Pure Dimethylformamide Research Articles

A Quantitative Analysis of Electrochemical CO2 Reduction on Copper in Organic Amide and Nitrile-Based Electrolytes.

Aqueous electrolytes used in CO2 electroreduction typically have a CO2 solubility of around 34 mM under ambient conditions, contributing to mass transfer limitations in the system. Non-aqueous electrolytes exhibit higher CO2 solubility (by 5-8-fold) and also provide possibilities to suppress the undesired hydrogen evolution reaction (HER). On the other hand, a proton donor is needed to produce many of the products commonly obtained with aqueous electrolytes. This work investigates the electrochemical CO2 reduction performance of copper in non-aqueous electrolytes based on dimethylformamide (DMF), n-methyl-2-pyrrolidone (NMP), and acetonitrile (ACN). The main objective is to analyze whether non-aqueous electrolytes are a viable alternative to aqueous electrolytes for hydrocarbon production. Additionally, the effects of aqueous/non-aqueous anolytes, membrane, and the selection of a potential window on the electrochemical CO2 reduction performance are addressed in this study. Experiments with pure DMF and NMP mainly produced oxalate with a faradaic efficiency (FE) reaching >80%; however, pure ACN mainly produced hydrogen and formate due to the presence of more residual water in the system. Addition of 5% (v/v) water to the non-aqueous electrolytes resulted in increased HER and formate production with negligible hydrocarbon production. Hence, we conclude that aqueous electrolytes remain a better choice for the production of hydrocarbons and alcohols on a copper electrode, while organic electrolytes based on DMF and NMP can be used to obtain a high selectivity toward oxalate and formate.

Resonance Raman Scattering Spectra of Co(II)- and Cu-5,10,15,20-Tetrakis[4-(N-methylpyridyl)]porphyrin in the dd Excited State and Mechanisms of Its Deactivation in a Solution and in Complexes with DNA

Resonance Raman scattering (RRS) spectra of the complexes of 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin with Co(II) and Cu(II) (CoIITMpyP4 and CuTMpyP4) in various solvents and in complexes with DNA are studied. Under nanosecond pulsed excitation, additional lines have been found in the RRS spectra of CoIITMpyP4 in a dimethylformamide (DMF) solution containing formic acid as an impurity and in a complex with DNA. At the same time, such lines are absent in the spectra of CoIITMpyP4 in pure DMF, dimethyl sulfoxide, water, and alcohols under the same excitation conditions. To interpret the experimental data, we have calculated the structure and vibrations of the solvate complexes of CoIITMpyP4 and CuTMpyP4 with water, methanol, and formic acid in the ground and in excited states. Based on the obtained data, additional lines in the Raman spectra are assigned to the dd excited state corresponding to the d(z2) → d(x2 – y2) transition, the lifetime of which increases with the formation of complexes of CoIITMpyP4 with formic acid. According to the calculation results, this correlates with a decrease in rate constant kic of the internal conversion due to an increase in energy gap ΔE between the ground and dd states of CoIITMpyP4. A decrease in the kic value in the case of binding of CoIITMpyP4 and CuTMpyP4 to DNA is caused by the additional interaction of the extra-ligand water molecule with one of its bases directly or via several water molecules immobilized on DNA surface. This complicates the conformational rearrangement of the water molecule in the dd excited state, which gives rise to an increase in the ΔE value.

Effects of ethyl acetate additive on Cu2ZnSnS4 solar cells fabricated with a facile dimethylformamide-based solution coating process

The solution based on dimethylformamide (DMF) has shown promising application prospects in the fabrication of high-efficiency Cu2ZnSnS4 solar cells. However, due to the high boiling temperature of the solvent, it is difficult to completely volatilize DMF during the evaporation process after spin coating, leading to remains of C and O atoms at grain boundaries, which severely restricts the photoelectric performance of solar cells. In this study, ethyl acetate (EA) with green character was used as an additive to optimize the film formation process of DMF-based CZTS precursor. The experimental results showed that using a small amount of EA additives could effectively improve morphology, crystallinity, composition distribution and electrical properties of the CZTS absorber. In addition, the CZTS and CdS heterojunctions exhibited a cliff-like energy band structure, and the optimized conduction band offset increased the activation energy required for the carrier recombination path, consequently reducing the carrier recombination. Compared with the pure DMF precursor solution, the photoelectric conversion efficiency of CZTS solar cells with an EA addition ratio of 10% was improved by 42%, and the open circuit voltage of the device reached 601 mV.

