Surface Modification of Fe_3O_4 Nanoparticles Prepared in High Temperture Organic Solution by Sodium Oleate

Sodium oleate was used as surface modification agent to modify Fe_3O_4 nanoparticles pre- pared in high temperature organic solution.Fe_3O_4 nanoparticles were transferred from organic phase to aqueous solution by the van der Waals interaction between the long aliphatic chain of oleate anion and the hydrophobic groups in the surface of Fe_3O_4 nanoparticles.Effects of concentration of sodium oleate, pH and temperature on surface modification of Fe_3O_4 nanoparticles were investigated.MSssbauer spec- troscopy,Transmission electron microscopy (TEM) and Fourier transform-infrared (FT-IR) spectroscopy were used to characterize samples before and after modification.The results show that the method is effective in transferring Fe_3O_4 nanoparticles from organic phase to aqueous solution.The ratio of Fe_3O_4 nanoparticles transferred from organic phase is as high as 86% and the content of transferred Fe_3O_4 nanoparticles in aqueous solution is 10.5mg·mL~(-1) on condition that the concertration of sodium oleate solution is 3mmol/L,the content of Fe_3O_4 nanoparticles in n-hexane is 12.28mg·mL~(-1),pH is 8.6,tem- perature is 60℃,respectively.The surface modified Fe_3O_4 nanoparticles with low concentration in aqueous solution can stably disperse in aqueous solution for a long time.