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<p>The environment and human health are at risk when industrial waste leaks into aquatic environments. Green-synthesized magnetite-maghemite nanocomposites (GSMMNs) were developed in this study as bio-synthesized adsorbents for removing heavy metals from water. The XRD, TEM, FT-IR, SEM–EDS, BET, VSM, and XPS analyses characterized the nanocomposites. The average particle size was 13.76&#xa0;nm by TEM analysis with a surface area of 158&#xa0;m<sup>2</sup>/g. The functional groups (C = O) and mixed Fe<sup>2</sup>⁺/Fe<sup>3</sup>⁺ states contribute to the adsorption confirmed by FT-IR and XPS. Batch studies showed optimal adsorption at pH 6.5, 1.5&#xa0;g/L dose, 30&#xa0;°C, and 20–30&#xa0;min contact time (initial concentration 5&#xa0;mg/L). Pb(II) and Cd(II) have maximal adsorption capacities of 35&#xa0;mg/g and 15&#xa0;mg/g, respectively, which decrease to 19&#xa0;mg/g and 8.1&#xa0;mg/g as a result of their antagonistic effects. The single and binary systems are followed by Langmuir and Sip models, respectively with a pseudo-second-order kinetic model (<i>R</i><sup>2</sup> = 0.99). An antagonistic effect was observed in the binary solution of Pb(II) and Cd(II), based on mathematical modeling. Co-existing ions and ionic strength have an impact on the adsorption following the sequence (PO₄<sup>3</sup>⁻ &gt; CO<sub>3</sub><sup>2</sup>⁻ &gt; SO₄<sup>2</sup>⁻ &gt; Ca<sup>2</sup>⁺ &gt; NO₃⁻ &gt; Cl⁻ &gt; K⁺). In a real water matrix, the adsorbent showed performance following the sequence: deionized water &gt; tube well water &gt; tap water &gt; river water. The GSMMNs showed promising potential as a cost-effective adsorbent with five regeneration cycles.</p> Graphical abstract <p></p>

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Green-synthesized magnetite-maghemite nanocomposites for the removal of lead and cadmium from water: competitive adsorption behavior and mechanism studies

  • 期刊论文

  • 发表日期：

    2025年6月1日

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  • Asma Siddiqa,
  • Most. Halima Khatun,
  • Md. Golam Mostafa

摘要

The environment and human health are at risk when industrial waste leaks into aquatic environments. Green-synthesized magnetite-maghemite nanocomposites (GSMMNs) were developed in this study as bio-synthesized adsorbents for removing heavy metals from water. The XRD, TEM, FT-IR, SEM–EDS, BET, VSM, and XPS analyses characterized the nanocomposites. The average particle size was 13.76 nm by TEM analysis with a surface area of 158 m2/g. The functional groups (C = O) and mixed Fe2⁺/Fe3⁺ states contribute to the adsorption confirmed by FT-IR and XPS. Batch studies showed optimal adsorption at pH 6.5, 1.5 g/L dose, 30 °C, and 20–30 min contact time (initial concentration 5 mg/L). Pb(II) and Cd(II) have maximal adsorption capacities of 35 mg/g and 15 mg/g, respectively, which decrease to 19 mg/g and 8.1 mg/g as a result of their antagonistic effects. The single and binary systems are followed by Langmuir and Sip models, respectively with a pseudo-second-order kinetic model (R2 = 0.99). An antagonistic effect was observed in the binary solution of Pb(II) and Cd(II), based on mathematical modeling. Co-existing ions and ionic strength have an impact on the adsorption following the sequence (PO₄3⁻ > CO32⁻ > SO₄2⁻ > Ca2⁺ > NO₃⁻ > Cl⁻ > K⁺). In a real water matrix, the adsorbent showed performance following the sequence: deionized water > tube well water > tap water > river water. The GSMMNs showed promising potential as a cost-effective adsorbent with five regeneration cycles.

Graphical abstract