Search

Cresols are valuable phenolic chemicals which are mainly separated from coal tar. The separation of cresols using sustainable technology is of importance for comprehensive utilization of coal tar. In this work, for extracting o‐, m‐, and p‐cresol from the model coal tar, an ionic liquid 1‐ethyl‐3‐methylimidazolium dicyanamide ([Emim][DCA]) was prepared. The influence of ionic liquid dosage, extraction time, and temperature on separating o‐, m‐, and p‐cresol was explored. The extraction efficiency was determined from the experimental results to assess the extraction ability of [Emim][DCA]. With the optimal conditions, o‐, m‐, and p‐cresol were extracted efficiently from the model coal tar and the extraction efficiencies of o‐cresol, m‐cresol, and p‐cresol were up to 99.50%, 99.65%, 98.38%, respectively. In the meantime, the extraction mechanism was determined by calculation of σ‐profile, interaction energy, and electron density. The results showed that [Emim][DCA] and cresols formed the complexes by hydrogen bond. The formation of hydrogen bond was verified by the FTIR spectra, which is helpful for designing the related ionic liquids for recovering the phenolic compounds from coal tar. In addition, the recyclability of the [Emim][DCA] was explored. [ABSTRACT FROM AUTHOR]

BACKGROUND 2,2,3,3‐Tetrafluoro‐1‐propanol (TFP) is a benign solvent and widely used in the electronics industry as a cleaning agent. Because water and TFP can form an azeotropic mixture, it consumes energy to separate TFP from its aqueous mixtures using conventional distillation. RESULTS: In this work, the zeolitic imidazolate framework‐8 porous ionic liquid (ZIF‐8‐PIL) and the ionic liquid (IL) N‐butyl pyridinium bis(trifluoromethyl sulfonyl) imide ([Bpy][NTf2]) are used as extractants to extract TFP from its aqueous solution. ZIF‐8‐PIL was synthesized by ZIF‐8 and IL [Bpy][NTf2]. The liquid–liquid equilibrium (LLE) data for the two systems (water + TFP + ZIF‐8‐PIL/IL) were determined at 298.15, 308.15 and 318.15 K under 101.3 kPa. The selectivity (S) and distribution coefficient (D) were examined to assess the extractive performance of ZIF‐8‐PIL and IL. The non‐random two‐liquid (NRTL) model was applied to fit the tie‐line data of the investigated mixtures. CONCLUSION: The results demonstrate that ZIF‐8‐PIL is a suitable extractant to separate TFP with values of S and D greater than unity. The NRTL model has better correlation performance for the ternary systems with root mean square deviation lower than 0.01. The obtained parameters satisfy the minimum state of the mixed Gibbs free energy, which indicated that the model parameters are reliable. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

BACKGROUND Phenol is an important chemical and has many applications in industry. It is mainly produced from coal tar. At present, the commonly used method in industry is caustic washing, which produces a lot of wastewater containing phenolic components, resulting in environmental contamination. Herein, a dual‐functionalized ionic liquid, 1‐hydroxyethyl‐3‐methylimidazolium propionate, was synthesized as a candidate for recovering phenol from a coal tar oil mixture. RESULTS: The performance of the ionic liquid was investigated by extraction experiments with various factors, including phase ratio, contact temperature and contact time. The optimal separation conditions for removing phenol using the ionic liquid were as follows: mDFIL:moil = 1:5; contact temperature, 25 °C; contact time, 30 min. The corresponding removal efficiency was 95.9%. The intermolecular interaction for separating phenol with the ionic liquid was verified to be hydrogen bond attraction using quantum chemical calculations and Fourier transform infrared spectrometry. CONCLUSIONS: The experimental and calculated results showed that 1‐hydroxyethyl‐3‐methylimidazolium propionate was a suitable extractant for removal of phenol from the oil mixture. This provides a reference for the dephenolization process of coal tar in industry. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have been applied as a promising solvent for the separation of different kinds of compounds. But the enormous combination possibilities of the cations and anions make it a challenging task to screen an appropriate IL for a specific application. Thus, the method for screening IL candidates based on the COSMO-SAC model is presented and illustrated to extract heterocyclic nitrogen compounds, indole and carbazole, from coal tar fractions. Also, the σ-profile analysis is used to evaluate the effect of different types of cations and anions, and systematically confirmed the structure–activity relationships for the extraction process. Then, 22 cations and 19 anions are screened as the initial structures of the potential extractants from a σ-profile database (containing 39 cations and 29 anions). Along with the rigorous evaluation criterion proposed in this work, three IL extractants are adopted. Afterwards, the extractive ability of the candidates is experimentally investigated. [ABSTRACT FROM AUTHOR]

• Three ILs [Bmim][H 2 PO 4 ], [Emim][PF 6 ] and [Bmim][PF 6 ] were used to extract IPA. • The LLE data for IPAC + IPA + ILs were determined and correlated. • The interactions between the ILs and IPA were explored. • [Bmim][H 2 PO 4 ] is a suitable extractant to recover IPA from IPAC. During the production of isopropyl acetate (IPAC), a mixture of IPAC and isopropanol (IPA) can be produced. Because IPAC and IPA can form a minimum azeotropic mixture with the azeotropic temperature of 354.08 K, it is difficult to separate such a mixture. In this work, liquid-liquid extraction is considered to separate the mixture of IPAC and IPA. Herein, the liquid-liquid equilibrium (LLE) data was determined and correlated for the separation of IPAC and IPA. For separating IPAC and IPA by extraction, three ionic liquids (ILs) 1-ethyl-3-methyl-imidazolium hexafluorophosphate, 1‑butyl‑3-methyl-imidazolium hexafluorophosphate and 1‑butyl‑3-methyl-imidazolium dihydrogen phosphate were selected as extractants. The liquid-liquid equilibrium phase behavior of ternary mixtures (IPAC + IPA + ILs) at 298.15 K was investigated. The distribution functions of charge density and interaction energy were determined by the COSMO-SAC model and Dmol3 in Materials Studio, and the interactions between molecules were explored. The experimental data showed that the three ILs can extract IPA from the mixture of IPAC and IPA and the IL [Bmim][H 2 PO 4 ] has a better extraction ability compared to the other ILs. The measured LLE data were fitted using the NRTL model and the interaction parameters were regressed, which is a favor in separating the mixture for industrial practice. [Display omitted] [ABSTRACT FROM AUTHOR]

