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In recent years, a large amount of emulsified oily wastewaters were produced from petroleum and food industries, resulting in severe environmental problems. In this study, a series of polyvinylpyrrolidone (PVP)-coated Fe3O4 magnetic nanoparticles (MNPs) were prepared via one-step solvothermal method by introducing various amounts or types of PVP. The synthesized MNPs were characterized by multiple techniques, and their demulsification performances were evaluated in petrochemical and vegetable oil wastewaters, respectively. Results showed that the introduction of PVP in solvothermal process could significantly enhance the demulsification efficiency of MNPs, although excessive addition of PVP could not further increase its efficiency. Moreover, the effects of pH, surfactant concentration of wastewater, and the recycle number of MNPs on the demulsification performance were investigated in detail. It was found that the demulsification efficiency decreased with the increase of pH and surfactant concentration, and the synthetic MNPs were still effective after being reused for 5 cycles under acidic and neutral conditions. It is expected that the development of the PVP-coated MNPs can provide a simple and powerful route for the oily wastewater treatment.

Fluorescence polystyrene microbeads have been widely used in the biomedical and chemical fields. One of the key applications is the suspension array technology (SAT) based on fluorescence encoded microbeads (FEMs)....

Magnetic materials perform well in the purification of histidine-rich proteins (His-proteins). In this work, a facile fabrication of yolk−shell magnetic Fe 3 O 4 @NiSiO 3 /Ni microspheres for the efficient purification of His-proteins has been reported. Yolk−shell Fe 3 O 4 @NiSiO 3 microspheres were prepared via hydrothermal reaction. Then Ni nanoparticles (NPs) were loaded on Fe 3 O 4 @NiSiO 3 microspheres after the adsorption and in situ reduction of nickel acetylacetonate. The yolk−shell Fe 3 O 4 @ NiSiO 3 /Ni microspheres had a hierarchical flower-like structure and large cavities. The size of the cavity depended on the reaction time. This indicated that the microspheres had a large specific surface area for loading of more Ni NPs, which was crucial to the high His-protein adsorption capacity of Fe 3 O 4 @NiSiO 3 /Ni microspheres. Fe 3 O 4 @NiSiO 3 /Ni microspheres had a high adsorption capacity for bovine hemoglobin (BHb, 2822 mg/g), which was better than the values of other His-protein adsorbents. Fe 3 O 4 @ NiSiO 3 /Ni microspheres still had a high BHb separation efficiency after seven separation cycles, indicating its good reusability and stability. Therefore, the as-prepared bifunctional yolk−shell Fe 3 O 4 @NiSiO 3 /Ni microspheres exhibited great practical application value for His-protein purification.

Magnetic polymer microspheres have been widely used in nucleic acid extraction, immunoassays, drug screening, compound identification, wastewater treatment and catalysis. However, the particle size and magnetic material content of magnetic...