Year: 2026
Type: preprint
Abstract: Heavy metal contamination including Pb 2+ ions in water systems threatens environmental and public health, requiring the need for designing adsorbents that are affordable, eco-friendly, and effective. Biochars produced from agricultural biomass serve a potential roadmap for heavy metal remediation, but how sequential physical and chemical modifications of biochars control their adsorption behavior still limited; hence, systematic understanding persists. This present research assessed performances of three adsorbents {raw palm-kernel chaff (RPKC), physically pyrolyzed palm-kernel chaff (PPKC), and physically pyrolyzed–chemically activated palm-kernel chaff (CPPKC) using H 3 PO 4 prepared from palm-kernel chaffs for removal of lead(II) ions from aqueous solutions. The adsorbents were characterized using FTIR, TGA, XRD, SEM–EDX, zeta potential, and BET surface area analysis. Batch adsorption experiments were performed to elucidate the effects of adsorbent dosage, pH, initial Pb 2+ concentration, contact time, temperature on adsorption characteristics. Systematic analysis of adsorption kinetics, isotherms, and thermodynamics, using established models, was carried out. Pyrolysis and chemical activation progressively induced structural and chemical changes such as enhanced surface heterogeneity, increased porosity, and improved thermal stability. Adsorbent CPPKC exhibited the highest BET surface area 116.13 m 2 /g, and pore volume 1.4327 cm 3 /g, but lowest PZC (point of zero charge) of 5.19. Adsorption kinetics was best described by Avrami model while equilibrium data fitted into the Liu isotherm adequately. Highest Pb 2+ removal of 6131.7 mg/g was exhibited by CPPKC. Thermodynamic analysis emphasized spontaneous and endothermic adsorption. This study justifies agricultural waste valorization as a feasible strategy for sustainable water treatment.
Source: Research Square
Institution: Federal University of Technology
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204997987