As a hopeful solvent, ionic liquids with tremendous combination of functional chemical sites in the cations and anions can make the separation process efficiently and selectively. Thus, to test the effect of the functional chemical sites in the cations and anions on extracting typical heterocyclic N -compound, indole was adopted as the representative compounds due to its high content and valuable application. In present work, NMP-based IL, [EtOHpyr][BuRA], with dual functional chemical sites was designed and employed to separate indole from diverse resources. The mechanism for the separation process was explored, the IL is evaluated to separate indole with the polarity analysis based on the COSMO-SAC model. Molecular dynamics simulation analysis contributed to understand the H-bonds interaction between indole and IL more indicative. The results demonstrated that the H-bonds between indole and dual functional chemical sites in [EtOHpyr][BuRA] served as the key driving force during the separation process. To validate the effect of functional chemical sites, [EtOHpyr][BF 4 ], [Etpyr][BuRA] and [Etpyr][BF 4 ] were also used for comparison. Furthermore, the influence of extraction of NMP-based ILs on indole, mass ratio (IL: model oil) and extraction temperature were investigated. Under the optimal conditions (25 ℃, mass ratio = 1:5), [EtOHpyr][BuRA] showed the best performance among those four ILs, which extraction efficiency can reach up to 95.15 wt%. The results agreed with the simulation results well. This work can provide an efficient designed ILs for the extraction of indole. [Display omitted] • The designed [EtOHpyr][BuRA] with dual functional chemical sites was used to separate indole. • The extraction mechanism was explored by MD simulations and QC calculations. • H-bonds between indole and [EtOHpyr][BuRA] served as the key driving force. • [EtOHpyr][BuRA] has the highest extraction efficiency of 95.15% among the four ILs. [ABSTRACT FROM AUTHOR]

To reduce the impact of nitrogen-containing aromatic compounds on environment during utilization of low-temperature coal tar (LTCT), it is necessary to extract indole from LTCT. In this study, two kinds of tetramethylguanidine-based ionic liquids (ILs) 1,1,3,3-tetramethylguanidine perchlorate ([TMG][ClO 4 ]) and 1,1,3,3-tetramethylguanidine lactate ([TMG][Lac]) were applied as the extractants to extract indole from the LTCT model oil. The ILs were synthesized by a one-step method and characterized by 1H NMR. The extraction performance of the ILs was evaluated using extraction efficiency (EE). The EE values are 95.2% for [TMG][Lac] and 81.9% for [TMG][ClO 4 ] with the extraction time of 30 min and the mass ratio of ILs to model oil (m IL / m oil) 0.1 at 298.15 K. The results showed that [TMG][Lac] had higher EE compared to [TMG][ClO 4 ] with the same extraction conditions. Meanwhile, the interactions between the IL [TMG][Lac] and the nitrogen-containing aromatics in the LTCT model oil were studied using the molecular dynamics (MD) simulations and quantum chemical (QC) calculations. The results showed that the H-bond between indole and the ILs was the driving force in extracting indole from the LTCT model oil, which helps design the related ILs for separating the nitrogen-containing aromatic hydrocarbons from LTCT. [Display omitted] • Two TMG-based ILs were prepared as the extractants for separating indole. • [TMG][Lac] is a suitable extractant with better performance for extracting indole. • The extraction mechanism was explored by MD simulations and QC calculations. • [TMG][Lac] can be regenerated and reused without significant change in EE. [ABSTRACT FROM AUTHOR]

