One-pot green synthesis of Ag/Ni/Fe3O4-activated carbon beads for recyclable photo-Fenton antibiotic removal and antibacterial action: mechanistic study and optimization

Abstract

A one-pot green synthesis approach was developed to fabricate Ag/Ni/Fe₃O₄-activated carbon beads (Ag/Ni/MACB) using Brucea javanica as a natural carbon precursor. Unlike conventional powdered catalysts, these millimeter-sized porous beads enable easy recovery and reusability, addressing a key limitation in heterogeneous Fenton systems. The Fe₃O₄ component facilitated Fenton-like reactions, while Ni and Ag nanoparticles synergistically enhanced electron transfer and visible-light absorption, significantly boosting photo-Fenton efficiency. The catalyst achieved 96.78% enrofloxacin (ENR) degradation under optimized conditions, with radical scavenger experiments confirming that ˙OH and ˙O₂⁻ were the dominant reactive species. Comprehensive characterization (XRD, SEM, TEM, BET, VSM, and FTIR) verified the uniform dispersion of Fe₃O₄, Ni, and Ag nanoparticles (10–50 nm) within the carbon matrix, ensuring structural stability and catalytic efficiency. The incorporation of Ag not only improved light absorption but also imparted strong antibacterial properties, effectively inhibiting Escherichia coli and Staphylococcus aureus. This dual functionality allows Ag/Ni/MACB to simultaneously degrade organic pollutants and eliminate bacterial contamination, demonstrating self-cleaning capability. The catalyst retained 83.61% efficiency after five cycles with negligible metal leaching, highlighting its long-term stability and recyclability. Additionally, the degradation pathway of ENR was elucidated, providing deeper insights into the reaction mechanism. By integrating sustainable material design, enhanced photocatalytic properties, and antibacterial action, Ag/Ni/MACB serves as a versatile and cost-effective solution for wastewater treatment, offering simultaneous pollutant degradation and microbial disinfection in a single step.