Cr-doped BiYO 3 photocatalyst for degradation of oxytetracycline under visible light irradiation

Chromium-doped BiYO 3 powders were synthesized by the Pechini method at low temperature between 400 and 800 °C for 1 h. From the XRD results it was observed the coexistence between tetragonal and cubic phases for samples calcined at 400 °C for 1 h. Meanwhile, for samples calcined at 600 and 800 °C, a single cubic phase was observed. The powders consisted of agglomerates of nanocrystals as shown in the SEM and TEM images. The specific surface area was in the order of 3.01–7.74 m 2 g −1 , obtained from BET analysis. The band gap of BiYO 3 and Cr-doped BiYO 3 was < 2.21 eV which corroborates that these materials absorb light in the visible region of the electromagnetic spectrum. The photocatalytic decomposition of oxytetracycline was successfully achieved using Cr-doped BiYO 3 , where the best performance was obtained with BiY 0.98 Cr 0.02 O 3 ceramic powders calcined at 800 °C for 1 h. For this composition the removal of oxytetracycline after 240 min of visible light irradiation was 100% of degradation and 75% of mineralization. The photocatalytic process was driven by the photo-holes, as a negligible production of · OH radicals was observed in tests using scavengers. The photocatalytic activity of the BiY 0.995 Cr 0.005 O 3 and BiY 0.98 Cr 0.02 O 3 materials was corroborated under more realistic conditions, using tap water and trace concentration of the antibiotic. The high stability of the photocatalyst was observed through four consecutive reaction cycles. The results demonstrate that the Cr-doping has clearly improved the catalytic performance of BiYO 3 for degradation of oxytetracycline under visible light irradiation.