Ultrafast removal of Ni(II) ions over a bio-based antibacterial adsorbent

Efficiently removing heavy metal ions and preventing bacterial growth were meaningful for wastewater purification, which still faced a long-term problem requiring the development of sustainable antibacterial adsorbent with both high uptake capacity and ultrafast adsorption rate. We fabricated a low-cost yet strong bio-based adsorbent using simple supramolecular self-assembly of tannic acid (TA) and polyethyleneimine (PEI) for fast and highly reversible absorption of Ni(II) ions. This adsorbent displayed an interconnected nanoparticle morphology, and its average size was ～41 nm. Benefiting from the abundant catechol/amine groups and meso-/macro-porous channel as well as high surface area (86.5 m 2 /g), this bio-based adsorbent could trap Ni(II) ions by rapidly forming Ni–O and Ni–N coordination bonds, thereby reaching adsorption equilibrium within 5 min, which almost exceeded most reported adsorbents by 6–330 times. Simultaneously, these structural merits also endowed this bio-based adsorbent with a high adsorption capacity (269.6 mg/g), superior to most other adsorbents. Furthermore, we discovered that the formed supramolecular nanostructure and the positive-charged surface of this bio-based adsorbent with bicomponent TA and PEI provided TA-PEI with about 100 % antibacterial activities against Escherichia coli and Staphylococcus aureus .