Ethanol-water Binary Mixtures Research Articles

Instability Analysis of the Drop Growth Mechanism on Condensation of a Water-Ethanol Binary Mixture.

When a water-ethanol binary mixture condenses, one observes dropwise condensation on the liquid film even though either substance is completely soluble in the other. The phenomenon is not well understood. This paper discusses liquid film instability using perturbation theory as the drop growth mechanism. The results show that in drop growth, the Marangoni number (Ma, i.e., the concentration dependence of the surface tension) plays a more important role than the absolute value of the surface tension. When a pure, single-component vapor condenses, dropwise condensation does not occur because Ma of a pure substance is always negative ; however, in a binary mixture, the surface tension may be different, and therefore the possibility exists that Ma is positive. If so, the mode of condensation may become dropwise. However, this will depend on the diffusive resistance which, if lowered, makes dropwise condensation more difficult.

Spectrophotometric Study of Zinc, Cadmium and Lead Complexes with Murexide in Binary Ethanol-Water Mixtures

Abstract The complexation reactions between murexide and Zn2+, Cd2+ and Pb2+ ions in C2H5OH-H2 mixtures have been investigated spectrophotometrically. Formation constants of the resulting 1:1 complexes were determined and found to vary in the order Pb2+ > Cd2+ > Zn2+, in all binary ethanol-water mixtures used. There is an inverse relationship between the complex formation constants and amount of water in the mixed solvent. A linear relationship was observed between log Kf for complexes and the mole fraction of ethanol.

The influence of electric fields on the intensity of rectification

The rectification of binary mixtures of ethanol-water and acetone-water was studied for the case of static, alternating and pulsed electric fields. It was found out that as electric discharge occured in a gas region the increase of mass transfer could be mainly due to electric wind turbulizing of the vapour phase. In this case the intensity of rectification mass transfer was to 1.7 times higher than under free condition. For the first time the rectification in the regime of electrohydrodynamical (EHD) spraying of liquids was investigated. To do this, the conditions of atomization by an electric field of conductive liquids with high surface tension are determined and realized in the rectifying column. The regime of EHD spraying of liquid was the most efficient one for the rectification in imposed electric fields. The mechanism of electric fields effects on mass transfer and the role of process parameters in these effects are discussed in detail. The new methods and equipment for the realization of mass transfer processes in gas-liquid systems were developed and investigated. It was shown that the EHD mass transfer apparatus has better diffusive and hydrodynamic characteristics compared with packed, pipe and cascade tray fractionating columns.

Pervaporation membranes for ethanol-water mixture prepared by plasma polymerization of fluorocarbons. II. Perfluoropropane membranes

Pervaporation membranes for ethanol-water binary mixtures were prepared by plasma polymerization of perfluoropropane (PFP). The plasma-polymerized thin films were deposited onto porous polysulfone (PS) filters as substrates with an average pore size from 0.1 to 0.45 μm. By adding argon carrier to PFP system, fluorine/carbon elemental ratios (F/C) of the produced membranes evaluated by X-ray photoelectron spectroscopy (XPS), showed a maximum value, then slightly decreased at higher partial pressure of Ar. This tendency was recognized more clearly by comparing the summation of −CF 3 and −CF 2-peak area percentages based on a whole C 18 peak area. As a measure of hydrophobicity, this value is more intelligible than the direct F/C ratio. The influence of substrate pore-size, plasma-treatment time and hydrophobicity of the membranes on the separation capability were studied. The ethanol-separation coefficient, (α EtOH), of PFP membranes increased slightly with decrease of the average pore-size of the substrates, but treatment time did not apparently affect the α EtOH. We classified the prepared membranes into two classes, i.e. the membranes showing higher and lower permeation fluxes than 0.5 kg/m 2-hr. The α EtOH was more evidently observed to increase with membrane hydrophobicity for the former class of PFP membranes. We suggest that, at least, three separation schemes might be necessary to understand the correlations found in each group.

Theoretical Analysis for the Condensation Heat Transfer of a Binary Vapor Mixture under the Thermal Equilibrium Condition.

The condensation heat transfer of ethanol-water binary vapor mixture is theoretically examined with regard to the assumption of thermal equilibrium in the vapor boundary layer. If the vapor in the boundary layer is subcooled, liquid droplets appear. Under this condition, the effects of the temperature difference between the wall and ambient, and the ambient ethanol mole fraction, on the heat transfer process are investigated. The results show that the heat transfer coefficient under equilibrium conditions decreases from that obtained without droplet formation (nonequilibrium) according to the total amount of the generated liquid droplets.

Traveling wave convection patterns in an annular cell

Fast traveling wave convection rolls, localized rolls, non-uniform velocity rolls and slow rolls are four distinct patterns observed during the evolution of convection patterns in an ethanol-water binary mixture. These Rayleigh-Bénard experiments were carried out in an annular cell with an aspect ratio of 80:2:1. The mixture has a separation ratio value of ψ ⋍ -0.09. The convection was driven by a constant heat flux less than 5% above the onset heat flux.

Liquid-phase adsorption of binary ethanol–water mixtures on high-silica adsorbents

A study was made of the adsorption of ethanol–water mixtures on adsorbents with high silicon-to-aluminium ratios and different structures. The shape of the resulting excess isotherms changes dramatically with the geometry and the growth of the channels and cavities inside the adsorbents. It is possible that water association within the free volume of the adsorbents causes the loss of efficiency of separation, although the adsorbents are distinctly hydrophobic. While the activity coefficients of the adsorbed phase for small channel systems (ZSM-5) show positive deviations from Raoult's law they change in the order ZSM-5, ZSM-35, US-Ex-zeolite with higher free adsorption volumes in the direction of the free liquid.