Isopropyl alcohol (IPA) and diisopropyl ether (DIPE) are widely used as biofuel additives in fuel processing. When IPA is produced by propylene hydration, a by-product IPA and DIPE is made. Since the existence of azeotropic point formed between IPA and DIPE, the separation of the azeotrope is achieved using special distillation technologies in industry, which requires high energy consumption. Liquid-liquid extraction was used to separate the mixture due to its energy saving in this work. Three imidazolium-based ionic liquids (ILs) 1-butyl-3-methylimidazolium thiocyanate ([BMIM]SCN), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]NTf 2) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF 4) were synthesized as the extractants. The influence of extraction time, extraction temperature, mass ratio of mixture (IPA + DIPE) to ILs and the initial content of IPA in the mixture (IPA + DIPE) on the extraction performance of ILs were studied. The optimal extraction conditions were determined using the response surface method (RSM). The results showed that the IL [BMIM]SCN had better extraction capacity for separation of the mixture (IPA + DIPE). The interactions between molecules were investigated by quantum chemical calculations. Finally, a conceptual separation process is designed to separate the mixture, which can provide a helpful technology to purify the biofuel additives. • Three ILs [BMIM]SCN, [BMIM]NTf 2 and [BMIM]BF 4 were synthesized as extractants to separate mixture (IPA + DIPE). • The extraction performance of the ILs was assessed and the optimal conditions were determined by RSM. • The interactions between IPA and the ILs were analyzed by quantum chemical calculations. • A separation process for purification of IPA and DIPE is proposed with [BMIM]SCN as the extractant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four green morpholino-based ionic liquids were synthesized in one step for the separation of NHNCs. • [C 1 Mor][PA] has multiple interaction sites. • Hydrogen bonding and van der Waals forces were shown to be the driving forces for extraction. • The extraction efficiency of [C 1 Mor][PA] for indole and pyrrole can reach 94.16% and 93.05%. • [C 1 Mor][PA] is renewable and the extraction efficiency is basically unchanged after recycling for many times. The separation of neutral heterocyclic nitrogen compounds (NHNCs) from coal tar contributes to the rational utilization of coal tar resources while reducing environmental pollution. In this study, four green morpholino-based ionic liquids were synthesized through a one-step scheme and utilized for extracting indole and pyrrole. The research findings showed that the anionic surface of the N -methyl morpholine pyruvate extractant, [C 1 Mor][PA], exhibits multiple interaction sites, which facilitates the extraction ability to interact with indole/pyrrole. Furthermore, its anion formed N–H⋯O hydrogen bonds with indole/pyrrole (also validated by infrared spectroscopy), while its cation was observed to form van der Waals forces interactions. Subsequently, experimental tests were employed to determine the extraction efficiency (EE) of [C 1 Mor][PA] for indole/pyrrole. High efficiencies were achieved under the optimal conditions. This work presents a simplified IL extractant and a more effective method for extracting potentially pollutant and high-value-added NHNCs. Also, to understand the molecular interactions between its complexes would have significant implications in developing more effective extraction techniques for indole and pyrrole. These discoveries have played an essential role in reducing atmospheric pollution and alleviating environmental issues, paving the way for subsequent developments in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyl-functionalized IL was prepared to separate phenols from LTCT. • The separation efficiency is higher than 98% for four phenols. • The intermolecular interactions were explored by MD simulations. • The IL [C 2 OH-4-pic][NO 3 ] can be regenerated without loss. Phenols are valuable chemicals and widely applied in chemical industry, which have a high content in coal cracking oils. The separation of phenols from coal tar oils is of significance. Usually, the caustic washing technology is adopted in industry, which is environmental unfriendly due to the discharge of a large amount of waste water. This work aims to effectively recover the high-added value phenolic compounds from coal tar oil using m -cresol as a typical phenolic compound by means of a hydroxyl supported ionic liquid N -hydroxyethyl-4-picoline nitrate ([C 2 OH-4-pic][NO 3 ]). The ionic liquid (IL) ([C 2 OH-4-pic][NO 3 ]) was synthesized and characterized by 1H NMR. The factors of separation temperature, mass ratio of IL to coal tar model oil, extraction time and coexistent aromatic content in coal tar model oil were investigated. Also, the extraction performance of the prepared IL for the different phenolic components were explored. The separation efficiency (E) of [C 2 OH-4-pic][NO 3 ] were 98.99% for m -cresol, 98.39% for o -cresol, 98.65% for p -cresol and 99.99% for phenol at 298.15 K with the mass ratio of 1:5 and the extraction time of 30 min. Afterwards, the intermolecular interactions between the IL and m -cresol were investigated by calculating the spatial and radial distribution function, averaged noncovalent interaction and self-diffusivity using molecular dynamics (MD) simulations and the formation of hydrogen bond was validated by FT-IR. The regeneration of [C 2 OH-4-pic][NO 3 ] was performed and was characterized by 1H NMR. Finally, the separation process was designed based on the above exploration. [ABSTRACT FROM AUTHOR]

• LLE data of 1-methoxy-2-propanol + water + extractants were measured. • The suitable extractant was discussed by partition coefficient and selectivity coefficient. • Explain the microscopic relationship of molecular structure by quantum chemical calculation. 1-Methoxy-2-propanol (PM) is extensively utilized in various industries, including coatings and semiconductor applications, owing to its low toxicity and affordability. However, PM + water mixture was an azeotrope with lowest boiling point, which presents a challenge in separating azeotropic mixture for industrial production. In this study, selectivity coefficient (S cal) and extractant loss (S L) were calculated using the open-source COSMO-SAC model by evaluating its activity coefficients at infinite dilution. Then, four extractants, butyl propionate, butyl acetate, 4-methyl-2-pentanone (MIBK) and isobutyl alcohol, were selected and verified. The ternary liquid–liquid equilibrium (LLE) data measurement for water + PM + butyl propionate/ butyl acetate/MIBK/ isobutyl alcohol systems were achieved at 298.15 K and 101.3 kPa. In addition, distribution coefficient (D) and selectivity coefficient (S) were calculated by the achieved data and used as indexes to further judge the performance of the extractants. Meanwhile, the widely adopted NRTL activity coefficient model was applied to regress LLE data, the corresponding root mean square deviation (RMSD) was less than 0.008. Accuracy of the regressed binary interaction parameters were evaluated through the Gibbs energy topology analysis. Besides, the possible extraction ability was investigated and confirmed at the micro level, of which the electrostatic potential (ESP), H-bond length, complexes' interaction energy were explored. Further, the radial distribution function (RDF) was achieved by molecular dynamics (MD) simulation to further explain its interactions. This study can provide new theoretical guidance for organic extractants selection,then used for the separation of PM from azeotropic mixtures. [ABSTRACT FROM AUTHOR]

