Flower-like CoFe-LDH Activated Peroxymonosulfate for Tetracycline Degradation: Efficiency and Mechanism

The overuse of antibiotics has led to their widespread environmental residues, posing a significant threat to the ecological environment. In this study, a flower-like spherical CoFe-layered double hydroxide (CoFe-LDH) catalyst was prepared using a hydrothermal method. The degradation performance of the CoFe-LDH/peroxymonosulfate (PMS) system was systematically investigated using tetracycline (TC) as a model pollutant. The CoFe-LDH exhibited a three-dimensional nanoflower-like spherical structure formed by interlaced nanosheets, featuring smooth surfaces and well-defined edges. This hierarchical porous structure facilitates the exposure of active sites. The CoFe-LDH/PMS system demonstrated remarkable degradation efficiency, achieving over 90.17% TC removal within 10 min. As the dosage of CoFe-LDH and PMS increases, the degradation rate of TC improves significantly, but the marginal improvement effect decreases. TC degradation efficiency increased with pH up to an optimum at pH 5.0, beyond which it declined. The anions—Cl−, NO3−, and SO42−—all exhibited inhibitory effects on TC degradation; the TC removal rates decreased to 77.88%, 80.58%, and 82.78%, respectively. The removal experiments of different organic pollutants, such as oxytetracycline (88.91%), methylene blue (98.36%), and ciprofloxacin (84.52%), as well as actual water experiments, such as lake water (92.48%) and tap water (80.86%), have demonstrated the good universality of the CoFe-LDH/PMS system. Radical quenching experiments confirmed that •OH and SO4•− were the dominant reactive species.