Controllable synthesis of bismuth tungstate photocatalysts with different morphologies for degradation of antibiotics under visible-light irradiation

The bismuth tungstate with different morphologies was controllably synthesized by simple hydrothermal synthesis under different pH and different hydrothermal reaction time (HRT). Under the influence of these two conditions, the results show that with the increase of pH, the sample gradually changed from orthogonal phase Bi₂WO₆ to cubic Bi_3.84W_0.16O_6.24 and the morphology changed from lamellas composed of nanorods to octahedral particles, as well as the photo-catalytic activity of Bi_3.84W_0.16O_6.24 was far less than that of Bi₂WO₆. Additionally, with the increase of HRT, the thickness of flaky Bi₂WO₆ is thinner, the crystallinity is more stable, and the direction of growth is changed from lamellar to flower buds. The photo-catalytic activity of lamellar BWO-8/BWO-T-10 (prepared in lower pH and lower HRT) is the best. After radiation of 2 h, the degradation efficiency of tetracycline is 85% and the kinetic reaction rate constant is 0.0135 min⁻¹. After three cycles of reusing, it still maintains high stability. The catalytic mechanism analysis shows that the active particle^.OH produced by the photoelectron hole to the reaction has strong oxidizing property, which can quickly decompose tetracycline.