Kinetics of the Biacetyl-sensitised Photo-oxidation of C.I. Acid Orange 7

A kinetic model for the biacetyl-sensitised photo-oxidation of C.I. Acid Orange 7 in aqueous solution during continuous irradiation at 365 nm is presented. Biacetyl was taken as a model for naturally occurring carbonyl species in polymers such as oxidised cellulose and lignin involved in photosensitised degradation of azo species. Quenching of triplet biacetyl by the dye and by oxidation products as well as quenching of singlet oxygen by water and by oxidation products was accounted for. The equations derived from the model describe the relationship between the measured quantum yield of dye fading and dye concentration. Reaction rate parameters were calculated by a nonlinear least squares method, and were in accordance with literature values and values measured by flash photolysis