Chitosan–magnetite nanocomposites (CMNs) as magnetic carrier particles for removal of Fe(III) from aqueous solutions

This research focuses on removal of Fe(III) from aqueous solution using chitosan–magnetite nanocomposites as potential sorbent. The presence of nanosized magnetic particles within the nanocomposites was confirmed by TEM and SAED analysis. The particles with diameter 508 μm and 84 μm, follow Frendlich sorption isotherm at 30 °C, and the Frendlich constants (KF, 1/n) have been found to be 5.974 mg g−1, 2.66 and 35.98 mg g−1, 1.385, respectively. Out of various kinetic models, the experimental data for dynamic uptake of Fe(III) is best fitted on ‘pseudo-second order’ kinetic model. The linear nature of plots between log (% sorption) and log (time) is indicative of intra-particle diffusion. For the particles with diameters 508 μm and 84 μm, the value of kid was found to be 1.78 mg l−1 min−0.5 and 2.13 mg l−1 min−0.5. The sorption mean free energy from the Dubinin–Radushkevic isotherm was found to be 7.04 kJ mol−1 indicating chemical nature of sorption. The increase in chitosan content in sorbent particles is found to enhance the Fe(III) uptake. The various thermodynamic parameters have also been evaluated. Finally, the presence of Cu2+ ions in the sorbate is found to decrease the uptake of Fe(III).