Micellization behavior of binary mixtures of amino sulfonate amphoteric surfactant with different octylphenol polyoxyethylene ethers in aqueous salt solution: Both cationic and hydrophilic effects

Micellization behavior of binary mixtures of amino sulfonate amphoteric surfactant with different octylphenol polyoxyethylene ethers in aqueous salt solution: Both cationic and hydrophilic effects

The effect of different valent inorganic cations and the hydrophilic group of surfactant on themicellization behavior of binary surfactant mixtures constituted by an amphoteric surfactant, sodium3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS), and three nonionic surfactantsoctylphenol polyoxyethylene ether (OP-n) with different numbers of oxyethylene glycol ethers (n),namely, OP-10, OP-7, and OP-4 was investigated in aqueous solution. These inorganic cations includeNa+, K+, Mg2+, Ca2+, Ba2+, Al3+ and Fe3+. Both the tensiometry and the UV–vis spectrophotometry usingpyrene as a probe were adopted to determine the critical micelle concentrations (cmc) of individual ormixed surfactants. Interaction parameters between two surfactants and other parameters were obtainedbased on the regular solution theory, the pseudophase separation model, Rubingh’s model, etc. Thermodynamic parameters including Gibbs energy of micellization and thermodynamic stability werealso calculated by both the equation proposed by Molyneux et al. and Maeda’s treatment, respectively. The effect of different valent cations on both the mixed cmc of surfactant mixtures and the molar fractionof C12AS in mixed micelle (X1) can be explained theoretically by the salting-out effect, electrostaticinteraction and steric effect. For three binary surfactant mixtures, the chain length of hydrophilic groupof surfactant results in different micellization behaviors. On adding salts, the interaction parametersshow that there exists a synergistic effect between two surfactants, and the effect increases withincreasing the ratio of valence (Z) and atom radius (R) of cation, especially, for the C12AS/OP-4 mixture. With increasing the Z/R value of cation, a deviation of X1 from the ideal value shows a divergence forthree binary surfactant mixtures because of different hydrophilicities of surfactant. Thermodynamicparameters indicate that the addition of cations with a large Z/R value can be contributive moreeffectively to the formation of stable mixed micelle than the case in the presence of cations with a smallZ/R value.

The effect of different valent inorganic cations and the hydrophilic group of surfactant on themicellization behavior of binary surfactant mixtures constituted by an amphoteric surfactant, sodium3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS), and three nonionic surfactantsoctylphenol polyoxyethylene ether (OP-n) with different numbers of oxyethylene glycol ethers (n),namely, OP-10, OP-7, and OP-4 was investigated in aqueous solution. These inorganic cations includeNa+, K+, Mg2+, Ca2+, Ba2+, Al3+ and Fe3+. Both the tensiometry and the UV–vis spectrophotometry usingpyrene as a probe were adopted to determine the critical micelle concentrations (cmc) of individual ormixed surfactants. Interaction parameters between two surfactants and other parameters were obtainedbased on the regular solution theory, the pseudophase separation model, Rubingh’s model, etc. Thermodynamic parameters including Gibbs energy of micellization and thermodynamic stability werealso calculated by both the equation proposed by Molyneux et al. and Maeda’s treatment, respectively. The effect of different valent cations on both the mixed cmc of surfactant mixtures and the molar fractionof C12AS in mixed micelle (X1) can be explained theoretically by the salting-out effect, electrostaticinteraction and steric effect. For three binary surfactant mixtures, the chain length of hydrophilic groupof surfactant results in different micellization behaviors. On adding salts, the interaction parametersshow that there exists a synergistic effect between two surfactants, and the effect increases withincreasing the ratio of valence (Z) and atom radius (R) of cation, especially, for the C12AS/OP-4 mixture. With increasing the Z/R value of cation, a deviation of X1 from the ideal value shows a divergence forthree binary surfactant mixtures because of different hydrophilicities of surfactant. Thermodynamicparameters indicate that the addition of cations with a large Z/R value can be contributive moreeffectively to the formation of stable mixed micelle than the case in the presence of cations with a smallZ/R value.