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<p>The presence of heavy metals in water bodies poses significant threats to human health and ecosystems. Despite advances in green nanotechnology for water remediation, competitive adsorption in binary heavy metal systems remains poorly understood, particularly for plant mediated nanoadsorbents using endemic African species. This study synthesized magnetic iron oxide nanoparticles (Fe<sub>2</sub>O<sub>3</sub>) using <i>Icacina oliviformis</i> (false yam) leaf extract, a drought–resistant West African agricultural weed previously unexplored in nanomaterial synthesis. The green synthesis approach employed plant biomolecules as stabilizing agents, thereby enhancing the nanoparticles’ biocompatibility and surface reactivity. Characterization using SEM/EDX, UV–Vis spectroscopy, and FTIR confirmed the successful synthesis of the nanocomposite with magnetic properties that facilitate easy separation and reuse. Batch adsorption experiments were conducted to evaluate the removal of three toxic metals in binary systems (Cd–Pb, Cd–Hg, and Pb–Hg) under varying conditions of initial concentration, contact time, temperature, adsorbent dosage, and pH. The nanoadsorbent demonstrated high removal efficiencies, achieving 88.42% for the Cd–Pb system at pH 10, 99.07% for Pb–Cd at a dosage of 0.13&#xa0;g, and 97.20% for the Cd–Hg system at a dosage of 0.11&#xa0;g. Adsorption kinetics fitted the pseudo-second-order model for Cd and Pb, while Hg adsorption followed the pseudo-first-order model. Competitive Langmuir isotherm analysis revealed selectivity coefficients of Pb/Cd = 2.34 and Hg/Cd = 1.89, confirming Pb &gt; Hg &gt; Cd preference driven by ionic radius (Pb <sup>2+</sup>: 1.19&#xa0;Å &gt; Hg<sup>2+</sup>: 1.02&#xa0;Å &gt; Cd<sup>2+</sup>: 0.95&#xa0;Å) and electronegativity differences. The Freundlich model also described the isotherms across all systems. Thermodynamic analysis confirmed spontaneous exothermic adsorption with a positive entropy contribution. Reusability tests demonstrated acceptable minimal efficiency loss over four regeneration cycles. The FYL–Fe<sub>2</sub>O<sub>3</sub> nanocomposite represents a promising sustainable, low-cost nanoadsorbent for multimetal remediation, valorizing agricultural waste into accessible technology for resource-limited communities.</p>

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Functionalized Icacina oliviformis magnetic Fe2O3 nanoparticles for competitive heavy metal removal from contaminated water

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月22日

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  • Ibrahim Abdul-Gafaru,
  • Samuel Jerry Cobbina,
  • Michael Kumi,
  • Lawrence Yawson

摘要

The presence of heavy metals in water bodies poses significant threats to human health and ecosystems. Despite advances in green nanotechnology for water remediation, competitive adsorption in binary heavy metal systems remains poorly understood, particularly for plant mediated nanoadsorbents using endemic African species. This study synthesized magnetic iron oxide nanoparticles (Fe2O3) using Icacina oliviformis (false yam) leaf extract, a drought–resistant West African agricultural weed previously unexplored in nanomaterial synthesis. The green synthesis approach employed plant biomolecules as stabilizing agents, thereby enhancing the nanoparticles’ biocompatibility and surface reactivity. Characterization using SEM/EDX, UV–Vis spectroscopy, and FTIR confirmed the successful synthesis of the nanocomposite with magnetic properties that facilitate easy separation and reuse. Batch adsorption experiments were conducted to evaluate the removal of three toxic metals in binary systems (Cd–Pb, Cd–Hg, and Pb–Hg) under varying conditions of initial concentration, contact time, temperature, adsorbent dosage, and pH. The nanoadsorbent demonstrated high removal efficiencies, achieving 88.42% for the Cd–Pb system at pH 10, 99.07% for Pb–Cd at a dosage of 0.13 g, and 97.20% for the Cd–Hg system at a dosage of 0.11 g. Adsorption kinetics fitted the pseudo-second-order model for Cd and Pb, while Hg adsorption followed the pseudo-first-order model. Competitive Langmuir isotherm analysis revealed selectivity coefficients of Pb/Cd = 2.34 and Hg/Cd = 1.89, confirming Pb > Hg > Cd preference driven by ionic radius (Pb 2+: 1.19 Å > Hg2+: 1.02 Å > Cd2+: 0.95 Å) and electronegativity differences. The Freundlich model also described the isotherms across all systems. Thermodynamic analysis confirmed spontaneous exothermic adsorption with a positive entropy contribution. Reusability tests demonstrated acceptable minimal efficiency loss over four regeneration cycles. The FYL–Fe2O3 nanocomposite represents a promising sustainable, low-cost nanoadsorbent for multimetal remediation, valorizing agricultural waste into accessible technology for resource-limited communities.