Near-UV-VIS light induced acid orange 7 bleaching in the presence of SiW12O404- catalyst

The azo dye acid orange 7 (AO7) was decolourized by SiW12O405-, the one-electron photo-chemically reduced form of SiW12O404- catalyst, in aqueous solutions of aerated and de-aerated sacrificial electron donor isopropanol. Under our experimental conditions, the AO7 decay rate depended upon the competition between the azo dye and molecular oxygen for SiW12O405-. The colour removal rate constant was found as 5.2 x 10(4) M-1 s(-1) by applying AO7-O-2 competition kinetics based on a simple kinetic reaction scheme. (C) 2002 Elsevier Science B.V. All rights reserved.