Sodium surfactant mixtures

At the termination of the activity period, each participant s hands were held over a bowl and doused with 250 mL of a dilute dioctyl sodium sulfosucci-nate (anionic surfactant) mixture. This soap wash was followed by a 250-mL rinse with deionized water. The soap and water fractions were stored together in the same container. Fifteen grams of sodium chloride were added to the container to facilitate phase separation. The chlorpyrifos was partitioned with 200 mL of ethyl acetate, which was also used to rinse the bowl. The ethyl acetate extract was later analyzed for chlorpyrifos content. The amount of test substance removed was used to assess adult hand exposures and dose and also to assess the theoretical amount of test substance removed when children put their hands in their mouths. 

Surfactant mixtures were used as obtained and are listed with their properties in Table II. Sodium chloride and calcium chloride were Fisher reagent grade. Deuterium oxide was Aldrich Gold Label and had a surface tension of 70.4 mN/m at 23°C measured with a W iI heImy pi ate tens i ometer. 

D. J.F. Taylor, R.K. Thomas, and J. Penfold The Adsorption of Oppositely Charged Polyelectrolyte/Surfactant Mixtures Neutron Reflection from Dodecyl Trimethy-lammonium Bromide and Sodium Poly(Styrene Sulfonate) at the AirAVater Interface. Langmuir 18, 4748 (2002). 

E. Staples, I. Tucker, J. Penfold, R.K. Thomas, and D.J.F. Taylor Organization of Polymer-Surfactant Mixtures at the Air-Water Interface Sodium Dodecyl Sulfate and Poly Dimethyldiallylammonium Chloride. Langmuir 18, 5147 (2002). 

Dissolve the Sodium Citrate and sodium borate in approximately 20 ml water. Apply heat if necessary to dissolve. Combine the surfactants, propylene glycol and ethyl alcohol. Add the Sodium Citrate and sodium borate solution to the surfactants mixture. Add the sodium xylene sulfonate. Adjust the pH to 9.5 using TEA or dilute sodium hydroxide. Bring the volume of the mixture to 100 ml using water. 

The results showed distinct and regular changes for the aqueous solubility region in pentanol surfactant mixtures. With increased electrolyte content, the "minimum amount of water for solubility was enhanced, the solubility limit towards the pentanol water axis was shifted to higher soap concentrations, and the "maximum solubility of the aqueous sodium chloride solution was obtained for higher surfactant alcohol ratios (Figure 2). 

However, it is not recommended that one use rapidly distributing surfactants exclusively because surfactant mixtures (e.g., Lipoid S75/poloxamer 188 [30] or tyloxapol/lecithin [27]) might lead to lower particle sizes and higher storage stability compared with formulations with only one surfactant. The addition of sodium glycocholate to the aqueous phase as coemulsifying agent decreases the particle size, too [27],... 

Interaction between the surface-active components in surfactant mixtures and with the solubilizate can both increase and decrease solubilization into the mixed micelles. Thus, the addition of small quantities of sodium dodecyl sulfate sharply decreases the solubilization of Butobarbitone by micellar solutions of a commercial POE nonionic, Ci2H2s(0C2H4)230H. The competitive interaction of the sodium dodecyl sulfate with the oxyethylene groups on the surface of the micelles of the nonionic surfactant is believed to be the cause of this phenomenon (Treiner, 1985). On the other hand, a mixture of sodium dodecyl sulfate and sorbitan monopalmitate in aqueous solution (Span 40) solubilized dimethylaminoazobenzene more than either surfactant by itself, with maximum solubilization observed at a 9 1 molar ratio of the anionic to the nonionic (Fukuda, 1958). 

Figure 3.11 Variations of optimum salinity (5) as a function of the temperature (7) for an anionic surfactant (0 wt.% Nl), a non-ionic (100 wt.% Nl) surfactant and their mixtures. The systems contain equal amounts of water and n-heptane, 3 wt.% 2-butanol and 1 wt.% surfactant mixture (Nl + Al). Nl, polyethoxylated nonylphenol with an average of 6.5 ethyleneoxide units Al, petroleum sulphonate sodium salt with an average molecular weight of 420 g/mol.

The synergisms of mixtures of anionic-cationic surfactant systems can be used to form middle-phase micro emulsions without adding short-chain alcohols [109, 110]. The surfactants studied were sodium dihexyl sulphosuccinate and benzethonium chloride. The amount of sodium chloride required for the middle-phase microemulsion decreased dramatically as an equimolar anionic-cationic surfactant mixture was approached. Under optimum middle-phase microemulsion conditions, mixed anionic-cationic surfactant systems solubilised more oil than the anionic surfactant alone. Upadhyaya et al. [109] proposed a model for the interaction of branched-tail surfactants (Fig. 8.16). According to this model the anionic-cationic pair allows oil to penetrate between surfactant tails and increases the oil solubilisation capacity of the surfactant aggregate. Detergency studies were conducted to test the capacity of these mixed surfactant systems to remove oil from... 

