Preparation and characterization of nano SiO2@CeO2 extracted from blast furnace slag and uranium extraction waste for wastewater treatment

Abstract

Nowadays, ceramic oxides such as SiO2, CeO2 and their hybrid SiO2@CeO2 are considered as interesting materials for many applications. In the present work, SiO2 nanoparticles (NPs) were extracted from blast furnace slag (waste material derived from iron industry) by chemical method. On the other hand, CeO2 NPs were also extracted from radioactive nitrate solution waste using tris(2-ethylhexyl) phosphate solvent (TEHP). A simple precipitation and calcination method was used to prepare silica functionalized by ceria i.e. SiO2@CeO2 core-shell nanoparticles. In order to examine phase composition, structural characteristics, morphological, surface area and physical properties, the prepared NPs were characterized by various techniques. These techniques were XRF, XRD, Raman spectroscopy, Nitrogen adsorption–desorption isotherms, DLS, TEM, and Zeta potential. The activity of prepared SiO2 and hybrid SiO2@CeO2 materials towards the adsorption and photocatalytic degradation of methylene blue dye (MB) was investigated in absence (dark) or presence of UV–visible light. The results revealed that CeO2, SiO2 and SiO2@CeO2 nanoparticles having high surface area, high pore volume and small particle sizes were successfully prepared using the aforementioned waste materials. SiO2 NPs exhibited higher absorption capacity for MB in dark due to its higher negative surface charge as indicated by its zeta potential result. On the other hand, enhanced photocatalytic activity was obtained after coating CeO2 on SiO2 nanoparticles as compared with that of single SiO2. The overall adsorption efficiencies for MB in dark followed by UV light using SiO2 and SiO2@CeO2 were 94% and 99.1%, respectively. The kinetic studies indicated that the reaction proceeded as a pseudo-second order reaction.