Performance and Mechanism of GO-MCM-Fe Composite Catalyst Activating Persulfate to Remove Levofloxacin Hydrochloride in Water

A composite catalyst of MCM-41-supported graphene oxide (GO) and iron (GO-MCM-Fe) was synthesized with solvothermal method and shown for the first time to be an efficient peroxydisulfate (PDS) activator to remove levofloxacin hydrochloride (LVF) in water. A total of 97.10% of LVF were removed within 10 min in the GO-MCM-Fe/PDS system. And the apparent rate constant of the GO-MCM-/Fe/PDS system was 11.78 and 1.35 times that of the GO-MCM-Fe system and MCM-Fe/PDS system, respectively. GO-MCM-Fe catalyst achieved lower iron ions (0.27%) than MCM-Fe (0.89%) at 60 min. Although GO could strengthen stability of the catalyst; this effect was negatively related with GO dosages in this work. And 5%wt Fe and 30 mL GO solution were chosen as the optimal condition for catalyst synthesis. The GO-MCM-Fe catalyst could be reused and the LVF removal ratio reached about 86% even after the fifth run. Both SO₄⁻· and ·OH played the important roles and the latter was a dominant role. Additionally, in the process of GO-MCM-Fe activating PDS, there existed a redox interaction between the C=C of GO and Fe³⁺, in which the C=C of GO was oxidized into C=O; meanwhile, Fe³⁺ was reduced to Fe²⁺ which further activated PDS to generate radicals. This study provides a promising catalyst in effectively activating PDS to remove organic pollutants in water.