Sucrose Recovery from Diluted Cane Molasses by Using Mass Transfer to the Third Liquid Layer at Contacting with Ethanol

Abstract

A simple rate-based method is proposed for recovering sucrose from sugarcane molasses, focusing on its feasibility for continuous recovery. When ethanol is gently poured onto diluted molasses, sucrose is transferred to ethanol layer along with water, resulting in the formation of a distinct third layer comprising sucrose positioned between the ethanol and diluted molasses. Although this third liquid layer is metastable and dissipates when vigorously stirred, its sucrose concentration reaches a level suitable for sucrose crystal formation. Consequently, a semicontinuous operation for sucrose recovery from diluted molasses is achieved by continuously extracting the third layer while supplying ethanol to the diluted molasses. The concentration changes of sucrose within the third liquid layer over time are predicted using simple mass-transfer models based on diffusion and axial dispersion. While the prediction yields limited success, it underscores the importance of mass transfer from the liquid jet in the third layer and the role of mild mixing within the third layer in facilitating its growth and interior mass transfer. To the best of our knowledge, this study presents the first effective utilization of the third liquid layer in solvent extraction offering a method to control its formation and mass transfer for sugar recovery from molasses.