Catalytic degradation of norfloxacin using persulfate activation by Ni-Fe layered double hydroxide catalyst supported on activated carbon

Abstract

This study investigated the catalytic degradation of Norfloxacin (NOR), a persistent fluoroquinolone antibiotic, using a novel Ni-Fe Layered Double Hydroxide supported on Activated Carbon (NiFe-LDH@AC) as a catalyst. The composite was designed to activate persulfate (PDS) and generate sulfate radicals for NOR degradation in aqueous solutions. Characterization techniques such as XRD, SEM, EDS, TEM, FTIR, and BET confirmed the successful synthesis and structural integrity of the composite. The optimal degradation was achieved with a NiFe-LDH@AC ratio of 2:1, 0.3 g/L catalyst dosage, and 1 g/L PDS, resulting in 86% NOR removal efficiency within 60 min at neutral pH and ambient temperature for an initial concentration of 50 mg/L, and 100% removal for initial concentrations of 10 mg/L and 20 mg/L under the same conditions. The activation energy of the reaction was calculated as 58.27 kJ/mol. Radical scavenging experiments identified sulfate (SO₄˙⁻) and hydroxyl (^•OH) radicals as the dominant reactive species, but the SO₄˙⁻ played a larger role. Furthermore, the catalyst exhibited good reusability, maintaining 75% degradation efficiency after four cycles, and showed minimal metal leaching. The study also proposed a mechanism for PDS activation using XPS analysis and suggested NOR degradation pathways through LC-ESI-MS/MS analysis. Moreover, the NiFe-LDH@AC/PDS system demonstrated 84% NOR degradation and 55% COD removal in real treated wastewater. Results demonstrated that the NiFe-LDH@AC composite effectively activated PDS, achieving high NOR removal efficiency, making it a promising sustainable material for wastewater treatment.