Are cationic polymers effective for cane sugar juice processing?

It is standard practice to clarify mixed juice by the defecation process in Australian sugar mills. Rapid flocculation of the mud particles is achieved using anionic copolymers (sodium acrylate-co-acrylamide). This work reports on efforts to enhance the performance of these flocculants by addition of cationic polymers as 'flocculant aids'. Homopolymers of dimethylaminoethyl methacrylate methyl chloride (DMAEMAMeCI) and copolymers of this monomer and acrylamide were prepared and tested as flocculant aids. Their effectiveness was also compared to selected commercially available cationic polymers. Addition of commercial polymers (and polymers prepared in this study) at the recommended dosage of 5-10 ppm was found to be ineffective in improving juice quality. However, there was marked impact on the clarity of the juice at relatively high concentrations (50-200 ppm) for these polymers. Results from the homopolymer tests indicated that their effectiveness as flocculant aids was generally insensitive to molecular weight. The performance of the copolymers suggest that synthesis of flocculant aids giving substantial improvement in the quality of clarified juice at reasonable polymer concentration is possible, resulting in improved raw sugar quality.