Study on hysteresis in perovskite solar cells fabricated using different solvents under ambient conditions

We have investigated the dependency of hysteresis in all-ambient-processed perovskite solar cells on the solvent used for the synthesization of perovskite. Methylammonium lead iodide (MAI) perovskite solar cells have been fabricated using the two-step sequential spin coating method. The influences of PbI2 precursor on the cell performance and its hysteresis are investigated using four different solvents of pure dimethylformamide (DMF), pure dimethyl sulfoxide (DMSO) and mixtures of DMF:DMSO with the ratios of (4:1) and (1:4). The results indicate that a small amount of DMSO in DMF leads to produce large grains of perovskite with proper coverages at the interfaces with hole and electron transport layers. The best conversion efficiency of 10.9% was obtained for the cell prepared by the solvent of (4:1) for DMF:DMSO. The best hysteresis was also obtained from the same cell with the hysteresis index of 0.009.

Solvation structures of Na+ Cl− ion pair in DMF-water and DMF-methanol mixtures

ABSTRACT We have studied the solvation structures of Na+ Cl− ion pair in DMF (dimethyl formamide)-water and DMF-methanol binary mixtures using constrained molecular dynamics technique. The resulting potentials of mean force shows prominent minima corresponding to contact ion pairs (CIPs) and solvent assisted ion pairs (SAIPs) in all mole fractions of DMF except in pure DMF. The stabilities of CIPs increase with an increase in mole fraction of DMF in both the binary mixtures. The CIPs in DMF-methanol mixtures are more stable than the CIPs in DMF-water mixtures. The formation of the ion pair is found to be entropically driven in both the mixtures. Preferential solvation analysis through excess coordination numbers shows that Na+ and Cl− are preferentially solvated by water in DMF-water and by methanol in DMF-methanol binary mixtures. The rate of dissociation of the ion pair is larger in DMF-water mixtures than in DMF-methanol mixtures.

Спектры РКР Co(II)- и Cu-5,10,15,20-тетракис[4-(N-метилпиридил)]порфирина в возбужденном dd-состоянии и механизмы его дезактивации в растворе и комплексах с ДНК

A study of the resonance Raman scattering (RRS) spectra of Co(II)- and Cu-5,10,15,20-tetrakis [4-(N-methylpyridyl)]porphyrin (CoIITMpyP4, CuTMpyP4) in various solvents and in complex with DNA was carried out. Additional lines were found in the RRS spectra of CoIITMpyP4 in a dimethylformamide (DMF) solution containing formic acid as an impurity, as well as for its complex with DNA under nanosecond pulsed excitation. At the same time, under the same excitation conditions, such lines are absent in the spectra of CoIITMpyP4 solutions in pure DMF, dimethyl sulfoxide, water, and alcohols. To interpret the experimental data, we performed calculations of the structure and vibrations for the solvate complexes of CoII - and CuTMpyP4 with water, methanol and formic acid in the ground and in excited states. Based on the data obtained, additional lines in the Raman spectra were assigned to the excited dd-state corresponding to the d(z2) d(x2-y2) transition, the lifetime of which increases with the formation of complexes of CoIITMpyP4 with formic acid. According to the calculation results, this correlates with a decrease in the rate constant of the internal conversion kic due to an increase in the energy gap E between the ground and dd states of CoIITMpyP4. In the case of CoII and CuTMpyP4 binding to DNA, the decrease in kic is due to the additional interaction of the extra-liganding water molecule directly or with the participation of several immobilized DNA water molecules with one of its bases. This complicates the conformational rearrangement of the water molecule in the dd-state, which contributes to an increase in E.

Pd and Pd,In nanoparticles supported on polymer fibres as catalysts for the nitrate and nitrite reduction in aqueous media

The presence of high concentrations of nitrate and nitrite ions in water sources is an actual environmental problem. Nowadays, there are several technologies for nitrate and nitrite treatment, but most of them involve the concentration of the ions which are later necessary to be decomposed in a second step. The catalytic elimination of nitrates and nitrites from water is a very promising method because the ions are transformed into the harmless N2(g). Two types of synthetic polymeric fibers were proposed as supports of palladium and indium catalytic species with low metallic loading (Pd:In = 1:0.25 wt.%). They were synthesized by electrospinning method with a Pd/In weight ratio 1:0.25. PdInDA catalyst was prepared by dissolving poly (methyl methacrylate) (PMMA) with a mixture of acetone/dimethylformamide, whereas the polymer (PMMA) was dissolved in pure dimethylformamide for the synthesis of PdD and PdInD catalysts. Both bimetallic solids gave rise to good selectivity to N2(g). However, the PdInDA reached middle nitrate conversions (around 50 %) with low ammonia production (under 0.1Nppm). The characterization results suggested that the active sites remained unchanged after the reaction. This proposal involves a green chemical method with low consumption of reactants and producing a small quantity of waste.

