Aqueous two phase systems (ATPS), consisting of two incompatible aqueous solutions, are widely used in biological extraction. In recent years, many experimental studies on the phase behavior of ionic liquid(IL)–inorganic salt ATPS systems have been reported but few investigations of the thermodynamics of the IL-based ATPS have been reported. In this work, the Extended UNIQUAC model is modified to calculate the equilibrium of [Bmim]Cl–K2HPO4–H2O ATPS at 298.15 K. All the interaction parameters of the model are salt specific. The results show that the experimental compositions of tie lines are correlated successfully using the proposed model. The root mean square deviation of the mass fraction is 0.0256.

•Solubilities of K3PO4, K2HPO4 and K2CO3 in aqueous systems containing ionic liquid are determined and calculated using Pitzer's equations.•New interaction parameters are obtained.•The predicted and experimental solubilities are in a very good agreement.Solubilities of potassium phosphate (K3PO4), potassium hydrogen phosphate (K2HPO4) and potassium carbonate (K2CO3) in aqueous systems containing the ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) were determined by cloud-point measurements in the temperature of 298.15 K at atmospheric pressure. The solubility equilibrium data were correlated and calculated by using Extended Pitzer thermodynamic model. In addition, the new Pitzer ion interaction parameters of the mixed-electrolyte solution were obtained by using an optimization program based on Simplex Method of Nelder–Mead algorithm. Comparison of calculated results by using the new interaction parameters at 298.15 K was expressed by the relative standard deviations between the regressed solubility values and the experimental data. Results indicate that predictions of the present model are in well accordance with experimental values, which supports the reliability of the model prediction.

Castor oil-based ionic liquid microemulsions are promising alternatives for petroleum-based biolubricant basestocks. This study presents the phase behavior of castor oil-based ionic liquid microemulsions through phase manifestation, and the areas of the single-phase domain (SME) were calculated accordingly to further illustrate the phase-forming capacities of the designed microemulsions. The results indicated that the phase-forming capacities of castor oil-based ionic liquid microemulsions depended largely on the ionic liquid ions, surfactant types, and cosurfactant chain lengths. The SME of different anion-based ionic liquid microemulsions showed the following sequences: [BMIM][Tf2N]-based > [BMIM][PF6]-based > [BMIM][BF4]-based. The longer carbon chain of ionic liquid cations in single surfactant-based systems and the larger percentage of ionic liquid-based surfactant in mixed surfactants-based systems both gave rise to the phase-forming capacities of castor oil-based ionic liquid microemulsions. Given the presence of ionic liquid–castor oil amphiphilic balance in the designed systems, the castor oil–surfactant micelles achieved maximum solubilization capacity for [BMIM][BF4] when the ethoxylated groups’ number of surfactant was about eight in single surfactant microemulsion. In addition, n-hexanol donated a higher phase-forming capacity than n-butanol, while n-octanol brought about a different phase behavior due to the spontaneous curvature effect and oil nature of long-chain alcohols (C ≥ 7) in the castor-oil based ionic liquid microemulsions. Thus, this study presented useful information for formulating optimum castor oil-based ionic liquid microemulsion biolubricants based on different ionic liquids, surfactants, and cosurfactants, which were not evaluated in previous research.

This study evaluated the effects of ionic liquids (ILs) on the formation of aqueous biphasic systems (ABS) with organic salts. Phase diagrams, tie lines, and respective tie line lengths were determined at 298 K and atmospheric pressure. Using imidazolium-based ILs, the effects of the IL anions and salt anions, as well as the addition of dipolar aprotic solvents (DAS) on ABS formation were investigated. In general, the IL with hydrogen bond basicity ranging between 0.38 and 0.60 formed ABS with organic salts. However, those below this range were insoluble, and those above this range did not undergo phase separation. The salt anion capacity to induce ABS increased with increased valence and decreased Gibbs free energy of hydration. Moreover, the biphasic area for the IL-based ABS reduced with increased DAS concentration.