Pervaporation Separation of Water-Ethanol through Modified Polyacrylonitrile Membranes

In the present work the separation of water-ethanol binary mixture through polyacrylonitrile (PAN) and its modified membranes was studied using pervaparation processes. PAN was chosen as a base polymer because of its high affinity with water. As a result, homogeneous PAN membrane has an extremely high selectivity toward water and has low fiuxes in pervaparation. Membrane morphology of PAN influences to a great extent on the membrane performance when separating the aqueous ethanol solution. This study investigates the way to control the membrane morphology and the membrane performance. The key factors affecting the membrane morphology include the membrane casting variables such as concentration of casting solution, solvent evaporation temperature, solvent evaporation pressure, the membrane thickness and the presence of nonsolvents in casting solution. Membranes we investigated are homogeneous, blend-type and copolymer-type PAN membranes. A statistical method was adopted in the experiment. As a consequence it was possible to effectively predict fiuxes and separafion factors using these membranes to dehydrate aqueous ethanol solution.

Liquid Phase Adsorption of Binary Ethanol-Water Mixtures on Isomorphously Substituted ZSM-5 Zeolites

Liquid Phase Adsorption of Binary Ethanol-Water Mixtures on Isomorphously Substituted ZSM-5 Zeolites

Liquid Phase Adsorption of Binary Ethanol-Water Mixtures on Isomorphously Substituted ZSM-5 Zeolites

Liquid Phase Adsorption of Binary Ethanol-Water Mixtures on Isomorphously Substituted ZSM-5 Zeolites

Application of the Kirkwood-Buff theory of solutions to the surface phase between the water-ethanol binary liquid mixture and its vapor

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplication of the Kirkwood-Buff theory of solutions to the surface phase between the water-ethanol binary liquid mixture and its vaporE. Tronel-Peyroz, J. M. Douillard, R. Bennes, and M. PrivatCite this: Langmuir 1989, 5, 1, 54–58Publication Date (Print):January 1, 1989Publication History Published online1 May 2002Published inissue 1 January 1989https://doi.org/10.1021/la00085a011RIGHTS & PERMISSIONSArticle Views149Altmetric-Citations9LEARN 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 (570 KB) Get e-Alerts Get e-Alerts

Liquid-phase adsorption of binary ethanol–water mixtures on NaZSM-5 zeolites with different silicon/aluminium ratios

A systematic study was made on the adsorption of ethanol–water mixtures on NaZSM-5 zeolites, synthesized with different Si/ Al ratios. The excess isotherms were analysed by means of energetic homogeneous and energetic heterogeneous adsorbent models. For the first model, the equilibrium constants increase with increased Si/ Al ratio. Using the model of an energetic heterogeneous adsorbent, an energy difference distribution function with two maxima appears, which is due to London-type interactions and the specific interactions of the zeolites with the adsorbed molecules.

Laminar forced convection condensation of binary mixtures on a flat plate.

This paper deals with the theoretical analysis of laminar forced convection condensation of binary mixtures on a flat plate. Similarity solutions for seven kinds of binary mixtures of ethanol-water, R 22-R 114, R 114-R 11, air-water, air-ethanol, air-R 22, air-114 along with several pseudo-mixtures of low Shmidt number and low ρ-μ ratio are numerically obtained. Two expressions among the boundary values at the vapour-liquid interface concerning heat and mass flaxes through the vapour boundary layer are newly proposed, which contain the characteristics of condensation of superheated and saturated pure vapours and those of single phase forced convection. The heat and mass fluxes calculated from the simultaneous algebraic equations which are composed of the present new expressions, previous expression for liquid film heat transfer, phase equilibrium conditions and miscible condition, agree with those from the similarity solutions within 1-3% error.

Polymer membrane as a reaction field. III. : Effect of membrane polarity on selective separation of a water—ethanol binary mixture through synthetic polymer membranes

Polymer membrane as a reaction field. III. : Effect of membrane polarity on selective separation of a water—ethanol binary mixture through synthetic polymer membranes

Polymer Membrane as a Reaction Field II. Effect of Membrane Environment on Permselectivity for Water–Ethanol Binary Mixtures

Polymer Membrane as a Reaction Field II. Effect of Membrane Environment on Permselectivity for Water–Ethanol Binary Mixtures

Spectroscopic properties of anisole in mixed polar solvents

Absorption and emission spectra, fluorescence quantum yields and lifetimes were studied for anisole in binary ethanol-water mixtures. The spectroscopic and photophysical properties show an exceptional behaviour in the aqueous solution. In water a strong nonradiative process, originating from the fluorescent state decreases the emission yield and lifetime. The results are discussed in terms of short range interactions between the solute and solvent.

The radiolysis of binary ethanol-water mixtures

Hydrogen, nitrite, acetyldehyde, 2,3-butanediol and hydrocarbon yields produced by the radiolysis of lithium nitrate in binary ethanol-water mixtures containing respectively 5, 10 and 15 moles dm −3 of alcohol have been determined. The “free-ion” solvated electron yields support the low value of G e S − (0·9−1·2) for pure ethanol. The results also show that the “molecular” acetaldehyde yield is not formed by the dismutation of hydroxyethyl radicals.