Bifunctional Fe3O4 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/nFe3O4 composite via bioextrusion. Bifunction of Fe3O4 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 nFe3O4-induced microstructure of Zn-St-MOCP/nFe3O4 composite, submicronic pores and nanopores were observed with Fe3O4 NPs onto the inner surface of micron channels. According to the XPS, XRD, FTIR, TGA analyses, it is probably due to the coordination between Fe3+/2+ and Zn2+/hydroxy groups and the recombination of St chains in crystalline/amorphous zones interfered by Fe3O4 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 nFe3O4-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.