Application of Sorghum Starch for Preparing Superabsorbent

Abstract

Starch was extracted from Sorghum bicolor grains by alkali steeping method and was utilized for the production of absorbent material by grafting and crosslinking with binary mixtures of vinyl monomers viz. acrylic acid and acrylamide. Both unmodified and modified starches were characterized with Thermogravimetric analysis, Infra-Red spectroscopy, Scanning electron microscopy and X-ray diffraction analysis, to ascertain the modification of the starch. The parameters of the reaction system viz. initiator concentration, monomer concentration, starch to monomer ratio, etc. were optimized. The modified starch showed enhanced water absorption in the range of 49–85 g/g. Absorbency of the products increased after treatment with aqueous alkali solution due to saponification at higher temperature. The saponified products showed increased water absorption level in the range of 245–400 g/g. The product thus obtained using optimized condition of grafting, on saponification found to be highly superabsorbent displaying the water absorbency of 400 g/g. The influence of pH on absorption of water was also tested and best results were obtained at pH 7–8.