Preparation of nanochitin-contained magnetic chitosan microfibers via continuous injection gelation method for removal of Ni(II) ion from aqueous solution

In this study, nanochitin-contained magnetic chitosan (FPCC) microfibers were prepared successfully via continuous injection gelation method and employed to remove Ni(II) ion from aqueous solution. Firstly, Fe 3 O 4 -nanoparticles were encapsulated into ε-caprolactam (CL) monomer solution in the presence of polystyrene (PSE), followed by CL anionic ring-opening polymerization and PSE removal, and obtained magnetic polyamide 6 (PA 6) microparticles (FP). After that, the economical FPCC microfibers can be prepared by adding FP microparticles and nanochitin (n-CT) into poly(vinyl alcohol)/chitosan hybrids (PVA/CTS). The obtained FPCC microfibers had shown significant advantages in production, separation, and adsorption when compared to the hydrogel beads prepared by the traditional method (instantaneous gelation method). Within 10 h, 99.7% Ni(II) could be adsorbed by FPCC magnetic microfibers (adsorbent dosage: 1 g, pH: 4.1, and temperature: 293 K). More attractively, the hybridized microfibers could be easily separated from the aqueous solution through a magnetic separation method after Ni(II) adsorption. Ni(II) adsorption behaviors of the hybrid microfibers conform to the Langmuir isotherm model and pseudo-second-order kinetic model. Besides, the possible adsorption mechanism was also discussed.