Degradation and Detoxicity of Tetracycline by an Enhanced Sonolysis

Abstract

Tetracycline is named by its four special benzene rings in molecular structure, which has been proven as a strong inhibition chemical for many kinds of bacterial. To solve the problem of residual tetracycline containing in municipal and medicine industrial wastewater effluents, this study tried to combine the ultrasound with transition metals (including Co²⁺, Ag⁺ and Fe²⁺) and oxidizing agents (persulphate ions, S₂O₈^2- and hydrogen peroxide, H₂O₂) with a continuous dosing mode as an innovative "Enhanced sonolysis" for degrading the tetracycline. Experimental results indicated that the addition of Fe²⁺ and H₂O₂ with ultrasound showed the better performance than other combinations by Co²⁺, Ag⁺ and S₂O₈^2-. As the ultrasound coupled with 0.2 mM Fe²⁺ and 2 mM H₂O₂, more than 90.7% and 45.9% of tetracycline were degraded and mineralized. In addition, the toxicity was significantly reduced while the cell viability increased from 53.1% (un-treated) to 87.5% (treated). Effect of pH on the degradation of tetracycline in this study was insignificant but pH 3 showed the better efficiency. It was concluded that the enhanced sonolysis was effective on the degradation, mineralization and detoxicity of tetracycline solution.