Clouding and thermodynamic behaviours of nonionic surfactant: Effects of cefixime trihydrate drug and different electrolytes

Abstract

Here, the clouding behavior of the nonionic surfactant Tween-80 (TW-80) was examined in the presence of cefixime trihydrate (CMT), either alone or with various electrolytes, such as chlorides, sulphates, and carbonates of sodium, potassium and ammonium. CMT is a cephalosporin antibiotic drug, used to treat numerous bacterial infections. In aqueous systems, the cloud point (CP) value of the CMT and TW-80 mixture (CMT + TW-80) was decreased by raising the CMT concentration, while holding the TW-80 concentration constant. The CP values of CMT + TW-80 mixture was also reduced in the presence of various salts, compared with that in aqueous medium. Anions decreased the CP values of studied systems in the following order: Na2CO3 > Na2SO4 > NaCl; K2CO3 > K2SO4 > KCl; (NH4)2CO3 > (NH4)2SO4 > NH4Cl; cations decreased the CP values of studied system in the following order: NaCl > KCl > NH4Cl; Na2SO4 > K2SO4 > (NH4)2SO4; and Na2CO3 > K2CO3 > (NH4)2CO3. Positive ΔG0c values were found for all the studied systems, indicating the non-spontaneous nature of clouding. In the presence of drugs and salts, the ΔH0c and ΔS0c values were negative for almost all cases, and these values reduced with increasing salt concentrations. The ΔH0c and ΔS0c values disclose the presence of exothermic interactions between CMT and TW-80. The thermodynamic transfer parameters for the current systems were also assessed and discussed thoroughly.