Three cresol isomers (o -, m -, and p -cresols) derived from coal-based products are valuable compounds mainly used in the fine chemical and pharmaceutical industries. For the clean production of cresols without using strong acid and alkali aqueous solutions, liquid-liquid extraction was adopted, and four eco-friendly amine ionic liquids (AILs) were synthesized and characterized as extractants. The toxicity of AILs was evaluated using an algal toxicity assessment. The results showed that AILs can be considered practically nonharmful. The effects of stirring time, m AILs : m mixtures , extraction temperature, and initial content for extraction of cresols were investigated. The results showed that the AILs exhibited better performance for the extraction of the three cresol isomers. At the initial cresol content of m cresol : m oil = 1:10, the AIL N,N,N′,N′ -tetramethylguanidine acetate ([N-tmg][Ac]) could extract cresols with an extraction efficiency of more than 97% under the optimal extraction conditions m AILs : m mixtures = 1:5, stirring time of 30 min, temperature of 25 °C. In addition, the intermolecular interactions were analyzed using quantum chemistry calculations. The results demonstrated that the hydrogen bonds (H-bonds) formed between the anions in the AILs and the phenolic hydroxyl groups of cresols were the major driving forces for the extraction of cresols. Finally, the reusability of the [N-tmg] [Ac] and [TEA] [Ac] AILs was explored, and the recovered AILs were confirmed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Compared with traditional technologies that utilize strong acid and alkali aqueous solutions, the proposed method can avoid the discharge of acid and alkali wastewater, providing a promising route for the cleaner production of cresols from coal-based products. [Display omitted] • Four eco-friendly AILs were prepared as the extractants for separating cresols. • The algae toxicity assessment showed that four AILs were actually harmless. • Four AILs were suitable extractant with better performance for extracting cresols. • The intermolecular interactions were explored by quantum chemistry calculations. • The AILs were regenerated for reusability without significant change in EE. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thiourea based ILs for separation of Cu2+ from water were synthesized. • Pseudokirchneriella subcapitata was used to test the toxicity of ILs. • A model of cyclic extraction was proposed. • The mechanism of decreasing toxicity and improving E was discussed. With the increasing pressure on environmental protection, it was important to achieve an environmentally friendly and efficient medium to separate Cu2+ from electroplating wastewater. Therefore, two thiourea based hydrophobic ILs were screened and synthesized, which could be used as efficient extractants to extract Cu2+ by introducing ethyl and carboxyl groups as functional groups. A three-step method was adopted, then its structure was characterized. Meanwhile, the extraction experiments were optimized, and the extraction mechanism was explored by electrostatic potential analysis and FT-IR characterization. The extraction efficiency (E) of the adopted ILs reached to 96% and 99%, respectively, under 298.15 K and the ratio of extractant to solution to be extracted 1:50. The circulation extraction was investigated under the optimal conditions, it was proved that the adopted ILs had good separation result. Meanwhile, Pseudokirchneriella subcapitata was selected as the object of ILs toxicity test. The values of the concentration for 50% of maximal effect (EC 50) were 1-(3-isopropylthiourea propyl) imidazole hexafluorophosphate ([HIPSM][PF 6 ]): 79.09 mg/L and 1-(3-isopropyl thiourea carboxyethyl) imidazole hexafluorophosphate ([ITPSCM][PF 6 ]): 177.5 mg/L, respectively. σ -profile polarity analysis was adopted to judge the change of interaction between ILs and non-polar biofilm and deduced the principle of toxicity reduction. The results showed that the introduction of carboxyl group not only improved the E , but also reduced the ecological toxicity of the adopted ILs, making the adopted ILs more environmentally friendly. [ABSTRACT FROM AUTHOR]

To separate the azeotrope of ethanol and ethyl methyl carbonate (EMC) using ionic liquids (ILs), the σ-profiles of imidazolium-based ILs with different anions [BF 4 ] − , [HSO 4 ] − , [PF 6 ] − and [ClO 4 ] − were calculated by the COSMO-SAC model. Based on the analysis results, 1-ethyl-3-methylimidazolium hydrosulfate ([Emim][HSO 4 ]), 1-propyl-3-methylimidazolium hydrosulfate ([Prmim][HSO 4 ]), 1-butyl-3-methyl-imidazolium hydrosulfate ([Bmim][HSO 4 ]) were selected as extractants to separate ethanol and EMC. The liquid-liquid tie-line data for the ternary systems ethanol + EMC + ILs were measured at 298.15 K under 101.3 kPa, and the influence of ILs with the different alkyl chain length of the cations on the phase behavior was explored. The distribution coefficient and selectivity were calculated to evaluate the extraction capacity of the studied ILs. Meanwhile, the NRTL model was adopted to correlate the experimental results, and the interaction parameters of the NRTL model were also optimized. [ABSTRACT FROM AUTHOR]

The mixture of propylene glycol methyl ether and water form a minimum-boiling azeotrope. To separate the binary azeotropic system, energy-saving liquid–liquid extraction combined with either heterogeneous azeotropic distillation or extractive distillation processes based upon traditional two-column heterogeneous azeotropic distillation and three-column extractive distillation processes were proposed, using chloroform and 2-ethylhexanoic acid as solvents, respectively. The minimum total annual cost (TAC), based on a sequential iterative optimization procedure, and CO 2 emissions for the two processes were determined. Liquid–liquid extraction combined with heterogeneous azeotropic distillation process achieved significant reductions of 40.24% in the TAC and 45.37% in CO 2 emissions compared with the traditional two-column heterogeneous azeotropic distillation process. The liquid–liquid extraction combined with extractive distillation process achieved TAC and CO 2 emission reductions of 34.18% and 43.95%, respectively, compared with the traditional three-column extractive distillation process. Thus, the two processes are more attractive in terms of both economics and environmental protection. [ABSTRACT FROM AUTHOR]

