Precipitation of amorphous SiO2 particles and their properties

TLDR

The synthesis of amorphous SiO₂ particles was optimized by neutralizing sodium silicate with H₂SO₄, and the resulting particles were characterized by XRD, FT‑IR, FE‑SEM, EDS, and microelectrophoresis. XRD showed an amorphous peak at 2θ = 21.8°, primary particles were 15–30 nm and aggregated into larger particles, the specific surface area reached up to 130 m² g⁻¹, EDS revealed no sulfate or other ion contamination, and microelectrophoresis yielded a pHzpc of 1.7.

Abstract

The experimental conditions were optimized for the synthesis of amorphous SiO2 particles by the reaction of neutralization of sodium silicate solution with H2SO4 solution. Amorphous SiO2 particles were characterized by XRD, FT-IR, FE-SEM, EDS and microelectrophoresis. The amorphous peak was located at 2θ = 21.8º in the XRD pattern. Primary SiO2 particles were ~ 15 to ~ 30 nm in size and they aggregated into bigger particles. Amorphous SiO2 particles showed a specific surface area up to 130 m²g-1, dependent on the parameters of the precipitation process. The EDS spectrum of amorphous SiO2 particles did not show contamination with sulfate or other ions, which cannot be excluded in traces. pHzpc =1.7 was obtained by microelectrophoresis.