Simultaneous degradation of non-emissive and emissive dyes on visible light illuminated TiO2 surface

Simultaneous photocatalytic degradation of non-emissive dye, acid blue1 (AB1) and emissive dyes (eosinY or thionine) in air-equilibrated aqueous suspension of TiO2 semiconductor photocatalyst has been achieved at ambient conditions. Under visible light irradiation AB I undergoes appreciable degradation in presence of a sensitizing dye (eosinY or thionine). However, concomitant decoloration of eosinY (EY) or thionine (Th) due to self-sensitized degradation was also noticed. Mechanistic proposals for the photocatalytic degradation of AB1 using a 150 W Xe lamp with a UV-filter (lambda > 420 nm) as well as without a UV-filter, are discussed. Formation of reactive O-center dot(2)-/(HO2)-H-center dot radicals is proposed to be responsible for the degradation of the selected dyes, AB1, EY and Th. (c) 2006 Elsevier B.V. All rights reserved.