EFFECT OF ADDITION OF KX-TYPE ELECTROLYTES AND TEMPERATURE ON THE CRITICAL MICELLAR CONCENTRATIONS OF 1-CETYLPYRIDINIUM AND CARBETHOPENDECINIUM BROMIDES

The critical micellar concentrations (cmc) of the title cationic surfa ctants were measured in aqueous solutions at 25-degrees-C in the prese nce of KBr, KF, KCl, KI, KSCN, KNO3, KAc and HCOOK. The conductometric and, in part, potentiometric methods employing ion selective electrod es were used. For 1-cetylpyridinium bromide in the absence of any of t he electrolytes, the decreasing temperature dependence of cmc was meas ured conductometrically over the region of 12 - 40-degrees-C and the a ssociation degree of the micelles with Br- anions was calculated. The decrease in cmc of the two surfactants due to the presence of electrol ytes (in concentrations up to tenfold cmc) was expressed by means of a semiempirical equation. There are indications that I- and SCN- anions enter into specific interactions with micelles.