Refnement of Cane Molasses with Membrane Technology for Clarifcation and Color Removal

Abstract

Recovery of sugars from cane molasses (i.e. the by-product of sugar industries) is of great interest to industry and academia. The prerequisite for refning cane molasses is removal of pigments and suspended solids present in the molasses. In this work, the utilization of membrane separation for clarifcation and decoloration of cane molasses has been examined. Three operation modes (dilution-concentration, dilution-concentration-diafltration, and dilution-diafltration-concentration) were employed for color removal with a tight 2 kDa ultrafltration (UF) membrane. Results showed that the operation modes with diafltration could result in higher sugar recovery than dilution-concentration mode, though the latter had the higher permeate flux. Then, in order to further improve the permeate flux of the 2 kDa UF, fve pretreatments were carried out to remove suspended solids and large pigments. It was found that the pretreatment with ceramic membrane fltration was better than centrifuge and precipitation, particularly in terms of permeate flux for the tight UF membrane. Although the permeate flux for the tight UF after a UF pretreatment equipped with a 150 kDa UF membrane was higher than that with a 50 kDa UF membrane, the permeate flux during the pretreatment was the highest for the 50 kDa UF. The obtained decolorized syrup can be further purifed by nanofltration for the separation of sucrose and reducing sugars. Thus, refnement of cane molasses with membrane technology provides an alternative to conventional refnement methods and shows promising prospects of industrial application.