Magnetic chitin hydrogels prepared from Hericium erinaceus residues with tunable characteristics: A novel biosorbent for Cu2+ removal

Development of sustainable biomaterials from wasted resources has been widely advocated recently. In this study, chitin was extracted from Hericium erinaceus residues and used as the main framework to in situ synthesize series of magnetic chitin hydrogels for Cu2+ removal. Results showed that the extracted chitin with 1.56x105 g/mol molecular weight and 51.83% degree of acetylation was completely composed of glucosamine. After introduction of Fe3O4 particles, the magnetic chitin hydrogels exhibited preferable adsorption capacity for Cu2+ than its native form. Besides, the magnetic chitin hydrogels showed paramagnetic behavior and improved mechanical property but the slight reduced swelling and thermal performance. Moreover, the swelling, mechanical, magnetic and adsorption properties were found to be Fe3O4 content-dependent, indicating its specific tunable performance. Therefore, this work provided a new alternative renewable resource for chitin and facile procedure to prepare magnetic chitin hydrogels as a promising candidate material for heavy metal removal system.