reduction potentials of five ILs including two novel ILs that contain 1,2,4-triazolium as cation were evaluated experimentally using cyclic voltammetry (CV) and compared with computational modeling using Tmolex software and Conductor like Screening Model for Real Solvents (COSMO-RS). We investigate the parameters that affect the ILs’ reduction stability such as the lowest unoccupied molecular orbital (LUMO) energy levels of the cations and anions, as well as the effect of the molecular interaction between them. We conclude that while using the computational method, the individual values of the LUMO of the cations or anions without taking into consideration the molecular interaction might misguide the prediction of the ILs reduction stability.

Prediction of acid pKa values in the solvent acetone based on COSMO-RS.

In this contribution we extent the use of the conductor-like screening model for realistic solvation (COSMO-RS) to the prediction of pKa values in acetone, a commonly used dipolar aprotic solvent. For this, we calculated the Gibbs free energy of dissociation of 120 organic acids (nine acrylic acids, 87 benzoic acids, nine phenols, and 15 benzenesulfonamides) using COSMO-RS at the two levels BP-TZVP and BP-TZVPD-FINE and determined the parameters for a linear free energy relation for the prediction by performing linear fits to experimental values. Our results suggest that the data set dissects into two groups, with the phenols being different from the other three subsets. The acrylic and benzoic acids and the sulfonamides can be treated together and yield an excellent linear correlation ( ) with an RMSD of only ~0.3. The slope is found to be significantly smaller than the theoretical value ( ), only 45% of it, which is in accordance with findings in the literature. The phenols, however, while similarly well correlated in their own subset with an RMSD of 1.7-1.9, exhibit a slope larger than one. We discuss both a higher uncertainty in the reference values as well as physical origins as possible reasons.

Carbon Dioxide Solubility in Nonionic Deep Eutectic Solvents Containing Phenolic Alcohols.

Deep eutectic solvents (DES) are a new class of green solvents that have shown unique properties in several process applications. This study evaluates nonionic DES containing phenolic alcohols as solvents for carbon dioxide (CO2) capture applications. Potential phenolic alcohols and the molar ratio between DES constituents were preselected for experimental investigations based on the conductor-like screening model for realistic solvation (COSMO-RS). CO2 solubility was experimentally determined in two different DES, namely, L-menthol/thymol in 1:2 molar ratio and thymol/2,6-xylenol in 1:1 molar ratio, at various temperatures and pressures. CO2 solubility in the studied systems was higher than that reported in the literature for ionic DES and ionic liquids. This study demonstrates that nonionic DES containing phenolic alcohols can be excellent, inexpensive, and simple solvents for CO2 capture.

Systematic method of screening deep eutectic solvents as extractive solvents for m-cresol/cumene separation

Deep eutectic solvents (DESs) have been widely applied as extractive solvents for the separation of phenolic compounds from low-temperature coal tar (LTCT). However, systematic study of screening suitable DESs from numerous candidates for this separation process is still scarce. In this work, a systematic method of screening promising DESs as extractive solvents is proposed for the separation of m-cresol/cumene, as a representative phenolic compound/neutral oil mixture in LTCT. Experimental data of DES-involved systems are collected from literature to validate the reliability of conductor-like screening model for real solvents (COSMO-RS), which serves as the foundation for thermodynamic calculation and process simulation. Then, the crucial influencing factors for DESs screening (i.e., salt and solvent, and the molar ratio) on the thermodynamic properties are investigated by COSMO-RS. After that, a systematic DESs screening method combining the calculation of infinite dilution thermodynamic properties, the estimation of melting point and viscosity, the calculation of liquid-liquid equilibria, and the evaluation of process performance is proposed. The results indicate that chlorocholine chloride (CChC): acetic acid (AA) (1:2) and choline chloride (ChCl): ethylene glycol (EG) (1:3) are identified as the optimum DESs for m-cresol/cumene separation. Finally, the high separation performances of CChC:AA (1:2) and ChCl:EG (1:3) are confirmed by extraction experiments.

