Study on ce-doped nonstoichiometric nanosilica for promoting properties of polysulfone membranes

Abstract

Using the sol-gel method a series of nonstoichiometric nanosilica doped with the rare earth element Ce (CeSiO, x = 0.0-0.14) were prepared in order to modify the physicochemical properties of the nanosilica surface and to enhance the strength of the Ce-nanosilica/polysulfone composite membranes. The CeSiO samples were characterized by Fourier transform infrared spectra, X-ray diffraction and X-ray photoelectron spectra. The observations from these characterizations suggest that most Ce atoms enter the silica framework to form a Ce-O-Si solid solution while the cubic CeO phase is segregated when x > 0.08. Transmission electron microscopy images show that CeSiO particles are spherical with a uniform size distribution in the range of 30-50nm and contain some inner pores with sizes up to a few nanometers. Specifically, CeSiO-700 calcined at 700 °C shows the biggest surface area, the smallest pore size and the highest hydrophilicity, which makes the CeSiO/polysulfone composite membranes (8.0wt %) exhibit the strongest mechanical strength (3.223MPa), which is enhanced by more than 100% in comparison with the pure polymer membrane