A recyclable and regenerable magnetic chitosan absorbent for dye uptake

• A recyclable and regenerable magnetic polysaccharide absorbent for methylene blue (MB) removal was developed.
• The self-assembly of polysaccharide with magnetic nanopartices did not alter the saturation magnetization value of the absorbent.
• The removal ability of MB after desorption did not reduce, demonstrating an excellent regeneration ability.
• The proposed strategy provides new insights into utilizing polysaccharides for environmental remediation.

A recyclable and regenerable magnetic polysaccharide absorbent for methylene blue (MB) removal was prepared by coating magnetic polyethyleneimine nanoparticles (PEI@MNPs) with sulfonated chitosan (SCS) and further cross-linked with glutaraldehyde. The driving force for coating is the electrostactic interaction between positively charged PEI and negatively charged SCS. Infrared spectra, zeta potential, thermal gravimetric analysis and X-ray diffraction demonstrated the successful synthesis of magnetic polysaccharide absorbent. The self-assembly of polysaccharide with magnetic nanopartices did not alter the saturation magnetization value of the absorbent confirmed by vibrating sample magnetometer. The nanoparticles showed fast removal (about 30 min reached equilibrium) of MB. In particular, the removal ability of MB after desorption did not reduce, demonstrating an excellent regeneration ability. Our study provides new insights into utilizing polysaccharides for environmental remediation and creating advanced magnetic materials for various promising applications.