Methanol-ethanol Mixtures Research Articles

A re-appraisal of the concept of ideal mixtures through a computer simulation study of the methanol-ethanol mixtures

Methanol-ethanol mixtures under ambient conditions of temperature and pressure are studied by computer simulations, with the aim to sort out how the ideality of this type of mixtures differs from that of a textbook example of an ideal mixture. This study reveals two types of ideality, one which is related to simple disorder, such as in benzene-cyclohexane mixtures, and another found in complex disorder mixtures of associated liquids. It underlines the importance of distinguishing between concentration fluctuations, which are shared by both types of systems, and the structural heterogeneity, which characterises the second class of disorder. Methanol-1propanol mixtures are equally studied and show a quasi-ideality with many respect comparable to that of the methanol-ethanol mixtures, hinting at the existence of a super-ideality in neat mono-ol binary mixtures, driven essentially by the strong hydrogen bonding and underlying hydroxyl group clustering.

Determining optimum pulse mode for ultrasound enhanced biodiesel production

This study evaluated the most suitable pulse mode (pulse ON–OFF pattern) for transesterification of waste cooking oil (WCO) using sodium hydroxide. Pulse sonication effect was investigated using ethanol, methanol, and ethanol–methanol mixtures to convert waste cooking oil into biodiesel. The importance of duty cycle (pulse-mode operation) and the role of reaction temperature during the conversion process were discussed. A maximum biodiesel yield of 99% was obtained for a pulse ON–OFF combination of 7s–2s at 150W power output, and the optimum reaction conditions of 9:1 alcohol-to-oil molar ratio (50%-ethanol, 50%-methanol), 1wt.% of NaOH, and 1.5min reaction time.

Hydrogen production through sodium borohydride ethanolysis

In this work, sodium borohydride (SB) ethanolysis was explored for the first time as a method to generate hydrogen for Polymer Exchange Membrane Fuel Cells. Ethanolysis by-product was characterized by Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, and Nuclear Magnetic Resonance. Metal and acid catalysts were tested. RuCl3·3H2O was the best metal catalyst. Acetic acid was selected for the study because of its effectiveness, low cost and relative greenness. The maximum gravimetric hydrogen density obtained was 2.1% wt. The addition of water produces an increase in hydrogen generation rate and a decrease in conversion. The use of ethanol-methanol mixtures produces an increase in reaction rates in absence of catalyst. As a proof of concept the reaction was performed in a small reactor which operates by the addition of ethanolic acetic acid solutions to solid SB (in the form of granules). The reactor produces stable and constant hydrogen generation in the range of 20–80 ml min−1 during 1 h at constant temperature (around 27–35 °C).

Broadband complex permittivity determination using a two-port U-shaped coplanar waveguide with artificial neutral network algorithm

A two-port U-shaped Coplanar Waveguide (U-CPW) used for broadband complex permittivity measurement of high loss solutions is presented. Compared with the one-port measurement device, this two-port U-CPW coupled with artificial neural networks algorithm has the ability of reducing the multiple-solutions. Also, the measured T/R (transmission/reflection) coefficients were used instead of simulated reflection coefficients for training the neural networks that enhanced the accuracy of measurement results. Two real-valued neural networks associated with the U-CPW are used to reconstruct the two parts of the complex permittivity separately from the measured T/R coefficients. First, a large number of measured T/R coefficients of broadband frequency points of ethanol-water mixtures along with their theoretical complex permittivity are used to train two separate neural networks. Second, the trained networks are employed to reconstruct the complex permittivity of other solutions using the measured T/R coefficients. Compared with the results of Cole-Cole equation, the reconstructed results of methanol-water mixtures and ethanol-methanol mixtures at different volume fractions have been obtained with sufficient degree of accuracy in the frequency range 1-3 GHz at 20 ◦ C. For predicted values using the developed artificial neural network (ANN) architecture and those obtained from literature, the average relative errors of real and imaginary parts of complex permittivity are 2.27% and 2.12%, respectively.

Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol–methanol mixtures

This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol–methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol–methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1–2min reaction time at a power output rate between 75 and 150W. It was shown that the transesterification reactions using ethanol–methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

A 125-GHz Permittivity Sensor With Read-Out Circuit in a 250-nm SiGe BiCMOS Technology