Multitask Quantum Study of the Curcumin-Based Complex Physicochemical and Biological Properties.

Density functional theory (DFT), time-dependent density functional theory (TDDFT), quantum theory of atoms in molecules (QTAIM), and extended transition state natural orbitals for chemical valence (ETS-NOCV) have all been used to investigate the physicochemical and biological properties of curcumin and three complexes, i.e., Cur-M (M = Ni, Cu, and Mg). Based on DFT calculations, the enolic form (Cur-Enol) is more stable than the anti-diketone form (Cur-Anti diketone) favored for complexation. This enolic form stability was explained by the presence of three intramolecular hydrogen bonds according to the QTAIM analysis. Furthermore, the ETS-NOCV technique revealed that the enolic form had more significant antioxidant activity compared with the anti-diketone form. The calculations from the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) showed that the dimethyl sulfoxide (DMSO) solvent could dissolve all the curcumin tautomers Cur-Enol, Cur-Anti-diketone and Cur-Cu, Cur-Mg, and Cur-Ni complexes in contrast to benzene, acetone, octanol, ethanol, methanol, and water. Furthermore, except for Cur-Mg, which had a relatively low solubility (14 g/L), all complexes were insoluble in water. Cur-Anti-diketone was considerably more soluble than Cur-Enol in the examined solvents.

Amino Acid Ionic Liquids as a Potential Adjuvant for Fungicide Formulations: COSMO-RS Prediction and Dissolution Mechanism Elucidation

Screening green solvents to improve the solubility of insoluble pesticides in water is a significant development direction for pesticide formulations in the future. Amino acid ionic liquids (AAILs) have strong dissolution properties and are widely used in dissolution. In this work, the conductor-like screening model for real solvents (COSMO-RS) as a solvent screening tool was used to screen AAILs with good solubility for two insoluble fungicides (fludioxonil and cyprodinil) and the physicochemical properties (viscosity, density, and CMC) of AAILs were characterized. The results showed that the selected AAILs had good solubility effects on fungicides, wherein the solubility of fludioxonil and cyprodinil in 1-ethyl-1-methyl-pyrrolidinium glycinate ([Empy][Gly]) was 115.78 and 67.17 g/L, respectively. The mechanism of the AAIL dissolving the fungicide was explored by theoretical calculation and IR characterization, indicating that the hydrogen bond interaction was the main driving force for AAILs to dissolve fungicides. The solubilization effects of AAILs in different systems were explored, and the results showed that the solubilization effect in aqueous solution was positively correlated with the content of AAILs, which was not only related to the interaction between fungicides and AAILs, but also the formation of micelles as an essential factor. Moreover, the impact of the biosurfactant rhamnolipid (Rha) and AAILs on the solubilization effect was explored, and most AAILs demonstrated a synergistic solubilization effect after adding Rha, which was expected. Finally, the inhibitory effects of organic solvent adjuvant methanol and eight AAILs on wheat growth were measured. Three [Empy] ILs showed less inhibitory effects on wheat than methanol under the same concentration. The research results indicated that AAILs had a promising research prospect as cosolvents in pesticide formulations.

Solubility determination and prediction for FOX-7 in three binary solvents at different temperatures

ABSTRACT The solid–liquid equilibrium and thermodynamic properties of FOX-7 in three binary mixed solvents (N-methyl pyrrolidone-water, N,N-dimethylacetamide-water and 1,4-Butyrolactone-water) are studied by focused beam reflectance measurement (FBRM) dynamic detection method and the solubility is predicted by conductor-like screening model for real solvents (COSMO-RS) under atmospheric pressure from 298.15 to 343.15 K. The results show that the solubility of FOX-7 increase with the increasing temperature and the mole fraction of N-methyl pyrrolidone, N,N-dimethylacetamide and 1,4-Butyrolactone. The solubility data can be well correlated by Apelblat, van’t Hoff and Yaws equation. The data of hybrid thermodynamic parameters (including the hybrid enthalpy, entropy, and Gibbs energy) show that the dissolution process is endothermic, non-spontaneous and enthalpy driven. In addition, COSMO-RS can accurately predict the increasing trend of solubility with increasing of temperature and mole fraction of solvent. However, the COSMO-RS overestimates solubility in three binary solvents except for x NMP = 0.1575, the average mean squared quadratic error becomes larger with an increasing mole fraction of water. Solubility data and thermodynamic parameters can lay a foundation for the crystallization and spheroidization modification of FOX-7.

