Xylene-in-water emulsion

SHARMA AND SRIVASTAVA Stability of Xylene in Water Emulsion... 

The present paper deals with kinetics of coagulation of Phthallylsulfathiazole stabilized xylene in water emulsion in the presence of some cationic detergents. Rate of flocculation, rate of coalescence and rate of creaming have been determined. To estimate the stability of the present systems their zeta potentials have been measured and stability factors calculated. Temperature effect on the system was also studied. 

Phthallylsulfathiazole stabilized xylene in water emulsion was found to be negatively charged. Since this compound is acidic in nature, the -COOH group ionises to furnish negatively charged carboxylate anions which impart the same charge on emulsion droplets at alkaline pH 10.48 by virtue of the adsorption of the emulgent. 

Figure 3 Experimental data for creaming in xylene-in-water emulsions. The volume of the transparent semm left below the creaming emulsion, scaled with the total volume of the liquid mixture, is plotted against the time elapsed after ceasing the agitation. The emulsion is stabilized with 3-lactoglo-bulin, whose concentrations, corresponding to the separate curves, are shown in the figure. The empty and full symbols denote, respectively, coarse emulsion (mean drop size 5 pm) and fine emulsion (mean drop size 0.35 pm).

Kinetics of Xylene Coagulation in Water Emulsion Stabilized by Phthalylsulfathiazole... 

The stability of an emulsion depends not only on the surfactant type, but also on die nature of the organic phase. To characterize die oil phase, the concept of a necessary (required) HLB number is used. This number is taken to be equal to die HLB number of die surfactant which ensures the best possible emulsification of the oil. Tables of necessary HLB numbers for various oils were published in Ref 258. For example, with respect to oil-in-water emulsions, the necessary HLB number is 17 for oleic acid, 15 for toluene, 14 for xylene and cetyl alcohol, 10.5 to 12 for mineral oils, 7.5 to 8 for vegetable oils, 5 to 7 for vaseline, and 4 for paraffin. In Refs 263 and 264 the necessary HLB numbers for various oils are compared with the relative dielectric permittivity of the oil e. In the series of saturated hydrocarbons, a weak inverse dependence between the necessary HLB number and e was observed (264) e.g., e =... 

Emulsives are solutions of toxicant in water-immiscible organic solvents, commonly at 15 ndash 50%, with a few percent of surface-active agent to promote emulsification, wetting, and spreading. The choice of solvent is predicated upon solvency, safety to plants and animals, volatility, flammabiUty, compatibihty, odor, and cost. The most commonly used solvents are kerosene, xylenes and related petroleum fractions, methyl isobutyl ketone, and amyl acetate. Water emulsion sprays from such emulsive concentrates are widely used in plant protection and for household insect control. 

The introduction of Hquid crystals as stabilizing elements for emulsions occurred in 1969 when it was found that the sudden stabilization at emulsifier concentrations in excess of 2.5% of a water—% xylene emulsion by a commercial octa(ethylene glycol) nonylphenyl ether was due to the formation of a Hquid crystalline phase in the emulsion (26). Later investigations confirmed the strong stabilizing action of these stmctures (27). 

An emulsifiable concentrate is prepared from pesticides that are soluble in common organic solvents, such as xylene and kerosene. Using emulsifiers in the composition causes the formulation to disperse into small particles, called an emulsion, when diluted in water. 

In the conventional emulsion polymerization, a hydrophobic monomer is emulsified in water and polymerization initiated with a water-soluble initiator. Emulson polymerization can also be carried out as an inverse emulsion polymerization [Poehlein, 1986]. Here, an aqueous solution of a hydrophilic monomer is emulsified in a nonpolar organic solvent such as xylene or paraffin and polymerization initiated with an oil-soluble initiator. The two types of emulsion polymerizations are referred to as oil-in-water (o/w) and water-in-oil (w/o) emulsions, respectively. Inverse emulsion polymerization is used in various commerical polymerizations and copolymerizations of acrylamide as well as other water-soluble monomers. The end use of the reverse latices often involves their addition to water at the point of application. The polymer dissolves readily in water, and the aqueous solution is used in applications such as secondary oil recovery and flocculation (clarification of wastewater, metal recovery). 

