Magnetic cross-linked chitosan for efficient removing anionic and cationic dyes from aqueous solution.

Herein, a novel magnetic cross-linked chitosan CS-BA@Fe 3 O 4 was rationally synthesized by cross-linked with epichlorohydrin and coated with Fe 3 O 4 to the acylated chitosan, which was prepared by the reaction of chitosan with benzenetricarboxylic anhydride. The as-obtained absorbent was characterized by FTIR, XRD, VSM, TGA, TEM, BET, SEM and EDS. The results showed that the maximum adsorption capacities of CR and CV were 471.46 ± 16.97 mg/g and 515.91 ± 25.12 mg/g at 318.15 K, respectively. The main adsorption mechanisms were H-bonding and electrostatic interaction. The kinetic data were in good agreement with the pseudo-second-order model and closed to adsorption equilibrium at 30 min. Thermodynamic studies showed that the adsorption on CS-BA@Fe 3 O 4 were spontaneous and endothermic. More importantly, the adsorbent exhibited excellent regeneration properties after 6 cycles and remarkable stability under harsh environments including strong acid, strong alkali, multi-salt and mixed dyes conditions. Therefore, abundant efforts revealed a broad application prospect of CS-BA@Fe 3 O 4 in water remediation. • A novel magnetic cross-linked functionalized chitosan adsorbent was synthesized. • Langmuir, Freundrich and Tempkin models fitted the data at three temperatures. • Maximum adsorption capacity for CR and CV were 471.5 and 515.9 mg/g, respectively. • At high concentration, the adsorption process were close to equilibrium at 30 min. • The adsorbent showed good selectivity, salt resistance and reusability. [ABSTRACT FROM AUTHOR]