Harnessing Waste-Derived Biochar Decorated with ZnO-ZrO₂ Nanoparticles for Economical and High-Efficiency Fluoride Remediation

Groundwater fluoride pollution is a significant public health concern particularly in regions where cost-effective and efficient treatment solutions are not feasible. However, many improved biochar-based adsorbents have been studied, but reaching high removal effectiveness at realistic fluoride concentrations with minimal material consumption still remains a critical problem. In this study, a novel zinc–zirconium oxide-modified biochar composite (BZ2) was prepared from coconut shell biochar to improve the fluoride adsorption performance by the synergistic dual metal oxide modification. XRD, SEM and EDAX studies verified the effective incorporation and homogenous distribution of crystalline ZnO and ZrO2 nanoparticles in the porous charcoal matrix. Batch adsorption tests were performed to investigate the effects of adsorbent dosage, contact time, pH and temperature at an initial fluoride content of 5 mg L−1, which represents the real ground water conditions. The composite BZ2 showed superior removal effectiveness (98