Adsorption of Sodium Oleate on Nano-sized Fe3O4 Particles Prepared by Coprecipitation

Nano-sized Fe3O4 is one of the most important magnetic materials wildly applied in various fields and sodium oleate (SO) is a very useful anionic surfactant for dispersing nano-particles in aqueous solution in the practical applications of nano-particles. However, studies of its adsorption properties on Fe3O4 nano-particles are scarce. This work firstly characterized the shape, size and phase structure of the nano-sized magnetite (Fe3O4) particles synthesized with chemical co-precipitation in aqueous solution by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Then, the UV absorbance behaviors of sodium oleate (SO) aqueous solution were explored and the adsorption of SO on nano-sized Fe3O4 particles was carried out. Based on the UV characteristics of SO, the isothermal adsorption of SO on these magnetite nanoparticles was measured under pH 10.5 at room temperature. Meanwhile, Fourier-transform infrared spectroscopy (FT-IR) was used to confirm the attachment of SO on the magnetic particles. Moreover, the adsorption equilibrium isotherm was fitted well by the Langmuir mode and proved that this adsorption was a monolayer adsorption. Keywords: Fe3O4 nanoparticles, Sodium oleate, Absorption, Adsorption, UV Spectrophotometry