Role of vanadia and titania phases in the removal of methylene blue by adsorption and photocatalytic degradation

Abstract

Total removal of methylene blue (MB) over vanadia (V2O5)-modified titania (TiO2) composite demonstrated that the V2O5 and TiO2 phases played a vital role in the adsorption and photodegradation of MB, respectively. The 10 mol% of V2O5-modified TiO2 (10V-TiO2) showed the highest removal of MB, i.e., 26-and 2-folds better adsorption capacity than that of undoped TiO2 and V2O5, respectively. The presence of surface hydroxyl, pores, and the highest amount of V5+ species in 10V-TiO2 could be responsible for the high adsorption of MB. V2O5 induced anatase to rutile phase transformation and shifted absorption properties of TiO2 to the visible light region. Considering the rutile phase has lower bandgap energy (3.0 eV), its presence in the sample has enhanced the photodegradation of MB. The photodegradation of MB followed pseudo-second-order reaction. The reusability test elucidated that the photodegradation performance of 10V-TiO2 was improved by 30-folds after the second cycle, with total MB removal due to the exposure of more TiO2 to MB.