Synthesis and Electrophoretic Concentration of Hydroxyapatite Nanoparticles in Reverse Micelles of Oxyethylated Surfactant

Abstract

By photon correlation spectroscopy the formation of hydroxyapatite nanoparticles in reverse micelles of oxyethylated surfactant Tergitol NP-4 is studied depending on the solubilization capacity of a micellar solution. Stable organosols are obtained, the electrophoretic concentration and the separation of hydroxyapatite nanoparticles from the surfactant excess and synthesis by-products are performed in the presence of an anionic surfactant AOT. According to the transmission electron microscopy data, the shape of hydroxyapatite nanoparticles is elongated (length 40-80 nm, thickness 5-20 nm), which is well consistent with the n-averaged hydrodynamic diameter determined by photon correlation spectroscopy. The nanoparticles are positively charged; their ζ-potential changes from 10 mV to 42 mV, depending on the surfactant and solvent types.