To separate isopropanol from its aqueous solution, isobutyl acetate, butyl acetate and butyl propionate were adopted as the extractive solvents, and the liquid-liquid equilibrium (LLE) data for the ternary systems (isobutyl acetate / butyl acetate / butyl propionate) + isopropanol + water were determined at 298.15 K and 308.15 K under atmospheric pressure. The experimental LLE data were correlated by the NRTL and UNIQUAC models, and the values of the root mean square deviations ( RMSD ) were less than 1%. And the binary interaction parameters of the NRTL and UNIQUAC models were optimized. Meantime, the distribution coefficient and selectivity were calculated to evaluate the extraction capacity of the solvents. As a result, butyl propionate is a desirable extractive solvent compared with the other two solvents. [ABSTRACT FROM AUTHOR]

• 1. Three ILs [BMIM]SCN, [BMIM]DCA and [BMIM]NTf 2 were synthesized to extract IPA. • 2. The LLE data for the ternary mixtures DIPE + IPA + ILs were determined and correlated. • 3. The interactions between IPA and the ILs [BMIM]SCN / [BMIM]DCA / [BMIM]NTf 2 were explored. During production of isopropyl alcohol (IPA) by propylene hydration, a mixture of diisopropyl ether (DIPE) and IPA is obtained as a byproduct. Because DIPE and IPA have similar boiling points, an azeotrope can be formed. It is not feasible to separate the mixture (DIPE + IPA) using conventional distillation technology. In this work, the mixture (DIPE + IPA) was separated by liquid–liquid extraction and three imidazolium based ionic liquids (ILs) with different anions including 1-butyl-3-methylimidazolium thiocyanate ([BMIM]SCN), 1-butyl-3-methylimidazolium dicyanamide ([BMIM]DCA) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]NTf 2) were selected as the extractants. The effect of the ILs on liquid–liquid phase behavior for the ternary systems (DIPE + IPA + ILs) was discussed. Partition ratio (P) and selectivity (S) were calculated to assess the extraction ability of the ILs. The NRTL thermodynamic model was used to correlate the experimental data. The interactions between the ILs and (DIPE / IPA) were explored by analyzing electrostatic potentials, hydrogen bond length and reduced density gradient, which can help to design the ILs with reasonable structures for separating such azeotropic mixtures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three Mor-based ILs were synthesized and used for the separation of NHNCs. • Hydrogen bond and van der Waals forces as driving forces for extraction were proved. • The hydrogen bonds between [C 1 C 4 Mor][SCN] and NHNCs were verified by FT-IR. • [C 1 C 4 Mor][SCN] was recycled four times to maintain great extraction performance. Indole and pyrrole that are present in coal tar and fuel oil are representatives of nitrogen heterocyclic neutral compounds (NHNCs). On the one hand, the presence of NHNCs in the hydrodenitrogenation (HDN) process deactivated the catalyst while causing harm to the environment. On the other hand, NHNCs were irreplaceable basic raw materials and intermediates in industry. Therefore, the separation of NHNCs from oil was necessary. In this work, morpholine-based ionic liquids (Mor-based ILs) with low toxicity and biodegradability were considered as green extractants for NHNCs, three Mor-based ILs 1-methyl morpholine p -toluenesulfonate ([C 1 Mor][TOS]), 1-methyl morpholine benzoate ([C 1 Mor][BEN]) and 1-butyl-1-methyl morpholinium thiocyanate ([C 1 C 4 Mor][SCN]) were synthesized and then characterized by 1H NMR. All of them were applied to the extraction of NHNCs, and their extraction performance was evaluated by extraction efficiency (EE). The order of the EE for NHNCs was [C 1 C 4 Mor][SCN] > [C 1 Mor][TOS] > [C 1 Mor][BEN]. Based on this, the extraction conditions of the promising [C 1 C 4 Mor][SCN] were optimized, and the EE was 96.89 % and 95.62 % for indole and pyrrole, respectively. Moreover, quantum chemical (QC) calculations were adopted to evaluate the extraction performance at the microscopic nature of the differences, and the theoretical analysis and experiments agreed well with each other. Then the mechanism of NHNCs extraction by [C 1 C 4 Mor][SCN] was explored at the molecular level based on density functional theory (DFT). The results showed that N H⋯N hydrogen bonding interaction was formed between anion and NHNCs, while the cation interacted with NHNCs as van der Waals interaction. Finally, the reusability of IL was investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three biocompatible functionalized ionic liquids were synthesized for the separation of indole. • The polarity of biocompatible functionalized ionic liquids was analyzed. • The link between intramolecular and intermolecular interactions was discussed. • The results of theoretical analysis were verified by extraction experiments. Organic Lewis acid compounds such as indole were compounds with high added value and mainly distributed in coal-based fuel pyrolysis product. Traditional indole acquisition methods inevitably produce pollutants without atomic economy, so it was extremely urgent to develop a greener and more sustainable strategy to separate indole. Then, the relatively mild liquid–liquid extraction method was selected. In order to reduce the environmental pollution and ecological toxicity of the extractants themselves, three biocompatible functionalized ionic liquids (ILs) were synthesized by one-step reaction and their structures were characterized. The probable cites on ILs were explored by σ -profile and ESP analysis, pointing out that the presence of hydroxyl groups on cations and O atoms on anions