Recent development in cellulose nanocrystal-based hydrogel for decolouration of methylene blue from aqueous solution: a review

Due to its high specific surface area, high specific strength, hydrophilicity, biodegradability and abundance of surface hydroxyl groups, the unique structural features and remarkable physicochemical properties of cellulose nanocrystals (CNCs) have generated considerable interest in the production of hydrogels. This review discusses the development of cellulose nanocrystal-based hydrogel preparation and its adsorption properties for the removal of cationic methylene blue dye from wastewater over the last decade. In this comprehensive study, we discussed the synthesis of various cellulose nanocrystal-based hydrogels, their characteristics and their ability to remove cationic methylene blue dye that is widely used in wet textile processing. Subsequently, adsorption isotherm and kinetic models of methylene blue removal efficiencies that determine the mechanism of adsorption of cellulose nanocrystal-hydrogels are also addressed. The study revealed that the introduction of other polysaccharides such as chitosan and alginate into cellulose nanocrystal-based hydrogels have shown remarkably enhanced adsorption capacity for methylene blue, which is a good indication for future research in the removal of organic dye pollutants from wastewater. A comprehensive analysis on the production and properties of hydrogel-based cellulose nanocrystals (CNCs). The evaluation of the adsorption capacity of methylene blue on CNC-based hydrogel is studied for its mechanism, kinetics and isotherms. The hydrogel prepared by adding a second polysaccharide, such as chitosan, and alginates significantly improved methylene blue adsorption ability.