Recent Progress on the Design and Applications of PolysaccharideBased Graft Copolymer Hydrogels as Adsorbents for Wastewater Purification

Gum polysaccharides are comprised of different monosaccharide units joined together by O-glycosidic linkages. The structural diversity of different polysaccharides is due to differences in degree of polymerization, monosaccharide composition, chain shapes, and linkage types. Gum polysaccharides are commonly used in both food and nonfood industries as stabilizers, thickening and gelling agents, crystallization inhibitors, and encapsulating agents. [ 1 ] Therefore, they are commonly known as gums or hydrocolloids. In nature, polysaccharide gums occur as storage materials, cell wall components, exudates, and Gum polysaccharides are one of the most abundant bio-based polymers. They are generally derived from plants as exudates or from microorganisms and have diverse applications in many industries, especially in the food industries where they are used as emulsifi ers and thickeners. In their natural form, gum polysaccharides have poor mechanical and physical properties; therefore, they are frequently modifi ed with various synthetic monomers such as acrylamide and acrylic acid using graft copolymerization. Graft copolymerization is one of the most trusted and widely used synthetic methods for the modifi cation of gum polysaccharides. Gum polysaccharides modifi ed in this way have improved mechanical and physicochemical properties. Furthermore, gum polysaccharides contain a variety of functional groups, for example, carboxylic acid and hydroxyl groups; therefore, they have been used extensively as adsorbents for the removal of different impurities from wastewater such as toxic heavy metal cations and synthetic dyes. Here, the chemical and physical properties of gum polysaccharides, different methods of graft copolymerization, and the use of graft copolymer gum-polysaccharide-based hydrogels are reviewed in detail for the removal of toxic heavy metal cations and synthetic dyes from aqueous solutions. Recent Progress on the Design and Applications of Polysaccharide-Based Graft Copolymer Hydrogels as Adsorbents for Wastewater Purifi cation