Photocatalytic performance of Ag/AgBr modified TiO2: critical impacts and wastewater sample study

To improve the visible-light photocatalytic performance of TiO2 for practical application, Ag/AgBr modified TiO2 was fabricated in ionic liquid-water medium via a facile hydrothermal-reduction method. The visible-light catalytic activity of as-prepared Ag/AgBr/TiO2 was measured using tetracycline (TC) as the target pollutant. Characterizations by various techniques (SEM-EDS, XRD, XPS and DRS) and the quenching experiments with scavengers for possible active species (h(+), O-center dot(2)- and center dot OH) were executed to probe the mechanism underlying the photocatalytic performance. Critical impacts from the catalyst and solution chemistry were evaluated in the mediums of TC solution, simulated wastewater and real wastewater sample. The results suggested that: (1) benefitting from the visible-light sensitive Ag/AgBr and high specific surface area TiO2, Ag/AgBr/TiO2 exhibits fair stability and remarkable visible-light photocatalytic activity; (2) under optimized conditions, Ag/AgBr/TiO2 provides higher visible-light catalytic activity than Ag/AgBr and TiO2; (3) the coexisting inorganic ions with high concentration in the simulated wastewater sample depress TC photo-degradation, and the impacts varies with the species of inorganic ions; (4) COD removal rate about 65.5% in real wastewater sample proves that Ag/AgBr/TiO2 can mineralize TC promptly and almost completely.