Tetracycline hydrochloride degradation by activation of peroxymonosulfate with lanthanum copper Ruddlesden-Popper perovskite oxide: Performance and mechanism

ABO(3)-type perovskite oxides have been regarded as a kind of potential catalyst for peroxymonosulfate (PMS) activation. But some limitations such as specific pH conditions and coexisting ion interference restrict its practical application. Herein, a lanthanum copper Ruddlesden-Popper perovskite oxide (La2CuO4) was successfully synthesized through the sol-gel process and applied in the activation of PMS. And for the first time the La2CuO4/PMS system was used for tetracycline hydrochloride (TC-HCl) degradation. Results showed that La2CuO4 was a potential PMS activation catalyst in the removal of antibiotics. At optimized condition (0.2 g/L catalysts, 1 mM PMS, pH(0) 6.9), 96.05% of TC-HCl was removed in 30 min. In experiments of debugging control conditions, over a wide pH range of 3-11, more than 90% of TC-HCl can be removed. In the natural water treatment process, TC-HCl removal rates of about 84.2% and 70.3% were obtained in tap water and River water, respectively. According to the reusability and stability tests and the results of FTIR and XPS analysis, La2CuO4 had high structural and chemical stability. Electron paramagnetic resonance (EPR) suggested that the active species including center dot OH, SO4-center dot and O-1(2) were detected in degradation reaction. Finally, reasonable reaction mechanisms and possible degradation pathways of TC-HCl were proposed. These results indicate that La2CuO4 can act as a potential catalyst for PMS activation to degrade TC-HCl in water.