Engineering zinc-doped magnesium ferrite oxide/polypyrrole to remove excess fluoride from drinking water

The presence of fluoride ions in water has been demonstrated to induce severe health complications, known as fluorosis, on a global scale, with a particular prevalence observed in Senegal. The objective of this study was to develop an effective adsorbent based on zinc-magnesium ferrite oxide encapsulated by pyrrole. The oxide was synthesized by the sol–gel method, then polymerized by the oxidative polymerization method, and characterized using Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy (SEM and TEM). The adsorbent demonstrated fluoride adsorption efficiency within 30 min, exhibiting an adsorption quantity of 1.9 mg/g at an initial concentration of 5.4 mg/L at pH = 6.5. Several isotherm models were tested, such as Langmuir, Temkin, and Freundlich. The Freundlich model gave the best fit in this study and was utilised to delineate the adsorption isotherm, while the pseudo-second-order model was employed to describe the adsorption kinetics. Moreover, the thermodynamic study demonstrated that the adsorption process is endothermic and spontaneous. Infrared spectroscopy has demonstrated that the process of fluorine removal is concurrent with ion exchange and electrostatic interaction. The regeneration process has been repeated up to five times. The adsorbent has been successfully applied in the treatment of water supplies.