Glycerol trioleate-based ionic liquid microemulsions are promising biolubricant alternatives. This study presents the formation and the phase behavior of glycerol trioleate-based ionic liquid microemulsions. Areas of the single-phase domain were calculated to illustrate the phase-forming capacities of the designed systems. The effects of ionic liquid anions and cations, oxyethylene groups’ number of surfactant, mass ratio of surfactant to co-surfactant, chain length of co-surfactant, and temperature on the phase behavior and phase-forming capacities of glycerol trioleate-based ionic liquid microemulsions were investigated using pseudo-ternary phase diagrams. The results showed that the phase-forming capacities of glycerol trioleate-based ionic liquid microemulsions with different ionic liquids were Tf2N−-based > PF6−-based > BF4−-based, OMIM+-based > HMIM+-based > BMIM+-based > EMIM+-based. The designed systems contained ionic liquid-glycerol trioleate amphiphilic balance; thus, glycerol trioleate-surfactant micelles achieved the maximum solubilization capacity for the ionic liquid when the surfactant had approximately five oxyethylene groups with a surfactant to co-surfactant mass ratio of 4:1. Moreover, increasing the temperature and the aliphatic chain length of co-surfactant from C2 to C6 enhanced the ability of glycerol trioleate and ionic liquids to form microemulsions.

•PEO coatings containing TiO2–Al2O3 composite oxides were formed in microchannel.•Morphology and composition of the films were affected by electrical parameters.•The films inside and outside the channel exhibited different growth behaviors.•The shielding and mass transfer effects induced by microchannel were found.In an attempt to develop new methods to fabricate in-situ catalytic layers for microreactor, the plasma electrolytic oxidation (PEO) process for coating deposition was utilized and the growth behavior of the oxide film was studied. PEO coatings containing TiO2–Al2O3 composite oxides were formed on the aluminum substrate engraved with a microchannel on the surface, and the effects of applied voltage on the microstructure and composition of the obtained coatings were investigated. It was found that the morphology and composition of the layers were strongly influenced by process parameters, high applied voltage gave rise to the amount of Ti in the layers, and decreased the porosity of the coating surface. Moreover, the comparison of the coatings formed inside and outside the microchannel clearly indicates a significant change in their microstructure, which could be explained by the shielding and mass transfer effects induced by the deep and narrow channel.

•ABS was used for recycling ILs along with its cosolvents.•Effect of IL, salt and temperature on KDMSO was determined.•KDMSO results from the densities and pH values of two phases.To combine ionic liquid (IL) recovery with cosolvent separation in biomass processing, the quaternary aqueous biphasic systems (ABSs) formed by IL, kosmotropic salt and water in the presence of dimethyl sulfoxide (DMSO) are herein proposed. Three main parameters were evaluated through the phase diagrams and the DMSO partitioning process: the IL cation and anion structure, the salt anion, and the temperature. In all systems and conditions texted, DMSO preferentially dissolves in the IL-rich phase. The results obtained indicate that, the partitioning process is essentially controlled by the IL cation interactions with DMSO. The partition coefficients (KDMSO) displays a maximum for the system formed by [C6mim]Cl. The KDMSO value increases monotonically with the initial concentration of DMSO, and it decreases in the systems with different salts: K3PO4 > K2HPO4 > K2CO3 > KOH. The increase of temperature reduces the partition coefficients. Moreover, densities and pH of both aqueous phases were measured at 298.15 K to evaluate the properties of the systems. The results gathered indicate that the densities and pH values of the two phases can be affected by the nature of IL and its initial concentrations, and the smaller density differences between the fluids, the lower the partition coefficients of DMSO.

Esterification of oleic acid was carried out in a 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4)/Triton X-100 + 1-hexyl-3-methylimidazolium hydrogen sulfate ([Hmim]HSO4)/cyclohexane microemulsion. A pseudo ternary phase diagram of the designed systems was drawn to investigate the phase behavior of the microemulsion, with the surfactant [Hmim]HSO4 acting as a catalyst. The effects of various reaction parameters were explored. The results showed that the maximum yield of lauryl oleate reaches 91.17% and its selectivity reaches 98.55% under optimum reaction conditions. The reaction was carried out with 8 wt% catalyst at 373 K for 6 h. The molar ratios of [Bmim]BF4 to the surfactant and of oleic acid to lauryl alcohol were 0.24 and 0.2, respectively. Comparison reactions between different alcohols and oleic acid were also performed, and the results showed that long alkyl chain alcohols promote the reaction rate. UV-vis absorption spectra demonstrated that the generated water enters the [Bmim]BF4 microdomain of the ionic liquid microemulsions. A possible mechanism of the reaction was also presented. All the results indicate that the [Bmim]BF4/TX-100 + [Hmim]HSO4/cyclohexane microemulsion is a very efficient catalyst system for esterification reactions.