Crystallization and grain growth regulation through Lewis acid-base adduct formation in hot cast perovskite-based solar cells

The precise control of perovskite crystallization process that could provide smooth films with large grains is a prerequisite for solar cell fabrication to achieve higher efficiencies. To regulate this crystallization process and to achieve it multiple times remains a humongous challenge. This process has been reproducibly demonstrated here through efficient molecular exchange via a Lewis acid-base adduct formation. In this work, a Lewis acid-base adduct approach in concurrence with hot casting technique was employed to efficiently control the perovskite crystallization by judiciously adding dimethyl sulfoxide (DMSO) to a precursor solution of lead iodide (PbI 2 ) and methyl ammonium chloride (MACl) in dimethylformamide (DMF). High quality perovskite films were fabricated by precisely controlling the volume of DMSO which resulted in low recombination rate and which had better light harvesting ability. Uniform films of MAPbCl x I 3-x having large grain size were formed reproducibly on addition of 1.5 equivalents (eq.) DMSO to the precursor solution. Perovskite solar cells fabricated using this solution resulted in maximum power conversion efficiency (PCE) of 14.11% with enhanced stability as compared to the reduced PCE values obtained with other DMSO ratios and pure DMF solution cast films. • Hot casting using Lewis acid-base approach resulted in large grain perovskite. • 1.5 equivalents of Lewis base (DMSO) gave largest grain size and smooth film. • A power conversion efficiency >14% achieved in inverted perovskite solar cell. • This method also improved the overall stability of the solar cells.

Pressure‐Induced Vapor Synthesis of Carbon‐Encapsulated SiOx/C Composite Spheres with Optimized Composition for Long‐Life, High‐Rate, and High‐Areal‐Capacity Lithium‐Ion Battery Anodes

SiOx exhibits a high specific capacity as anode materials for lithium‐ion batteries. However, it is still a challenge to achieve long life, high rate performance, and high areal capacity for the SiOx materials. Herein, carbon‐encapsulated SiOx/C composite spheres are prepared by a high pressure caused by heating SiOx/C spheres in pure dimethylformamide in a sealed vessel. The SiOx/C spheres with different compositions are synthesized by pyrolysis of different liquid siloxanes and hexamethyldisilane in a sealed vessel and subsequent heat treatment. The electrochemical performances are strongly dependent on the composition of the SiOx/C spheres. The specific capacity and initial coulombic efficiency (ICE) greatly increase, and cyclability slightly decreases with a decrease in the x value from 1.28 to 0.59. However, the capacity, ICE, and cyclability greatly decrease with a further decrease in the x value because of the formation of SiC. The carbon‐encapsulated SiO0.59/C spheres exhibit a high reversible capacity (1561.3 mAh g−1), an outstanding cyclability (0.0332% capacity loss per cycle during 500 cycles at 1 A g−1), a good rate performance (245.3 mAh g−1 at 10 A g−1), and a high areal capacity (4.08 mAh cm−2). Formation of the spherical morphology and carbon‐encapsulating layers is a result of the high vapor pressure generated at a high temperature.

Improving Charge Transport via Intermediate‐Controlled Crystal Growth in 2D Perovskite Solar Cells

AbstractReduced‐dimensional hybrid perovskite semiconductors have recently attracted significant attention due to their promising stability and optoelectronic properties. However, the issue of poor charge transport in 2D perovskites limits its application. Here, studies on intermediate‐controlled crystal growth are reported to improve charge carrier transport in 2D perovskite thin films. It is shown that the coordination strength of solvents with perovskite precursor affects the initial state of intermediate phase formation as well as the subsequent perovskite layer growth. Tuning the solvent composition with a mixture (5:5) of dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) leads to the growth of highly orientated 2D perovskite films with much‐improved optoelectronic properties (faster transport by ≈50x, longer carrier lifetime by ≈4x, and lower defect density by ≈30x) than the film prepared with pure DMF. Consequently, perovskite solar cells based on DMF/DMSO (5:5) show >80% efficiency improvement than the devices based on pure DMF.

