Synthesis of nZVI@reduced graphene oxide: an efficient catalyst for degradation of 1,1,1-trichloroethane (TCA) in percarbonate system

Abstract

Graphene-oxide-supported nano zero-valent iron (nZVI) composite (nZVI–rGO) was synthesized and tested as an efficient percarbonate activator for degradation of 1,1,1-trichloroethane (TCA). Significant dispersion of nZVI on the surface of reduced graphene oxide (rGO) was observed, with good limitation of nanoparticle agglomeration and aggregation. Good TCA degradation efficiency of 90% was achieved in 2.5 h in presence of 0.8 g/l nZVI–rGO catalyst and 30 mM sodium percarbonate (SPC) oxidant; however, excessive catalyst or oxidant concentration reduced the degradation efficiency. Investigation of reactive oxygen species using radical probe compounds as well as radical scavengers confirmed presence of hydroxyl (OH·) and superoxide ( $${\text{O}}_{2}^{\cdot - }$$ ) radicals that are responsible for the TCA degradation. The morphology and surface characteristics of the heterogeneous catalyst were analyzed by transmission electron microscopy and scanning electron microscopy. Brunauer–Emmett–Teller analysis revealed that the synthesized catalyst had large surface area and small particle size of 299.12 m2/g and 20.10 nm, respectively, compared with 5.33 m2/g and 1.12 µm for bare graphene oxide. X-ray diffraction analysis revealed good dispersion of nZVI on the surface of rGO. Fourier-transform infrared characteristic peaks confirmed strong attachment of Fe onto the rGO surface. Energy-dispersive spectroscopy analysis validated the stoichiometric composition of the prepared Fe/rGO material. In conclusion, use of nZVI–rGO-activated SPC could represent an alternative technique for remediation of TCA-contaminated groundwater.