Dilute Alcohol Solutions Research Articles

Effect of addition of alcohols on gas holdup and backmixing in bubble columns

AbstractGas holdup and axial dispersion coefficient data for dilute aqueous alcohol solutions and two different diameter columns at larger gas and liquid velocities compared to those of Schügerl et al. (1977) are presented. Data for cocurrent and batch systems are qualitatively explained using Zuber and Findlay's theory (1965) and bubble structure, and quantified further using a dynamic gas disengagement technique. Unified empirical correlations for the gas holdup and axial dispersion coefficients are presented.

Electron structure investigation of 3-iodo-5-nitro-4-hydroxybenzonitrile and some of its derivatives

A new synthesis for Nitroxynil has been elaborated. The IR and UV spectra of Nitroxynil have been measured and the π-electron properties were calculated by the quantum chemical PPP and MIM methods. The UV bands have been assigned and the pK a value was calculated from the pH dependence of the spectrum. Certain parameters needed for the calculation have been optimized with the aid of some subsystems of the Nitroxynil. The strong red shift occuring in alkaline media as well as in aqueous and dilute alcoholic solutions is interpreted by the ionization of hydroxy group and is justified by theoretical calculations

Ethanolamine thioglycollate as a chemical agent for the neutralization & removal of oxidised pyrite

A new technique for the removal of decay products from pyrltized fossil material is now employed in the British Museum (Natural History) Palaeontology Laboratory involving the use of ethanolamine thioglycollate. Dilute alcoholic solutions of this reagent effectively neutralize acidic pyrite oxidation products and removes the sulphates produced in one operation. As the reaction takes place in a water-free solvent there is little risk of damaging the intact pyrite and an added bonus is that the reagent is alkaline, allowing calcareous specimens to be cleaned safely.

Formation, Packing, and Sintering of Monodisperse TiO2 Powders

Monodisperse TiO2 powders were synthesized by the controlled hydrolysis of dilute alcoholic solutions of titanium alkoxides. The state of powder aggregation in dispersions and powder packing in the green bodies strongly affected the sintering behavior. The sintering of uniformly packed powder compacts resulted in finegrained microstructures with >99% of theoretical density nt temperatures much lower than those required to sinter conventional TiO2 powders.

The viscosity of dilute aqueous solutions of aliphatic alcohols

Relative viscosities have been measured of dilute aqueous solutions of aliphatic alcohols, including methanol, ethanol, the propanols, the butanols and the pentanols, at temperatures of 278, 293 and 313 K at concentrations in the range 10-4-10-2 mol dm-3. The Jones and Dole B coefficients have been calculated and compared with literature data extrapolated to low concentrations.

Ethyl alcohol iphibits habituation of the nictitating membrane reflex response in the intact frog

Habituation of the nictitating membrane reflex response in the intact frog was examined under conditions of various alcohol doses, administered by whole-body immersion into dilute alcohol solutions. Alcohol both markedly reduced the initial response amplitudes and severely disrupted the habituation process in a dose-dependent manner. A theoretical discussion is presented in which the effects of alcohol on habituation in other systems, and the interaction of alcohol with known neural processes, are examined. The results and conclusions are consistent with other reports of presynaptic inhibition modulating habituation at an invertebrate central synapse.

P‐aminobenzoic acid as a sunscreen and its behaviour on the skin

Synopsis PABA (p-aminobenzoic acid), a highly regarded sunscreening agent, has recently been shown to exhibit different absorption characteristics when applied to excised hairless mouse epidermis than when in dilute alcoholic solution. In the present study the cause of the differences was investigated. The results show that at normal application amounts, considerable quantities of randomly dispersed PABA micro-crystals exist on the skin surface. The forward scattering spectrum of PABA on skin resembled more closely that of micro-crystalline aggregates than that of PABA in solution.

The internal pressure of aqueous dilute solutions of alcohols and ethers

The internal pressure of aqueous dilute solutions of alcohols and ethers

The internal pressure of aqueous dilute solutions of alcohols and ethers

The internal pressure of aqueous dilute solutions of alcohols and ethers

Application of living immobilized cells to the acceleration of the continuous conversions of ethanol (wort) to acetic acid (vinegar)—Hydrous titanium(IV) oxide-immobilized Acetobacter species

