Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Micellar and surface properties of aqueous dodecyltrimethylammonium bromide (DTAB) solutions have been studied in the absence and presence of several sodium salts including NaCl, NaH2PO4, Na2HPO4, Na2CO3, Na2SO4, Na3PO4, and Na3Cit. The values of critical micelle concentration (cmc), degree of anionic binding (ss), surface tension at the cmc (?cmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (?cmc), maximum surface excess concentration (Gmax), minimum surface area per molecule (Amin) at interface of air liquid, standard Gibbs free energy of micellization (?micGdeg ), and adsorption at air/water interfaces (?Gaddeg ) were evaluated from the conductivity and surface tension measurements at 298.15 K. The results show that all salts effectively reduce the cmc values of the cationic surfactant DTAB. The ability of the anions to promote the micellization of DTAB decreases in the order of Cit3 greater than PO43 greater than SO42 greater than CO32 greater than HPO42 greater than Cl greater than H2PO4 . The effect of anions of the added salts on the degree of anionic binding of DTAB in aqueous solutions was also studied, and it was found that for each electrolyte type z+:z , the order of ss values is approximately reverse to that of cmc. The obtained results were discussed on the basis of the interaction between the anions of added sodium salts and surfactant DTAB.