All systems shown in these figures can be perfectly described by the model defined by Eqs. (3.28)-(3.31) which supports this theoretical model based on Butler s equation for the chemical potentials of the surface layer, and the regular solution theory. In addition, this agreement is due to the certain choice of the dividing surface after Lucassen-Reynders, and to the fact that Eq. (3.31) was used to calculate the mean molar area of the surfactants mixture. It is important to note that in some cases (for mixtures of normal alcohols. Fig. 3.62, and mixtures of sodium dodecyl sulphate (Ci2S04Na) with 1-butanol and 1-nonanol, Figs. 3.63 and... 

Photon Correlation Spectroscopy Diameters of Dynasan 114, 116, and 118 Solid Lipid Nanoparticles Stabilized with Mixtures of Cholic Acid Sodium Salt (NaCh) and poloxamer 407 (5% Lipid, 0.5% Surfactant) to Assess the Influence of Different Surfactant Mixtures on the Enzymatic Degradation (Lipase/Colipase Assay) of Solid Lipid Nanoparticles... 

Figure 18 [99] shows the optimum formulation for three-phase behavior (as the optimum salinity) as a function of the composition of a mixture of anionic (sodium dodec)4 sulfate) and cationic (tetradecyltrimethylammonium bromide) species loaded with a considerable amount of alcohol to avoid the formation of liquid crystals. The surfactant pair was selected so that both individual surfactants produced a three-phase microemulsion-oil-water behavior at about the same salinity, i.e., 5-10% NaCl. As some cationic surfactant is added to the anionic one, the shaded region that indicates the three-phase behavior goes down (from left to right). This downward displacement and the fact that three-phase behavior is still exhibited means that the addition of a small amount of the cationic surfactant to the anionic one results in a less hydrophilic surfactant mixture. 

Hoeft [44] also studied the cooperative and competitive adsorption of ionic surfactant mixtures onto hydrophobic surfaces. When shorter alkyl chain surfactants (sodium octyl sulfonate and sodium decyl sulfonate) are adsorbed, the decyl will displace the octyl surfactant. For mixtures of sodium dodecyi sulfonate and sodium octyl sulfonate, however, there appears to be an association between the surfactant molecules leading to enhanced adsorption of the sodium dodecyi sulfonate with no depletion of the octyl sulfonate adsorption. This is shown in Fig, 2, where the lines indicate the expected adsorption determined using a two-component Langmuir adsorption isotherm with the adsorption parameters determined analyzing the data from adsorption of each species individually. Also shown in Fig. 2 is the concentration of surface-active materials in the aqueous phase at equilibrium. In each of these experiments the total molar concentration and amount of surfactant solution added to the latex was a constant, as was the amount of latex. Thus a lower value for the bulk concentration corresponds to greater adsorption. 

Preparation of solutions Aqueous solutions were prepared by dissolving 5% (W/W) of TRS 10-410 and 3% (W/W) isobutanol together with constant stirring. Desired concentration of sodium chloride in water was prepared separately and then known amounts of the surfactant mixture and the brine solution were mixed volumetrically. It should be noted that while the concentrations of surfactant and alcohol are expressed in percent weight based on total weight of aqueous phase, the concentration of sodium chloride is based on the total weight minus the weight of surfactant and alcohol. 

Amott method, to be preferentially oil-wet, RDI= —0.82. Laboratory work was undertaken to determine the feasibility of injecting alkaline solutions to improve oil recovery. These experiments were designed to produce surfactants in-situ. The surfactants would both lower the interfacial tension and react with the reservoir rock surface to modify the wettability of the porous media. The experimental work considered the injection of seawater and sodium hydroxide mixtures into cores. The experimental results show that the oil recovery was higher than 50% when the alkaline solution was injected. The conclusion was that surfactant produced by alkaline injection altered the rock wettability from oil-wet to intermediate-wet, increasing oU recovery. One precaution with alkaline flooding is that the range of reactions and the change in pH can cause unexpected variation in oil recovery if the reservoir and fluids are not well characterized. 

In experiment DW 2, the permeability was decreased from an initial value of 15.4 Darcy to a final waterflood value of 1.5 Darcy. Column DW 5 was plugged as a result of surfactant flooding. In both experiments, a surfactant mixture with sodium dioctyl sulfosuccinate was used without enough cosolvent to prevent gels. Sodium dihexyl sulfosuccinate is less prone to forming gels and less alcohol is needed to eliminate gel when it... 

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