History, Classification, Properties and Application of Hydrogels: An Overview

The term hydrogel was coined in 1894 as it was employed to explain a colloidal gel. The first report on the application of hydrogels was given by Wichterle and Lim in 1960, which was in the biomedical field. Hydrogels generally absorb a large amount of water, and this swelling is responsible for the rubbery and soft properties of hydrogel. Hydrogels have found applications in environmental, biomedical, food, etc., fields. This chapter presents a brief review of hydrogels—basic definition, classifications, preparations and applications. This chapter highlights among others, the application of polysaccharide-based hydrogels in adsorption and dye removal in water treatment.