Synthesis of Novel Magnetic NiFe2O4 Nanocomposite Grafted Chitosan and the Adsorption Mechanism of Cr(VI)

Abstract

This study prepared chitosan/NiFe2O4 (CNF) nanocomposites for the removal of Cr(VI) ions. The materials were characterized by various analytic methods including scanning electron microscopy, energy dispersive spectrometer, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and zeta potential. The adsorption performance of the nanocomposites was investigated and optimized with Cr(VI) as a target metal ion under various experimental conditions (contact time, adsorbent dosage, pH value, initial metal ion concentration). The results indicate that CNF exhibited better adsorption performance in comparison to original NiFe2O4 nanoparticles. Furthermore, the optimum adsorption capacity of CNF could be obtained within 120 min of contact time under pH 2.0 and 30 °C using 0.1 g CNF. Moreover, the experimental equilibrium data matched the Freundlich isotherm model under the studied concentrations for a specific temperature. The theoretical maximum adsorption capacity calculated with the Langmuir isotherm model reached 31.523 mg/g at 30 °C. Additionally, the adsorption kinetic data was found to be accorded well with the pseudo-second order kinetic model. Intraparticle diffusion was found to be one of the rate-limiting steps. Moreover, the metal-loaded adsorbents with good magnetic performance can easily be reclaimed from aqueous solution by magnetic separation, thus achieving solid–liquid separation, which suggests CNF as a potential recyclable adsorbent for hazardous Cr(VI) ions in waste-water.