Electrochemical Oxidation Mechanism of Tetracycline in Various Supporting Electrolytes Based on a Boron‐Doped Diamond Anode

The active free radical species vary with supporting electrolyte during electrochemical advanced oxidation processes, thus, resulting into the significant difference in removal rate and degradation pathways of organic compounds. Herein, the electrochemical oxidation behavior of tetracycline (TC) is studied based on the boron‐doped diamond anode in Na₂SO₄, NaCl, and NaNO₃ systems. It is revealed that the and ClO⁻ initialize the oxidation reaction of TC followed by the gradual degradation through ^•OH. Notably, the enhanced lifetime of ClO⁻ compared to ensures a more effective and prolonged degradation of TC. Thus, the TC removal rate in the NaCl system is remarkably larger than that in the Na₂SO₄ and NaNO₃ systems. Despite different degradation pathways across each system, consistent oxidation mechanism is identified: initial hydroxylation occurs at arbitrary positions on TC followed by the further oxidation of the hydroxyl group to form aldehyde or ketone. Ketones undergo direct oxidation to facilitate ring‐opening reaction; whereas aldehydes are further oxidized to form carboxylic acid and eventually transform into H₂O and CO₂. This work sheds deep insights into the oxidation mechanism of organic compounds across various supporting electrolytes, which benefits the efficient degradation of TC in practical applications.