The surface tension of the aqueous solution of octyldimethylphosphine oxide (OPO) and decyldimethylphosphine oxide (DePO) mixture was measured as a function of the total molality and the composition of the mixture at 298.15 K under atmospheric pressure. The experimental data were analyzed thermodynamically to evaluate the total surface density ΓH, the composition in the adsorbed film X2H, and the composition in the micelle X2M. The relations among the compositions of bulk solution, adsorbed film, and micelle were expressed in the form of phase diagram similar to the three-dimensional one; they were compared with the phase diagrams of ideal mixed film and micelle obtained theoretically. It was concluded that the OPO and DePO molecules mix ideally in the adsorbed film while the difference in their hydrophobic chain length causes a weaker interaction in the micelle because of a spherical shape of the micelle. This conclusion was supported by the fact that the 2-(octylsulfinyl)ethanol and 2-(decylsulfinyl)ethanol mixture behaves quite analogously.

No abstract

The adsorption of lanthanide(III) ions by the glutathione-(a-L-glutamyl-L-cysteinyl-glycine, GSH) monolayer on gold substrate (GSH/Au) is described and demonstrated for the recovery of lanthanide(III). This monolayer has been applied to the adsorption of lanthanide(III) ions in aqueous solutions as an adsorbent. The pH dependencies of the adsorption for lanthanide(III) ions have been examined to clarify the cation-exchange behavior of the adsorbent. Adsorption of lanthanide(III) ions was found to depend on the pH of the solution. The adsorption recovery for the 14 lanthanide(III) ions was investigated. 759

The surface tension of the aqueous solution of sodium 4′-(butylamino)azobenzene-4-sulfonate (SBAS) and octyl methyl sulfoxide (OMS) mixture was measured as a function of the total molality at various compositions and at 298.15 K under atmospheric pressure. The experimental results were analyzed by applying the thermodynamic relations. The phase diagrams of adsorption and micelle formation were found to suggest that SBAS and OMS molecules interact attractively with each other to form a negative azeotropic mixture in the adsorbed film at a low surface tension and in the micelle. These findings were qualitatively similar to those of the system of SBAS and 2-(octylsulfinyl)ethanol (OSE) and confirmed our conclusion that the strong interaction of dye and nonionic surfactant molecules at the interface may be the one of reasons why a nonionic surfactant acts as the leveling agent in dyeing process.

The surface tension of the aqueous solution of anionic dye and nonionic surfactant mixture was measured as a function of total concentration at various compositions and at 298.15 K under atmospheric pressure. The dye used is sodium 4′-(butylamino)azobenzene-4-sulfonate (SBAS) and the nonionic surfactant is 2-(octylsulfinyl)ethanol (OSE). By use of thermodynamic relations developed previously, the phase diagrams of adsorption and micelle formation were constructed. It was found that SBAS and OSE are completely miscible with each other in the adsorbed film and that the adsorbed film is enriched in OSE compared with the solution except for a composition close to pure OSE. It was concluded that SBAS and OSE interact attractively with each other in the adsorbed and micellar states and, furthermore, that the interaction is more attractive in the micelle than in the adsorbed film. The miscibility of dye and nonionic surfactant is suggested to play an important role in the working of nonionic surfactant as a levelling agent in dyeing process.