Various strains of Acetobacter species have been immobilized on hydrous titanium(IV) oxide or hydrous titanium(IV) chelated cellulose and used in the continuous conversion of a dilute aqueous alcoholic solution (in the form of‘charging wort’) into acetic acid (in the form of vinegar) in tower fermenter-type reactors. A strain of Acetobacter species producing extracellular polysaccharide aggregated in the presence of hydrous titanium(IV) oxide thereby enabling higher medium flow rates and an increased acetic acid output to be achieved. A strain of Acetobacter species not producing polysaccharide showed no effect with hydrous titanium(IV) oxide but did produce more acetic acid when a titanium(IV)-cellulose chelate was added to the fermentation, although aggregation was not observed. Mechanisms, which appear to conform to established results, are proposed for the aggregation of both strains of bacteria. Apparently, these water-insoluble titanium compounds can interact with the bacterial cells, increasing their density and thus making them more resistant to ‘wash out’ by increasing the rate at which they sediment in the fermenter. This enables a greater cell mass per unit volume to be achieved which in turn leads to an increase in conversion rate in the reactor.

Drag coefficient of relatively contaminated gas bubbles

AbstractBased on the velocity profiles around clean and relatively contaminated gas bubbles, the tangential and normal stress, pressure distribution at the surface around the gas bubbles, and finally the viscous, form and total drag coefficient of the gas bubbles were calculated and compared with experimental values for dilute aqueous solutions of alcohols. The theory verifies the experimental observation that the total drag coefficient of single gas bubbbles increases with the contamination factor. The effect of the void fraction of the gas bubble swarm on the total drag coefficient was examined by the use of a void function. Most of the void functions for the relatively contaminated gas bubble swarms were between the values of potential flow and that of solid spheres.

Relation between intramolecular mobility in glassy polystyrene and the effect of liquid media on mechanical properties

A study was made of the effect of physically active liquid media — dilute solutions of normal aliphatic alcohols—on mechanical properties of amorphous glassy PS at temperatures higher and lower than temperatures of the relaxation transition related to the motion of small sections of a macromolecule (smaller than the segment). It was shown that below the temperature of this relaxation transition the medium has an adsorption effect and is due to a reduction in interphase surface energy on the polymer-medium boundary. Above this temperature local plasticization becomes significant in the thin layer of the polymer against the apex of growing silvery cracks which is due to accelerated diffusion of liquid molecules in the material under stress.

Chemical Equilibrium Laws in a Lattice Model of Dilute Associated Solutions

Abstract Chemical equilibrium laws are discussed within the framework of the grand canonical ensemble and for lattice models of dilute solutions of aliphatic alcohols in a nonpolar solvent. A statistical interpretation of association constants in a lattice model and their connection with lattice model parameters are given and discussed.

Isentropic compressibility behaviour of dilute solutions of alcohols in water

The apparent molal adiabatic compressibility (ϕK) at 5, 15, 20, 25, 30 and 45°C have been obtained for dilute aqueous solutions of the following monofunctional aliphatic alcohols, from accurate sound velocity measurements carried out by the phase comparison interferometer and density measurements by the differential float balance: MeOH, EtOH, n-PrOH, n-BuOH, i-PrOH, i-BuOH, s-BuOH and t-BuOH. The limiting apparent molal compressibility (ϕ°K) values decrease with the increase in the chain length of solute molecules whereas the temperature coefficient ∂ϕ°K/∂T are positive and increase with chain length. At 5°C the ϕ°K values for all the alcohols except MeOH are negative. The ϕK(x2) curves have negative slopes for all alcohols except n-PrOH and n-BuOH. The negative and positive slopes of ϕK(x2) curves suggest occupation of cavities and solute–solute interactions, respectively. The temperature dependence of ϕ°K further enables a distinction to be made in the way the alcohols dissolve in water: substitutional dissolution for lower alcohols and interstitial dissolution for the higher members, as proposed by Franks and Ives.

Treatment of Forms of Lactose with Dilute Alcoholic Solutions of Sodium Hydroxide

Crystalline α-lactose hydrate treated with dilute solutions of sodium hydroxide (.02%) in methanol, ethanol, propanol, and butanol at refluxing temperatures for 2h was converted into β-lactose. Moisture above 4% (wt/vol) in the ethanol, propanol, or butanol solutions impaired the conversion. With methanol it was possible to obtain high yields of β-lactose provided the water content was below 10% (wt/vol). Alkaline alcoholic treatment at refluxing temperatures induced mutarotation on unstable anhydrous α-lactose and amorphous lactose, but β-lactose and stable anhydrous α-lactose showed slight variations under the same treatment.

