Snail shell-derived hydroxyapatite on ant clay: a sustainable solution for phosphate sequestration and circular agricultural reuse.
- 1Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus 22060 KPK Pakistan [email protected] [email protected] [email protected] [email protected].
- 2Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences & Technology Topi, District Swabi KPK 23640 Pakistan [email protected].
- 3School of Chemical, Biological, and Battery Engineering, Gachon University South Korea [email protected].
Abstract
In this study, a sustainable adsorbent comprising hydroxyapatite derived from snail shells and clay collected from ant nests was developed and used for the efficient removal of phosphate (PO₄ ³⁻) from aqueous solutions. The synthesized adsorbent was characterized using different characterization techniques like FTIR spectroscopy, XRD, SEM, TGA, PZC, and BET analysis to confirm its successful synthesis, morphology, thermal stability, surface charges, and surface area, respectively. The adsorbent was systematically investigated for phosphate adsorption by optimizing key experimental parameters, comprising contact time (25 min), adsorbent dosage (25 mg), initial phosphate concentration (5 mg L⁻¹), solution pH (5), and temperature (40 °C). Furthermore, the adsorption kinetics followed the pseudo-second-order model (R ² = 0.98), implying that the adsorption rate was controlled by the availability of active sites. The equilibrium data were best fitted to the Langmuir isotherm model (R ² = 0.98), with the maximum adsorption capacity of 97.18 mg g⁻¹. The thermodynamic analysis confirmed the endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) nature of the adsorption process. Real sample analysis validated the practical application, with 84.1% removal of PO₄ ³⁻. Exploratory machine-learning modelling of 84 experimental observations showed that SVR-RBF most accurately predicted phosphate-removal efficiency (cross-validated R ² = 0.789 ± 0.127), while Extra Trees regression provided the strongest prediction of adsorption capacity (cross-validated R ² = 0.894 ± 0.210). The modelled response trends were consistent with the experimentally identified optimum conditions, supporting the use of data-driven methods for adsorption-process interpretation and future optimization. Additionally, the PO₄ ³⁻-loaded adsorbent was evaluated as a fertilizer for wheat cultivation; it induced an enhanced growth performance compared to pristine ant clay, highlighting its potential for sustainable agricultural applications. Thus, this study established the adsorbent's efficacy in PO₄ ³⁻ removal and its suitability for improving growth parameters, including germination rate, shoot/root development, and chlorophyll/protein content, resulting in improved phosphorus bioavailability.
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BibTeX
@article{iqbal2026snail,
title = {{Snail shell-derived hydroxyapatite on ant clay: a sustainable solution for phosphate sequestration and circular agricultural reuse.}},
author = {Tayyab Iqbal and Mehr Un Nisa and Sadia Muhammad Khuidad and Ali Turab Jafry and Muhammad Faizan and Huma Ajab},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra07135j},
url = {https://europepmc.org/article/MED/42835898},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Snail shell-derived hydroxyapatite on ant clay: a sustainable solution for phosphate sequestration and circular agricultural reuse.
AU - Tayyab Iqbal
AU - Mehr Un Nisa
AU - Sadia Muhammad Khuidad
AU - Ali Turab Jafry
AU - Muhammad Faizan
AU - Huma Ajab
PY - 2026
DA - 2026/10/05
JO - RSC advances
DO - 10.1039/d6ra07135j
UR - https://europepmc.org/article/MED/42835898
AB - In this study, a sustainable adsorbent comprising hydroxyapatite derived from snail shells and clay collected from ant nests was developed and used for the efficient removal of phosphate (PO₄ ³⁻) from aqueous solutions. The synthesized adsorbent was characterized using different characterization techniques like FTIR spectroscopy, XRD, SEM, TGA, PZC, and BET analysis to confirm its successful synthesis, morphology, thermal stability, surface charges, and surface area, respectively. The adsorbent was systematically investigated for phosphate adsorption by optimizing key experimental parameters, comprising contact time (25 min), adsorbent dosage (25 mg), initial phosphate concentration (5 mg L⁻¹), solution pH (5), and temperature (40 °C). Furthermore, the adsorption kinetics followed the pseudo-second-order model (R ² = 0.98), implying that the adsorption rate was controlled by the availability of active sites. The equilibrium data were best fitted to the Langmuir isotherm model (R ² = 0.98), with the maximum adsorption capacity of 97.18 mg g⁻¹. The thermodynamic analysis confirmed the endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) nature of the adsorption process. Real sample analysis validated the practical application, with 84.1% removal of PO₄ ³⁻. Exploratory machine-learning modelling of 84 experimental observations showed that SVR-RBF most accurately predicted phosphate-removal efficiency (cross-validated R ² = 0.789 ± 0.127), while Extra Trees regression provided the strongest prediction of adsorption capacity (cross-validated R ² = 0.894 ± 0.210). The modelled response trends were consistent with the experimentally identified optimum conditions, supporting the use of data-driven methods for adsorption-process interpretation and future optimization. Additionally, the PO₄ ³⁻-loaded adsorbent was evaluated as a fertilizer for wheat cultivation; it induced an enhanced growth performance compared to pristine ant clay, highlighting its potential for sustainable agricultural applications. Thus, this study established the adsorbent's efficacy in PO₄ ³⁻ removal and its suitability for improving growth parameters, including germination rate, shoot/root development, and chlorophyll/protein content, resulting in improved phosphorus bioavailability.
SN - 2046-2069
ER -