The previous extension of solvent mixtures involved solvent interfaces. This organic-water interfacial technique has been successfully extended to the synthesis of phenylacetic and phenylenediacetic acids based on the use of surface-active palla-dium-(4-dimethylaminophenyl)diphenylphosphine complex in conjunction with dode-cyl sodium sulfate to effect the carbonylation of benzyl chloride and dichloro-p-xylene in a toluene-aqueous sodium hydroxide mixture. The product yields at 60°C and 1 atm are essentially quantitative based on the substrate conversions, although carbon monoxide also undergoes a slow hydrolysis reaction along with the carbonylation reactions. The side reaction produces formic acid and is catalyzed by aqueous base but not by palladium. The phosphine ligand is stable to the carbonylation reactions and the palladium can be recovered quantitatively as a compact emulsion between the organic and aqueous phases after the reaction, but the catalytic activity of the recovered palladium is about a third of its initial activity due to product inhibition (Zhong et al., 1996). 

An anionic mlcroemulslon system was based on blends of monoethanolamlne salts of bilinear dodecyl benzene sulfonic acid and branched pentadecyl o-xylene sulfonic acid. The bilinear structure results from the alkylation of benzene with a linear a-olefin. The former acts as a surfactant hydrophile (H) while the latter acts as a surfactant lipophile (L) at room temperature for the oil and water phases used in this study. The hydrophile tends to form water-continuous emulsions while the lipophile forms oil-continuous emulsions. The hydrophile-lipophile characteristics were varied by changing the weight ratio of H/L from 0.5 to 0.8. Decane was used as the oil phase and 2.0 wt. X NaCl In water as the aqueovis phase. The water-oil ratio was fixed at 95/5 and the total surfactant content was fixed at 2 g/dl. 

The presence of liquid crystal structures at both the w-o and o-w interfaces in multiple emulsions has been investigated by Kavaliunas and Frank (31). Microscopic examination of w/o/w emulsions between crossed polarizers revealed the presence of liquid crystal phases at both inner (w-o) and outer (o-w) interfaces in a w/o/w system composed of water, p-xylene and nonylphenol diethylene glycol ether. Liquid crystalline phases were also detected in o/w/o emulsions at both interfaces. The presence of these liquid crystal structures was found to improve the stability of the emulsions markedly. Matsumoto (32, 33) have concluded that the oil layers in w/o/w systems are likely to be composed of or contain,at least in proximity to the aqueous phase,multilamellar layers of the lipophilic surfactant used in the formulation this is postulated in part to explain the rate of volume flux of water through the oily layer. 

Emulsion polymerization typically refers to the polymerization of a nonaqueous material in water. The polymerization of a water-soluble material in a nonaqueous continuum has been called inverse emulsion polymerization. The inverse emulsion polymerization technique is used to synthesize a wide range of polymers for a variety of applications such as wall paper adhesive, waste water fiocculant, additives for oil recovery fluids, and retention aids. The emulsion polymerization technique involves water-soluble polymer, usually in aqueous solution, emulsified in continuous oil phase using water in oil emulsifier. The inverse emulsion is polymerized using an oil- or water-soluble initiator. The product is a colloidal dispersion of sub-microscopic particles with particle size ranging from 0.05 to 0.3 pm. The typical water-soluble monomers used are sodium p-vinyl benzene sulfonate, sodium vinyl sulfonate, 2-sulfo ethyl acrylate, acrylic acid, and acrylamide. The preferred emulsifiers are Sorbitan monostearate and the oil phase is xylene. The proposed kinetics involve initiation in polymer swollen micelles, which results in the production of high molecular weight colloidal dispersion of water-swollen polymer particles in oil. 

Chem. Descrip. Ethyleneglycol distearate CAS 91031-31-1 EINECS/ELINCS 211-014-3 Uses Emulsifier, thickener for cosmetics pearlescent, gloss aid tor shampoos emulsifier for paints, emulsion polymerization Properties Lt. yish. wh. flakes sol. in xylene disp. in ethanol, hexane insol. in water m.p. 60-65 C acid no. 5 max. sapon. no. 190-210 nonionic 100% cone. 

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