Development of Coconut Shell Hydrochar for Lead Removal from Pharmaceutical Wastewater

• Adegoke P. ADEBOLA

  Author

• Abubakar S. MOHAMMED

  Author

• Umaru MUSA

  Author

• Abubakar A. IBRAHIM

  Author

• Abubakar G. ISAH

  Author

• Mohammed U. GARBA

  Author

Lead (Pb²⁺) contamination of wastewater requires effective, low-cost, and sustainable treatment materials. This study investigated coconut shell hydrochar produced by hydrothermal carbonization (HTC) for Pb²⁺ removal from aqueous solution and pharmaceutical wastewater. Coconut shells were converted to hydrochar at 200, 220, and 240 °C and characterized using proximate, Fourier transform infrared spectroscopy – FTIR, ultimate analysis and BET surface area. The hydrochar produced at 240 °C exhibited a specific surface area of 560.45 m²/g and was selected for adsorption experiments. Batch adsorption studies evaluated the effects of pH, contact time, dosage concentration, temperature, and initial Pb²⁺ concentration. Adsorption equilibrium, kinetics, and thermodynamics were assessed using Langmuir, Freundlich, pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Pb²⁺ removal increased if contact time and adsorbent dosage increases reaching 99.19% at 120 min and 99.46% at 2.0 g/L, respectively. Increasing initial Pb²⁺ concentration increased adsorption capacity from 0.01665 to 0.180 mg/g but reduced percentage removal. The Freundlich model provided the best equilibrium fit (R² = 0.9996), while the Langmuir model gave R² = 0.9374 and a maximum adsorption capacity of 0.2502 mg/g. The pseudo-second-order model best fit the adsorption kinetics (R² = 0.955). Thermodynamic analysis indicated spontaneous and endothermic adsorption, with negative ΔG values (−0.708 to −2.443 kJ/mol), ΔH of 25.15 kJ/mol, and ΔS of 86.72 J/mol·K. Overall, coconut shell hydrochar showed promising potential for sustainable Pb²⁺ removal from wastewater.

• 70_Adebola et al. (2026)

Copyright (c) 2026 Adegoke P. ADEBOLA, Abubakar S. MOHAMMED, Umaru MUSA, Abubakar A. IBRAHIM, Abubakar G. ISAH, Mohammed U. GARBA (Author)

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.