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Micellar association in simultaneous presence of organic salts/additives
Author(s) -
Kumar Sanjeev,
Khan Ziya Ahmad
Publication year - 2002
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-002-0205-1
Subject(s) - chemistry , aqueous solution , salt (chemistry) , viscosity , micelle , micellar solutions , bromide , sodium salicylate , sodium salt , inorganic chemistry , sodium benzoate , sodium , sodium bromide , carboxylate , organic chemistry , physics , food science , quantum mechanics
Viscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium anthranilate, NaAn) and organic additives (1‐hexanol, C 6 OH; n ‐hexylamine, C 6 NH 2 ) at 30°C. On addition of C 6 OH or C 6 NH 2 , the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts. However, as the salt concentration was increased further, the effect of C 6 OH/C 6 NH 2 addition was different with different salts: The viscosity first increased; then a decrease was observed with the former while with C 6 NH 2 a decrease followed by constancy appeared in plots of relative viscosities (η r ) vs. organic additive concentrations. At further higher salt concentration, the magnitude of η r was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive pseudophase).