Influence of Synthesis Parameters in the Preparation of Silicon (IV) Oxide Nanoparticles from Dealuminated Metakaolin and Metakaolin with Na2SiO3

Abstract

SiO2 nanoparticle is a versatile material with diverse technological applications. However, the cost associated with the production from chemical and biological source is high and the quantity or yield produced is often small which cannot adequately meet the increasing demands of the population. Thus, there is need to prepare SiO2 nanoparticle from readily available material like kaolin. In this research work, SiO2 nanoparticles was synthesized from dealuminated metakaolin and metakaolin with Na2SiO3at different solution pH (5, 8 and 10), concentration of NaOH (0.5 M, 1 M and 2 M), calcination temperatures (600ºC, 700ºC and 800ºC). The prepared SiO2 nanoparticles was characterized by X-ray Diffraction (XRD), High Resolution Scanning Electron Microscope (HRSEM), and Energy Dispersive Spectroscopy (EDS). The XRD analysis demonstrated that SiO2 nanoparticle produced at calcination temperatures of 600ºC and 800ºC from dealuminated metakaolin and metakaolin with Na2SiO3 at 700ºC and 800ºC were highly and purely crystalline. While the optimum concentration of NaOH and pH to prepare pure SiO2nanoparticles from dealuminated metakaolin was 0.5 M and pH 8 respectively. The HRSEM analysis revealed morphological transformation from slate to rod-like, compacted trigonal to spherical structures depending on the applied synthesis conditions. EDS analysis revealed high amount of Si and O at the optimum synthesis conditions for both metakaolin with Na2SiO3 and dealuminated metakaolin except for SiO2 nanoparticles prepared at other conditions which contained impurities. Of all the two sources considered, the study demonstrated that highly crystalline and pure SiO2 nanoparticle could be synthesized from dealuminated metakaolin via hydrothermal route.