Solution properties of mixed surfactant systems (IV)

Abstract

Electric properties of mixed anionic-nonionic surfactant systems in aqueous solutions above the CMC have been studied in terms of pNa values, electrical conductivities, and dielectric constants; these systems are sodium 3, 6, 9-trioxaicosanoate (ECL)alkyl polyoxyethylene ethers (CmPOE; m---12,14,16, and 18). The degree of ionic dissociation of mixed micelle increases with increasing the number of carbon atoms of the alkyl group in the nonionic surfactant. The electrical conductivity increases with increasing the alkyl chain length in the nonionic surfactant, in spite of the increase of the activation energy for conduction. The size of mixed micelles also increases with increasing alkyl chain length. This may be attributed to the fact that the mixed micelle is formed more easi]y by a nonionic surfactant including long alkyl chains than for one having shorter alkyl chains.

Estimation of the critical micelle concentrations and the aggregation numbers of sodium alkyl sulfates by capillary-type isotachophoresis

“…The activity (a) of counter ion (Na +) in a surfactant solution can be expressed by the following Equation, suggested by Botre et al [29]: a = r" {Co + a. (c -c0)) (13) where y is the activity coefficient of the counterion (Na § a, the degree of ionic dissociation of micelle, Co, the CMC, and C, the concentration of SDS.…”

Fading phenomena of azo oil dye in anionic-nonionic surfactant solutions II. Effects of alkyl and/or oxyethylene groups in nonionic surfactant on the fading rate

“…chains than by one having shorter alkyl chains [18,20]. We have also reported that the mixed micelle is easier to form for a nonionic surfactant including shorter polyoxyethylene chains than for one including longer chains [16,21].…”

“…We have also reported the solution properties of anionic-nonionic mixed surfactant systems obtained from electrical [16][17][18] and surface tension measurements [19][20][21], and have investigated the mixed micelle formation. We found that two kinds ofmicelles would form more easily in hydrocarbon-hydrocarbon mixed surfactant solutions with decreasing alkyl chain length and/or with increasing polyoxyethylene chains in nonionic surfactant.…”

Fading phenomena of azo oil dye in anionic-nonionic surfactant solutions III. The effect of solubilizates on the fading behavior of azo oil dye in mixed surfactant systems

“…The fading rate of 4-OH accelerated with increasing the alkyl chain length or with decreasing the oxyethylene chain length in the nonionic surfactant molecule. The effect on it was larger for a system which could easily form a mixed micelle than for a system in which two kinds of micelles coexisted [9][10][11]. A singlet oxygen, which is caused by the hydrophilic-hydrophilic interaction when the two surfactants were mixed, is thought to attack the hydrazo form (tautomer) of 4-OH.…”