Carboxymethyl Chitosan-Fe3O4 Nanoparticles: Preparation and Adsorption Behavior toward Zn2+ Ions

A novel magnetic nanoadsorbent was prepared by the covalent binding of carboxymethyl chitosan (CMC) onto the surface of Fe3O4 magnetic nanoparticles, which was developed using a coprecipitating method. This nanoadsorbent was characterized by transmission electron microscopy (TEM) and X-ray diffraction patterns (XRD), etc. Moreover, the adsorption performance of the nanoadsorbent toward Zn2+ ions was investigated. The results showed that the mean diameter of the magnetic nanoadsorbent was 18 nm and the amount of CMC was about 5%. The nanoadsorbent showed high efficiency for the removal of Zn2+ ions. The adsorption rate was so rapid that the equilibrium was achieved within 2 min. The isotherm adsorption data obeyed the Langmuir model, with a maximum adsorption capacity of 20.4 mg·g−1 and an adsorption equilibrium constant of 0.0314 L·mg−1. The thermodynamic calculations indicated that the adsorption process was exothermic and that the enthalpy change was −5.68 kJ·mol−1.