In this paper, an integrated dielectric sensor with a read-out circuit in an unmodified SiGe BiCMOS technology at 125 GHz is presented. The sensor consists of a 500- $\mu{\hbox {m}}$ shorted half-wave coplanar-waveguide transmission line in the uppermost metal layer of the silicon process, while the read-out is obtained by reflection coefficient measurement with an integrated reflectometer and a signal source. The reflectometer is verified with a circuit breakout including an integrated dummy sensor. The reflectometer is able to measure the phase of the reflection coefficient from 117 to 134 GHz with a resolution of 0.1 $^{\circ}$ and a standard deviation of 0.082 $^{\circ}$ . The integrated sensor with the reflectometer circuit have been fabricated in a 190-GHz ${ f}_{ T}$ SiGe:C BiCMOS technology. It spans an area of 1.4 ${\hbox {mm}}^{2}$ and consumes 75 mA from a 3.3-V supply. The circuit has been assembled on a printed circuit board for characterization by immersion into test liquids. The sensor is controlled by a controller board and a personal computer enabling a measurement time of up to 1 ms per frequency point. Functionality of the sensor is demonstrated from 118 to 133 GHz with immersion of the sensor into different binary methanol–ethanol mixtures, showing good correlation between theory and measurement. The sensor shows a standard deviation of the measured phase of 0.220 $^{\circ}$ and is able to detect a difference in $\epsilon_{r}^{\prime}$ of 0.0125.

Potential Model Development Using Quantum Chemical Information for Molecular Simulation of Adsorption Equilibria of Water−Methanol (Ethanol) Mixtures in Zeolite NaA-4

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionPotential Model Development Using Quantum Chemical Information for Molecular Simulation of Adsorption Equilibria of Water−Methanol (Ethanol) Mixtures in Zeolite NaA-4Éva Csányi, Tamás Kristóf, and György Lendvay*Cite this: J. Phys. Chem. C 2010, 114, 49, 21892Publication Date (Web):November 22, 2010Publication History Published online22 November 2010Published inissue 16 December 2010https://doi.org/10.1021/jp110469yCopyright © 2010 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views280Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (77 KB) Get e-AlertsSUBJECTS:Adsorption,Alcohols,Ethanol,Molecular modeling Get e-Alerts

Pervaporation of binary water–alcohol and methanol–alcohol mixtures through microporous methylated silica membranes: Maxwell–Stefan modeling

The transport of pure water and methanol and the selective pervaporation of binary mixtures of water or methanol in alcohols (ethanol, isopropanol, butanol) are studied for two methylated microporous silica membranes as a function of feed composition (0–15 vol% water or methanol) at 60 °C. Flux data show interaction effects between the polar components in the feed. Alcohol molecules block water and methanol transport, whereas water and methanol block or enhance the alcohol transport. A simplified Maxwell–Stefan model is set up to predict fluxes from pure component pervaporation data and from literature adsorption coefficients. The Vignes equation is used to describe the concentration dependency of the mutual diffusion coefficient. The model allows a good quantitative prediction of the ethanol–water, isopropanol–water and ethanol–methanol mixtures, but needs improvement for the isopropanol–methanol and for the butanol mixtures either in water or in methanol.

Solubilities of N-[(4-bromo-3,5-difluorine) phenyl]-acrylamide in methanol–ethanol solution

N-[(4-bromo-3,5-difluorine)phenyl]acrylamide is a new monomer for polymerization reactions. Information on its corresponding solid–liquid equilibrium is essential for industrial product and process design. Using a laser detecting system, solubility data were measured for N-[(4-bromo-3,5-difluorine)phenyl]acrylamide dissolved in different compositions of methanol–ethanol mixtures at the temperature range from 287.75 K to 339.55 K. The solubility data were correlated with Apelblat equation and Buchowski–Ksiazczak λh equation. The Buchowski–Ksiazczak λh equation was found to regress the solubility data much better than the Apelblat equation.

The adsorption properties of short chain alcohols and Triton X-100 mixtures at the water–air interface

The adsorption behaviour at the water–air interface of aqueous solutions of Triton X-100 and methanol (ethanol) mixtures at constant Triton X-100 (TX-100) concentration equal to 10 −7, 10 −6, 10 −5, 10 −4, 6 × 10 −4 and 10 −3 M, respectively, in a wide range of alcohol concentration was investigated by surface tension measurements of solutions. The obtained values of the surface tension of aqueous solutions of “pure” methanol and ethanol and their mixtures with TX-100, as well as the values of propanol solutions and their mixtures with TX-100 as a function of alcohol concentration taken from the literature were compared with those calculated from the Szyszkowski, Connors and Fainerman and Miller equations. On the basis of this comparison it was stated that these equations can be useful for description of the solution surface tension in the wide range of alcohol concentration, but only at the concentrations of Triton X-100 corresponding to its unsaturated layer in the absence of alcohol. It was also stated that the Connors equation is more adequate for concentrated aqueous organic solutions. The measured values of the surface tension were used in the Gibbs equation to determine the surface excess concentration of Triton X-100 and alcohol. Next, on the basis of Gibbs adsorption isotherms those of Guggenheim and Adam and real adsorption isotherms were established. From the obtained adsorption isotherms it results that alcohol influences the shape of TX-100 isotherms in the whole range of alcohol and TX-100 concentration, but TX-100 influences the alcohol isotherms only at TX-100 concentration at which the saturated monolayer at the solution-air interface is formed in the absence of alcohol. This conclusion was confirmed by analysis of the composition of the surface layer in comparison to the composition of the bulk phase in the equilibrium state.

