Fabrication of ZnO/SiO2 and SiO2/α-Zn2SiO4 composites with dye adsorption and antimicrobial properties

Abstract

Zinc-silicon oxide composites were fabricated using direct precipitation. Sodium silicate isolated from rice husk ash and commercial zinc nitrate were used as starting materials. The as-prepared Zn-Si oxide composites were then subjected to two separate treatments: one without calcination (as-prepared sample, APS) and another with calcination at 1000°C (calcined sample, CS). The obtained samples were characterized using TGA-DSC, XRD, FT-IR, UV-DRS, PL spectroscopy, TEM and FESEM. The electron microscopy analysis confirmed that APS is in the form of ZnO/SiO2 with pseudo-amorphous particle shape, whereas CS consists of SiO2/α-Zn2SiO4 structure having interconnected fused-like particles with improved crystallinity. These results were in good agreement with XRD and FT-IR data. Additionally, the enhanced crystallinity of the CS led to a decrease in the absorption intensity of UV-DRS and an increase in its PL intensity. Activity studies revealed that the APS demonstrated better adsorption efficiency for Congo red removal but lesser antibacterial efficacy than the CS. It has been suggested that the surface and particle architectures of both APS and CS govern their activity performance.

Keywords

• zn-si oxide composite
• rice husk ash
• precipitation
• structural characterization
• optical properties