Technical-grade surfactant

Sottmann, T., Lade, M., Stolz, M. and Schomacker, R. (2002) Phase behavior of nonionic microemulsions prepared from technical-grade surfactants. Tenside Surf. Det., 39, 20-... 

Technical-grade surfactants with statistical distribution of polyoxyethylene chains. 

In view of these potentials for major reductions in preservative efficacy, considerable effort has gone into attempts to devise equations in which one might substitute variously derived system parameters such as partition coefficients, surfactant and polymer binding constants and oil water ratios in order to obtain estimates of residual preservative levels in aqueous phases. Although some modestly successful predictions have been obtained for very simple laboratory systems, they have proved of limited practical value as data for many of the required parameters are unavailable for technical grade ingredients or for the more complex commercial systems. 

The nonionic surfactant, nonylphenol deca(oxyethylene glycol) monoether, NP-EO10, supplied by Berol Kemi AB, Stenungsund, Sweden, was of technical grade and used without further purification. The main impurity is free polyethylene oxide. Analysis of the sample gave a polyethylene oxide content of = 3% (4). Note, that polyethylene oxide adsorbs on polystyrene latexes ( ), but a monolayer is reached at solution concentrations that are 10 times the concentration required to obtain a monolayer coverage with NP-EO q. The free polyethylene oxide, therefore, is expected to have negligible influence on the adsorption measurements. 

Materials. Styrene and butadiene monomers were polymerization grade, available from Dow Chemical Company. Acrylic acid was a technical grade monomer from Dow Badische. The polymeriza-tion surfactant was sodium dodecyldiphenyl oxide sulfonate available from Dow. The polymerization initiator was sodium persulfate, and bromoform and carbon tetrachloride the chain transfer agents. 

We have developed new reaction systems based on colloidal dispersions [23, 24], namely highly concentrated water-in-oil (gel) emulsions, which could overcome most of the disadvantages of the aqueoussolvent mixtures such as inactivation of the aldolase and incomplete aldehyde solubilization in the medium. These emulsions are characterized by volume fractions of dispersed phase higher than 0.73 [25] therefore, the droplets are deformed and/or polydisperse, separated by a thin film of continuous phase. Water-in-oil gel emulsions of water/Ci4E4/oil 90/4/6 wt%, where C14E4 is a technical grade poly(oxyethylene) tetradecyl ether surfactant, with an average of four moles of ethylene oxide per surfactant molecule and oil can be octane, decane, dodecane, tetradecane, hexadecane, or squalane, were typically chosen as reaction media [23, 26]. 

Microemulsions with technical-grade non-ionic surfactants... 

Despite all difficulties mentioned above, examples for C02 containing microemulsion stabilised by a technical grade non-ionic surfactant have been found (see Fig. 11.3 in Chapter 11). The studied system consists ofwater/NaCl- -propane/C02-Lutensol XL70 with varying amounts of C02 in n-propane/C02 mixtures. All measurements were carried out at p = 220 bar and at equal volume fractions of the two solvents [56], The respective phase diagrams have been studied as a function ofthe temperature T and the total surfactant... 

Chemicals The surfactant formulation consisted of fixed amounts of the surfactant TRS 10-410, a petroleum sulfonate (5 wt %) and isobutanol (3 wt %) in brine solutions of different sodium chloride concentrations up to 8.0 wt %. The oil used was dodecane. Double distilled water with conductivity less than 2 ys/cm was used throughout the experiments. Dodecane oil was of technical grade (95 mole %) supplied by Phillips Petroleum Company (Lot N-919). 

Surprisingly, microemulsion systems based on technical grade components show the typical sequence of phases observed in many model systems [4]. This demonstrates the universahty and robustness of the principles of microemulsion formation. Although derived from the studies of the phase behavior and the physical properties in microemulsion systems containing highly purified surfactants and hydrocarbons, the found systematics and empirical laws can be apphed to systems based on technical grade components. Hence, the systematic study of the phase behavior is crucial with respect to practical applications. 

First results show clearly that a microemulsion designed especially for the extraction of entrapped toxic compounds in surfaces can also be used as a nanoreactor for the decomposition of these chemicals by oxidizing agents and enzymes. Different degradation methods were already demonstrated to work in model microemulsion systems and can probably be applied also in practically important microemulsion systems. Here, technical grade components suitable for extraction and solubilization have to be used instead of purified surfactants and oils. 

FIGURE 7.16 Probability of foam film rupture after impact by drops of inherent liquid as function of film thickness for various surfactant concentrations. Drop velocity 2.74 m s . Surfactant technical grade alkyl sulfonate, (a) 5 x 10" M. (b) 10" M. (c) 5 x 10 M. (Reprinted from Chem. Eng. Process., 36, Franke, D., Pahl, M.H., 175. Copyright 1997, with permission from Elsevier.)... 

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