Mixtures Of Methyl Tert-butyl Ether Research Articles

Copolyimide molecular brushes with poly(methacrylic acid) side chains as additive to polyphthalamide membrane: Organization, physical, and transport properties

AbstractMacromolecules of complex architecture find application as modifiers of commercial polymeric membrane materials. In this work, copolyimide molecular brushes (coPI) composed of polyimide backbone and poly(methacrylic acid) side chains were used to modify poly(m‐phenylene iso‐phthalamide) (PPA). Structure, physical, mechanical, and transport properties of dense nonporous PPA/coPI membranes containing up to 10 wt% coPI were studied. The effect of included coPI on the membrane structure was estimated using atomic force microscopy and mechanical tests. The coPI modifier contributes to the additional formation of free volume elements evenly distributed throughout the membrane. Transport properties of PPA/coPI membranes were investigated via sorption tests and pervaporation separation of methanol (MeOH) and methyl tert‐butyl ether (MTBE) mixtures. The inclusion of coPI modifier in the PPA membrane leads to an increase in the total flux of the membrane. The highest separation factor was found for the PPA/coPI membrane containing 10 wt% coPI; transport properties of the best membrane were compared with the literature data on separation of the azeotropic MeOH–MTBE mixture.

Separation of methanol and ethanol from azeotropic MTBE mixtures using choline chloride-based deep eutectic solvents

In this study, the performance of five different choline chloride – based deep eutectic solvents (DESs), including ChCl – urea, ChCl – ethylene glycol, ChCl – glycerol, ChCl – 1,2- propanediol, and ChCl – glucose, has been experimentally and computationally investigated for the purpose of liquid – liquid extraction at 298.15 K and 1 atm. In this regard, the effect of them on the extraction efficiency to separate methanol and ethanol from azeotropic systems, methyl tert-butyl ether (MTBE) + ethanol and MTBE + methanol, is studied. To synthesize these DESs, chlorine chloride as a hydrogen bond acceptor (HBA) is blended with urea, ethylene glycol, glycerol, 1,2- propanediol, and glucose as hydrogen bond donors (HBDs). Through the investigation, it is revealed that all the studied DESs deliver a distribution coefficient, β, that is higher than unity (β > 1). Similarly, the measured selectivities for these DESs have presented values that are far greater than unity (S ≫ 1). This is advantageous as it demonstrates their industrial applications. Furthermore, to have a better view of how effective they are in terms of the extraction capacity, the experimental data have been compared to the performance of ionic liquids used for the liquid – liquid extraction of MTBE + methanol. The reliability of the tie-line compositions was checked by applying the Othmer–Tobias equation. Additionally, to show the consistency, UNIQUAC Functional-group Activity Coefficients (UNIFAC) as a thermodynamic model has been employed to predict the equilibrium tie-lines. The predicted data is compared with the experimentally measured data through the calculation of the root-mean-square deviation (RMSD), showing that both predicted and experimental data are in a good agreement together.

Extraction mechanism analysis and energy saving enhancement of extraction separation of methyl tert-butyl ether and methanol by ionic liquid based on molecular dynamics simulation

• The ILs extractant is screened by quantum chemistry and MD simulation. • The process flow of applying ILs in the production of MTBE was designed. • The sequential iterative optimization integrating reaction conditions is proposed. • The TAC in MTBE production was reduced by 26.77% when applying ILs. Methyl tert-butyl ether as an excellent gasoline additive has been widely used. There are a lot of mixtures of Methyl tert-butyl ether and methanol in the process of Methyl tert-butyl ether production. In this work, the interaction between different ionic liquids and methyl tert butyl ether / methanol was studied by the combination of quantum chemistry and molecular dynamics. In addition, there is little difference between the experimental data and the MD simulation results, indicating that the extraction performance can be predicted by MD simulation even without the phase equilibrium data. The interaction energy, radial and spatial distribution functions, and self-diffusion coefficients are calculated based on the molecular dynamics simulation results. It is proved that anions play a key role in the extraction process. The process of synthesis of methyl tert-butyl ether with ionic liquid extraction as separation unit was studied and the optimum process parameters were determined. Methyl tert-butyl ether with mole fraction greater than 99.9% could be obtained by ionic liquid extraction, and the use of Ionic liquids liquid-liquid extraction can save 26.77% of total annual cost than extractive distillation using conventional solvents. It plays a guiding role in the selection of green solvent ionic liquids extractant and the energy saving of liquid-liquid extraction.

