Photocatalytic degradation of dyes by AgBr/Ag_3PO_4 and the ecotoxicities of their degraded products
Pongsaton Amornpitoksuk;Sumetha Suwanboon;Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University;Center of Excellence in Nanotechnology for Energy (CENE), Prince of Songkla University;Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University;
Ag_3PO_4 powders were prepared through a precipitation reaction between AgNO_3 and precipitating agent solutions that were prepared by adjusting the amount of H_3PO_4 in the Na_3PO_4 solutions. The Ag_3PO_4 powders prepared from the precipitation solution with a pH of 6 showed the highest photocatalytic activity for decolorizing the methylene blue and rhodamine B dyes. These Ag_3PO_4 powders were further modified by the addition of KBr solutions to obtain AgBr/Ag_3PO_4 powders and these photocatalysts can decolorize the anionic dyes as reactive orange and methyl orange. The reactive species involved in the photocatalytic degradation process were evaluated for their inhibitory activity using the appropriate scavengers. After photocatalysis, mass spectrometry confirmed that the dyes were degraded to smaller molecules. The ecotoxicities of the dye solutions before and after treatment were evaluated by studying their ability to inhibit the growth of the bioindicator Chlorella vulgaris.