Enhanced adsorption capacity of cellulose hydrogel based on corn stalk for pollutants removal and mechanism exploration

Corn stalk is a biomass resource that is discarded in quantity. The reuse of biomass for pollution control is a promising method to utilize the wastes to treat wastes. The main component of corn stalk is cellulose, which is a fin material to prepare hydrogels. However, the low adsorption capacity of cellulose hydrogel limits its application in wastewater treatment. In our study, water-soluble polysaccharides were used to enhance the cellulose hydrogel adsorption capacity. Pectin, chitosan, sodium alginate, and three heteropolysaccharides (from corn stalk, ginkgo folium, and licorice) were crosslinked with corn stalk cellulose to form composite hydrogels. The morphological and structural performances of hydrogels were evaluated using scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analyzer (TGA), etc. The specific surface area, water retention capacity, and thermally resistance of hydrogels were improved after the modification. Methylene blue (MB), Pb 2+ , and tetracycline (TC) were taken as model contaminants. The MB adsorption was enhanced from 53.03 to 328.36 mg/g; the Pb 2+ adsorption was enhanced from 1.73 to 30.03 mg/g; the TC adsorption was enhanced from 0.50 to 16.49 mg/g. Moreover, the adsorption mechanisms were discussed. This work provides a way to treat the wastes with wastes. • The corn stalk was used to prepare cellulose hydrogels. • The hydrogels were used as an adsorbent to show “treating the wastes with wastes”. • The adsorption capacity of hydrogels was enhanced by water-soluble polysaccharides. • The enhanced hydrogels showed higher adsorption performance than before. • The mechanisms include electrostatic interaction, pore filling, and ion exchange.