Densities, viscosities and excess properties of binary liquid mixtures of methyl tert-butyl ether with methanol and diisopropyl ether from 308.15 to 318.15 K at 0.1 MPa

ABSTRACT Densities and viscosities of binary mixtures for methyl tert-butyl ether (MTBE) with methanol and diisopropyl ether (DIPE) have been measured at temperatures of 308.15, 313.15 and 318.15 K and at atmospheric pressure over the entire composition range. The measured densities and viscosities were fitted using Jouyban-Acree model where mean relative deviation (MRD) lesser than 0.02% are obtained for both predictions. The excess molar volumes and the viscosity deviations are calculated from measured densities and viscosities. Redlich-Kister equation is then used to correlate excess molar volumes and viscosity deviations where good fits have been achieved. Negative excess molar volume and viscosity deviation have been obtained for binary mixture MTBE + methanol at all investigated temperatures which indicating the presence of chemical and structural interactions. However, lack of specific interactions has been observed for binary mixture MTBE + DIPE based on positive excess molar volume and small negative values of viscosity deviation.

Densities, Viscosities and Excess Properties of Binary Liquid Mixtures of Methyl Tert-Butyl Ether (MTBE) with N-Methylaniline (NMA) from 308.15-318.15 K at 0.1 MPa

Densities, Viscosities and Excess Properties of Binary Liquid Mixtures of Methyl Tert-Butyl Ether (MTBE) with N-Methylaniline (NMA) from 308.15-318.15 K at 0.1 MPa

Graphene oxide – Filled polyimide membranes in pervaporative separation of azeotropic methanol–MTBE mixtures

Graphene oxide (GO)-polyimide mixed matrix membranes (MMMs) were produced using chloroform by solvent evaporation. These membranes have been used, for the first time, in pervaporation (PV) for the separation of azeotropic methanol (MeOH)- methyl tert-butyl ether (MTBE) mixtures (14.3 and 85.7%, respectively). The effect of GO loading in the PV process was investigated. The PV experiments were carried out at different feed operating temperatures (25–45 °C). Furthermore, an analysis of the PV process through the Arrhenius relationship has been given. The feed temperature (in the range of 25–45 °C) affected the permeation of both components producing an increase in total permeate flux; however, separation factor was compromised. Indeed, the best permeate fluxes (ca. 0.091 kg m−2 h−1) of the MMMs (4 wt% GO) were found at 45 °C, while the best separation factor (α = 28) was found at 1 wt% GO at 25 °C. In addition, the membranes were characterized by TGA, SEM, DSC, solvent uptake and mechanical test (Young’s modulus). Finally, the performance of the GO-polyimide membranes was compared with other polymeric and MMMs membranes at the azeotropic conditions.

Post-synthetic MIL-53(Al)-SO3H incorporated sulfonated polyarylethersulfone with cardo (SPES-C) membranes for separating methanol and methyl tert-butyl ether mixture