Properties of very dilute alcohol solutions

A detailed study is reported of the association behaviour of normal alcohols in very dilute solution (c < 0.2 mol/dm3) in benzene, carbon tetrachloride and alkane solvents using experimental i.r., N.M.R., dielectric constant, enthalpy and free energy of mixing data. The concentration dependence of the degree of association F(c) has been derived from these data and the results compared and critically assessed. The derived F(c) data have been found to be independent of the property used, while the hydrogen-bonding propensities of the OH groups are found to be independent of the alcohol chain length. The implications of the form of F(c) for association models is discussed and used together with dipole-dipole correlation data g(c) to obtain information on imer structure. An indication has been obtained of the cause of the distinctive forms of the F(c) and g(c) functions found for alcohol solutions in the different types of solvent.

Thermodynamic properties of aqueous organic solutes in relation to their structure. Part III. Apparent molal volumes and heat capacities of low molecular weight alcohols and polyols at 25 °C

The density and specific heat of dilute aqueous solutions of various alcohols and polyols have been measured at 25 °C. Such measurements have been carried out for the following solutes: methanol, ethanol, n-propanol, n-butanol, isobutanol, s-butanol, tert-butyl alcohol, n-pentanol. 3-pentanol, neo-pentanol, ethyleneglycol, 1,4-butanediol, 1,6-hexanediol, dimethyl-2,2-propanediol, 1,1,1-tris(hydroxymethyl)ethane, and pentaerythritol.The limiting apparent molal volume [Formula: see text] and heat capacities [Formula: see text] derived from these data exhibit some variations among the properties of isomers (e.g. branched vs. normal alkyl groups), but these variations cannot be conclusively attributed to specific effects in the hydration of the alkyl groups. On the other hand, the data allows one to derive group contributions to [Formula: see text] and [Formula: see text] namely [Formula: see text] for the methylene group, [Formula: see text] for the OH functional group and [Formula: see text] for the C—H of a terminal methyl group.The concentration dependence of [Formula: see text] brings out some interesting new features. With most of the alcohols, [Formula: see text] decreases with concentration, in a way related to the degree of hydrophobicity of the alcohol. Solute–solute interactions contribute to reduce [Formula: see text] of the hydrophilic solutes, but the opposite effect is observed with the most hydrophobic alcohols.

Elution of recoiled fragments from fission tracks by chemical etching

Polycarbonate films, which were exposed to fission fragments, were treated with different etching reagents. It was found that a dilute alcoholic solution of strong base gave an outstandingly higher etching rate than any aqueous solution. Etching with the alcoholic solution could conveniently be performed at room temperature. The etching rates by methanol solutions of the organic base R 4NOH, KOH, and NaOH were in the ratio of 4:2:1. The rates were found to be independent of aliphatic chain length of alcohols between methyl and amyl. When polycarbonate film irradiated from a fission source through 1 cm air was treated with 1 M KOH in methanol for 20 min, ca. 80% of the heavy fragments of uranium were leached out, whereas most of the light ones still remained in the target. Heavy atoms make shorter tracks than light ones according to their fission recoil energy and it appears that the elution rate depends only on the range of the fragments in the film. The difference in the formations of heavy and light tracks could be observed continuously when the etching was performed under a microscope.

HEATS OF SOLUTION OF COBALT(III) ACETYLACETONATE IN ALCOHOLS AND WATER

Abstract Heats of solution of cobalt(III) acetylacetonate in alcohols and water were measured and the results were related to the number of hydroxyl groups and the cohesive energy densities of solvents. Heats of solution of the same chelats were also measured in dilute carbon tetrachloride solutions of alcohols. From the results, it was found that alcohols can exist completely as monomer at an extremely low concentration range.

Magnetic resonance studies in aqueous systems. Part 2.—Chemical shift and relaxation time studies of hydroxylic protons in dilute alcohol + water mixtures

N.m.r. chemical shifts and relaxation times have been measured for hydroxylic protons in a series of dilute alcohol + water mixtures at different temperatures. The shifts are largely influenced by hydrogen bonding between alcohol and water molecules, resulting in low field shifts in dilute alcohol solutions. Hydrocarbon groups also shift the hydroxylic proton resonance, but to high fields. This effect is relatively small, particularly for small and spherical alkyl groups like t-butyl, but increases with chain length of the alkyl group. Water molecules have restricted motion in dilute alcohol + water mixtures. One of the main effects in restricting the molecular mobility of water molecules, for the short alkyl chain alcohols studied, particularly methanol and isopropyl alcohol, is hydrogen bonding interactions between alcohol hydroxyl groups and water molecules. Water molecules surrounding alkyl chains also have restricted motion and the effect increases with alcohol chain length. Contrary to some current theories, alcohol–water hydrogen bonding is important in these mixtures and should be taken into account in the interpretation of relevant thermodynamic data.