Lead sorption characteristics of various chicken bone part-derived chars

Recycling food waste for beneficial use is becoming increasingly important in resource-limited economy. In this study, waste chicken bones of different parts from restaurant industry were pyrolyzed at 600 °C and evaluated for char physicochemical properties and Pb sorption characteristics. Lead adsorption isotherms by different chicken bone chars were carried out with initial Pb concentration range of 1–1000 mg L⁻¹ at pH 5. The Pb adsorption data were better described by the Langmuir model (R² = 0.9289–0.9937; ARE = 22.7–29.3%) than the Freundlich model (R² = 0.8684–0.9544; ARE = 35.4–72.0%). Among the chars derived from different chicken bone parts, the tibia bone char exhibited the highest maximum Pb adsorption capacity of 263 mg g⁻¹ followed by the pelvis (222 mg g⁻¹), ribs (208 mg g⁻¹), clavicle (179 mg g⁻¹), vertebrae (159 mg g⁻¹), and humerus (135 mg g⁻¹). The Pb adsorption capacities were significantly and positively correlated with the surface area, phosphate release amount, and total phosphorus content of chicken bone chars (r ≥ 0.9711). On the other hand, approximately 75–88% of the adsorbed Pb on the chicken bone chars was desorbable with 0.1 M HCl, indicating their recyclability for reuse. Results demonstrated that chicken bone char could be used as an effective adsorbent for Pb removal in wastewater.