Preparation and antibacterial activity of mesoporous silica based on rice husk ash

Rice husk ash (RHA) is a widely discarded agricultural by-product, leading to environmental and health concerns due to its low density. In this study, we employed a hydrothermal reaction coupled with univariate and multi-parameter response surface method optimization to extract silicon, the key component, and prepare mesoporous silica (mSiO2) from RHA. Furthermore, silver nanoparticles (Ag-NPs) were synthesized in situ in the pores of mSiO2 to prepare mSiO2@Ag nanocomposites. The morphology, structure and composition of the prepared mSiO2@Ag were characterized using TEM, FT-IR, UV–Vis and XRD. To evaluate their antibacterial properties, Staphylococcus aureus and Escherichia coli were employed as model strains. The results revealed that the average particle size of the prepared mSiO2 and mSiO2@Ag nanocomposites were 98 nm (PDI = 0.023) and 278 nm (PDI = 0.062), respectively. The FT-IR and XRD analysis confirmed the presence of SiO2, Ag, and Ag2O characteristic peaks. The specific surface area and pore diameter of the mSiO2 were measured as 305 m2/g and 4 nm, respectively, whereas those of the mSiO2@Ag were significantly reduced. Remarkably, the mSiO2@Ag exhibited notable antibacterial activity, with MIC of 150 μg/mL and 200 μg/mL against S. aureus and E. coli, respectively. This research provides a novel avenue for the high-value utilization of RHA.