Valorizing Duck Bone into Regenerable Hydroxyapatite Biochar: Pyrolysis Effects on Divalent Heavy Metal Adsorption Mechanisms
4 affiliations
- 1Department of Mechanical Engineering, Faculty of Arts and Science, Chaiyaphum Rajabhat University, Chaiyaphum 36000, Thailand
- 2School of Energy and Environment, University of Phayao, Phayao 56000, Thailand
- 3Department of Environmental Health, Faculty of Public Health, Burapha University, Chonburi 20131, Thailand
- 4Field of Environmental Engineering, Faculty of Engineering, Mahasarakham University, Mahasarakham 44150, Thailand
Abstract
Duck bone, an under-used by-product of Southeast Asian poultry processing, was converted into hydroxyapatite-based bone char by single-step, reagent-free pyrolysis at 300, 400, and 500 °C and evaluated as a reusable Cu(II) adsorbent. Physical and chemical analyses showed progressive removal of the collagen–lipid matrix and preservation of a hydroxyapatite scaffold (98–99 wt% of the crystalline phases by Rietveld refinement, with minor calcite; apparent crystallite size ~7–8 nm across and ~23–25 nm along the c-axis). Surface area increased progressively from 33.0 to 84.2 m2 g−1 with pyrolysis temperature, whereas the Toth capacity increased steadily from 44.7 to 48.6 mg g−1, indicating that uptake is governed mainly by apatite-site accessibility rather than scaling proportionally with surface area. Sigmoidal Avrami kinetics with exponents of 1.25–1.48, sharply saturating isotherms, an endothermic enthalpy of 71–90 kJ mol−1, and points of zero charge of about pH 7–9.5 supported cooperative binding through Ca2+–Cu2+ ion exchange, phosphate and hydroxyl complexation, and proposed surface nucleation of Cu–phosphate clusters; Cu(OH)2 precipitation was not expected at the pH used. After five HCl regeneration cycles, DKB retained 73.1–80.0% of its initial efficiency, and the first-order decay constant decreased from 0.078 to 0.056 cycle−1 with increasing pyrolysis temperature. DKB produced at 500 °C combined the highest capacity, fastest kinetics, and greatest regeneration stability, establishing duck bone as a low-cost, circular feedstock for Cu(II) remediation.
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BibTeX
@article{hongthong2026valorizing,
title = {{Valorizing Duck Bone into Regenerable Hydroxyapatite Biochar: Pyrolysis Effects on Divalent Heavy Metal Adsorption Mechanisms}},
author = {Sukanya Hongthong and Torpong Kreethachat and Saksit Imman and Nopparat Suriyachai and Anusorn Boonpoke and Kowit Suwannahong and Pattaranun Maskhunthod and Surachai Wongcharee},
journal = {International Journal of Molecular Sciences},
year = {2026},
month = nov,
doi = {10.3390/ijms27219991},
url = {https://www.mdpi.com/1422-0067/27/21/9991},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Valorizing Duck Bone into Regenerable Hydroxyapatite Biochar: Pyrolysis Effects on Divalent Heavy Metal Adsorption Mechanisms
AU - Sukanya Hongthong
AU - Torpong Kreethachat
AU - Saksit Imman
AU - Nopparat Suriyachai
AU - Anusorn Boonpoke
AU - Kowit Suwannahong
AU - Pattaranun Maskhunthod
AU - Surachai Wongcharee
PY - 2026
DA - 2026/11/07
JO - International Journal of Molecular Sciences
DO - 10.3390/ijms27219991
UR - https://www.mdpi.com/1422-0067/27/21/9991
AB - Duck bone, an under-used by-product of Southeast Asian poultry processing, was converted into hydroxyapatite-based bone char by single-step, reagent-free pyrolysis at 300, 400, and 500 °C and evaluated as a reusable Cu(II) adsorbent. Physical and chemical analyses showed progressive removal of the collagen–lipid matrix and preservation of a hydroxyapatite scaffold (98–99 wt% of the crystalline phases by Rietveld refinement, with minor calcite; apparent crystallite size ~7–8 nm across and ~23–25 nm along the c-axis). Surface area increased progressively from 33.0 to 84.2 m2 g−1 with pyrolysis temperature, whereas the Toth capacity increased steadily from 44.7 to 48.6 mg g−1, indicating that uptake is governed mainly by apatite-site accessibility rather than scaling proportionally with surface area. Sigmoidal Avrami kinetics with exponents of 1.25–1.48, sharply saturating isotherms, an endothermic enthalpy of 71–90 kJ mol−1, and points of zero charge of about pH 7–9.5 supported cooperative binding through Ca2+–Cu2+ ion exchange, phosphate and hydroxyl complexation, and proposed surface nucleation of Cu–phosphate clusters; Cu(OH)2 precipitation was not expected at the pH used. After five HCl regeneration cycles, DKB retained 73.1–80.0% of its initial efficiency, and the first-order decay constant decreased from 0.078 to 0.056 cycle−1 with increasing pyrolysis temperature. DKB produced at 500 °C combined the highest capacity, fastest kinetics, and greatest regeneration stability, establishing duck bone as a low-cost, circular feedstock for Cu(II) remediation.
SN - 1422-0067
ER -