Magnetic chitosan composite for adsorption of cationic and anionic dyes in aqueous solution

A magnetic composite material composed of nano-magnetite (NMT), heulandite (HE), and cross-linked chitosan was prepared and used as an adsorbent for methylene blue (MB) and methyl orange (MO). The composite was characterized for the morphology, magnetic and surface properties. The optimal mass ratio of chitosan:HE:NMT for the best removal of both dyes was determined to be 1:1:0.33. The adsorption of MB and MO followed the pseudo-second order kinetics, and the maximum adsorption capacities were 45.1 and 149.2 mg g−1 at pH 5.5, respectively. The adsorption of MB increased with the pH increase, while MO adsorption showed an opposite trend.