The post-synthetic MIL-53(Al)-SO3H was prepared and incorporated into sulfonated polyarylethersulfone with cardo (SPES-C) polymer matrix to form mixed matrix membranes (MMMs). The as-prepared MIL-53(Al)-SO3H was characterized by wide angle X-ray diffraction (WAXRD), fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), intelligent gravimetric analysis (IGA), scanning electron microscope (SEM) and elemental analysis. Positron annihilation lifetime spectroscopy (PALS), thermo gravimetric analysis (TGA), SEM, FTIR and water contact angle measurements were performed to investigate the properties and structure of MMMs. The results showed that MIL-53(Al)-SO3H was successfully synthesized without crystal structure collapse. The particle sizes were in nanometer scale. MIL-53(Al)-SO3H preferentially adsorbed methanol (MeOH) over methyl tert-butyl ether (MTBE). MIL-53(Al)-SO3H dispersed in SPES-C phase uniformly and no obvious interfacial defects could be observed. The membrane hydrophilicity, swelling behavior as well as free volume parameters could be effectively tuned by changing filler loading. The as-prepared MMMs demonstrated excellent separation performance and encouraging long-term stability for MeOH (15 wt%)/MTBE mixture. With increasing the filler loading, the permeation flux increased and the separation factor showed an up and down trend. When MIL-53(Al)-SO3H loading was below 15 wt%, an antitrade-off phenomenon was obtained. M-15 with 15 wt% loading exhibited the optimal separation performance (permeation flux of 0.368 kg·m−2·h−1 and separation factor of 1990).

A Simple Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Measurement of Cortisol Level in Human Saliva.

A simple ultraperformance liquid chromatography-tandem mass spectrometry assay for measurement of cortisol level in human saliva was developed and validated. Saliva samples containing cortisol were spiked with tolperisone as internal standard (IS) and extracted with a mixture of methyl tert-butyl ether and hexane (8:2, v:v). After solvent evaporation, residue was reconstituted in 100 μl mobile phase. Analysis was performed on Atlantis dC18 column (2.1 × 100 mm, 3 μm particle size) with a mobile phase composed of acetonitrile and 2 mM ammonium acetate (50:50, v:v) and delivered at a flow rate of 0.3 ml/minute. Mass spectrometry acquisition was performed with multiple reaction monitoring in positive-ion mode for cortisol and IS (m/z: 363.1 → 121.0 and 246.0 → 97.9, respectively). Retention times of cortisol and IS were about 1.35 and 2.45 minutes, respectively. The relationship between cortisol level and peak area ratio of cortisol to IS was linear in the range of 0.5-100 ng/ml. Intra- and interday coefficient of variation and bias were ≤ 9.0% and ≤12.0%, respectively. Mean extraction recoveries of cortisol and IS from saliva samples were 92% and 94%, respectively. Using the method, cortisol was found to be ≥ 86% stable in processed (24 hours at room temperature or 48 hours at -20°C) and ≥ 91% stable in unprocessed (24 hours at room temperature or 20 weeks at -20°C) saliva samples. Further, the method was successfully applied to determine daily cortisol profile in saliva samples of a healthy volunteer.

Liquid-liquid equilibria for azeotropic mixture of methyl tert-butyl ether and methanol with ionic liquids at different temperatures

Searching for green solvents is imperative for the sustainable development of liquid-liquid extraction. Liquid-liquid equilibrium data for two ternary systems of methyl tert-butyl ether (MTBE) + methanol + N-methylimidazolium hydrosulfate ([MIM][HSO4]) and MTBE + methanol + 1-butyl-3-methylimidazolium hydrosulfate ([BMIM][HSO4]) were measured at 278.15 K, 298.15 K and 318.15 K at 101.325 kPa for this study. The values of the distribution coefficient and the separation factor were calculated based on the experimental data, and then, the extraction ability was determined. Factors affecting the phase behavior such as the nature of the ionic liquid and the temperature were discussed. NRTL and UNIQUAC models were applied to correlate the experimental tie-line data.

Anaerobic degradation of a mixture of MtBE, EtBE, TBA, and benzene under different redox conditions

