Synthesis and characterization of amorphous nano silica from South African coal fly ash

Abstract

In this study, amorphous silica nanoparticle was extracted from South African coal fly ash (SACFA), using a facile sol–gel synthesis method. Prepared amorphous silica nanoparticles (ASNPs) were characterized employing X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transition electron microscope (TEM), Brauer Emmett Teller (SBET) surface area analysis, and ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS). XRF analysis suggests SACFA as fly ash class F. the XRD pattern, reveals the structural compositing of SACFA and the amorphous nature of extracted SNP, while the FTIR assay shows the presence of silanol and siloxane groups. SEM and TEM analysis revealed primary silica nanoparticles were roughly spherical with sizes of about 98 nm. EDX spectral confirms the presence of SiO2. The findings of this study demonstrate a simple sol–gel method of synthesizing amorphous nano silica from SACFA, thus suggesting the utilization of SACFA in high-tech and complex material preparation and applications in a more inventive manner.