Zero-valent iron nanofibers (ZVINFs) immobilized on the surface of reduced ultra-large graphene oxide (rULGO) as a persulfate activator for treatment of landfill leachate

Abstract In this research, the performance of zero-valent iron nanofibers/reduced ultra-large graphene oxide (ZVINFs/rULGO) as a persulfate (PS) activator was investigated for the treatment of synthetic and real leachate. Ultra-large graphene oxide (ULGO) was prepared by chemical expansion of natural flake graphite using chromium trioxide and hydrogen peroxide and then oxidation using potassium permanganate. ZVINFs/rULGO was prepared by adding sodium borohydride as a reducing agent to a solution containing Fe(II) ions and ULGO. The material characterization was performed by XRD, SEM, EDS, and BET analysis. The effects of the pH, ZVINFs/rULGO dosage, PS/COD ratio, reaction time, and temperature on the removal of COD and NH3 were evaluated to find the optimum operational conditions (i.e., pH 3, ZVINFs/rULGO dosage: 1.6 g L−1, PS/COD: 3, and reaction time: 45 min). Under the optimum conditions, the removal efficiencies of COD and NH3 were 93.64 and 84.8%, respectively. The presence of ZVINFs/rULGO led to 3.8 and 4.2 times decrease in the activation energies of COD and NH3, respectively. Finally, the ZVINFs/rULGO-PS system was applied for removal of COD and NH3 in real leachate obtained from the Aradkouh’s landfill located in Tehran, Iran. The COD and NH3 removal efficiencies for the fresh leachate were 80.87 and 72.38%, respectively, and the biodegradability (BOD5/COD) of the real leachate enhanced from 0.25 to 0.52, respectively.