SCHEDULED MAINTENANCE
Magnetically recyclable Bi/Fe-based hierarchical nanostructures via self-assembly for environmental decontamination†
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Abstract
Pristine bismuth ferrite usually possesses weak magnetic properties (e.g., saturation magnetization Ms < 3 emu g−1) for practical magnetic separation applications. Herein, a superparamagnetic bismuth ferrite with coral-like hierarchical morphology (BFO-M) was fabricated through methanol solvothermal treatment of the as-prepared Bi2Fe4O9 nanoclusters (P-BFO). The BFO-M shows a higher Ms of ∼31 emu g−1 compared to that of P-BFO treated in water (BFO-A), in ethanol (BFO-E) and in ethylene glycol (BFO-G). Compared to single-crystalline Bi2Fe4O9 (PS) and Bi2Fe4O9 clusters (NSP), BFO-M shows an excellent organic pollutant removal rate by virtue of its high adsorption capacity and catalytic activity when methyl orange (MO) is used as the model organic pollutant. BFO-M also exhibits good visible light photo-Fenton oxidation rates for pharmaceuticals and pesticides. Even at a low catalyst loading of 0.12 g L−1, the removal rate of organic pollutants (e.g., 5-fluorouracil, isoproturon) can be ∼99% in 100 min under visible light irradiation. Besides, BFO-M is also a good adsorbent for different kinds of heavy metal ions (Pb(II), Cr(III), Cu(II), As(V), etc.). For example, its maximal adsorption capacity for Pb(II) is 214.5 mg g−1. The used BFO-M can be recovered via magnetic separation. The outstanding performances of BFO-M can be ascribed to its coral-like hierarchical morphology which consists of the self-assembly of 1D nanowires (∼6 nm in diameter) and 2D ultrathin nanoflakes (∼4.5 nm in thickness). A schematic illustration of its morphology formation is proposed.
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