Ultra-Small Pd(0) Nanoparticles into a Designed Semisynthetic Lipase: An Efficient and Recyclable Heterogeneous Biohybrid Catalyst for the Heck Reaction under Mild Conditions.

A novel heterogeneous enzyme-palladium (Pd) (0) nanoparticles (PdNPs) bionanohybrid has been synthesized by an efficient, green, and straightforward methodology. A designed Geobacillus thermocatenulatus lipase (GTL) variant genetically and then chemically modified by the introduction of a tailor-made cysteine-containing complementary peptide- was used as the stabilizing and reducing agent for the in situ formation of ultra-small PdNPs nanoparticles embedded on the protein structure. This bionanohybrid was an excellent catalyst in the synthesis of trans-ethyl cinnamate by Heck reaction at 65 °C. It showed the best catalytic performance in dimethylformamide (DMF) containing 10–25% of water as a solvent but was also able to catalyze the reaction in pure DMF or with a higher amount of water as co-solvent. The recyclability and stability were excellent, maintaining more than 90% of catalytic activity after five cycles of use.

Extractive distillation of methylal/methanol mixture using the mixture of dimethylformamide (DMF) and ionic liquid as entrainers

Methylal is used as an important synthetic fuel blended with diesel oil to reduce the particulate emissions of toxic gas pollutants without affecting the energy density. The mixed entrainers (dimethylformamide (DMF) + ionic liquid (IL)) are proposed to replace conventional DMF for the separation of methylal and methanol by extractive distillation. [EMIM]+[Ac]− might be the most promising entrainer screened by COSMO-RS model considering relative volatility and solvent capacity together. Vapor–liquid equilibrium (VLE) experiments demonstrated that the relative volatility of methylal to methanol is obviously improved after the addition of [EMIM]+[Ac]− into DMF. Moreover, the UNIFAC-Lei model was extended to the methylal-methanol-DMF-IL system, and the corresponding interaction parameters were obtained and input into the equilibrium (EQ) stage model established in this work. Based on the thermodynamic study, process simulation was developed. It was found that the overall heat duty of reboilers decreased 9.25% using the proposed mixed entrainers when compared to pure DMF. In addition, the COSMO-RS model and DFT calculation provide some theoretical insights into the separation mechanism.

Synthesis of N-Doped Graphene By Sonochemical Liquid Exfoliation and Its Electrochemical Performance for ORR in Alkaline Media

The graphene is a promising material for many potential application. However, industrial scale manufacturing has been limited because most of these methods are not readily scalable. The development of strategies that make viable large-scale production of graphene is a great challenge. A promising approach is the production of stable graphene dispersions from the exfoliation of graphite in water and organic solvents. The exfoliation of graphite by ultrasonication is a very versatile technique that has already demonstrated its effectiveness in dispersing graphene in solvents with different physical and chemical properties. In this contribution, we reported a fast and simple synthesis of graphene sheets from graphite flakes through ultrasound assisted method. Pure dimethylformamide (DMF) was used as organic solvent. Ultrasound time was evaluated in a range of 30 to 120 minutes. The quality of exfoliation and the morphology were determined by Scanning Electron Microscopy (SEM), Raman Spectroscopy (RS) and X-Ray diffraction (XRD). Additionally, graphene was functionalized by solvothermal treatment in order to obtain nitrogen doped graphene. Metal-free electrocatalyst were also obtained. The total nitrogen and carbon were determined using a CHNS analyzer. The functional groups determinates by FTIR found in graphene are carboxyl and amine groups. Preliminary results obtained by Raman spectroscopy indicates that nanocarbon materials has a molecular structure composed by a mixture of graphene and exfoliated graphite. The electrochemical performance of the material for the oxygen reduction reaction (ORR) was tested by rotation disk electrode technique (RDE). It was observed that stable graphene suspensions could be prepared using DMF. Results demonstrate that ultrasonication time is a key parameter to control the yield and size of graphene, when sonication time was higher than 60 minutes the production of graphene decreased. Electrochemical evaluation revealed that these materials are electroactive for ORR in alkaline media. Therefore, the sonochemical synthesis is an attractive massively scalable and simple method for preparation of graphene to energy applications.

