Abstract: Functional magnetic nanoparticles Fe3O4-CS@Fe3+ (CMNP@Fe3+ for short) were prepared by chemical co-precipitation and functional modification with sodium chondroitin sulfate and ferric ion, and their surface morphology was analyzed. CMNP@Fe3+ showed a spherical shape with a small diameter of about 20 nm, and they could be well dispersed in aqueous solution as proved by transmission electron microscope. It was found that the nanoparticles had superparamagnetic properties as indicated by the hysteresis loop. Fourier transform infrared spectrum revealed that sodium chondroitin sulfate and Fe3+coated the surface of Fe3O4 successfully. This study established a new method to extract phosvitin from hen egg yolk by taking advantage of the strong binding of Fe3+ on the surface of magnetic nanoparticles to phosvitin, and we also investigated the factors influencing the adsorption process. The magnetic nanoparticles had maximum adsorption capacity under the following conditions: solution pH 4.0, initial substrate concentration 10 mg/mL, and adsorption time 180 min. The adsorption kinetics of CMNP@Fe3+ for phosvitin was better described by a pseudo second-order kinetic model, and the theoretical adsorption capacity at the equilibrium state computed from the model was 625.00 mg/g. The adsorption data were fit to well the Freundlich isotherm model. This research may provide a reference for protein separation from eggs using magnetic particles.

Key words: phosvitin, magnetic nanopaticles, magnetic separation, sodium chondroitin sulfate, ferric ion