Effects of various media on micellization, adsorption and thermodynamic behaviour of imipramine hydrochloride and antimicrobial surfactant mixtures

The effect of various media (aqueous, NaCl, urea (U) and thiourea (TU)) on the micellization and adsorption activity of varied mixtures of imipramine hydrochloride (IMP) and benzethonium chloride (BZCl) is investigated via tensiometry. In an aqueous medium, the interactions between IMP and BZCl are also evaluated using UV-visible and FTIR spectroscopy. The interaction between components increases with increased mole fraction (<i>α</i> ₁) of BZCl in the mixed system (IMP + BZCl). Different parameters, such as micellar and the mixed monolayer component composition, the interaction parameters of the solution and the interface, the activity coefficients of the components in solution and at the interface, and thermodynamic parameters, are computed using different proposed theoretical models (i.e. Clint, Motomura, Rubingh and Rosen). The <i>cmc</i> values obtained for the pure components and mixtures (IMP + BZCl) of all the compositions are found to be less in NaCl than in the aqueous solution while found more in the presence of U or TU. TU is more effective in increasing the <i>cmc</i> of the pure and mixed systems than U. The Gibbs free energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo> <mml:mi>Δ</mml:mi></mml:mrow> <mml:msubsup><mml:mi>G</mml:mi> <mml:mrow><mml:mrow><mml:mi>mic</mml:mi></mml:mrow> </mml:mrow> <mml:mo>∘</mml:mo></mml:msubsup> <mml:mo>)</mml:mo></mml:math> values of the studied pure and mixed systems are negative, showing the spontaneous nature of the reaction.