Alcohols and surfactant

Ashokkumar M, Hall R, Mulvaney P, Grieser F (1997) Sonoluminescence from aqueous alcohol and surfactant solutions. J Phys Chem B 101 10845-10850... 

By using this technique only water insoluble monomers can be polymerised. In this process, the monomer is suspended as discrete droplets (0.1 to 1.0 mm diameter) in dilute aqueous solution containing protective colloids like polyvinyl alcohol and surfactants, etc. The droplets have large surface area and can readily transfer heat to water. Suspension is brought about by agitating the suspension. Protective colloids prevent coalescence of the droplets. A monomer soluble initiator is used. The product is obtained by filtration or spray drying. This process cannot be carried out yet in a continuous process hence batch processing has to be used. 

The lions share, 80-90%, of the alpha olefins produced in. the United States are used In five areas as comonomers in LLDPE (linear low density polyethylene) and HDPE (high density polyethylene), plasticizer alcohols, polyalpha olefins for use in synthetic lubricants, detergent alcohols, and surfactants. The comonomer demand started out exclusively as butene-1, but it is shifting toward hexene-1 and octene-1. Similarly, the specification... 

Medium-chain alcohols such as 2-butoxyethanol (BE) exist as microaggregates in water which in many respects resemble micellar systems. Mixed micelles can be formed between such alcohols and surfactants. The thermodynamics of the system BE-sodlum decanoate (Na-Dec)-water was studied through direct measurements of volumes (flow denslmetry), enthalpies and heat capacities (flow microcalorimetry). Data are reported as transfer functions. The observed trends are analyzed with a recently published chemical equilibrium model (J. Solution Chem. 13,1,1984). By adjusting the distribution constant and the thermodynamic property of the solute In the mixed micelle. It Is possible to fit nearly quantitatively the transfer of BE from water to aqueous NaDec. The model Is not as successful for the transfert of NaDec from water to aqueous BE at low BE concentrations Indicating self-association of NaDec Induced by BE. The model can be used to evaluate the thermodynamic properties of both components of the mixed micelle. 

This model was shown to account for the observed trends of enthalpies, volumes, compressibilities and heat capacities of many types of hydrophobic solutes (hydrocarbons, alcohols and surfactants) In micellar solutions and also for the observed trends for the transfer of hydrophobic solutes to some alcohol-water mixtures. This latter observation supports the view that some alcohol-water mixtures exist as microphases which In many respects resemble micellar systems (11-12). 

Pharmaceutical scientists assess and express drug permeation across membrane barriers in terms of flux. Flux measures the molar unit of a drug that permeates a resistant barrier (e.g., skin or gastrointestinal epithelial cells) per unit time and surface area (Box 13.1). Permeation enhancers, such as alcohols and surfactants, increase flux by modulating resistance factors that counteract drug diffusion across barriers at the site of administration. 

One can see that the thickness of the oil layers does not remain constant upon dilution. This is a consequence of the nonlinearity of the system of eqs 17, which takes into account the partition of the alcohol between oil, water, and interface and the dependence of the surface activity coefficients on the surface concentrations of all the components. Figure 6c, in which the product between the repeat distance d and 4> as a function of

deviations from the ideal dilution law during the water dilution, alcohol and surfactant molecules leave the interface, and this shrinks its area. 

High concentrations of short hydrocarbon chain length alcohols are known to break down micelles. However, in this work the analysis of the ultrasonic relaxation data to obtain kinetic information was restricted to alcohol and surfactant concentrations where the mean aggregation number of the surfactant did not show a significant decrease [2,3]. 

Cosolvents, such as ethanol or higher alcohols, and surfactants are often used in a formulation to enhance the solubility of sparingly soluble compounds or to modify the stability of the drug molecule. Cosolvents will change the polarity and, in some cases, the viscosity of the medium. This may influence the photochemical... 

The demixing curves in the W/S pseudoternary diagrams for the hexanol and pentanol systems have been calculated according to the above theoretical treatment. These lines have been determined in the following way. The calculation of the state equation is applied to a dilution line along such a line the inverse micelles have a constant radius R. The micelles contain the whole water (volume Vw), the surfactant (volume V ) and a part of the alcohol V. The rest of alcohol is in the oil continuous phase. We suppose that the alcohol-oil ratio in the continuous phase is constant and is equal to k. Besides, in the calculation of the micellar radius R one assumes that the surfactant and the alcohol molecules which are situated at the interface have a constant area per chain s. In mos of the previous studies s has been found constant and equal to 25 A2. This value is taken equal for the alcohol and surfactant chains. Consequently ... 