showed higher polarities. And the intramolecular interactions of ILs can be enhanced by increasing the number of the hydroxyl group on cations. Moreover, the intramolecular interactions of ILs had an important impact on the intermolecular interactions between ILs and indole. The formed hydrogen bonds (H-bonds) and van der Waals interactions were confirmed as separation driving forces. Meanwhile, the viscosity of the ILs was analyzed. The factors affecting the extraction efficiency were explored and the extraction conditions optimized, which was consistent with the above theoretical analysis. This work sheds light on linking the intermolecular interactions between ILs and indole based on the detailed discussions of intramolecular interactions in ILs, which also provides an idea for the greener design of ILs to separate typical organic Lewis acid type compounds from coal-based fuel pyrolysis product. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three 2-pyrrolidone-based brønsted acidic ionic liquids were prepared for separating quinoline from coal-based products. • [NHPy]HSO 4 and [NEPy]HSO 4 are suitable extractants with better performance for removing quinoline compared to [NMPy]HSO 4. • The removal mechanism of quinoline was explored by quantum chemical calculations. • [NHPy]HSO 4 can be regenerated and reused without significant change in RE. To acquire high value-added alkaline polycyclic nitrogen compounds (PNC) from coal-based products, in this work, three N -alkyl-2-pyrrolidone based brønsted acidic ionic liquids (PBILs) N -hydro-2-pyrrolidone hydrosulfate ([NHPy]HSO 4), N -ethyl-2-pyrrolidone hydrosulfate ([NEPy]HSO 4) and N -methyl-2-pyrrolidone hydrosulfate ([NMPy]HSO 4) were used as denitrogenation agents to remove quinoline from coal-based product model mixtures. The denitrogenation performance of the PBILs was evaluated using removal efficiency (RE). The RE values of the three PBILs [NHPy]HSO 4 , [NEPy]HSO 4 and [NMPy]HSO 4 for quinoline were 97.47%, 97.33% and 97.05%, respectively, with the optimal extraction denitrogenation conditions mass ratio of PBIL to coal-based products model mixture (M PBIL : M oil), 1:5; extraction denitrogenation temperature, 25 °C; extraction denitrogenation time, 30 min and initial quinoline content, 5 wt%. In addition, the interactions between the PBILs and quinoline in the coal-based product model mixtures were analyzed with quantum chemical calculations. The results showed that the intermolecular hydrogen bond (H-bond) formed between PBILs and quinoline was the main driving force for removing quinoline, but the intramolecular interactions formed between the cation and anion of PBILs partially inhibited quinoline removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two Pyridine-based ILs [EAPy][NTf 2 ] and [OHPy][NTf 2 ] were used to extract TFP. • The extraction capacity of [EAPy][NTf 2 ] and [OHPy][NTf 2 ] was evaluated. • The intermolecular interactions between the ILs and TFP / water were explored. • [EAPy][NTf 2 ] is a suitable extractant to recover TFP from its aqueous mixture. 2,2,3,3-Tetrafluoro-1-propanol (TFP) is benign solvent and applied in electronic industry. To recover TFP from its aqueous solution by liquid–liquid extraction, in this work, two pyridine-based ionic liquids (ILs) 1-ethyl acetate-pyridine bis(trifluoromethane)sulfonimide ([EAPy][NTf 2 ]) and 1-hydroxyethyl-pyridine bis(trifluoromethane)sulfonimide ([OHPy][NTf 2 ]) were adopted as extractants. The ILs [EAPy][NTf 2 ] and [OHPy][NTf 2 ] were synthesized and characterized. The extraction performance of the prepared ILs for extracting TFP from its aqueous solution was explored by changing extraction temperature, extraction time and mass ratio of IL to TFP solution. The extraction efficiency of [EAPy][NTf 2 ] and [OHPy][NTf 2 ] was 90.24% and 88.45% with the mass ratio of IL to TFP solution of 1.0 and extraction time of 10 min at 298.15 K. The intermolecular interaction was investigated by quantum chemistry calculations and molecular dynamics simulations. The results indicated that O atom of the IL anion formed strong hydrogen bond with H atom of TFP. In addition, the functional groups on the cations of the ILs showed the van der Waals (vdW) interaction between the ILs and TFP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Protic ionic liquid [Hnmp]HSO 4 was prepared to extract pyridine from model mixture. • The extraction mechanism of the PIL [Hnmp]HSO 4 was explored by σ-profiles and FT-IR. • The extraction performance to separate pyridine using [Hnmp]HSO 4 was explored. Pyridine is an important raw material and has been applied in pharmaceutical industry, which is mainly derived from coal pyrolysis mixture. In this study, for investigating the extraction of pyridine from coal pyrolysis mixture, a protic ionic liquid (PIL) N-methyl pyrrolidone hydrosulfate ([Hnmp]HSO 4) was synthesized as the extractant to extract pyridine from the mixture of toluene and hexane as a representative of coal pyrolysis mixture. The extraction performance of the prepared PIL was explored with the different extraction temperature, extraction time, mass ratio of PIL to model mixture and initial pyridine content. The highest extraction efficiency of the PIL [Hnmp]HSO 4 was 96.82% with the optimal conditions. The extraction mechanism was explored using the σ -profiles calculated by the COSMO-SAC model and the calculated results show that the hydrogen bond plays an important role in extracting pyridine. In addition, the FT-IR spectra was adopted to validate the formation of intramolecular hydrogen bond between pyridine and the PIL. [ABSTRACT FROM AUTHOR]

