Degradation Of Tetracyclines Via The Pulse Electro-catalysis Oxidation

As a typical of environmental contamination, tetracyclines lead to chronic toxicity, drugresistance and even seriously damage ecological and human health. due to its high efficiency,low energy consumption, no pollution and easy operation, the pulse electro-catalysis oxidationtechnology has received extensive attention. To date, all of the previous reports adopted voltageconstant current power supply in electro-catalysis oxidation. Thereby, the present work focusedon the application of μs-grade low-voltage pulse power supply in electro-catalysis oxidationtreatment of oxytetracycline （OTC） and chlortetracycline（CTC）. Additionly, the influencefactors and mechanism of degradation were investigated. This work would provide new ideasfor the practical application of removal of antibiotics in water environment.By using the electro-catalysis oxidation technology which using μs-grade low-voltagepulse power supply, the factors of electrolyte, electrolysis time, electrolyte concentration,solution pH, voltage and frequency were investigated for their impact on removal efficiency ofOTC and CTC using Ti/RuO₂-IrO₂-SnO₂electrode and HPLC as detection method. The resultsshowed that low-voltage pulse electrolysis had a very good treatment effect to OTC and CTC inwater, and the degradation efficiency of OTC and CTC reached98.94%and98.61%asmaximum after2minutes’ reaction. At the same time, the experimental results showed thatNaCl had done a better job on accelerating the reaction than Na2SO4as a catalyst, and to select amedium voltage value would improve removal efficiency and save construction costs. Theinitial pH and pulse frequency had little effect on the removal of OTC and CTC, but greatlyinfluenced the equipment service life and the final degradation products. The optimumelectrodeposit conditions when initial concentration of OTC or CTC is20mg/L are as follows:pulse frequency is6.0kHz, voltage is15V, concentration of NaCl is3g/L, pH value is3.In order to explore the mechanism of degradation, the samples were analysed by LC-MS.And the results indicated that in the electrolysis system OTC has undergone not onlyisomerization, dehydration and hydrogenation in turn, in which OTC was degraded toα-Apo-oxytetracycline, β-Apo-oxytetracycline, but also hydration reaction. And for CTC, it hashas undergone isomerization, dechlorination, dehydration, demethylation and to take offdimethylamino reaction.