Synthesis and characterization of spherical silica nanoparticles by modified Stöber process assisted by organic ligand

• A modified Stöber process for synthesis of spherical silica nanoparticles.
• Choosing Schiff base ligand as novel additive for synthesis spherical SiO2.
• Spherical silica nanoparticles were synthesized by sonochemical method.
• Investigation of ultrasonic power, irradiation time on morphology of products.

Spherical silica nanoparticles were synthesized via a sonochemical method based on modified Stöber process the reaction between TEOS (tetraethyl orthosilicate), methanol and ethylenediamine (en) in water, in the presence of organic Schiff base ligand (Salpn-NO2). The effects of preparation parameters such as: ultrasonic power, ultrasonic irradiation time and molar ratio of organic Schiff base ligand to TEOS were investigated to reach the optimum conditions. It was found that morphology, particle size and phase of the products could be affected by these parameters. The results exhibited that optimum conditions were 15 min, 60 W power and 1/10 M ratio. The as synthesized spherical silica nanoparticles were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible (UV–Vis) spectroscopy, and X-ray energy dispersive spectroscopy (EDS).