A method for preparing a nanocomposite ion exchange hydrogel includes graft polymerizing a monomer onto a carbohydrate to form a carbohydrate graft copolymer. Before, during, or after graft polymerizing, an adsorbent is modified with a cationic surfactant to form a surfactant modified adsorbent. Next, the surfactant modified adsorbent is dispersed and entrapped in the carbohydrate graft copolymer and crosslinked to form a crosslinked carbohydrate graft copolymer. The crosslinked carbohydrate graft copolymer is then isolated.