Covering structure and stability of nanosized Fe₃O₄ magnetic liquid

Fe₃O₄ nanoparticles were prepared with Chemical co-precipitation method. The covering structure and stability of nanosized Fe₃O₄ magnetic liquid effected by the dosage of sodium dodecyl benzene sulfonate (SDBS) were investigated with ball milling method. The samples were measured by X-ray diffraction (XRD), high-resolution retransmission electron microscopy (HRTEM), Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy(XPS). The results show that when the mass of Fe₃O₄ is 10 g in 50 mL water, pH is 4.5 and the ball milling time is 5 h, the better dosage of SDBS is 0.8 g. SDBS is adsorbed on the surface of Fe₃O₄ nanoparticles with spinel structure by multi-layer chemisorption and physisorption. And the Fe-O-S chemical bond makes the encasing structure difficult to be broken, and the magnetic liquid is stable.