Enhancement of Solubility and Mass-Transfer Coefficient of 1,2-Dihydroxy-9,10-Anthraquinone (Alizarin) Through Hydrotropy

Abstract

The effect of hydrotropes potassium p-toluene sulfonate (KPTS), citric acid, and nicotinamide on the solubility and mass-transfer coefficient of 1,2-dihydroxy-9,10-anthraquinone (alizarin) was studied. Solubility studies were carried out under a wide range of hydrotrope concentrations (0 to 3.0 mol Á L À1 ) and different system temperatures (303 to 333 K). It was observed that the solubility and mass-transfer coefficient of alizarin increases with an increase in hydrotrope concentration and system temperature. The maximum enhancement factor, the ratio of the value of solubility in the presence and absence of a hydrotrope, was determined for all experiments under study. The effectivity of hydrotropes was measured by the determination of the Setschenow constant, K s . The order of effectiveness of various hydrotropes based on K s values is potassium p-toluene sulfonate > citric acid > nicotinamide.