Designing of highly efficient chitosan-based bimetallic Zr–Fe, three-dimensional bio-architecture for mitigating fluoride from water

The presence of fluoride in ground water is a growing concern. Thus, herein, a metal-impregnated chitosan-based 3D polymer microsphere (CH@Zr5–Fe) is designed to mitigate elevated fluoride from water. The CH@Zr5–Fe, having surface area (SA: 8.03 m² g⁻¹) and porosity (pore volume: 0.006789 cm³ g⁻¹), has shown significant efficacy toward fluoride. The advanced instruments, i.e., SEM, XRD, FTIR, Raman, and XPS analysis, etc., were used to elucidate the structural and morphological characterization. The maximum adsorption capacity (q_{e max}) was found as 108.85 mg g⁻¹ under given experimental condition (dose: 150 mg L⁻¹, pH: 7.0 ± 2.0, time: 180 min at 295 K). The adsorption isotherm was well fitted with Freundlich isotherm model (R² = 0.992), and the adsorption kinetics followed a pseudo-second-order (PSO) model, which are suggesting the involvement of both physical and chemical processes. Optimal conditions for fluoride removal were identified, along with insights into interference from bicarbonate and phosphate ions. With a point of zero charge (pH_pzc) of 7.62, the CH@Zr5–Fe adsorbent exhibited promising potential for practical application for treating fluoride-contaminated water, thus, offering a viable alternative for combating fluoride contamination in groundwater.