Surfactant purified

Triton X-100 surfactant (Rohm and Haas, Philadelphia, PA). The surfactemt minimized electroosmotlc flow. The terminating electrolyte was 0.01 H H-hexanolc acid (Kodak) and contained 0.5% Triton X-100 surfactant (purified by fractional distillation). The Triton X-100 surfact2uit was purified by dialysis to remove low-molecul u -welght anionic impurities. 

Please note that detailed analysis of UV-Vis-NIR spectra features of dispersions of surfactant-purified SWCNT constitute a useful tool to assess the degree of purity of a given batch of CNTs, providing the ability for optimization and/or comparison of production or purification methods. ... 

Pashley R M and Israelachvili J N 1981 A comparison of surface forces and interfacial properties of mica in purified surfactant solutions Colloids Surf. 2 169-87... 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

Water Treatment. Flotation in water treatment is used both for the removal of dissolved ions such as Cu ", Cr ", or (PO or surfactants and suspended soHds as in the case of sludge treatment. The final product in this case is purified water rather than a mineral concentrate. Furthermore, water is treated either for drinking purposes (potable water preparation) or safe disposal to the environment. 

However in the case that SWCNTs were purified by the centrifugal separation using an aqueous solution of cationic surfactants or by the microfiltration... 

Sodium dodecyl sulfate is commonly used as the standard surfactant in many chemical and physicochemical determinations. It is often taken as the surfactant of reference when comparing surfactants. This can be explained by the fact that sodium dodecyl sulfate is the surfactant that can be obtained with the highest degree of purity. It can easily be produced by chlorosulfation or sulfation of pure dodecanol and purified by crystallization to obtain crystals of purity near to 100%. In addition, sodium dodecyl sulfate has outstanding surfactant properties. 

The reaction product with monoethanolamine acts as a thickening agent [41,101] and with alcohols as an emollient [40]. Also reaction products with amino acids and oligo- or polypeptides for use in cosmetic formulations are known [43]. Sorbitan esters from ether carboxylates are described as emulsifiers or mild surfactants in cosmetic formulations [39] and alkyl ether carboxylic acid taurides as nonirritant anionic surfactants for cosmetic cleaners in particular [44]. Using unsaturated ether carboxylates it is possible to make viscous formulations based on combinations of unsaturated and saturated ether carboxylates [111]. Highly purified alkyl ether carboxylates based on alcohol ethoxylates with low free alcohol content have also been described [112]. 

Nanoparticles may be purified from the ME constituting components (surfactant and organic phase) via freeze-dr5nng [18] or a cross-flow ultrafiltration [19]. However, the use of isolated nanoparticles as the catalysts requires their separation from the reaction mixture after reaction via ultrafiltration. 

The reverse ME technique provides an easy route to obtain monodispersed metal nanoparticles of the defined size. To prepare supported catalyst, metal nanoparticles are first purified from the ME components (liquid phase and excess of surfactant) while retaining their size and monodispersity and then deposited on a structured support. Due to the size control, the synthesized material exhibits high catalytic activity and selectivity in alkyne hydrogenation. Structured support allows suitable catalyst handling and reuse. The method of the catalyst preparation is not difficult and is recommended for the... 

The B. licheniformis JF-2 strain produces a very effective surfactant under conditions typical of oil reservoirs. The partially purified biosurfactant from JF-2 was shown to be the most active microbial surfactant found, and it gave an interfacial tension against decane of 0.016 mN/m. An optimal production of the surfactant was obtained in cultures grown in the presence of 5% NaCl at a temperature of 45° C and pH of 7. TTie major endproducts of fermentation were lactic acid and acetic acid, with smaller amounts of formic acid and acetoin. The growth and biosurfactant formation were also observed in anaerobic cultures supplemented with a suitable electron acceptor, such as NaNO3[1106]. 

