Enhanced photoactivity and anatase thermal stability of silica-alumina mixed oxide additives on sot-gel nanocrystalline titania

Nanocrystalline titania with silica and silica-alumina mixed oxide as additives has been prepared through a sequential approach sot-gel method starting from titanyl sulphate in aqueous medium. The mixed oxide added titania shows increased anatase phase stability and high surface area. The complete transformation of anatase to rutile in the mixed oxide added titania occurs only above 1100 degrees C. The silica and silica-alumina added titania precursor even after calcination at 800 degrees C show specific surface area of 53 m(2) g(-1) and 63 m(2) g(-1) respectively. Further, the mixed oxide added titania sample shows excellent photoactivity compared to the commercially available Hombikat UV 100 titania, with respect to degradation of methylene blue. The addition of mixed oxide has resulted in better properties with respect to specific surface area, increased anatase to rutile phase transformation and photocatalytic activity of titania. (c) 2006 Elsevier B.V. All rights reserved.