Analysis of methanol–ethanol mixtures from falsified beverages using a dual biosensors amperometric system based on alcohol dehydrogenase and alcohol oxidase

A portable bienzymatic analytical system was developed for the chronoamperometric analysis of methanol–ethanol mixtures. The system consists of two biosensors, one based on alcohol dehydrogenase (ADH) that responds only to the ethanol and the second one based on alcohol oxidase (AOX) that responds to both methanol and ethanol. The transducers were screen-printed electrodes (SPEs) modified with mediators: Meldola blue for ADH and Co-phthalocyanine for AOX. The calibration graph of the ADH biosensor is linear between 0.3 and 8 mmol/L ethanol. The AOX biosensor is able to quantify both analytes in mixtures that contain methanol between 3 and 70 mmol/L and ethanol ranging from 15 to 110 mmol/L. Interferences due to non-specific oxidations from common oxidizable compounds like gallic acid and ascorbic acid were smaller in the case of transducer based on Meldola blue. The analytical system was successfully tested on real samples: non-alcoholised beer (NAB) spiked with ethanol or methanol and a falsified rose wine (FRW).

Convective diffusion coefficient in the gas phase in evaporation of binary liquids

A semiempirical correlation is proposed to determine the convective diffusion coefficients in the gas phase in the evaporation of binary liquids into an inert gas. The calculated and experimental data on the evaporation of n-butanol-water, ethanol-water, and ethanol-methanol mixtures into argon are shown to be in satisfactory agreement.

Streaming current, permeability, and microelectrophoresis of polystyrene latices in methanol?ethanol mixtures

The influence of the solvent (methanol–ethanol mixtures) on the electrokinetic behavior of polystyrene latices with sulfate groups was studied (methanol content was increased by 0.2 at a constant KBr concentration of 1 mM). Viscosity, density, and dielectric constant ( η , ρ , and ε ) were determined at experimental conditions. Two latices (with different surface charge densities and sizes) were used. Electrophoresis measurements were used for dilute dispersions. Streaming current and hydrodynamic permeability were measured for porous plugs. Linear trends in the electrokinetic measurements were observed in the whole molar fraction range. The experimental data obtained from different techniques allow determining the zeta potential according to a well-established classical relationship. The results obtained were analyzed on the basis of the solvent mixture properties and the electrical interface behavior. In addition, permeability data provided valuable information to interpret effects at the solid–liquid interface of the porous plug.

Streaming current, permeability, and microelectrophoresis of polystyrene latices in methanol–ethanol mixtures

The influence of the solvent (methanol–ethanol mixtures) on the electrokinetic behavior of polystyrene latices with sulfate groups was studied (methanol content was increased by 0.2 at a constant KBr concentration of 1 mM). Viscosity, density, and dielectric constant ( η, ρ, and ε) were determined at experimental conditions. Two latices (with different surface charge densities and sizes) were used. Electrophoresis measurements were used for dilute dispersions. Streaming current and hydrodynamic permeability were measured for porous plugs. Linear trends in the electrokinetic measurements were observed in the whole molar fraction range. The experimental data obtained from different techniques allow determining the zeta potential according to a well-established classical relationship. The results obtained were analyzed on the basis of the solvent mixture properties and the electrical interface behavior. In addition, permeability data provided valuable information to interpret effects at the solid–liquid interface of the porous plug.

Higher-alcohols biorefinery: improvement of catalyst for ethanol conversion.

The concept of a biorefinery for higher-alcohol production is to integrate ethanol and methanol formation via fermentation and biomass gasification, respectively, with conversion of these simple alcohol intermediates into higher alcohols via the Guerbet reaction. 1-Butanol results from the self-condensation of ethanol in this multistep reaction occurring on a single catalytic bed. Combining methanol with ethanol gives a mixture of propanol, isobutanol, and 2-methyl-1-butanol. All of these higher alcohols are useful as solvents, chemical intermediates, and fuel additives and, consequently, have higher market values than the simple alcohol intermediates. Several new catalysts for the condensation of ethanol and alcohol mixtures to higher alcohols were designed and tested under a variety of conditions. Reactions of methanol-ethanol mixtures gave as high as 100% conversion of the ethanol to form high yields of isobutanol with smaller amounts of 1-propanol, the amounts in the mixture depending on the starting mixture. The most successful catalysts are multifunctional with basic and hydrogen transfer components.

