Efficient sonochemical catalytic degradation of tetracycline using TiO2 fractured nanoshells
Zhiyuan Zong, Emma Gilbert, Cherie Wong, Lillian N. Usadi, Yi Qin, Yihao Huang, Jason L. Raymond, Nick Hankins, James Kwan
Abstract
• TiO 2 fractured nanoshells combined with cylindrically converging ultrasound waves were used for water decontamination. • Complete removal (100 %) of 5 ppm aqueous tetracycline was achieved within six minutes. • Moderate acoustic pressure amplitude (10.6 MPa, peak to peak) and low power input (21 W) exhibited optimal energy efficiency. • The reported process achieved the lowest energy consumption and CO 2 emission when compared to other sono/photo-based AOPs. Overexposure to antibiotics originating in wastewater has profound environmental and health implications. Conventional treatment methods are not fully effective in removing certain antibiotics, such as the commonly used antibiotic, tetracycline, leading to its accumulation in water catchments. Alternative antibiotic removal strategies are garnering attention, including sonocatalytic oxidative processes. In this work, we investigated the degradation of tetracycline using a combination of TiO 2 fractured nanoshells (TFNs) and an advanced sonochemical reactor design. The study encompassed an examination of multiple process parameters to understand their effects on the degradation of tetracycline. These included tetracycline adsorption on TFNs, reaction time, initial tetracycline concentration, solvent pH, acoustic pressure amplitude, number of acoustic cycles, catalyst dosage, TFNs' reusability, and the impact of adjuvants such as light and H 2 O 2 . Though TFNs adsorbed tetracycline, the addition of ultrasound was able to degrade tetracycline completely (with 100% degradation) within six minutes. Under the optimal operating conditions, the proposed sonocatalytic system consumed 80% less energy compared to the values reported in recently published sonocatalytic research. It also had the lowest CO 2 footprint when compared to the other sono-/photo-based technologies. This study suggests that optimizing the reaction system and operating the reaction under low power and at a lower duty cycle are effective in achieving efficient cavitation for sonocatalytic reactions.