• Three ILs [Emim][NTf 2 ], [Bmim][NTf 2 ] and [Hmim][NTf 2 ] were used to extract DFE. • The LLE data for water + DFE + ILs were determined and correlated. • The interactions between the ILs and DFE were explored. • [Hmim][NTf 2 ] is a suitable extractant to recover DFE from its aqueous mixture. 2,2-difluoroethanol (DFE) is a significant fine chemical in chemical industry. During its applications, an aqueous solution is often observed. Because DFE and water will form azeotropic mixture, it is infeasible to regenerate DFE from the mixture (DFE + water) by general distillation. In this research, for regenerating 2,2-difluoroethanol from its aqueous mixture by extraction, three hydrophobic imidazole-based ionic liquids (ILs), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Hmim][NTf 2 ]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf 2 ]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][NTf 2 ]) were picked as the extraction agents. The liquid–liquid phase behavior of the systems (water + DFE + ILs) were explored at 298.15 K and 101.3 kPa. The NRTL model was applied to regress the determined tie-line data. To assess the separating power of the three ionic liquids, selectivity (S) and distribution coefficient (D) for ILs were computed and compared. In addition, the σ-profiles, interaction energy, hydrogen bond length between the ionic liquids and (DFE/water) were computed to ascertain the interactions between the ILs and (DFE/water). [ABSTRACT FROM AUTHOR]

• Two ILs [BMP][Tf 2 N] and [OMIM][OTf] were selected to extract allyl alcohol. • The interactions between the ILs and allyl alcohol were explored. • The LLE data for water + allyl alcohol + ILs were determined and correlated. • The ILs extraction capability was assessed with selectivity and partition ratio. Allyl alcohol is a remarkable chemical intermediate. During its preparation by allyl acetate hydrolysis, an aqueous mixture is usually obtained. Because allyl alcohol can form a minimum boiling point azeotropic mixture with water, it is impossible to separate such a mixture by conventional distillation. In this work, for recovering allyl alcohol by extraction, the ionic liquid extractants (ILs) were adopted by the model of COSMO-SAC and two ILs 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP][Tf 2 N]) and 1-octyl-3-methylimidazolium trifluoromethanesulfonate ([OMIM][OTf]) were selected. The length of the hydrogen bond and the energy of the interaction between the ILs and (allyl alcohol/water) were calculated by quantum chemical calculations. The experimental liquid–liquid phase equilibrium (LLE) data for the ternary systems (water + allyl alcohol + [OMIM][OTf]/[BMP][Tf 2 N]) were explored at 298.15 K. The [OMIM][OTf] and [BMP][Tf 2 N] extraction capability was assessed with selectivity and partition ratio. In addition, the NRTL model was used to fit the measured tie-line values. [ABSTRACT FROM AUTHOR]

• Three ionic liquids were adopted to separate the azeotrope NBAC and NBA. • The LLE data for NBAC + NBA + ILs were measured and correlated by the NRTL model. • The interaction was explored by hydrogen bond length and interaction energy. • The influence of the carbon chain length of cations on phase behavior was explored. To separate the azeotropic mixture n -butyl acetate and n- butanol by liquid–liquid extraction, three ionic liquids (ILs) 1-ethyl-3-methylimidazolium dihydrogen phosphate ([Emim]H 2 PO 4) , 1-butyl-3-methylimidazolium dihydrogen phosphate ([Bmim]H 2 PO 4) and 1-hexyl-3-methylimidazolium dihydrogen phosphate ([Hmim]H 2 PO 4) were adopted as extractants. The liquid–liquid equilibrium data for the ternary mixtures (n -butyl acetate + n- butanol + [Emim]H 2 PO 4 /[Bmim]H 2 PO 4 /[Hmim]H 2 PO 4) was measured at 298.15 K and 101.3 kPa. The extraction capacity of the ionic liquids was evaluated by partition coefficient and selectivity. The NRTL model was applied to fit the measured data with the root mean square deviation less than 0.009. The hydrogen bond length and interaction energy between the ionic liquids and n -butyl acetate/ n- butanol was calculated and the effect of the ionic liquid cations with different carbon chain length was explored. [ABSTRACT FROM AUTHOR]

Since phenol is a high value-added compound in chemical industry, which is separated from coal tar, in this work, the imidazolium-based ionic liquid, 1-ethyl-3-methyl imidazolium lactate ([EMIM][LAC]) was prepared as extractant to separate phenol from the model oil. The prepared [EMIM][LAC] was characterized by 1H NMR. The effects of extraction temperature, time, and IL/model oil mass ratio were explored. The results showed that [EMIM][LAC] can extract phenol efficiently. Then, the separation mechanism between phenol and [EMIM][LAC] was investigated by discussing the surface-charge density distribution obtained by the COSMO-SAC model and intermolecular interaction obtained by quantum chemical calculations. The results showed that [EMIM][LAC] was a suitable extractant due to hydrogen bond formed by the IL and phenol. Moreover, the chemical bond for [EMIM][LAC] with phenol was further validated by FT-IR spectra. • The effective IL [EMIM][LAC] is prepared to extract phenol from coal tar. • The extraction performance on phenol using [EMIM][LAC] was explored. • The extraction mechanism was confirmed by quantum chemical calculations and FT-IR. [ABSTRACT FROM AUTHOR]

Separation of cresols from coal tar is of significance in chemical industry. In this work, a high-efficiency and green hydroxyl ammonium ionic liquid ethanolamine lactate ([HMEA]L) was applied as an extractant to extract three different cresols (o- , m- , and p- cresol) from low-temperature coal tar. The ionic liquid [HMEA]L was synthesized with ethanolamine and lactic acid and characterized by 1H NMR, TGA and FT-IR. The extraction efficiency and distribution coefficient were determined to assess the extraction performance of the [HMEA]L. The results show that [HMEA]L displays high extraction efficiency and distribution coefficient for separating p -cresol from model oil. In addition, molecular dynamics (MD) simulation has been applied to explore the extraction mechanism of cresols from the model oil. The interaction energies, radial and spatial distribution function, and self-diffusion coefficient were calculated from the MD simulation results, and the extraction mechanism was further explored by FT-IR. It can be concluded that both cation and anion took effect on extraction. However, the anion displayed a more important role on extracting cresols from the model oil. Finally, the recovery and reuse of the [HMEA]L were explored in this work. • The ionic liquid [HMEA]L was synthesized for separating cresols from coal tar. • The extraction capacity of [HMEA]L was evaluated by EE and D. • The molecule level interaction mechanism was explored by MD simulation. • The recovered [HMEA]L was reused with high extraction efficiency. [ABSTRACT FROM AUTHOR]