Mathematical representation of electrophoretic mobility of basic drugs in ternary solvent buffers in capillary zone electrophoresis

The electrophoretic mobilities of two β-blocker drugs, i.e., labetalol and atenolol, have been determined in a mixed solvent background electrolyte system containing sodium acetate+acetic acid as buffering agent and different volume fractions of water, methanol and ethanol using capillary electrophoresis. The produced data and three other sets collected from a recent work are employed to study the accuracy and prediction capability of a mathematical model to calculate the electrophoretic mobility with respect to the volume fractions of the solvents in the mixture. The results show that the proposed model is able to correlate/predict the mobility within an acceptable error range and it is possible to use the model in industry to achieve the optimum solvent composition for the buffer where using a ternary solvent system is required. The average percentage deviations (APDs) obtained for correlated and predicted data points are 0.71–2.48 and 1.72–4.39%, respectively. The accuracy of the proposed model is compared with that of a mixture response surface method and the results show that the proposed model is superior from both correlation and prediction points of view. The possibility of calculation of the mobility of chemically related drugs in water–methanol–ethanol mixtures using the proposed model is also shown and the produced prediction APD is ∼8%.

Effect of Nonchromophoric Ligands on the Spectral Characteristics of Ruthenium(II) (2,2'-Bipyridine)diphosphine Complexes

The electronic absorption and luminescence spectra of the complexes cis-[Ru(bpy)(dppe)X2] [bpy is 2,2'-bipyridine, dppe is 1,2-bis(diphenylphosphino)ethane] in 4 : 1 ethanol-methanol mixtures at 77 and 293 K were measured, and the luminescence decay times were determined. As the field strength of the nonchromophoric ligand X increases in the order I- < Br- < Cl- < 1/2(CO32-) < NCS- < NO2- < CN-, the electronic transitions are blue-shifted, and the luminescence decay time becomes longer.

Microwave dielectric characterization of binary mixtures of water, methanol, and ethanol

The complex dielectric constants of binary mixtures of water–methanol and water–ethanol in the frequency range from 45 MHz to 26.5 GHz, and binary mixtures of methanol–ethanol in the range from 200 MHz to 26.5 GHz have been measured with various volume fractions around room temperature by means of an open-ended coaxial sensor and a network analyzer. Methanol–ethanol mixtures display a near-Debye dispersion while water–alcohol mixtures show a Cole–Davidson dispersion. The logarithm of relaxation time log τ and dielectric decrement Δε for methanol–ethanol mixtures show a good linear relation with the volume fraction of methanol, while log τ and Δε extracted with the Debye function for water–alcohol mixtures display a near-linear relation with volume fraction of water. Two simple formulas are proposed for identifying the volume fractions of the components in binary mixtures of alcohol–alcohol and water–alcohol from a knowledge of τ and Δε for the pure liquids and the mixtures. The validity of these formulas has been demonstrated with three blind tests. The relation between the mole fraction of water and log τ for water–methanol and water–ethanol mixtures extracted by the use of a Cole–Davidson function clearly shows two linear regions, which implies a change of relaxation mechanism with mole fraction.

Influence of the kind of the alcoholic modifier on chiral separation on a Chiralpak AD column

The enantioselective separation of substituted 3-phenoxy-1,2-propanediols (PPDs) and aziridinecarboxylic acid derivatives (ACAs) on Chiralpak AD, an amylose-based chiral stationary phase, was investigated. All solutes could be separated using hexane-alcohol mobile phases. The retention times for sixteen out of seventeen substituted PPDs and from all the ACAs increased on changing the alcoholic modifier from 2-propanol to ethanol or ethanol-methanol mixtures. The separation factors of sixteen out of seventeen PPDs and nine out of twelve ACAs were improved using ethanol or ethanol-methanol mixtures instead of 2-propanol.

Some Experimental Data Concerning the Effect of the Composition of Liquid Mixtures (Methanol-Ethanol) on the Electrophoretic Coefficient

The electrophoretic mobility of quartz particles in methanol-ethanol mixtures has been measured. The ζ-potential has been shown to play a significant role in the internal structure of the electrophoretic coefficient (l 21 ) for the quartz-methanol-ethanol system. The ζ-potential has been calculated from the results of electrophoretic mobility and streaming potential experiments. The disagreement between the ζ values thus obtained has been adjusted to some extent by introducing a corrective factor, F s , into the streaming potential measurements. F s itself was calculated by two methods and its validity tested by comparing the values found for the ζ-potential according to both electrokinetic techniques