Effect of hydrotropes on solubility and mass-transfer coefficient of butyl acetate

This paper presents a comprehensive study on the effect of citric acid, sodium benzoate, sodium salicylate, and urea (hydrotropes) on the solubility and mass-transfer coefficient for the extraction of butyl acetate in water. The influence of a wide range of hydrotrope concentrations (0-3.0 mol/L) and different temperatures (303 K to 333 K) on the solubility of butyl acetate has been studied. The influence of different hydrotrope concentrations on the mass-transfer coefficient for the butyl acetate +water system has been ascertained. The Setschenow constant, K-s, a measure of the effectiveness of hydrotrope, has been determined for each case. The solubility of butyl acetate increases with increase in hydrotrope concentration and also with temperature. Consequent to the increase in the solubility of butyl acetate, the mass-transfer coefficient was also found to increase with increase in hydrotrope concentration. A minimum hydrotrope concentration was found essential to show a significant increase in the solubility and mass-transfer coefficient for the butyl acetate + water system. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass-transfer coefficient.