The increasing use of biobased fuels and fuel additives can potentially change the typical fuel-related contamination in soil and groundwater. Anaerobic biotransformation of the biofuel additive ethyl tert-butyl ether (EtBE), as well as of methyl tert-butyl ether (MtBE), benzene, and tert-butyl alcohol (TBA, a possible oxygenate metabolite), was studied at an industrially contaminated site and in the laboratory. Analysis of groundwater samples indicated that in the field MtBE was degraded, yielding TBA as major product. In batch microcosms, MtBE was degraded under different conditions: unamended control, with medium without added electron acceptors, or with ferrihydrite or sulfate (with or without medium) as electron acceptor, respectively. Degradation of EtBE was not observed under any of these conditions tested. TBA was partially depleted in parallel with MtBE. Results of microcosm experiments with MtBE substrate analogues, i.e., syringate, vanillate, or ferulate, were in line with the hypothesis that the observed TBA degradation is a cometabolic process. Microcosms with ferulate, syringate, isopropanol, or diethyl ether showed EtBE depletion up to 86.5% of the initial concentration after 83 days. Benzene was degraded in the unamended controls, with medium without added electron acceptors and with ferrihydrite, sulfate, or chlorate as electron acceptor, respectively. In the presence of nitrate, benzene was only degraded after addition of an anaerobic benzene-degrading community. Nitrate and chlorate hindered MtBE, EtBE, and TBA degradation.

MEASUREMENT OF VOLUMETRIC AND VISCOMETRIC PROPERTIES OF BINARY MIXTURES OF METHYL TERT-BUTYL ETHER (MTBE) + 1-ALCOHOL FROM 293.15 TO 308.15 K AND AT ATMOSPHERIC PRESSURE

Densities and viscosities of binary mixtures of methyl tert-butyl ether (MTBE) with 1-alkanols include 1-butanol, or +1-pentanol, or +1-hexanol, or +1-heptanol were measured as a function of composition from 293.15 to 308.15 K at atmospheric pressure. The temperatures studied were 293.15, 298.15, 303.15 and 308.15 K. The experimental results have been used to calculate the viscosity deviation Dh and volumetric properties such as , and . Both and Dh values were negative over the entire range of mole fraction for all temperatures and systems studied. The results for all volumetric and viscometric properties are discussed on the basis of molecular interactions between the components of the mixtures.

Isothermal and Isobaric Vapor–Liquid Equilibrium and Excess Molar Enthalpy of the Binary Mixtures of 2-Methoxy-2-methylpropane + 2-Methyl-2-butanol or + 2-Butanol

Low molecular weight ethers have been used for many years as enhancers for fossil fuels combustion. A gradual replacement of mineral oils by bio-oils requires additional knowledge about the thermodynamic properties of bio-alcohol and ether mixtures. In this work, isothermal vapor–liquid equilibria (VLE) of the binary mixture of methyl tert-butyl ether (MTBE, 2-methoxy-2-methylpropane) with 2-methyl-2-butanol and MTBE with 2-butanol were measured isothermally at 323 K and at constant 90.1 kPa pressure with a recirculation still apparatus. Excess molar enthalpy (hE) was measured for two binary mixtures at 308 K, 323 K, and 363 K by using a SETARAM C80 calorimeter equipped with a flow mixing cell. A comprehensive consistency analysis was performed for the obtained data, and the experimental data were correlated with the nonrandom two liquid and universal quasichemical activity coefficient models. The results were compared with UNIFAC-Dortmund and COSMO-RS predictive models. The investigated mixtures are clos...

Liquid–liquid equilibria for ternary mixtures of methyl tert-butyl ether, ethyl tert-butyl ether, water and imidazolium-based ionic liquids at 298.15 K

The ternary liquid–liquid equilibria (LLE) were analytically determined at 298.15K for the following systems: {methyl tert-butyl ether (MTBE)+water+1-ethyl-3-methylimidazolium-ethylsulfate (EMISE)}, {MTBE+water+1-butyl-3-methylimidazolium-tetrafluoroborate ([Bmim][BF4])}, {ethyl tert-butyl ether (ETBE)+water+EMISE}and {ETBE+water+[Bmim][BF4]}.All the determination were carried out at atmospheric pressure using stirred and thermo-regulated cells. The experimental data were correlated with the well-known NRTL and UNIQUAC activity coefficient models. In addition, distribution coefficients with selectivity of the ionic liquids EMISE and [Bmim][BF4] for water in the MTBE or ETBE phase were determined.