Effect of solvents on photonic crystallinity in graphene oxide dispersions

Structural color reflections from graphene oxide (GO) dispersions in binary mixtures of deionized water and organic solvents were obtained, and they were investigated at varying GO concentrations using three organic solvents: 1,4-dioxane, N-methyl-2-pyrrolidone (NMP), and dimethylformamide (DMF). Adding organic solvents in the aqueous GO dispersion changes the peak wavelength of the reflection spectrum and the purity of the reflection color, and in particular, the dependence of the peak wavelength on the GO concentration was more sensitive in the binary organic solvents than in pure water. This phenomenon can be explained by considering both the variations of the reflective index and the electrical screening effect in the binary solvents. However, only weak structural coloration based on the second order Bragg reflection was obtained in GO dispersions in pure DMF solvent, and even no structural coloration was observed in organic GO dispersions prepared using dried GO powder. These phenomena are related to the gelation at low concentration and the geometrical deformation of GO particles. Electrical switching of the structural color reflection was also demonstrated.

Influence of Plasticizers on the Electrical Conductivity of Polyacrylonitrile (PAN)/Lithium-Montmorillonite (Li-MMT) Polymer Composite Electrolyte

With the current trend of miniaturization and portability of electronic gadgets, the development of polymer composite electrolyte (PCE) gained much research interest. In this study PAN matrix was plasticized with various dimethyl formamide (DMF)/ propylene carbonate (PC) ratios. X-ray diffraction (XRD) analysis revealed that both DMF and PC reduce the crystallinity of PAN. Yet, films with higher amount of PC caused much decrease in crystallinity, which is indicated by lowering of full with at half maximum (FWHM) at the utmost 57% when the DMF/PC ratio is 1:2. Differential scanning calorimetry (DSC) analysis also revealed that glass transition temperature (Tg) of PAN decreased from 83.34°C to 50.27°C when plasticized with pure DMF and to temperature lower than ambient condition when PC alone was used. Upon incorporation of 15 wt% Li-MMT, PCEs with pure DMF exhibited the highest electrical conductivity, which is 3.6x10-8 S/cm based on electrochemical impedance spectroscopy (EIS). This suggests that the electrical conductivity is not dictated by the decrease on polymer host crystallinity alone. The type of plasticizer and appropriate combination was shown to have an effect wherein the plasticizer that causes higher degree of solvation and has lower boiling point is thought to provide more hopping sites for electrons due to higher amount of broken bonds in the nitrile group of PAN.

High-Throughput Two-Dimensional Infrared (2D IR) Spectroscopy Achieved by Interfacing Microfluidic Technology with a High Repetition Rate 2D IR Spectrometer.

The precision control of microfluidic technology was successfully interfaced with a 100 kHz two-dimensional infrared (2D IR) spectrometer to observe the sensitivity of the anion cyanate (OCN-) to the surrounding solvent environment in a high-throughput manner. Producing high-throughput 2D IR spectroscopy measurements allows us to observe the vibrational response of cyanate in mixed solvent environments. Changes in solvation environment around the cyanate ion yield frequency shifts from 2150 to 2165 cm-1 when moving from a pure dimethylformamide solvent environment to a pure methanol environment. 2D IR spectra were captured laterally across microfluidic devices tailored to produce a tunable gradient to observe the OCN- vibrational response to mixed solvent environments. These experiments reveal that there is no preferential solvation of cyanate in this system; instead, a more complex local solvent environment is observed.

Colloidal Precursor-Induced Growth of Ultra-Even CH3NH3PbI3 for High-Performance Paintable Carbon-Based Perovskite Solar Cells.