Phase Behavior. The surfactant formulations for enhanced oil recovery consist of surfactant, alcohol and brine with or without added oil. As the alcohol and surfactant are added to equal volumes of oil and brine, the surfactant partitioning between oil and brine phases depends on the relative solubilities of the surfactant in each phase. If most of the surfactant remains in the brine phase, the system becomes two phases, and the aqueous phase consists of micelles or oil-in-water microemulsions depending upon the amount of oil solubilized. If most of the surfactant remains in the oil phase, a two-phase system is formed with reversed micelles or the water-in-oil microemulsion in equilibrium with an aqueous phase. 

In the present research on miniemulsions, the maximum stability was found at ionic surfactant to fatty alcohol molar ratios of between 1 1 and 1 3, when the alcohol and surfactant had near equal chain lengths (22,23). 

Baviere, M., Wade, W.H., Schechter, R.S., 1981. The effect of salt, alcohol and surfactant on optimum middle phase composition. In Shah, D.O. (Ed.), Surface Phenomena in Enhanced Oil Recovery. Plenum, pp. 117—135. 

Fats and Oils The Raw Materials of Oleochemistry. Fats and oils are triglycerides (i.e., fatty acid esters of glycerol). They are the starting materials for the production of fatty acid methyl esters, which are important intermediates in the production of fatty alcohols and surfactants [198] by the oleochemical route, which has great ecological benefits [199]. The fatty acid methyl esters are produced either by the esterification of fatty acids after hydrolysis of the triglycerides or by direct transesterification with methanol. The overall transesterification reaction is as follows ... 

Neutral pH cleaner compatible with many substrates mixture of modified alcohols and surfactants... 

To date the chemical trapping method has been used to estimate interfacial concentrations of water, alcohols, and counterions in cationic micelles and microemulsions [65,128] the affinity of cationic micelles toward Cl versus Br", expressed as an ion-exchange constant [Eq. (11)] [129], and interfacial alcohol/water molar ratios in microemulsions and distributions of 1-butanol and 1-hexanol between aggregate interfaces and bulk aqueous phases (O/W microemulsions) [130] and bulk oil phases (W/O microemulsions) over a range of alcohol and surfactant concentrations [131]. The focus here is on results in microemulsions. 

Alcohols and surfactant molecules compete for adsorption on the stationary phase. Alcohol addition reduces the amount of adsorbed surfactant [19,20, 23]. Table 6.5 lists the amounts of adsorbed surfactant when micellar mobile phases with or without alcohol was used [7]. The surfactant desorption is dependent on the alcohol chain length [7, 19]. Surfactant desorption is linked to a Of reduction that should decrease the HETP (eq. 6.6). The kinetics of the surfactant adsorption-desorption process is enhanced by alcohol addition [5, 7,21]. Spectroscopic studies have shown that short chain alcohols (C1-C3) wet a monomeric C18 silica bonded layer without changing its organization. Oppositely, long chain alcohols (C7-C10)... 

Ionic compounds added to the micellar system for pH or ionic strength adjustment increase usually the surfactant adsorption. Organic solvents, in contrast, decrease the amount of adsorbed surfactant. The alkyl chains of propanol and longer -alcohols form on the stationary phase a monolayer similar to that of adsorbed surfactant molecules, with the hydroxyl group oriented toward the aqueous phase. Alcohol and surfactant molecules compete for adsorption sites. For ionic surfactants, the desorbing ability depends on the organic solvent polarity (methanol adsorbed surfactant molecules decreases linearly with the organic solvent concentration. 

Adhesion in Solutions of Organic Acids and Alcohols. Changes in adhesion due to the presence of organic acids, alcohols, and surfactants with detergent properties were examined in [4, 75, 86]. 

This study supports the assumption that the alcohol influences the phase behavior of oil-brine-surfactant system and its effect is related to the saturation concentration in the water-phase. On the other hand, the ternary phase diagram with a constant amount of the cosolvent seems to be more valuable for selecting microemulsion formulations than the pseudo-ternary representation in which both alcohol and surfactant are varied simultaneously. 

THE EFFECT OF SALT, ALCOHOL AND SURFACTANT ON OPTIMUM MIDDLE PHASE COMPOSITION... 

In this work, salt, alcohol and surfactant effects are investigated, at different water-to-oil ratios to determine their influence on phase behavior. A linear relationship is found between the logarithm of water-oil ratio in the middle phase and the salinity. Moreover, in the middle of the range of salt or alcohol concentration giving a three-phase system, the water-oil ratio in the middle phase has a value close to unity (value defined as an optimum), whatever the overall water-oil ratio may be. 

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