Bifunctional Fe 3 O 4 nanoparticles as magnet and inducer in bioextruded fabrication of starch-based composite with hierarchical pore architecture.

Starch (St) was used as green and renewable matrix (> 80%, db) for the preparation of Zn-St-MOCP/nFe ₃ O ₄ composite via bioextrusion. Bifunction of Fe ₃ O ₄ NPs as magnet and pore-inducer was confirmed and could be more homogeneously embedded in the St-based framework with hierarchical porous structure via SEM-EDS mapping. For the nFe ₃ O ₄ -induced microstructure of Zn-St-MOCP/nFe ₃ O ₄ composite, submicronic pores and nanopores were observed with Fe ₃ O ₄ NPs onto the inner surface of micron channels. According to the XPS, XRD, FTIR, TGA analyses, it is probably due to the coordination between Fe ^3+/2+ and Zn ²⁺ /hydroxy groups and the recombination of St chains in crystalline/amorphous zones interfered by Fe ₃ O ₄ NPs. Saturation magnetization value was measured with an excellent separation behavior. Seven kinetic equations were conducted for the fitting of dye adsorption data. Overall, the nFe ₃ O ₄ -assisted bioextrusion strategy is developed for the continuous fabrication of bio-based materials with rapid magnetic separation and hierarchical-pore architecture promising in practical adsorption.
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