Self-Excited Oscillating Cavitation Jet Combined with Fenton’s Reagent for Tetracycline Degradation in Water: Optimization of Geometric Structure and Operating Parameters

Abstract

This study utilizes a novel self-excited oscillatory hydrodynamic cavitation (HC) device for tetracycline degradation. The effects of key parameters, including cavity length, inlet-to-outlet diameter ratio, and operational conditions (inlet pressure of 0.3–0.8 MPa), as well as the initial tetracycline concentration (5.0–20.0 mg/L) and the addition of common inorganic anions, on tetracycline degradation are systematically explored. The results show that the self-excited oscillating hydrodynamic cavitator, with a cavity length of 23.0 mm and an inlet-to-outlet diameter ratio of 0.75 (inlet diameter: 3.0 mm; outlet diameter: 4.0 mm), generates a strong HC effect. Under an inlet pressure of 0.5 MPa and an initial tetracycline concentration of 10.0 mg/L, the degradation rate reaches 51.32 ± 0.56%. The three common inorganic anions, CO32−, NO3−, and SO42−, all inhibit tetracycline degradation. The addition of Fenton’s reagent further enhances the degradation efficiency of tetracycline via hydrodynamic cavitation. The optimal molar ratio of Fenton’s reagent (TC:Fe2+:H2O2 = 1:1:10) is determined, resulting in a tetracycline degradation rate of 85.91 ± 0.29% after 120 min of reaction. The self-excited oscillatory hydrodynamic cavitator proposed in this study offers a simple structure, high reliability, and improved degradation efficiency, providing a novel approach to antibiotic treatment.