Development of a novel magnetite–chitosan composite for the removal of fluoride from drinking water: adsorption modeling and optimization

Abstract

Magnetic nanoparticles (MNPs) have recently been adopted by researchers in the field of adsorption/biosorption for separation of pollutants from aqueous solutions. In this paper, chitosan was impregnated with magnetite nanoparticles through a chemical co-precipitation method to fabricate hybrid adsorbents of Fe₃O₄–chitosan. The physicochemical and structural properties of the adsorbent were characterized, and then the performance of the adsorbent was evaluated for fluoride removal from water. The operational factors affecting the adsorption process, including pH, contact time, adsorbent dosage, initial fluoride concentration, and temperature, were studied. Various isotherm and kinetic models were also used to evaluate the fit of the experimental data with the modeled results. The equilibrium data were well described by the Freundlich model. The kinetics of the adsorption process followed the pseudo-second-order model. Recycling results suggested that the Fe₃O₄–chitosan particles maintain a great reusability potential for five consecutive cycles. Findings also showed that the Fe₃O₄–chitosan can be easily regenerated via acid treatment. The results of the present work highlighted the potential of using the Fe₃O₄–chitosan magnetic composite for the removal of fluoride from water. In conclusion, Fe₃O₄–chitosan can be considered as an appropriate adsorbent for fluoride removal from water, because it can be separated both quickly and easily, it has high efficiency, and it does not lead to secondary pollution.