Basis Of Surfactants Research Articles

Uklanjanje hidrolizovane reaktivne boje sa pamučne tkanine nakon bojenja

Removal of hydrolysed reactive dye is an important stage in cotton dyeing as it affects the exploitation and hygienic properties of textile products. As a major consumer of water and chemicals, this work process is being studied from the point of view of saving natural resources and environmental protection. In this paper, studied was the effect of washing agents on the basis of surfactants with different ionogenicity as well as pure water on the removal of hydrolyzed reactive dyes having different functional groups. The obtained results suggest that clean water with a larger bath ratio (1:30) and a washing time of 30 min can be an effective remover for hydrolysed monoreactive dye. In the removal of the hydrolysed bifunctional dye, beside the bath ratio and washing times, the concentration of surfactants can also have a significant effect on the process efficiency.

The estimation of posibility of stearic and oleic acids' TLC-separation with eluents containing surfactants

The possibility of separation of oleic and stearic acids with mobile phases on the basis of surfactants was estimated by the method of a thin-layer chromatography. The influence of surfactant's type and concentration on the retention parameters of the studied acids when using of normal-phase plates for a thin-layer chromatography of Sorbfil UV-254 is investigated in the work. The influence on mobility of oleic and stearic acids of the anionic sodium n-dodecylsulphate, cationic cetylpyridinium chloride and non-ionic Tween-80 in the range of concentration from 1·10-5 mol/l to 0.1 mol/l is estimated. The mixed mobile phases on the basis of two last surfactants taken in various concentrations are also investigated. The рН of eluents was varied in the range from 1 to 9. The addition of 2-propanol into the mobile phase containing surfactant didn't lead to improvement of acids' distribution efficiency. The best results have been received with the eluent, containing 1·10-5 mol/l of cetylpyridinium chloride and boric buffer solution with pH 9. Preliminary modification of silica gel surface with cetylpyridinium chloride did not change the results of chromatography. For clarification of relation of acids' retention with a length of a hydrophobic fragment, and, therefore, a contribution of hydrophobic interactions, in system with the mixed mobile phase on the basis of cetylpyridinium chloride and Tween-80 at pH 3 formic acid, acetic acid, propionic acid, hexanoic acid and myristic acid were analyzed. The smallest mobility was observed for myristic acid (lgPo/w=6.09±0.19) that indicates very strong hydrophobic interactions of acid with the surface of silica gel modified by surfactants. Such interactions are the main reason of bad mobility of studied oleic (lgPo/w=7.7±0.2) and stearic (lgPo/w=8.22±0.19) acids in system with the surfactant-containing eluents. For the manifestation of acidic zones after chromatography, a solution of phosphomolybdic acid, a solution of rhodamine B, a solution of sulfuric acid and an iodine chamber were tested. The best visualization of TLC-сhromatogram is obtained after sprinkle the plates by 6% solution of sulfuric acid in ethanol with their subsequent heating at 110 °C.

Micellar catalysis in the systems arylamine-diphenylamine-NO 2 −

By methods of UV and IR spectroscopy and thermogravimetry reactions of diazotizaion and azo coupling were studied in the systems of primary arylamine (p-nitro-, p-carboxy- and p-sulfoaniline)- diphenylamine -nitrite ion in water and micellar media on the basis of surfactants. The micellar catalysis effect of sodium dodecylsulfate in the micellar media was revealed. Rate of diazotization was shown to be independent of the surfactants of various types. Formation of ionic associates of azo dyes with dodecylsulfate anions in premicellar region was established and physicochemical characteristics of the associates were estimated.

Nucleophilic Substitution in Carboxylic Esters in Oil-In-Water Microemulsions

In hydrolysis and aminolysis of p-nitrophenyl esters of carboxylic acids in oil-in-water microemulsions on the basis of surfactants of various nature, a complex mechanism of the effect of the medium is operative, including shift of acid-base equilibria in the nucleophile. The rate constants of the processes studied are quantitatively related to the surface potential of the microdroplet. Varied hydrophobicity of the nucleophile and substrate changes the site of the reaction act and the relative contributions of aminolysis and hydrolysis.