Influence of Chain Structures of Starch on Water Absorption and Copper Binding of Starch-Graft-Itaconic Acid Hydrogels

Bio-based hydrogels destined for use as low cost renewable biosorbents are synthesized. The impact of the two components of starch, amylose, and amylopectin, on the properties of the hydrogels is assessed. Hydrogels are synthesized by solution based graft copolymerization of itaconic acid monomers on a corn starch backbone in the presence of an acrylamide crosslinker and the potassium persulfate/sodium bisulfite redox initiator pair. Three types of corn starch are used: normal corn starch, waxy starch, and high amylose starch. The amylose:amylopectin ratios are: 27:73 for normal starch (NS), 70:30 for high amylose starch (HAS), and 0:100 for waxy starch (WS). Swelling tests performed in a variety of solutions show no significant differences in swelling capacity among the hydrogels. The hydrogels also perform similarly in copper adsorption tests. Overall, these results indicate that native corn starch is as effective as amylopectin and amylose-rich starch.