Powdered MXene-integrated magnetic hydrogel for the high-capacity adsorption and rapid separation of microplastics from water

Microplastics pose a persistent threat to aquatic ecosystems, driving interest in magnetic hydrogel adsorbents. However, conventional Fe₃O₄-based systems suffer from iron leaching during reuse, creating secondary pollution. MXene addresses this limitation and additionally enhances interfacial interactions with target pollutants. Although MXene-hydrogel composites have been reported for heavy metals, dyes, and pharmaceuticals, to our knowledge this is the first report of a magnetic MXene-alginate composite for microplastic capture. We therefore compared a baseline Alginate/Polyvinylpyrrolidone/Fe₃O₄ composite (M1) with its MXene-reinforced counterpart (M2), each in bead and powdered forms, for removing polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) microplastics (5–75 μm). Beads showed poor removal (<40%) regardless of composition, whereas powdered forms performed markedly better (96%) due to greater exposed surface area and closer size matching with the target MPs. Within the powdered format, M2 raised removal from 30.83 ± 3.62% to 48.6 ± 7.50% (PP), 65.83 ± 5.18% to 76 ± 4% (PS), and 70.8 ± 4.7% to 96.2 ± 1.45% (PET). This same reinforcement also resolved M1's iron leaching (6.86 ± 0.46 mg L − 1 , above the WHO aesthetic guideline of 2 mg L − 1 ), reducing it below threshold at pH 6. Under these conditions, powdered M2 achieved 486 ± 14.1, 760.33 ± 17, and 962.34 ± 8.02 mg g − 1 for PP, PS, and PET, equilibrating within 15 min, with performance retained across tap, lake, and seawater and 75 ± 3.5% capacity after six regeneration cycles, positioning powdered MXene-reinforced magnetic alginate hydrogel (M2) as a practical platform for microplastic remediation.