Adsorption behavior of nanoplastics from water onto magnetic biochar in single and binary heavy metal systems: A combined experimental and DFT study.

Under batch conditions with 100 mg/L polystyrene nanoplastics, magnetic biochar shows treatment-dependent apparent uptake capacities of 24.25 mg/g (metal-free) versus 19.40, 14.48, and 21.14 mg/g for Pb(II), Zn(II), and Pb(II)/Zn(II).

• Why it matters: Coexisting heavy metals can change nanoplastic removal, but single- versus mixed-metal comparisons are confounded by differing metal concentrations.
• What they did: They measured apparent uptake of dispersed polystyrene by magnetic biochar with metals added at 50 mg/L each (metal-free, Pb(II), Zn(II), and binary Pb(II)/Zn(II)), then used SEM-EDS, XPS, and finite-cluster DFT to probe aggregation and interfacial metal arrangements.
• The result: The binary Pb(II)/Zn(II) uptake was numerically higher than either single-metal value yet stayed below the metal-free control, implying the response depends on metal identity, total loading, and local PS–MBC interfacial configuration.

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