Adsorptive Fluoride Removal Using Zirconium-infused Agar-agar Based Activated Biochar Derived from Ricinus communis Leaves (Zr-AAABC)

Excess fluoride in drinking water poses significant health risks, necessitating the development of efficient and sustainable removal methods. This study investigates using a novel hybrid material, zirconium-loaded agar-agar-based activated biochar (Zr-AAABC), derived from Ricinus communis leaves, for fluoride removal from a water-based solution. The Zr-AAABC was synthesised by impregnating biochar from castor tree leaves with zirconium metal ions, utilising chemical and thermal activation techniques, including a 24-hour treatment with 2M sulfuric acid. Temperature (20-90°C), adsorbent dose (0.1-1.5 mg/L), adsorption duration (10-180 minutes), pH levels (1-13), and initial concentration of fluoride (10-100 mg/L) were among the variables tested to determine Zr-AAABC's adsorption performance. We validated the bio adsorbent's composition and structure using SEM, FTIR and ImageJ software. The results of the adsorption experiment, which demonstrated a good match with the Langmuir isotherm model and pseudo-second-order kinetic model, are consistent with monolayer adsorption on a homogeneous surface. The optimal parameters for fluoride removal were as follows: 1 g adsorbent dose, 2 hours of contact time, 60°C temperature, 10 mg/L starting fluoride concentration, and pH 7. We obtained 92% fluoride removal under the above conditions. However, we obtained only 82% fluoride removal using activated castor leaf biochar. Our results suggest that Zr-AAABC provides a sustainable and efficient alternative to conventional water filtration methods, including standard biochar, with significant potential for fluoride removal.