Experimental Determination and Computational Prediction of Dehydroabietic Acid Solubility in (-)-α-Pinene + (-)-β-Caryophyllene + P-Cymene System.

The solubility of dehydroabietic acid in (−)-α-pinene, p-cymene, (−)-β-caryophyllene, (−)-α-pinene + p-cymene, (−)-β-caryophyllene + p-cymene and (−)-α-pinene + (−)-β-caryophyllene were determined using the laser monitoring method at atmospheric pressure. The solubility of dehydroabietic acid was positively correlated with temperature from 295.15 to 339.46 K. (−)-α-pinene, p-cymene, and (−)-β-caryophyllene were found to be suitable for the solubilization of dehydroabietic acid. In addition, the non-random two liquid (NRTL), universal quasi-chemical (UNIQUAC), modified Apelblat, modified Wilson, modified Wilson–van’t Hoff, and λh models were applied to correlate the determined solubility data. The modified Apelblat model gave the minor deviation for dehydroabietic acid in monosolvents, while the λh equation showed the best result in the binary solvents. A comparative analysis of compatibility between solutes and solvents was carried out using Hansen solubility parameters. The thermodynamic functions of ΔsolH0, ΔsolS0, ΔsolG0 were calculated according to the van’t Hoff equation, indicating that the dissolution was an entropy-driven heat absorption process. The Conductor-like Screening Model for Real Solvents (COSMO-RS) combined with an experimental value was applied to predict the reasonable solubility data of dehydroabietic acid in the selected solvents systems. The interaction energy of the dehydroabietic acid with the solvent was analyzed by COSMO-RS.

Comparison of two computational methods for solvent screening in countercurrent and centrifugal partition chromatography

Countercurrent and centrifugal partition chromatography are techniques applied in the separation and isolation of compounds from natural extracts. One of the key design parameters of these processes is the selection of the biphasic solvent system that provides for the adequate partitioning of the solutes. To address this challenging task, the fully predictive Conductor-like Screening Model for Real Solvents (COSMO-RS) and the semi-predictive Non-Random Two-Liquid Segment Activity Coefficient (NRTL-SAC) model were applied to estimate the partition coefficients (K) of four model phenolic compounds (vanillin, ferulic acid, (S)-hesperetin and quercetin) in different solvent systems. Complementing the experimental data collected in the literature, partition coefficients of each solute in binary, or quaternary, solvent systems were measured at 298.2 K.Higher deviations from the experimental data were obtained using the predictive COSMO-RS model, with an average RMSD (root-mean-square deviation) in log(K) of 1.17 of all four solutes (61 data points), providing a satisfactory quantitative description only for the systems containing vanillin (RSMD = 0.57). For the NRTL-SAC model, the molecular parameters of the solutes were initially calculated by correlating a set of K and solubility (x, in mole fraction) data (16 partition coefficients and 44 solubility data points), for which average RMSD values of 0.07 and 0.41 were obtained in log(K) and log(x), respectively. The predictions of the remaining log(K) data (45 partition coefficients) resulted in an average RMSD of 0.43, suggesting that the NRTL-SAC model was a more reliable quantitative solvent screening tool. Depending on the amount of available solubility and partition data, both models can be valuable alternatives in the preliminary stages of solvent screening destined to select the optimal mobile and stationary phases for a given separation.

