A novel catalyst combining nickel and iron layered double hydroxides supported on activated carbon has shown remarkable efficiency for the degradation of norfloxacin (NOR), a persistent fluoroquinolone antibiotic, through the activation of persulfate (PDS). This innovative approach, detailed by researchers A. Adly, M.M. Galal, and M.E. Matta, reveals significant promise for addressing the growing concerns about antibiotic pollution and resistance.
The background of antibiotics and their impact on the environment is harrowing. Their use has surged globally, reaching 34.8 billion defined daily doses by 2015. Alarmingly, approximately 75% of NOR is excreted unmetabolized, accumulating in aquatic ecosystems and contributing to the rise of antibiotic-resistant bacteria.
Traditional wastewater treatment methods fall short of effectively removing such recalcitrant compounds. Chemical methods, especially Advanced Oxidation Processes (AOPs), have emerged as effective solutions. The newly developed NiFe-LDH@AC combines the catalytic strengths of layered double hydroxides (LDHs) with the high surface area of activated carbon to advance PDS activation, generating sulfate radicals capable of oxidizing NOR efficiently.
The research reveals optimal degradation conditions: using 0.3 g/L of the catalyst, 1 g/L of PDS, and maintaining neutral pH, researchers recorded up to 100% removal efficiency for initial concentrations of 10 mg/L and 20 mg/L of NOR. Even at higher concentrations, the system displayed impressive degradation capabilities, achieving 86% removal of NOR at 50 mg/L concentration within just 60 minutes.
The catalyst's activation energy was calculated to be 58.27 kJ/mol, and the degradation mechanism was primarily identified through radical scavenging experiments, differentiably showing the sulfate (SO₄˙⁻) and hydroxyl (•OH) radicals—the former was found to play a more significant role.
Importantly, the catalyst also demonstrated robustness and reusability. After four catalytic cycles, it maintained about 75% activity, with negligible metal leaching observed, highlighting its practical viability for real-world applications. Appropriately, the study included assessments reflecting real wastewater conditions, achieving 84% NOR degradation and reducing chemical oxygen demand (COD) by 55% when tested with wastewater samples.
Adopting the NiFe-LDH@AC method could revolutionize strategies for managing antibiotic contamination, providing scalable solutions for wastewater treatment facilities aiming to mitigate the adverse effects of pharmaceuticals on aquatic environments. The results of this research not only characterize how effective PDS activation through layered double hydroxides can be but also open avenues for future explorations aimed at optimizing catalyst configurations for other persistent contaminants.