Synergistic degradation of bisphenol A in heterogeneous Fenton and photo-Fenton systems catalyzed by graphitized carbon-nano zero valent iron

Abstract

Fenton-like processes have gained widespread acceptance due to their high oxidative potential and environmental compatibility. In this study, a composite of graphitized carbon and nZVI (GC-nZVI) was synthesized and applied toward the degradation of bisphenol A (BPA) in water. The morphological structure and stability of GC-nZVI were evaluated using different characterization techniques including X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Our results showed that the catalytic graphitization of carbon occurred simultaneously with the carbothermal reduction of iron oxide, and ZVI was distributed uniformly on the carbon material. Excluding the adsorption effect, there was almost no degradation of BPA using GC-nZVI only. However, in the presence of H2O2 and UVA radiation, BPA was rapidly degraded. The synergistic effect of the photo-Fenton process carried out in the presence of H2O2 showed that 90% of BPA degradation was obtained after 60 min using only 50 mg L–1 of GC-nZVI and 0.5 mM of H2O2 at pH 6. The generation of HO• has been demonstrated using chemical competition experiments and the photo-Fenton process, which could eliminate 66% of BPA within 15 min under the same conditions. Finally, recycling experiments have shown that after three cycles of BPA and H2O2 addition, a degradation efficiency of 71% was achieved over 60 min. The GC-nZVI/H2O2/UVA system demonstrated great potential for advanced oxidation processes and had good application prospects in the treatment of actual wastewater.