Deep eutectic solvents for the removal of lead contaminants in mangrove soil

The remediation of heavy metal contaminated mangrove soil with proper washing agents is critical for reducing the harmfulness of heavy metal contaminated soil to the environment. This work is aimed to investigate the potential of natural-based deep eutectic solvents as soil washing agents. Choline chloride (ChCl) and two organic acids, lactic acid and levulinic acid, are used as degradable and natural washing agents to remove Pb in the soil. Results verified that ChCl: Lactic Acid (1:2) [ChCl-LacA] and ChCl: Levulinic Acid (1:2) [ChCl-LevA] were found to be suitable for the removal of Pb from the contaminated soils, which significantly lowers the total Pb concentration in the soil. The high distribution ratio from the Conductor-like Screening Model for Real Solvents (COSMO-RS) screening gave an early indication that natural acid DESs are effective soil washing agents. The effect of washing agent concentration, soil to liquid ratio, contact time, and the interaction between acid DESs and metal ions was evaluated. ChCl-LacA and ChCl-LevA remove lead to 97% and 99%, respectively, under optimum conditions. ICP-MS, XRD, and FTIR spectroscopy analysis clarified the interaction between DES and metal ions. As a washing agent, green and natural DESs provide an environmentally sustainable alternative. Employing soil washing to remove heavy metals is a simple, rapid, and cheap remediation technology that could potentially be used in mitigating soil pollution.

Comparison of saturation vapor pressures of <i>α</i>-pinene + O<sub>3</sub> oxidation products derived from COSMO-RS computations and thermal desorption experiments

Abstract. Accurate information on gas-to-particle partitioning is needed to model secondary organic aerosol formation. However, determining reliable saturation vapor pressures of atmospherically relevant multifunctional organic compounds is extremely difficult. We estimated saturation vapor pressures of α-pinene-ozonolysis-derived secondary organic aerosol constituents using Filter Inlet for Gases and AEROsols (FIGAERO)–chemical ionization mass spectrometer (CIMS) experiments and conductor-like screening model for real solvents (COSMO-RS). We found a good agreement between experimental and computational saturation vapor pressures for molecules with molar masses around 190 g mol−1 and higher, most within a factor of 3 comparing the average of the experimental vapor pressures and the COSMO-RS estimate of the isomer closest to the experiments. Smaller molecules likely have saturation vapor pressures that are too high to be measured using our experimental setup. The molecules with molar masses below 190 g mol−1 that have differences of several orders of magnitude between the computational and experimental saturation vapor pressures observed in our experiments are likely products of thermal decomposition occurring during thermal desorption. For example, dehydration and decarboxylation reactions are able to explain some of the discrepancies between experimental and computational saturation vapor pressures. Based on our estimates, FIGAERO–CIMS can best be used to determine saturation vapor pressures of compounds with low and extremely low volatilities at least down to 10−10 Pa in saturation vapor pressure.

Evaluation of Deep Eutectic Solvent Performance for the Extraction of Free 3‐Monochloropropane‐1,2‐diol (3‐MCPD) from Model Oil – COSMO‐RS and Experimental Validation

AbstractMany precautionary elements are associated with food safety, including the elimination or reduction of contaminants below tolerable daily intake. However, efforts have yet to provide a long‐term sustainable solution. Here, the use of conductor‐like screening model for real solvent (COSMO‐RS) is employed to screen 53 potential solvents for the sustainable extraction of 3‐monochloropropane‐1,2‐diol (3‐MCPD) from model edible oil for the first time. The sigma profiles of the five best deep eutectic solvents (DESs) with high selectivity and capacity are found to confirm their interaction with 3‐MCPD at nonpolar and hydrogen bond donor regions. COSMO‐RS is further utilized to validate the extractive viability of two selected DESs. As quantified using 1H NMR, tetrabutylammonium bromide/sulfolane (1:7) exhibits the highest relative percentage removal of 3‐MCPD, followed by zinc chloride/glycerol/H2O (1:2:1) in only a single extraction cycle. The reliability of the extraction and quantification methods is established by acquiring five‐point calibration linearity and relative standard deviation.Practical applications: Following recent regulatory limits imposed by the European Union, the palm oil industry is instructed to adhere to the new maximum threshold for 3‐MCPD and its esters. This work can potentially elevate the image of the palm oil industry by providing a practical and reliable solution to tackle the food safety issue.

