Nonpolar Surfactant Research Articles

Zeta Potential of Nanobubbles Generated by Ultrasonication in Aqueous Alkyl Polyglycoside Solutions

A simple and convenient method to measure microelectrophoretic mobilities was proposed to determine the zeta potential of nanobubbles generated by ultrasonication. Bubbles in pure water solutions and in aqueous solutions of alkyl polyglycoside (AG) with different alkyl chain lengths and degrees of polymerization in the head group were sonicated with a palladium-coated electrode designed specially by the manufacturer. The zeta potentials of bubbles with ordinary cationic and ionic surfactants are consistent with others' previous results. The average size of the bubbles generated by sonication is in the range of 300 to 500 nm. The zeta potentials of bubbles in both pure water and AG solutions at all pH values are negative. As the chain length of AG increases, zeta potentials significantly decrease at high pH. For nonionic AG, a possible charging mechanism based on known mechanisms is suggested to explain the negative charge, known to be unusual. Even with a very high concentration of H+ ions in solution the bubbles are charged negatively because the interface is covered with slightly acidic alcohol groups of AGs. At high pH, the less polar the surfactant, the more negative the charge, since nonpolar surfactant molecules induce the adsorption of OH− ions, rather than H+ ions that prefer hydration by water molecules.

Solubilization of Dye in Lamellar Liquid Crystal of System Igepal CO-610 and H2O

ABSTRACT The solubilization and spectrum characteristics of a dye mixture, Morefast Red 101, in the lamellar liquid crystal (LLC( of the system Igepal CO-610 and H2O were studied by measurements of phase behavior, low angle X-ray diffraction, UV and visible spectrum. Pure dye molecules, NAHPA, were located in the hydrocarbon chain part of the LLC bilayer of the solvents for the formulated dye. Of the solvents, n-propanol was evenly distributed between all parts of the liquid crystal while the bis(2-ethylhexyl)amine was localized to the space between the mirroring terminal methyl groups of the layered structure. In this manner the influence of the different components was compensated and the net result of the added dye was no effect on the interlayer spacing of the lamellar liquid crystal. The UV spectrum of the dye showed an interesting feature. After addition of water to the solution of dye in the relatively nonpolar surfactant the change in the dye spectrum showed a less polar environment of the dye in ...

Wettability of Wool Fibers

The critical surface tension of wool fibers was measured using the sink-float technique with various classes of test liquids. Nonpolar organic liquids and aqueous surfactants gave similar values of γ, but much lower values were obtained with butanol/water mixtures. Adsorption of butanol on the surface of the fibers is thought to be responsible for the low values of γ in the latter case. Removal of lipid material from the surface of fibers by extraction increases γ from 30 mN/m to 37 mN/m, similar to that obtained for horn keratin or polypeptide material. Exposure of fibers to a corona discharge in air at atmospheric pressure also increases γ.