Magnetic Fe/carbon/sodium alginate hydrogels for efficient degradation of norfloxacin in simulated wastewater

The activation of hydrogen peroxide (H2O2) by Fe/carbon composites has been widely used for the removal of antibiotics. However, the secondary pollution of iron ions limits the application of Fe2+/H2O2 system. In this work, three kinds of hydrogel materials combining metal-organic framework (MOF)-derived magnetic Fe/porous carbon (MagFePC) with sodium alginate (SA), polyacrylic acid (PAA) and agarose (AG) were prepared by different methods for removal of norfloxacin (NOR) antibiotics in simulated wastewater. After comparison, MagFePC/SA hydrogels synthesized by a titration forming method were found to have the advantages of good toughness, abundant pores and best Fenton activity. MagFePC/SA can effectively activate H2O2 to remove NOR under neutral conditions, and there was almost no leaching of iron ions, causing no secondary pollution to the environment. The effects of pH, ionic strength and surfactants on the degradation performance for NOR were studied. Mechanism study revealed that ·O2− and 1O2 were the main active species for the degradation of NOR, and the materials still had good stability and reusability after repeated cycles. More important, we built a simple automated unit for wastewater treatment under laboratory conditions that can completely degrade a 5 mg/L NOR solution at a flow rate of 2 mL/min. Current works showed that MagFePC/SA had the advantages of simple synthesis, outstanding degradability, excellent stability and eco-friendly reaction, which was a wastewater treatment material with good prospect for industrial application.