Because the reaction of an amine with an acyl chloride is much faster than the hydrolysis of the acyl chloride, the reaction can usually be carried out in an aqueous alkali solution. This is well known as the Schotten-Baumann procedure.6 For example, a number of N-acyl taxol analogs have been prepared under Schotten-Baumann conditions by the reaction of A-debenzoyltaxol with various acid chlorides (Eq. 9.4).7 Highly purified /V-long-chain-acyl neutral amino acids such as potassium AMauroyTy-aminobutyrate, useful as surfactants for detergent... 

Such an idea was patented in 1981 (14). Besides research by Scamehom and Schechter (15) provided an experimental illustration of this by batch adsorption tests of kaolinite with some purified anionic/nonionic products. Our objective was to enlarge and test this technique under the dynamic flow conditions of industrial surfactant injection in an adsorbent porous medium. 

Filtration is also used to purify CNTs. Bandow [29] have reported a procedure for a one-step SWNT purification by microfiltration in an aqueous solution with a cationic surfactant. Shelimov [30] developed an ultrasonically assisted filtration method which allows the purity of nanotubes to reach >90%. 

Purification is often required for the beads obtained by the techniques described above since undesired substances such as surfactants, coupling agents, etc. need to be removed. This is also valid for dye molecules noncovalently adsorbed on the surface of the beads since they usually have different properties (sensitivity, cross-talk to other analytes, leaching, etc.) compared to the molecules located in the core. The dye-doped beads can be purified by repeated precipitation which is achieved by adding salts (typically sodium chloride). In certain cases (typically for large beads) the addition of salts is not necessary so that the beads can be isolated by centrifugation. Washing with ethanol often helps remove lipophilic dye molecules adsorbed on the surface provided that the polymer is not swellable. Alternatively, dialysis can be useful especially if a hydrophilic water-soluble indicator is covalently coupled to the bead surface. 

Monolayer films are usually spread from a dilute solution in an appropriate volatile and highly purified solvent. Small droplets of solution are spotted at 40 or SO points on the clean subphase surface using a micrometer syringe. Adequate time, say 20 min, must be allowed for the surfactant film to spread evenly and also for the solvent to evaporate completely. Since certain solvents are retained in some... 

Recent years have seen a revival of interest in the study of surfactants and their properties, in part due to their potentialities for use in enhanced oil recovery. In addition, greater awareness of the effects of impurities, the availability of a variety of high-purity surfactants from a number of commercial sources, and improved methods for characterizing and purifying materials have resulted in an increased number of investigations containing data on surfactant properties from which reliable conclusions can be drawn. 

The molar absorptivities for the two betaines and the three sulfobetaines in aqueous solution are listed in Table I. Before being used for surface tension measurements, aqueous solution of surfactants were further purified by repeated passage (12) through minicolumns (SEP-PAK Cjs Cartridge, Waters Assoc., Milford Mass.) of octadecylsilanized silica gel. The concentration of surfactant in the effluent from these columns was determined by ultraviolet absorbance, using the molar absorptivities listed in Table I. 

There has been a recent revival of interest in zwitterionic surfactants (L 4) because of certain useful properties shown by these molecules, including 1) mild behavior on the skin, 2) compatability with both anionics and cationics, 3) adsorption onto skin and hair, and 4) lime soap dispersing ability. Although this type of surfactant has been produced and used industrially for the last few decades, there have been few studies of the properties of well purified surfactants of this type (5-11) and almost all of these have been concerned with the micellar properties of these compounds rather than with their behavior at interfaces. 

Cloud point extraction from biological and clinical samples. The most frequent use of CPE is for the separation and purification of biological analytes, principally proteins. In this way, the cloud point technique has been used as an effective tool to isolate and purify proteins when combined with chromatographic separations. Most of the applications deal with the separation of hydrophobic from hydrophilic proteins, with the hydrophobic proteins having more affinity for the surfactant-rich phase, and the hydrophilic proteins remaining in the dilute aqueous phase. The separation of biomaterials and clinical analytes by CPE has been described [105,106,113]. 

---