Subrahmanyam Machiraju

Photocatalytic activity of Ce-modified SBA-15 for the degradation of isoproturon

Cerium (Ce)-modified SBA-15 and Al-grafted SBA-15 are prepared and compared their photocatalytic activity for isoproturon degradation. The Al-SBA-15 is prepared by postsynthetic grafting method and cerium-modified samples are prepared by the impregnation technique. All the samples are characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and N 2 adsorption/desorption analysis. The samples show well-ordered mesoporous structure and it is confirmed by XRD. The UV–vis DRS of Ce-modified sample shows a red shift compared to SBA-15 and the cerium species are stabilized in + 3 oxidation state at lower cerium contents. The presence of Ce3+ species is also substantiated by XPS analysis. The higher amount of Ce3+ species are accompanied by oxygen vacancies which are formed due to the contact of ceria with the support. The N2 adsorption/desorption analysis of the samples show type-IV isotherms characteristic of mesoporous materials. Photocatalytic activity evaluation studies are made on all the samples for the degradation of isoproturon. Among them, 0.3 (wt%) Ce-modified Al-SBA-15 catalyst has shown a maximum activity in comparison with Ce-modified SBA-15. The better activity is attributed to the synergistic effect of mesoporosity and the presence of Ce3+ species along with oxygen vacancies.