Aim:
The micellization behavior of cationic surfactants have been studied in the presence of food additives.
Objectives:
Micellization behaviour of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and
tetradecyltrimethylammonium bromide (TTAB) has been studied in water and in various concentrations of salts (food
additives) L-glutamic acid, sodium propionate, sodium citrate tribasic dihydrate and disodium tartrate dihydrate at
(298.15, 308.15 and 318.15) K.
Methods:
Two methods used in the present study are specific conductance measurements and spectroscopy (NMR) studies.
Results:
From the specific conductance(κ), various parameters such as critical micelle concentration (CMC), degree of
ionization of micelle (α), standard Gibbs free energy (ΔGom), enthalpy (ΔHom), and entropy (ΔSom) of micellization have
also been calculated. Thermodynamic parameters related to the micellization process were also analyzed through NMR
studies.
Conclusion:
The CMC values are influenced by the presence of food additive. The magnitude of CMC values increase
with increase in concentration of food additive. In all the cases, enthalpy of micellization, ∆Hom values are found to be
negative whereas entropy of micellization, ∆S
om values are positive which indicate that hydrophobic interactions play a
major role in the micellization process. Also, NMR studies reveal that tartrate and citrate are more hydrated than glutamic
acid and propionate, resulting in more downfield shift.
