Highly Efficient Ultrasound-Driven Ti³⁺-Doped TiO₂ with Oxygen Vacancies: A Promising Visible-Light Catalyst for Complete Sonophotocatalytic Degradation of Tetracycline

Tetracycline (TC), a widely prescribed antibiotic to treat bacterial infections in humans and animals, poses a substantial threat to the environment due to its extensive use. To address this issue, a TiO2-based photocatalyst was employed for the effective sonophotocatalytic degradation of TC. The ultrasound-driven TiO2 synthesis induced oxygen vacancies and Ti3+ species, enhancing the sonophotocatalytic efficiency. The formation of Ti3+ and oxygen vacancies was confirmed by using various analytical techniques. The synthesized TiO2 with ultrasound (TiO2 US) demonstrates remarkable TC degradation under halogen lamp irradiation, achieving an efficiency of ∼96%, 1.56 times higher than that of TiO2 synthesized without ultrasound (TiO2 WUS). Under diffuse sunlight, TiO2 US and TiO2 WUS exhibit degradation efficiencies of 95 and 79%, respectively. Notably, TiO2 US effectively degraded the hospital effluent, achieving 83% degradation efficiency. This nanophotocatalyst displays appreciable reusability and stability, offering a promising solution for efficiently degrading persistent emerging contaminants.