Ionic liquid screening of Octachlorodibenzo-p-dioxin captured from water samples by [formula omitted]-profile analysis for microextraction applications

The extraction of octachlorodibenzo-p-dioxin (OCDD) is very challenging due to its highly non-polar nature, demanding the use of large amounts of toxic solvents. Ionic Liquids (ILs) for OCDD extraction were screened to replace traditional solvents using the Conductor-like Screening MOdel for Real Solvents (COSMO-RS). The analysis was performed by studying the σ-profile of a variety of commercially available cations and anions employed in the literature. The effects of different alkyl chain lengths and configurations were studied in cations. In the case of anions, different reported structures, including fluorine- or oxygen-bearing structures, were assessed. Results indicate that the alkyl chain, symmetry, and nature of the central atom in the cations are critical factors to achieve high affinity to OCDD. The polarity of anions was found to be modified by adding highly electronegative atoms, a steric hindrance to the central atom and the use of planar geometries with symmetrical groups. The performance of ILs for extracting OCDD was compared with that of conventional solvent extractants used for quantifying dioxins in the US EPA-1613 method. Finally, three cations and anions are proposed as candidates for dioxin extraction.

Retraction of "Challenges in Predicting Aqueous Solubility of Organic Molecules Using the COSMO-RS Model".

The conductor-like screening model for real solvents (COSMO-RS) is an emerging tool for predicting the thermodynamic properties of small molecules, such as activity coefficients, vapor pressure, and solubility in mixed solvents. We have evaluated the validity and performance of the COSMO-RS model in predicting aqueous solubility using a high-fidelity experimental data set containing 1852 small organic molecules. Our analysis indicates that overreliance on distributions of the screening charge densities on the outer surface of the molecule, known as the σ-profile, leads to frequent overestimation or underestimation, rendering the predicted aqueous solubility of organic molecules unreliable. Despite our efforts to refine the inherent parameters of the COSMO-RS model using a comprehensive experimental data set, the prediction accuracy remained limited (R2 ∼ 0.5). We analyzed the correlation between prediction accuracy and common molecular descriptors, such as dipole moment, molar mass, symmetry of charges, and types of charge centers. A notable challenge of COSMO-RS prediction arises from the electronegative atoms, which likely generate uneven charge distributions in the σ-profile, leading to overtly strong hydrogen bond corrections and thereby causing overestimation of aqueous solubilities.

Measurement and correlation of the solubility of kojic acid in pure and binary solvents

The solubility of kojic acid in seven pure solvents (isopropanol, n-butanol, 2-butanol, n-pentanol, acetonitrile, methyl acetate, THF) and two binary solvents (2-methoxyethanol + water, 2-ethoxyethanol + water) were determined from 278.15 K to 323.15 K under 101.3 kPa by the gravimetric method. Besides, the modified Apelblat equation, λh model, van't Hoff model, NRTL model, Wilson model and UNIQUAC model were selected to correlate the experimental data in pure solvents, and the modified Apelblat equation, λh model, van't Hoff model, NRTL model, CNIBS/R-K model and the modified Apelblat-Jouyban-Acree model were applied for binary solvents. The results indicated that in this work the modified Apelblat model had the highest accuracy among those semi-empirical models, while UNIQUAC model was the most representative local component model with the best fitting effect among all models. The solubility of kojic acid in all the tested pure and binary solvent systems monotonously increased with increasing of the temperature. Under the isothermal condition, the solubility value of kojic acid increased first and then decreased with the increase of the mass fraction of 2-methoxyethanol and 2-ethoxyethanol, and reached the maximum value when the mass fraction of 2-methoxyethanol and 2-ethoxyethanol were 0.9 and 0.7, respectively. The solubility parameters of solvents were determined by the improved mixing rule. According to the solubility parameters obtained, the co-solvency in the binary solvent mixtures can be explained. To further explain the observed phenomena, the molecular electrostatic potential surface (MEPS), Hirshfeld surface analysis (HS) and KAT-LSER model were applied. Furthermore, the standard thermodynamic properties of the mixtures, including Gibbs energy, entropy and enthalpy were calculated and discussed, which indicated that the dissolution of the kojic acid in all solvents was spontaneous and entropy-driven. The conductor-like screening model for real solvents (COSMO-RS) was also applied to calculate solvation free energy of kojic acid in the studied solvents. The results showed a reasonable explanation to the dissolution behavior of kojic acid.