Carbon-based hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted intense attention due to their relatively high stability. However, their power conversion efficiency (PCE) is still low, especially for the simplest paintable carbon-based PSCs (C-PSCs), whose performance is greatly limited by poor contact at the perovskite/carbon interface. To enhance interface contact, it is important to fabricate an even-surface perovskite layer in a porous scaffold, which is not usually feasible due to roughness of the crystal precursor. Herein, colloidal engineering is applied to replace the traditional crystal precursor with a colloidal precursor, in which a small amount of dimethyl sulfoxide (DMSO) is added into the conventional PbI2 dimethylformamide (DMF) solution. After deposition, PbI2(DMSO) adduct colloids (which are approximately tens of nanometers in size) are stabilized and dispersed in DMF to form a colloidal film. Compared with PbI2 and PbI2(DMSO) adduct crystal precursors deposited from pure DMF and DMSO solvents, respectively, the PbI2(DMSO) adduct colloidal precursor is highly mobile and flexible, allowing an ultra-even surface to be obtained in a TiO2 porous scaffold. Furthermore, this ultra-even surface is well-maintained after chemical conversion to CH3NH3PbI3 in a CH3NH3I solution. As a result, the contact at the CH3NH3PbI3/carbon interface is significantly enhanced, which largely boosts the fill factor and PCE of C-PSCs. Impressively, the achieved champion PCE of 14.58% is among the highest reported for C-PSCs.

Individually Dispersed Wood-Based Cellulose Nanocrystals.

Good dispersion of cellulose nanocrystals (CNCs) in the polymer matrix is one of the key factors to obtaining good properties in the resulting nanocomposites. However, the preparation of individually dispersed CNCs in solvents or in polymer matrices has been a challenge. In this study, individually dispersed wood-based CNCs have been successfully prepared in solvents, including dimethylformamide (DMF), H2O, and a mixture of H2O/DMF, by sonication of moisture-containing CNCs. The CNCs dispersions were characterized by dynamic light scattering (DLS). It is found that CNCs containing above about 3.8 wt % moisture is critical for achieving individually dispersed CNC in solvents. Hydrodynamic radius (Rh) of CNCs is smaller in H2O/DMF co-solvent mixture than that in pure DMF or in pure H2O under same sonication treatment conditions. Experimental results have been corroborated using molecular simulation study.

A thermodynamic study of interaction of Ag+, Mg2+, Ca2+, and K+ cations with 4-hydroxyphenyl-2,5-bis(2-benzofuranyl)pyridine in some binary mixed non-aqueous solvents

In the present work the complexation process between Ag+ and Mg2+ cations and 4-hydroxyphenyl-2,5-bis(2-benzofuranyl)pyridine (HBFPY) ligand was studied in pure dimethylformamide (DMF), ethanol (EtOH), acetonitrile (AN) and in (DMF-EtOH), (AN-EtOH) and (DMF-AN) binary mixed solvent solutions at different temperatures using the conductometric method. Also in this work the complexation reaction between Ca2+, K+ cations and HBFPY ligand, was studied in pure dimethylformamide (DMF), propanol (PrOH), 1,4-dioxane (DOX), ethanol (EtOH) and in DMF-PrOH, DMF-DOX and DMF-EtOH binary mixed solvent solutions at different temperatures using the conductometric method. The conductance data show that the stoichiometry of the complexes formed between this ligand and the studied cations is 1 : 1 [ML]. In most cases, addition of HBFPY to solutions of these cations, causes a continuous increase in the molar conductivities which indicates that the mobility of complexed cations is more than the uncomplexed ones. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program, GENPLOT. The stability constant of [Mg(HBFPY)]2+ complex in various neat solvents at 15°C decreases in order: EtOH > DMF > AN and the stability constant of [Ag(HBFPY)]+ complex in various neat solvents at 35°C decreases in order: DMF > EtOH. The values of standard enthalpy changes (ΔH°c) for complexation reactions were obtained from the slope of the Van’t Hoff plots and the changes in standard entropy (ΔS°c) were calculated from the relationship ΔH°c,295.15= ΔH°c–298.15ΔS°c.

Process intensification on the separation of benzene and thiophene by extractive distillation

The separation of benzene and trace thiophene by extractive distillation was intensified in two aspects, that is, selection of a suitable entrainer and improvement of the process. The mixture of dimethylformamide (DMF) and an ionic liquid (IL) was chosen as the entrainer. Vapor–liquid equilibrium (VLE) experiments using pure DMF and a mixed entrainer were conducted, and UNIFAC model for ILs was extended to the benzene‐thiophene‐DMF‐IL system. The results demonstrated that volatilization loss of DMF in the vapor phase was significantly reduced by adding IL. Moreover, an improved process with only four columns using a mixed entrainer was proposed. The results indicated that the improved process is more promising for decreasing energy consumption and equipment investment compared with the conventional six‐column process. The total heat duties of reboilers and condensers was decreased by 6.47% and 6.41%, respectively. The process intensification strategy may be directly extended to separate trace components of other systems. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4470–4480, 2015