Analysis of Oxcarbazepine and the 10‐Hydroxycarbazepine Enantiomers in Plasma by LC‐MS/MS: Application in a Pharmacokinetic Study

Oxcarbazepine is a second-generation antiepileptic drug indicated as monotherapy or adjunctive therapy in the treatment of partial seizures or generalized tonic-clonic seizures in adults and children. It undergoes rapid presystemic reduction with formation of the active metabolite 10-hydroxycarbazepine (MHD), which has a chiral center at position 10, with the enantiomers (S)-(+)- and R-(-)-MHD showing similar antiepileptic effects. This study presents the development and validation of a method of sequential analysis of oxcarbazepine and MHD enantiomers in plasma using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Aliquots of 100 μL of plasma were extracted with a mixture of methyl tert-butyl ether: dichloromethane (2:1). The separation of oxcarbazepine and the MHD enantiomers was obtained on a chiral phase Chiralcel OD-H column, using a mixture of hexane:ethanol:isopropanol (80:15:5, v/v/v) as mobile phase at a flow rate of 1.3 mL/min with a split ratio of 1:5, and quantification was performed by LC-MS/MS. The limit of quantification was 12.5 ng oxcarbazepine and 31.25 ng of each MHD enantiomer/mL of plasma. The method was applied in the study of kinetic disposition of oxcarbazepine and the MHD enantiomers in the steady state after oral administration of 300 mg/12 h oxcarbazepine in a healthy volunteer. The maximum plasma concentration of oxcarbazepine was 1.2 µg/mL at 0.75 h. The kinetic disposition of MHD is enantioselective, with a higher proportion of the S-(+)-MHD enantiomer compared to R-(-)-MHD and an AUC(0-12) S-(+)/R-(-) ratio of 5.44.

Pervaporation of water–ethanol and methanol–MTBE mixtures using poly (vinyl alcohol)/cellulose acetate blended membranes

Poly (vinyl alcohol) (PVA) and cellulose acetate (CA) are widely used as membrane materials. Here PVA/CA blended membranes were prepared over a range of 0–100wt% CA loading, and applied to separate water–ethanol and methanol–methyl tert-butyl ether (MTBE) mixtures by pervaporation. They were characterized by tensile strength testing, contact angle metering and wide angle X-ray diffraction (XRD), scanning electron microscopy (SEM) and positron annihilation lifetime spectroscopy (PALS). Phase separation was observed from the membrane cross-section. As the CA loading increases, the radius of free volume cavity and fractional free volume of the blended membranes increase simultaneously. The as-prepared blended membranes exhibit good separation performance in pervaporation of water (15wt%)–ethanol and methanol (15wt%)–MTBE mixtures. Blending has improved permeability of the PVA membrane and selectivity of the CA membrane. The total flux greatly increases whereas separation factor falls with increasing CA loading. The permeances of water and methanol are higher than 8000gpu and continually increase with CA loading. The results will provide guidance and reference for designing high efficient polymer blended membranes.

Development and validation of a liquid chromatography–tandem mass spectrometry method for simultaneous determination of amlodipine, atorvastatin and its metabolites ortho-hydroxy atorvastatin and para-hydroxy atorvastatin in human plasma and its application in a bioequivalence study

A sensitive, simple and rapid high-performance liquid chromatography coupled with positive ion electrospray ionization-tandem mass spectrometry (HPLC–ESI-MS/MS) method was developed for the simultaneous determination of amlodipine, atorvastatin and its metabolites ortho-hydroxy atorvastatin and para-hydroxy atorvastatin in human plasma. The analytes were extracted from human plasma through liquid–liquid extraction method. A mixture of methyl tert-butyl ether and ethyl acetate (50:50, v/v) was used as the extractant. The chromatographic separation was achieved on a CAPCELLPAK CR 1:4 (5μm, 150mm×2.0mm i.d.) column within 6.0min with the mobile phase consisted of acetonitrile and ammonium acetate buffer (20mM) containing 0.3% formic acid (50:50, v/v). Data acquisition was carried out in multiple reaction monitoring (MRM) mode. The method was validated and was successfully applied to the bioequivalence study of combination tablets containing AM and AT with coadministered individual drugs in 50 healthy Chinese male volunteers.

