Hydrotropic Aggregation Behavior of Butyl Stearate

Abstract

On investigation for the solubility and mass transfer coefficient of butyl stearate through hydrotropy has been studied. This study was carried out using hydrotropes such as citric acid, urea, nicotinamide, sodium salicylate under the influence of a wide range of hydrotrope concentrations [(0 to 3) mol ·L-1 ] and different system temperatures [(303 to 333) K]. It has been distinctively observed and noted that the solubility of butyl stearate increases with an increase in hydrotrope concentration and also with system temperature likely similar to the several organic compounds and drugs A Minimum Hydrotrope Concentration (MHC) in the aqueous phase was required to initiate significant solubilization of butyl stearate. Consequent to the increase in the solubilization of butyl stearate, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. A threshold value similar to MHC is to be maintained to have an appreciable enhancement in mass transfer coefficient. The maximum enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, has been determined for all sets of experimentations. To ascertain the hydrotropic aggregation behavior of butyl stearate, thermodynamic parameters such as gibb's free energy, enthalpy, and entropy of butyl stearate were determined. The gibb's free energy decreases with an increase in system temperature. The aggregation of hydrotropes was found to be exothermic in nature and favored by a positive value of entropy.