This study presents the formation and phase behavior of vegetable oil-based ionic liquid microemulsions (ILMs). Castor oil, jatropha oil, and soybean oil were used as oil phases of the ILMs respectively. The effects of the mass ratio of surfactant to cosurfactant (Km) and temperature on the phase behavior of ILMs were investigated by pseudo ternary phase diagrams. The results indicated that the homogeneous and stable microemulsions composed of target vegetable oils, ionic liquid, Triton X-100, and n-butanol could form at ambient condition successfully. The size of a single-phase region area was in a sequence: castor oil-based ILMs > jatropha oil-based ILMs > soybean oil-based ILMs. Each vegetable oil-based ILMs corresponded to an optimum Km since the ionic liquid-oil amphiphilic balance existed in ILM systems. A maximum single phase region area of each system was observed when Km = 1:0, 2:1, and 2:1, respectively. Moreover, a larger single phase region area of vegetable oil-based ILMs could be obtained by increasing the temperature.

Recovery of ionic liquids (IL) is necessary and urgent because of increasing production costs and potential environmental pollution. Dipolar aprotic solvents (dimethyl sulfoxide, DMSO; N,N-dimethylformamide, DMF; and N,N-dimethylacetamide, DMCA) and polar protic solvents (methanol, ethanol, and n-butanol) were used as cosolvents and antisolvents, respectively. These compounds have crucial effects on the separation and purification of ILs. We determined the effect of different polar solvents on the formation of aqueous biphasic systems (ABSs) using K3PO4 to control the hydrophobicity of 1-alkyl-3-methylimidazolium chloride ([Cnmim]Cl). Phase equilibria of the ABSs comprising IL + K3PO4 + water in the presence of the polar solvents were obtained at 298 K and at atmospheric pressure. In general, the IL aptitude that induced the formation of ABS in the presence of the polar solvents increased with decreasing hydrogen bond basicity and polarizability of the polar solvents in the following order: none < methanol < ethanol ≈ DMSO < n-butanol ≈ DMF < DMCA. Densities, pH value, conductivities, and surface tensions of both aqueous phases were experimentally measured.

•IL microemulsions contained ESBO, TX-100, n-butanol and bmimBF4 was formed at 25 °C.•ESBO based IL microemulsions presented high Km-dependence.•ESBO based IL microemulsions presented high temperature-independence.•Conductivity, DLS, UV–visible and FTIR spectra were used as characterization methods.The phase behavior of the quaternary system consisting of epoxidized soybean oil (ESBO), Triton X-100, n-butanol and ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) was investigated. To the best of our knowledge, this is the first report on the formation and characterization of ESBO based IL microemulsions. Effects of temperature and the mass ratio of surfactant to cosurfactant on phase behavior of ESBO based IL microemulsions were investigated by calculating the single-phase region areas. The results showed that the researched systems presented relatively high Km-dependence and temperature-independence. The microstructures and structural transitions of the microemulsion system were explored by conductivity measurements. Similarly to traditional aqueous IL microemulsions, the microemulsions exhibited IL-in-ESBO (IL/O), bicontinuous (BC) and ESBO-in-IL (O/IL) microstructures. The size and size distribution of bmimBF4 domains in the IL/O microemulsion was investigated by dynamic light scattering. UV–visible absorption spectroscopy with methyl orange as a probe was used to characterize the polarity of researched IL/O microemulsions.

Cathodic plasma electrolysis was conducted in 1-propanol solutions and submicron diamond carbon was synthesized by the plasma electrochemical reactions under atmospheric pressure. The structure of the carbon particles was characterized by X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The effects of applied potential difference and treatment time on the structure of the prepared carbon products of PE processes were studied.

