Hydroxyapatite biomaterial production from chicken (femur and beak) and fishbone waste through a chemical less method for Cd 2+ removal from shipbuilding wastewater.

Hydroxyapatite (HAp) powder was produced from chicken (femur and beak) and fishbone wastes and used as a green adsorbent to decrease Cd ²⁺ from aqueous media. The HAp powder was generated at 900 °C and characterized using physicochemical techniques. Chicken femur' HAp (16.72 m ² /g) had a higher surface compared to chicken beak and fishbone ones. The solution pH was the most important parameter in removing Cd ²⁺ . The highest Cd ²⁺ removal was achieved at pH 6, temperature of 25 °C, contact time of 80 min, and adsorbent mass of 2 g/L. The Cd ²⁺ adsorption data fitted well with the quasi-second-order model in kinetics and the Freundlich model in isotherm. The highest adsorption capacity of Cd ²⁺ using HAp-chicken femur, HAp-fish bone, and HAp-chicken beak was determined 22.94 mg/g, 21.54 mg/g, and 21.45 mg/g, respectively. The Cd ²⁺ adsorption using HAp powder was a spontaneous and exothermic process and accidental collisions at the liquid-solid interface were reduced. The decrease of Cd ²⁺ adsorption efficiency was not significant after multiple recovery steps of the desired powders. In addition to Cd ²⁺ , other parameters of real wastewater (shipbuilding industry) were reduced by the proposed adsorbents. The utilization of hydroxyapatite powder is expected to be a cheap and eco-friendly method for eliminating metals such as Cd ²⁺ .
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