Abstract
Mixed association behavior of cationic nature of drug amitriptyline hydrochloride (AMHCl) and surfactant benzethonium chloride (BTC) have been studied at five mole fractions of BTC (alpha(1)) via surface tension (ST) and fluorescence methods at 298.15 K in occurrence of three dissimilar media (H2O, electrolyte (NaCl), urea (UR)) to evaluate the interactions present amongst them. The evaluated values of critical micelle concentration (cmc) come out beneath the values of cmc(id) (ideal cmc value) demonstrating attractive interactions amongst the studied constituents (AMHCl and BTC) within mixed micelles. Electrolyte decreases the cmc value of the system while the effect of UR is found to increase in cmc. The micellar mole fraction of BTC (X-1(R)) analyzed by the Rubingh model in solution mixture, mole fraction at mixed monolayer (X-1(sigma)) determined by Rosen model and argued in detail. The interaction parameter in the solution mixture (beta(Rb)) and at the interfacial surface (beta(sigma)) is constantly achieved negative in the entire cases. Activity coefficients of the mixed micellar system (f(1)(Rb) (BTC) and f(2)(Rb) (AMHCl)) and mixed monolayer (f(1)(sigma) (BTC) and f(2)(sigma) (AMHCl)) were forever less than one telling the nonideal behavior of systems. Various surface parameters have been estimated along with various thermodynamic parameters have also been assessed. Fluorescence measurements were carried out to evaluate further results for the above-stated system in all studied media. At 298.15 K, the aggregation number (N-agg) values computed by means of pyrene (PY) as a fluorescent probe along with many other related parameters were also estimated. (C) 2019 Elsevier B.V. All rights reserved.