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 Ag2O 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 Ag2O and azo species. The intermediates of the photodegradation of the azo species over Ag2O 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.