• Ionic liquid [Emim][SCN] was synthesized to extract p-cresol from model oil. • The extraction conditions to separate cresol using [Emim][SCN] were explored. • The extraction mechanism was analyzed by quantum chemical calculation and FT-IR. Cresol is a valuable chemical raw material which is mainly separated from coal tar. In this work, imidazolium-based ionic liquid (IL) 1-ethyl-3-methyl imidazolium thiocyanate ([Emim][SCN]) was synthesized and used to separate cresol from coal tar. The extraction effect of IL on p -cresol was investigated, and the key experimental factors such as mass ratio of extraction agent to model oil, extraction temperature, and extraction time were studied and optimized. Under optimal conditions, the extract efficiency can reach up to 98.25%. Furthermore, quantum chemical calculation was used to explore the interaction of cresol with IL at the molecular level. And the calculation results were verified by infrared spectrum analysis. The results show that H-bond between the cresol and IL [Emim][SCN] are the main driving force of this separation process, and the interaction with p -cresol is the strongest. [ABSTRACT FROM AUTHOR]

For separating azeotropic mixture 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, two kinds of imidazolium-based ionic liquids 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([HMIM][OTf]) and 1-octyl-3-methylimidazolium trifluoromethanesulfonate ([OMIM][OTf]) were adopted to separate TFP and water. The liquid-liquid equilibrium behavior for the mixtures (water + TFP + [HMIM][OTf]) and (water + TFP + [OMIM][OTf]) were measured at temperature of 298.15 K and pressure of 101.3 kPa. The extraction ability of [HMIM][OTf] and [OMIM][OTf] was explored with partition ratio and selectivity. In the meantime, the hydrogen bond lengths, total electron density, interaction energies and deformation electron density were calculated to analyze the interactions between the [HMIM][OTf]/[OMIM][OTf] and (TFP/water). Also, the liquid-liquid equilibrium data was fitted by the NRTL model. • Two ionic liquids [HMIM][OTf] and [OMIM][OTf] were adopted to separate the azeotrope TFP and water. • The LLE data for the ternary systems water + TFP + ILs were measured and correlated by the NRTL model. • The hydrogen bond length, interaction energy, total and deformation electron densities were calculated. • The influence of the alkyl chain length of cations on phase behavior was explored. [ABSTRACT FROM AUTHOR]

• The LLE data for isobutyl acetate + isobutyl alcohol + ILs were measured and correlated by the NRTL model. • The distribution coefficient and selectivity were calculated. • The σ-profiles and interaction energies were calculated to explore interaction ILs with (isobutyl alcohol/isobutyl acetate). • [Bmim][H 2 PO 4 ] is suitable as extractant to separate the azeotropic mixture IBA and IBAC. For separation of the azeotropic mixture isobutyl alcohol and isobutyl acetate, liquid-liquid extraction was adopted in this work and three imidazolium-based ionic liquids with different anions 1-butyl-3-methylimidazolium dihydrogen phosphate ([Bmim][H 2 PO 4 ]), 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim][HSO 4 ]) and 1-butyl-3-methylimidazolium methyl sulfate ([Bmim][MeSO 4 ]) were chosen as extractants. The liquid – liquid equilibrium data (LLE) for isobutyl alcohol + isobutyl acetate + ([Bmim][H 2 PO 4 ]/[Bmim][HSO 4 ]/[Bmim][MeSO 4 ]) were determined at 298.15 K and 101.3 kPa. The distribution coefficient and selectivity were calculated to evaluate extraction capability of the selected extractants. Furthermore, the σ-profiles and interaction energies based on conductor-like screening segment activity coefficient model (COSMO-SAC) were calculated to provide theoretical insight to interactions among the components. Also, the measured LLE data was correlated by the NRTL model and binary interaction parameters were regressed which is helpful for the separation process design and optimization. [ABSTRACT FROM AUTHOR]

• The LLE phase behavior for TFP + H 2 O + cyclohexanone was explored at different temperatures. • The experimental data were fitted by the NRTL model. • The interaction energies between cyclohexanone and (H 2 O/TFP) were analyzed. Due to the existence of azeotropic point for the mixture 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, liquid-liquid extraction was adopted to separate TFP from its aqueous mixture with cyclohexanone as extractant in this work. The liquid-liquid phase behaviour for the mixture (TFP + water + cyclohexanone) was investigated at T = (293.15, 303.15 and 313.15) K and p = 101.3 kPa. Both selectivity and partition ratio were used for evaluating the extraction performance of cyclohexanone. Also, the NRTL activity coefficient model was applied to fit the measured LLE data with the regressed the parameters. Meanwhile, the binary interaction parameters were validated to be coherent with the measured LLE data based on the mixing surface analysis of Gibbs energy topology. The calculated values of root-mean-square deviation are 0.024, 0.017 and 0.018 at three temperatures, respectively, which indicates the correlated results agree well with the experimental values. Furthermore, the interaction energies between the components were investigated using DMol3 module to explore the molecular interactions between the components in the mixture. [ABSTRACT FROM AUTHOR]