Co₃O₄ confined in activated carbon-supported Mg/Al-LDH for µM peroxymonosulfate activation with minute-level antibiotics degradation

Herein, an efficient and stable catalyst of Co₃O₄@LDH-AC was innovatively prepared through uniform loading of an activated carbon substrate with Mg/Al layered double hydroxide (Mg/Al-LDH) followed by dispersing Co₃O₄ nanoparticles in the confined space of LDH. This unique flower-like spherical structure significantly improved the adsorption capacity and would increase the concentration of reactants in the confined space. Experimental results showed that levofloxacin (LFX) completely degraded in 4 min with the addition of µM peroxymonosulfate (PMS). The fast conversion of Co²⁺ and Co³⁺ in catalyst for the generation of highly reactive species is revealed via EPR, in-situ Raman, in-situ FT-IR, and XPS. Further tests of 5Co₃O₄@LDH-AC in effluent of hospital wastewater treatment showed that it not only possessed strong anti-interference capabilities, but also maintained stable catalytic activity in fixed-bed reactor for a long operation time. Therefore, the excellent catalytic performance in confined space offers the possibility of application for the degradation of micropollutants in real pharmaceutical wastewater discharged from hospital (800–1200 tons/day, COD > 150 mg/L).