Degradation pathways and efficiencies of acid blue 1 by photocatalytic reaction with ZnO nanopowder

The ZnO-mediated photocatalysis process has been successfully applied to degradation of Acid Blue 1 (AB 1) dye pollutants. To obtain a better understanding, the mechanistic details of this ZnO-assisted photodegradation of the AB1 dye with low Watt UV irradiation, a large number of the photodegradation intermediates were separated, identified, and characterized by the HPLC-PDA-ESI-MS and GC-MS techniques. The degradation progresses through competitive reactions such as N-de-ethylation, destruction of the conjugated structure, hydroxylation on the benzene ring, hydroxylation on sulfonylated benzene ring, and substitution. The probable photodegradation pathways were proposed and discussed.