Rehab Khaled Mahmoud1and Rafat M. Amin
In this study, interaction of 2-ketoglutaric acid (GL) with anion surfactant, sodium lauryl sulfate (SLS) in aqueous solution have been investigated using electric conductivity at different temperatures from 298.15-308.15 K. From the specific conductivity data, the critical micellar concentration, degree of counter ion association, degree of counterion dissociation, free energy of transfer of hydrophobic chain from the medium to interior of the micelle, and surface contribution, standard free energy of micellization, standard enthalpy of micellization, and standard entropy of micellization of sodium lauryl sulfate have been computed. The experimental data show that cmc values of SLS increase with increasing temperature. The thermodynamic parameters of micellization and the effect of additives on these parameters have been used to study the interactions between the 2-ketoglutaric acid and SLS in the micellar systems. Also, the dissociation constants (pKa's) of 2-ketoglutatic acid were studied in aqueous and aqueous micellar solution of sodium lauryl sulfate–water mixtures (0.01 to 0.30 mol·dm-3) at 298 ± 0.1 K, using a pH-metric technique. The protonation constants are calculated using computer program HYPERQUAD and the best fit chemical model is based on the statistical parameters. Based on the results obtained from the study, a charge of anionic surfactant leads to an electrostatic interaction between surfactant and the (GL) molecule. The electrostatic interactions can be attractive forces and influence of separation of protons and consequently decrease the acidity strength.
