Degradation of microcystin-LR by highly efficient AgBr/Ag₃PO₄/TiO₂ heterojunction photocatalyst under simulated solar light irradiation

Highlights: • AgBr/Ag₃PO₄/TiO₂ consisting of less silver content possessed much higher photocatalytic activity than AgBr/Ag₃PO₄. • Reactive h⁺ and • OH played the major roles for MC-LR degradation by AgBr/Ag₃PO₄/TiO₂. • AgBr/Ag₃PO₄/TiO₂ photocatalyst was more stable than AgBr/Ag₃PO₄ in successive runs. • MC-LR was degraded into intermediates of smaller molecule weight (m/z < 770) by AgBr/Ag₃PO₄/TiO_2. - Abstract: A novel photocatalyst AgBr/Ag₃PO₄/TiO₂ was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO₂ (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag₃PO₄ under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag₃PO₄/TiO₂ was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag₃PO₄. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag₃PO₄ in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag₃PO₄. The quenching effects of different scavengers proved that reactive h⁺ and • OH played important roles for MC-LR degradation