Abstract:

Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi₂SiO₅ species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and N₂ adsorption/desorption techniques. EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi₂SiO₅, which is substantiated by XRD. The UV–Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica. FTIR spectra illustrate the formation of Bi–O–Si linkages in the porous silica framework. SEM and TEM show the spherical morphology, whereas N₂ adsorption/desorption study confirms the porosity of the prepared materials. The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa TiO₂.

Key words: Acrylic emulsion, Emulsion polymerization technique, Porous silica, Bi2SiO5, Photocatalytic degradation, Isoproturon