Although aprotic solvents (ASs) have been largely explored as cosolvents of ionic liquids (ILs) for biomass resources pretreatment, the separation and recovery of ILs along with ASs were seldom investigated. To evaluate the influence of ASs on the phase behavior of IL-based aqueous biphasic systems (ABSs) formed with 1-N-butyl-3-methylimidazolium chloride ([Bmim]Cl) and salts (K3PO4 and K2HPO4), different ASs including dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and N,N-dimethyl acetamide (DMAC), and different concentrations of these ASs were investigated. It is shown that biphasic area increased when the concentrations of aprotic solvents increase, and the ability of the ASs to induce ABSs follows the trend: DMAC > DMF > DMSO. The phase diagram data suggest that the higher concentration, molar volume, and intrinsic hydrophobicity of aprotic solvents resulting in greater biphasic area in IL-based ABS’s. Furthermore, the quaternary ABSs have a prominent advantage that the IL could be recovered along with aprotic solvents. The recovery yield of [Bmim]Cl and DMAC could reach 96.14 % and 67.16 %, respectively.

The degradation process of methyl orange solution by dielectric barrier discharge (DBD) plasma using a board-DBD reactor was studied. The percentage destruction reached 99% after 35 min treatment. The pH value of the methyl orange solution decreased with the treatment time and it reached a constant value when discharged for 20 min. The COD value of the methyl orange solution decreased by 57.9% for 30 min treatment. The degradation path was suggested based on the analysis of the molecular structure of methyl orange, intermediate products and the molecular bond energies.Highlights► Methyl orange solution was treated using DBD plasma. ► The percentage destruction reaches 99% after 35 mins treatment. ► Three stages were suggested for the methyl orange solution degradation. ► The degradation path of methyl orange molecules was analyzed.

Biodegradable trimethylolpropane triesters of oleic acid were synthesized by esterification of trimethylolpropane and oleic acid over a multi-SO3H-functionalized strong Brønsted acidic ionic liquid as the catalyst. The results showed that the esterification can proceed satisfactorily over the catalyst at an ambient pressure even without simultaneous removal of water. Under the optimal reaction conditions (temperature: 100 °C, reaction time: 3 h, reactant molar ratio: 3.6:1, and catalyst amount, high conversion rate of trimethylolpropane (99.0%) and selectivity of trimethylolpropane triester (92.1%) were obtained. The ionic liquid was reused six times after the removal of water and no obvious change in catalytic activity was detected. Operational simplicity, high yields along with good reusability makes the multi-SO3H-functionalized ionic liquid a promising catalyst for the esterification of trimethylolpropane with oleic acid.

A series of pyridinium ionic liquids were synthesized and characterized. Acid-catalyzed transesterifications of Jatropha oil were carried out with these ionic liquids under mild reaction conditions. [BSPy]CF3SO3 showed the best catalytic activity and biphasic behavior in the proposed process. The products could simply be separated from the catalyst phase. The catalyst exhibited constant activity for seven successive cycles after being recycled.

This paper investigated the glow discharge plasma electrolysis (GDPE) of methanol solutions for hydrogen generation. It is known that H2 and HCHO are the dominant products of methanol decomposition during GDPE. The experimental results indicate that high-energy electrons are the most important species to initiate methanol decomposition. Likewise, it was shown that discharged polarity, discharged voltage, and methanol concentration have important influences on hydrogen yield, energy consumption, hydrogen concentration, and hydrogen and formaldehyde output. The hydrogen yield (G(H2)) of cathodic GDPE (CGDPE) was found to be higher than that of anodic GDPE (AGDPE). In addition, the hydrogen concentration in liberated gas from CGDPE remains above 88% after the separation of HCHO when the applied voltage is higher than 750 V. The energy consumption (Wr) of CGDPE is significantly less than AGDPE. Furthermore, Wr decreased with the increase in discharged voltage, while G(H2) increased with methanol concentration. The experimental results show that the GDPE of methanol solutions is a promising technique for the simultaneous production of hydrogen and formaldehyde.