Thermodynamic investigation of the interaction between amino acids arginine and glutamic acid in micellization of cationic surfactant cetyltrimethylammonium bromide: a conductometric study

Pourmahdi-Tazeh Abadi, Vahid; Dezhampanah, Hamid

doi:10.22075/chem.2025.37280.2357

Thermodynamic investigation of the interaction between amino acids arginine and glutamic acid in micellization of cationic surfactant cetyltrimethylammonium bromide: a conductometric study

Document Type : Original Article

Authors

Vahid Pourmahdi-Tazeh Abadi

Hamid Dezhampanah

Department of Applied Chemistry, Faculty of Chemistry, University of Guilan, Rasht, Iran

10.22075/chem.2025.37280.2357

Abstract

In this research, the effect of cationic micelles cetyltrimethylammonium bromide (CTAB) on interactions of two amino acids arginine and glutamic acid in aqueous solution have been investigated varying concentrations (0.001, 0.005 and 0.01 M) at different temperatures (298.15–328.15 K). The electrical conductivity measurement was used to calculate the effect of temperature and concentration of added amino acids on the micellization of surfactant and the results have been discussed in terms of two amino acids + CTAB, hydrophobic and electrostatic interactions in aqueous medium. The results showed that the values of critical micellization concentration (CMC) decreased with increasing concentration of arginine, while it increased with increasing concentration of glutamic acid. Using CMC and α values, thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) have been determined in the presence of amino acids (arginine and glutamic acid). ΔG° values are negative in all conditions with negative ΔH° and positive ΔS°, which indicates that the interaction between amino acid and surfactant is spontaneous. Therefore, both hydrophobic and electrostatic forces play a role in promoting the reaction. Also, the larger values of TΔS° compared to ΔH° show that the main driving force of the process is entropy and enthalpy has a smaller contribution.

Keywords

Amino acid

Cetyltrimethylammonium bromide

Conductometric

Glutamic acid

Micelliszation

Subjects