Polyethersulfone membrane assembled with CoFe-layered double hydroxide nanosheets for antibiotic removal via nanoconfined catalysis

Developing an effective catalytic system to remove antibiotics released from anthropogenic activities is urgently needed, as they pose significant risks to both ecosystems and human health. This study has investigated the potential of integrating CoFe-layered double hydroxide (LDH) nanocatalysts onto polyethersulfone (PES) membranes in order to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. Under the optimal conditions, near-neutral pH, 0.3 mM PMS, and catalyst loading of 1.5 mg/cm², the membrane achieved up to 96.5% TC removal with a water flux of 197.6 LMH, and maintained superior stability (∼93% after 10 cycles). When compared with conventional batch systems, the developed catalytic membrane demonstrated an enhanced degradation rate, with an ultrashort hydraulic retention time of 108.8 ms. Besides, the membrane exhibited strong resilience across a wide pH range and effectively removed various different dye pollutants. Despite considerable interferences from water matrix components such as dissolved organic matter (DOM), Cl¯, and CO₃^2¯, the system maintained robust performance with over 80% TC removal. Mechanistic studies revealed the involvement of multiple reactive oxygen species (ROS), including SO₄•¯, •OH, O₂•⁻, and ¹O₂. Although cobalt was identified as the primary active center, the role of iron was also pronounced. Density functional theory (DFT) simulations demonstrated electron transfer at both the Co and Fe sites, suggesting internal electron-transfer pathways for a redox cycle, which is crucial for continuous TC degradation. Overall, this study has provided additional insights into the design of hybrid membrane systems and highlights their potential practical applications in micropollutant removal.