Visible-light-driven peroxydisulfate activation by biochar-loaded Fe-Cu layered double hydroxide for penicillin G degradation: Performance, mechanism and application potential.

The biochar-loaded Fe-Cu layered double hydroxide (FeCu-LDH@BC) catalyst was synthesized via a simple hydrothermal method and used to activate peroxydisulfate (PDS) for penicillin G (PG) degradation under visible light. The physicochemical properties of FeCu-LDH@BC were characterized using SEM, XPS, UV-DRS, SEM-EDS, HRTEM, XRD, BET, PL spectrum, FT-IR, Raman spectrum, TG-DSC, TPD, and EIS, showing that biochar (BC) enhanced the optical properties of FeCu-LDH. Notably, the FeCu-LDH@BC + PDS + Light system achieved a 98.79% degradation efficiency for PG in just 10 min. Furthermore, FeCu-LDH@BC retained excellent activity after four reuse cycles. LSV results indicated enhanced electron transfer in the FeCu-LDH@BC + PDS + Light system, suggesting a synergistic effect between the photocatalytic and PDS activation systems. The interconversion of h, SO·⁻, O, and ·OH species was found to play a key role in PG degradation. Density functional theory was used to identify PG sites susceptible to radical attack, and the possible degradation pathway was proposed based on liquid chromatography-mass spectrometry results. Toxicity evaluation using the TEST software confirmed that the intermediates formed were significantly less toxic than PG. Lastly, the FeCu-LDH@BC + PDS + Light system removed 37.45% of total organic carbon and 63.74% of chemical oxygen demand from real wastewater within 120 min. The type and transformation pathways of organic matter in the wastewater were analyzed using 3D Excitation Emission Matrix spectroscopy to assess the system's application potential.