Degradation of Tetracycline through peroxymonosulfate activation with Co/Fe-LDH modified magnetic hydrochar: Synergistic effect and low toxicity

In this work, 2LDH-CoFe2O4@BHC catalyst was prepared by modifying magnetic corncob-based hydrochar (CoFe2O4@BHC) with Co/Fe layered double hydroxide (Co/Fe-LDH), which was used to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. 2LDH-CoFe2O4@BHC demonstrated effective activation of PMS and rapid removal of TC (100 %) within 10 min by leveraging structural modulation and synergistic interactions among multiple components. In contrast, BHC (26.02 %), CoFe2O4 (59.25 %), and CoFe2O4@BHC (61.88 %) presented poor removal efficiency. Furthermore, it was shown that both the free radicals (SO4•-) and non-free radicals (1O2) were essential in the degradation process, and the catalytic mechanism was revealed to be a synergistic process with the characterization results from in-situ Raman, electrochemical characterization, and X-ray photoelectron spectroscopy (XPS). The catalytic performance of 2LDH-CoFe2O4@BHC was also evaluated using a self-developed fixed-bed reactor, demonstrating its strong stability and resistance to interference during long-term operation. The potential degradation pathway of TC in the 2LDH-CoFe2O4@BHC + PMS system was suggested based on the quadrupole time-of-flight mass spectrometry (QTOF/MS) findings. It was found that the toxicity of the intermediates produced by TC degradation significantly reduced. This study presented an insight for the decomposition of organic pollutants by synthetic biochar-loaded catalysts.