Visible-light-driven photocatalytic degradation of non-azo dyes over Ag2O and its acceleration by the addition of an azo dye

In this study, we reveal that the photodegradation of non-azo dyes using Ag 2 O as a visible-light-driven photocatalyst is accelerated by the addition of an azo dye. Upon addition of methyl orange, the time taken for the photodegradation of Rhodamine B and methylene blue was significantly shortened from 50 to 18 min and from 20 to 8 min, respectively. This acceleration is not sensitive to the type of azo dye and solution pH. The results indicate that this acceleration can be ascribed to the synergistic effect of the Ag 2 O and azo species. The intermediates of the photodegradation of the azo species over Ag 2 O have aniline-, sulfanilic-acid-, and phenol-type structures, and these species promote the photodecomposition of the non-azo organics. This acceleration has promising applications in dye wastewater photodegradation treatment.