Enhancement of Solubility and Mass Transfer Coefficient of Cinnamic Acid Through Hydrotropy

Abstract

The effect of hydrotropes such as sodium benzoate, sodium salicylate and nicotinamide on the solubility and mass transfer coefficient of cinnamic acid has been investigated. The solubility studies were carried out under a wide range of hydrotrope concentrations (0 to 3.0 mol/L) and different system temperatures (303 K to 333 K). It has been observed that the solubility and mass transfer coefficient of cinnamic acid increases with increase in hydrotrope concentration and also with system temperature. A minimum hydrotrope concentration was essential to initiate significant increase in the solubility and mass transfer coefficient. The maximum enhancement factor, which is the ratio of the solubility of cinnamic acid in the presence and absence of a hydrotrope, has been determined for all sets of experimentations. The solubility of cinnamic acid was almost 15-fold enhanced in 2.5 mol/L aqueous sodium benzoate solution at 333 K compared to that of its solubility in water. The effectiveness of hydrotropes was measured in terms of Setschenow constant K_s and the highest value has been observed as 0.454 for sodium benzoate.