Densities, viscosities and refractive indices of binary liquid mixtures of methyl tert-butyl ether or ethyl tert-butyl ether with a hydrocarbon fuel

The densities and viscosities of mixtures of a hydrocarbon fuel (JP-10) with methyl tert-butyl ether (MTBE) or ethyl tert-butyl ether (ETBE) were determined at different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15)K, over the entire composition range. Excess molar volumes, viscosity deviation and excess Gibbs energies of activation of mixtures were calculated and fitted to the Redlich–Kister equation. The excess molar volumes are negative over the entire range of composition. The viscosity data have been correlated with several semi-empirical equations. The thermodynamic functions of activation were also calculated. The refractive indices of the systems were also measured for temperatures of (293.15, 303.15 and 313.15)K. The results provide important information on the research and application of JP-10 and fuel ethers as additives.

Liquid–liquid equilibria at 298.15 K for ternary mixtures of methyl tert-butyl ether + methanol (or ethanol) + imidazolium-based ionic liquids at atmospheric pressure

Liquid–liquid equilibria (LLE) were determined for ternary systems {methyl tert-butyl ether (MTBE)+methanol+1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4])}, {MTBE+ethanol+[Bmim][BF4]}, {MTBE+methanol+1-ethyl-3-methylimidazolium ethylsulfate (EMISE)} and {MTBE+ethanol+EMISE} at 298.15K and atmospheric pressure. The experimental apparatus used a jacketed glass equilibrium cell. The experimental data were correlated with the well-known nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models. In addition, the distribution coefficients and the selectivity of the imidazolium-based ionic liquids to methanol and ethanol in the MTBE phase were determined.

Simultaneous analysis of antiretroviral drugs abacavir and tenofovir in human hair by liquid chromatography–tandem mass spectrometry

A sensitive and reproducible method has been developed and validated for the simultaneous quantification of the key antiretroviral drugs abacavir and tenofovir in hair using LC–MS/MS. The method was validated according to the US Food and Drug Administration (FDA) guidelines for the parameters: specificity, stability, limits of detection (LOD), limits of quantification (LOQ), linearity, accuracy, precision and recovery. Hair samples (50mg) were decontaminated and subjected to methanolic extraction, where 1ml methanol was added along with the internal standard abacavir-d4 at a final concentration of 0.15ng/mg hair. After 16h, the drugs were recovered by liquid–liquid extraction using ammonium acetate buffer and a mixture of methyl tert-butyl ether:ethyl acetate (1:1). The samples were reconstituted with 200μl acetonitrile:water (1:1) prior to injection for LC–MS/MS. The LOD and LOQ values were 0.06 and 0.12ng/mg (drug/hair) for both drugs. Calibration curves were linear in the concentration range of 0.12–4.0ng/mg of drug/hair with regression coefficient (r2) value of 0.999 for both drugs. The data for accuracy, precision and recovery were within the FDA limits. The concentrations of the drugs in the hair samples ranged from 0.12ng/mg to 4.48ng/mg and 0.32ng/mg to 1.67ng/mg for tenofovir and abacavir, respectively. This is the first full report of a method for the simultaneous determination of these two key antiretroviral drugs in hair. The newly developed method is useful for future routine analysis of tenofovir and abacavir in human hair and could be used in therapeutic drug monitoring and adherence to medicines studies, which would be helpful in decision making regarding treatment change in combination anti-retroviral therapies.

Effect of the nature of an extractant on the composition and properties of lipids extracted from peat

The effect of an extractant on the yield of lipids depending on the moisture content of peat was studied. A maximum yield of lipids was obtained upon extraction with a mixture of methyl tert-butyl ether and ethanol in a ratio of 1: 1. It was found that the use of an ethyl acetate-ethanol or methyl tert-butyl ether-ethanol solvent mixture led to a decrease in the acid and peroxide numbers of lipids regardless of the moisture content of peat. The antioxidant activity of lipids increased with the moisture content of peat.