Ionic liquids design for efficient separation of anthracene and carbazole

• COSMO-RS is applied to screen ionic liquids for separation of anthracene and carbazole. • The anthracene with high purity can be obtained by ionic liquids. • The anthracene and carbazole do not form solid solutions in Ionic liquids. • The separation mechanism of anthracene and carbazole in Ionic liquids is discussed. Anthracene (ANT) and carbazole (CAR) are highly value-added compounds in chemical industry. They are always mixed in preliminary processing products of high temperature coal tar and need to be separated and purified. In this study, ionic liquids (ILs) were used to separate ANT and CAR. [C 3 PY], [PM 2 IM] and [PMPIP] cations along with 7 classes of anions were screened by the conductor-like screening model for real solvents (COSMO-RS). [PMPIP][TFAc] (IL a ) and [PMPIP][Ac] (IL b ) were selected and synthesized. The structures of ILs were studied by σ-profile at the micro-level to analysis the hydrogen bonds formed between anion of ILs and H-N of CAR. The ternary phase diagrams of ANT-CAR-ILs were plotted to analysis the separation efficiency. Two ILs were used as extractant to separate ANT and CAR. The separation results showed that the synthesized ILs were the highly efficient solvents. The purity of refined ANT separated by IL b was improved to 97.87 wt%, with a yield of 80.04 wt%. The separation mechanism of ANT and CAR was further discussed.

Screening ionic liquids for dissolving hemicellulose by COSMO-RS based on the selective model.

The utilization of biomass resources has attracted more and more attention due to the consumption of non-renewable resources. Compared with cellulose and lignin, hemicellulose has been less studied. Some ionic liquids (ILs) have been proved to be excellent solvents for lignocellulosic pretreatment. However, screening of more efficient ILs is difficult due to numerous possible ILs. Computational chemistry has been proved effective in solvent screening, but a precise model is indispensable. In this work, we focused on building several appropriate models and selected the most suitable one. According to the structure of hemicellulose, six hemicellulose models were constructed and the mid-dimer of the xylan chain hemicellulose (MDXC) model was proved to be the best compared with the reported experimental results. Based on the MDXC model, 1368 ILs were screened to evaluate their ability to dissolve hemicellulose by Conductor-like Screening Model for Real Solvents (COSMO-RS). The activity coefficient (γ), excess enthalpy (HE), and σ-profile indicated that the hydrogen-bond (H-bond) played a vital role in the dissolution of hemicellulose. Anions played a more critical role than cations, where small anions with H-bond acceptor groups could enhance the molecular interactions with hemicellulose. This work provided a thermodynamic understanding of hemicellulose and IL solvent systems. It highlights the importance of building appropriate solute models, which may be necessary to predict of the other thermodynamic properties in the future.

Efficient Extraction of Fermentation Inhibitors by Means of Green Hydrophobic Deep Eutectic Solvents.

