摘要:

The temperature-induced percolation behaviors of AOT reverse micelles in the presence of nonionic surfactants have been studied. The effects of water content, solvent and concentration of electrolyte in solubilized water have also been investigated. It was found that the percolation temperature of AOT reverse micelles was decreased by adding nonionic surfactants, and more pronounced effects were observed with the increase of EO chain length and content of nonionic surfactants. The increase of molecular volume of the solvent and the increase of concentration of the added NaCl electrolyte have shown assisting and resisting effects on the process, respectively. The apparent hydrodynamic diameter of droplets of different mixed reverse micelles has been measured using dynamic light scattering, by which the percolating mechanism of mixed reverse micelles was discussed in combination with the results obtained from conductivity measurements.

ISSN:0193-2691    

DOI:10.1080/01932699908943805

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Sucrose monoalkanoates (SE) form microemulsions by mixing with lipophilic cosurfactants such as the middle-chain alcohols, or sucrose polyalkanoates. In the case that sucrose monododecanoate is combined with hexanol, a middle-phase microemulsion is produced and coexists with excess water and oil phases at optimum mixing fraction of SE and hexanol. The bicontinuous structure of the microemulsion was confirmed by means of self-diffusion coefficient on NMR measurement.

ISSN:0193-2691    

DOI:10.1080/01932699908943806

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The orthogonal-test-design method was used to determine the optimum prescription of middle-phase microemulsion for tertiary oil recovery. The results indicate that in the petrolium sulphonate(PS) – the mixed alcohols(iso-propanol and n-butanol) - mineral water(7000ppm) – simulating oil(kerosen with 5.0% crude oil added) system, the optimum composition of the middle-phase microemulsion contains 2.0%PS and 2.2% the mixed alcohols(the weight ratio between iso-propanol and n-butanol is 9:1). The values of solubilization parameter, interfacial tension, and efficiency for oil recovery are 11.5ml/g, 3.30 ×10-4mN/m, and 94.6% respectively for the optimum flooding system.

ISSN:0193-2691    

DOI:10.1080/01932699908943807

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The aggregation and surface activity of N-butyl-2-pyrrolidone (BP) in water is investigated using surface tension, solubilization, fluorescence and NMR methods. The micelle point is high (˜1.0 M) as expected for the butyl chain length, and the aggregation number is approximately 5, with pre-association below the c.m.c. Despite the low aggregation number, the fluorescence data indicate that the interior of the aggregate is similar to pure liquid BP. The adsorption of BP at the solution/air interface goes to a maxmum near the c.m.c, corresponding to an area of 45 ± 1 Å2/molecule.

ISSN:0193-2691    

DOI:10.1080/01932699908943808

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Two techniques for extraction and purification were excersized in order to obtain a purified saponins extract from several sources (fenugreek, soybean, locust bean and sesame). The results indicate that fenugreek steroid saponins extract has the best surface properties and reduces the surface tension to 33.3 mN/m and the tetradecane-water interfacial tension from 44 mN/m to 7.5 mN/m. The HLB value was evaluated and found to be 18. Three different types of oil (n-tetradecane, soybean oil, tricaprylin) were emulsified with a 6 wt% aqueous solution of saponins to give an average droplet size of 0.7 μm (yet stable after month). An effective synergism is seen when these emulsions were prepared with sucrose fatty acid esters as co-surfactant. Furthermore, the foaming power was evaluated.

ISSN:0193-2691    

DOI:10.1080/01932699908943809

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Adsorption isotherms of nonionic polyvinylpyrrolidone (PVP) and anionic ionized polyacrylic acid (PAA) polymers on single Na-montmorillonite clay and γ-alumina adsorbents in 0.01M NaCl and pH 5.6 are reported and compared to results obtained with aqueous adsorbent mixtures. Microeiectrophoretic behaviours of adsorbents are also observed.

ISSN:0193-2691    

DOI:10.1080/01932699908943810

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

New monodisperse nonionic surfactant molecules based on lysine with two different fatty acid chains in the hydrophobic part and one or two polyoxyethylene methoxy capped chain s (EOn-Me) in the hydrophilic head group were synthesized and their physicochemical and toxicity properties were compared to the symmetrical homologs with the same number of methylene groups in the acyl fatty chains. Our findings indicate that the asymmetry studied results in higher surface active properties and in a greater capacity for micellization when compared with their symmetrical analogs, albeit with a slight increase in toxicity.

ISSN:0193-2691    

DOI:10.1080/01932699908943811

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Photocatalysis over irradiated Ti02has been proved to efficiently abate more than 80% of the organic carbon pertaining to a commercial humic acid (HA). The presence of HA up to 50 mg L−1has been found to decrease the degradation rate of some model pollutants, namely phenol, 2,4-dichlorophenol and tetrachloromethane. However, the total organic carbon measurements and chloride evolution ensure that the disappearance of the initial pollutants is not due to binding to HA structure, but to an efficient mineralization process. HA' s are able to scavenge both the oxidative and the reductive active species as shown by the inhibiting effect on the rate of disappearance of phenol and 2,4-dichlorophenol (essentially oxidative), and of CCI4 (initially reductive).

ISSN:0193-2691    

DOI:10.1080/01932699908943812

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A quick and convenient route to prepare a highly viscoelastic mixture of two oppositely charged polyelectrolytes is presented. The investigation was essentially performed at a fixed total polyelectrolyte concentration. The phase behaviour was studied at varying ratios between the two oppositely charged polyions. The mixtures phase separated associatively at mixing ratios in the vicinity of overall charge neutrality, while by screening the attractive forces with NaCl the precipitate could be dissolved. At certain mixing ratios off charge neutrality the mixtures were highly viscoelastic single-phase solutions in the absence of screening electrolyte. When NaCl was added to such a solution the viscoelasticity decreased strongly since the attractive forces between the oppositely charged polyions were screened. Therefore, by contacting an initially salt free mixture of polyions with a brine solution of known concentration, the diffusion of salt into the polyion matrices could be monitored by following the rheology of the mixture as a function of the contact time. It is shown that the transport of NaCl inside the polyion matrices was diffusion controlled.

ISSN:0193-2691    

DOI:10.1080/01932699908943813

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper reports on studies of the rheological properties of cationic starch (CS)/ surfactant systems. The degree of substitution of the CS was 0.1 - 0.8. Surfactants investigated were sodium dodecyl sulfate (SDS), potassium octanoate (KOct), sodium decanoate (NaDe)potassium dodecanoate (KDod), sodium oleate (NaOl) and sodium erucate (NaEr). Aggregation of surfactant micelles with the polymer produces a hydrophobic and pseudoplastic gel-like complex phase with low water content and high viscosity. The rheological behavior of the gels is described by the Herschel-Bulkley model. In dilute aqueous solution the CS/surfactant aggregate structure resembles a randomly coiled polymer network, in which polymer molecules are linked by micelles. The rheological data for the gel are compatible with the assumption that the surfactants form liquid crystalline structures with the polymer anchored to the surfactant aggregates, as recently suggested for analogous systems. However, this conjecture needs to be corroborated by more direct determinations of the structure.

ISSN:0193-2691    

DOI:10.1080/01932699908943814

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor