Removal of fluoride from groundwater using a zeolite A supported magnetite biochar composite

Prolonged consumption of excess fluoride concentration (> 1.5 mg/L) from groundwater notably poses serious health effects, including dental and skeletal fluorosis in the Rift Valley area of Ethiopia. In this study, a zeolite A supported magnetite biochar composite (Z-A/M-BC) was synthesized through a pyrolysis method for the removal of fluoride from groundwater. The as-synthesized adsorbent was characterized using FT-IR, PXRD, SEM-EDX, PZC, and BET analysis to identify the functional group, phase structure, surface morphology, elemental composition, surface charge distribution, and surface area, respectively. The pH_ZPC determination for Z-A/M-BC is found to be 6.75, suggesting a large portion of the adsorbent with pH less than this value becomes protonated and positively charged and thus is favorable for fluoride removal through electrostatic attraction. Interestingly, the BET analysis results also exhibited that the synthesized Z-A/M-BC composite had a high surface area of 496.17 m²/g, which is accessible for capturing fluoride from groundwater. The adsorption study was commenced via optimization of reaction parameters: pH, adsorbent dose, initial concentration (C_o), and contact time. The highest fluoride removal efficiency (95.80%) and capacity (6.39 mg/g) were recorded at pH 5, 1.2 g/L of adsorbent dose, 6 h of contact time, and 10 mg/L of C_o. The removal performance of the Z-A/M-BC composite was also tested in a real sample of groundwater having 12.25 mg/L of fluoride C_o which was collected from Kenteri town, Ethiopia. It was found to be 88.98% removal efficiency and 7.27 mg/g capacity, respectively. At last, the reusability study was conducted for 5 successive runs and found 95.80%, 90.40%, 87.30%, 85.40%, and 70.20% removal efficiency for the first, second, third, fourth, and fifth cycles, respectively. These confirm that the Z-A/M-BC adsorbent is promising for the removal of fluoride from groundwater at a large scale.