Synthesis and assessment of novel cationic graft copolymer as flocculant for sugarcane juice

The present work focuses on comparing the performance of novel cationic graft copolymer polyvinylpyrrolidone-graft-poly(acrylamide-co-diallyldimethylammonium chloride) (PVP-g-p(AM-co-DADMAC)) synthesized via microwave-assisted technique, with varying amounts of monomers acrylamide (AM) and diallyldimethylammonium chloride (DADMAC) as a flocculant for sugarcane juice. The intended grafting was supported by extensive characterization of the material by various physicochemical methods. As compared to only AM or DADMAC grafted onto PVP, grafted copolymer with highest DADMAC-to-AM ratio was found to be more effective in removing colloids from fresh unaltered cane juice. The mode of action of the synthesized flocculant was explained by synergistic bridging and charge neutralization mechanism. The best grade of PVP-g-p(AM-co-DADMAC) at an optimum dose of only four ppm (within US FDA approved limit) showed a good reduction in the zeta potential (− 7.8 to − 2.9 mV) of the juice along with the formation of large-size floc (618 nm) without affecting the percentage of natural sugar content (degree brix- °bx).