Plant tannin foam anchored iron nanoparticles: Efficient and recyclable degradation of tetracycline antibiotics under high salt conditions

The degradation of antibiotics in industrial wastewater with high salt concentrations is a critical challenge for the treatment of pharmaceutical wastewater. We developed a salt-tolerant catalyst by anchoring FeNPs in an amphiphilic tannin foam, enabling high-performance catalytic degradation of tetracycline in high salt concentrations. The high-salt tolerant catalyst effectively stabilized and dispersed FeNPs due to abundant polyphenol hydroxyls and the steric hindrance of the aromatic backbone. The amphiphilic nature of the tannin foam facilitated the effective adsorption of tetracycline, even under high salt condition of 1.0 mol/L NaCl. The salt-tolerant catalyst was effective for tetracycline, chlorotetracycline, and minocycline degradation, with significantly alleviated toxicity observed in degradation intermediates. The catalyst was highly recyclable, with a 6th cycle removal rate of 86.3%.