The methods for hydrogen yield efficiency improvements, the gaseous stream purification in gaseous biofuels generation, and the biomass pretreatment are considered as the main trends in research devoted to gaseous biofuel production. The environmental aspect related to the liquid stream purification arises. Moreover, the management of post-fermentation broth with the application of various biorefining techniques gains importance. Chemical compounds occurring in the exhausted liquid phase after biomass pretreatment and subsequent dark and photo fermentation processes are considered as value-added by products. The most valuable are furfural (FF), 5-hydroxymethylfurfural (HMF), and levulinic acid (LA). Enriching their solutions can be carried with the application of liquid–liquid extraction with the use of a suitable solvent. In these studies, hydrophobic deep eutectic solvents (DESs) were tested as extractants. The screening of 56 DESs was carried out using the Conductor-like Screening Model for Real Solvents (COSMO-RS). DESs which exposed the highest inhibitory effect on fermentation and negligible water solubility were prepared. The LA, FF, and HMF were analyzed using FT-IR and NMR spectroscopy. In addition, the basic physicochemical properties of DES were carefully studied. In the second part of the paper, deep eutectic solvents were used for the extraction of FF, LA, and HMF from post-fermentation broth (PFB). The main extraction parameters, i.e., temperature, pH, and DES: PFB volume ratio (VDES:VPFB), were optimized by means of a Box–Behnken design model. Two approaches have been proposed for extraction process. In the first approach, DES was used as a solvent. In the second, one of the DES components was added to the sample, and DES was generated in situ. To enhance the post-fermentation broth management, optimization of the parameters promoting HMF, FF, and LA extraction was carried under real conditions. Moreover, the antimicrobial effect of the extraction of FF, HMF, and LA was investigated to define the possibility of simultaneous separation of microbial parts and denatured peptides via precipitation.

Integrating Technoeconomic, Environmental, and Safety Criteria in Solvent Screening for Extraction Processes: The Case of Algae Lipid Extraction

Volatile organic solvents derived from fossil resources are typically used in extraction processes, but this usually involves high energy consumption for solvent recovery and negative environmental impacts due to solvents’ hazardous, volatile, and flammable nature. This study presents a systematic approach to solvent screening, using molecular and process simulation techniques, data analysis, and classification methods applying technoeconomic, environmental, and safety criteria. This methodology is demonstrated for lipid extraction from wet algae biomass in biofuel production. First, relevant thermodynamic equilibrium data are predicted with the Conductor-like screening model for real solvents (COSMO-RS) method. The resulting solvents are clustered according to their partition coefficient and selectivity toward the target solute and then screened further, considering their physicochemical properties and health, safety, and environmental (HSE) performance. Finally, the lipid extraction process is simulated in Aspen Plus using all screened solvents to obtain technical, economic, and environmental performance data. Out of 88 initial candidates, cyclohexane, limonene, and ethyl tert-butyl ether are identified as potential alternatives to the benchmark solvent, hexane. While these solvents tend to be more expensive and their recovery is more energy-intensive (higher boiling points) compared to hexane, they have a higher selectivity toward lipids, thus reducing the solvent intensity of the process, and are less volatile and nonhazardous according to the HSE classification. This methodology can be applied to other extraction process applications or implemented at early stages in the process design to evaluate technoeconomic, environmental, and safety trade-offs when considering and selecting more sustainable alternatives to fossil-derived solvents.

Development of quantitative structure-property relationship to predict the viscosity of deep eutectic solvent for CO2 capture using molecular descriptor

Transport properties of deep eutectic solvent (DES), such as viscosity, are essential for selecting and designing processes based on these “green solvents” for CO2 capture and separation. Although experimental values for the viscosity of DES are available for a large number of systems, the number of potential hydrogen bond acceptors and hydrogen bond donors to form eutectic mixtures make the experimental characterization and screening of these systems impractical. A computational method able to predict the viscosity of DES would be highly valuable. The present study is aimed to develop a method to predict the viscosity of DESs using interaction energy descriptors derived from Conductor like Screening Model for Real Solvent (COSMO-RS). The stepwise multiple linear regression was implemented to select the optimal number of molecular descriptors and temperature based on an extensive database covering 947 viscosity data points for a wide range of DESs. The new model showed a good correlation between experimental and predicted values, with R-squared (R2) and average absolute relative deviation (AARD) of 0.9734 and 15.22%, respectively, for the overall dataset. In addition, the model showed that the viscosity of DES was significantly influenced by the hydrogen bonding between the anion of the hydrogen bond acceptor and the hydrogen bond donor molecules. The electrostatic-misfit and van der Waals forces were shown to have a marginal impact on the viscosities. In conclusion, the developed model provides an effective tool to predict the viscosity of DES and allows a fundamental understanding of the molecular level interactions on this property.