Sugar Decolorization through Selective Adsorption onto Functionalized Accurel Hydrophobic Polymeric Support

The functionalized polypropylene-based hydrophobic Accurel products were probed for their use in sugar decolorization. The pore distribution of Accurel products falls between the macroporous and mesoporous domains. Their specific surface areas are typically in the range S BET = 20–35 m2/g. Commercial decolorizing activated charcoal and ion-exchange resin (Indion 803-S) were chosen for comparison with the Accurel products. The adsorption capacities of the characterized adsorbents were found to be comparable to those of adsorbents currently used for sugar refining. Geometrical optimization was performed at the density functional theory (DFT) level to gain insight into the mode of interaction between the quaternary ammonium cation containing methyl groups attached to the nitrogen center. The alkyl chain can be assumed as the bulky surface on which the quaternary ammonium nitrogen was attached. The electrostatic potential surface of the ammonium cation indicates that methyl groups are bulky enough to resist the attack of the carboxylate anion of the phenolics on the nitrogen center. However, there are possibilities for hydrophobic interactions between the methyl functional group and phenolic acids. Urea, a hydrogen-bond breaker, reduced the decolorizing efficiency, suggesting hydrophobic adsorption. In this article, we describe a new sugar decolorization process for application in sugar refineries. It is our view that the information contained herein will be useful for designing sugar decolorization units.