The Dechlorination Activity of Sulfide-Modified Nanoscale Zero-Valent Iron for Pentachlorophenol and its Enhanced Reaction

The activity of nanoscale zero-valent iron (nZVI) can be promoted with sulfidation. The physicochemical property of sulfide-modified nanoscale zero-valent iron (S-nZVI) was synthesized with the borohydride reduction method using the specific surface area (BET), X-ray diffraction (XRD), scanning electron microscopy (TEM), infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The dechlorination of pentachlorophenol (PCP) with S-nZVI was studied with high performance liquid chromatography and ion chromatography. As the results showed, compared with nZVI, S-nZVI had a significant change in the particle aggregation degree and porosity; the removal of pentachlorophenol (PCP) was evidently affected by the ratio of n(Fe²⁺)/n(S^2-) and the solution pH as well as the aging and re-vulcanization of S-nZVI material in the reductive dechlorination experiment; the dechlorination efficiency of PCP reached a maximum at n(Fe²⁺)/n(S^2-)=60 and the degradation of PCP with S-nZVI increased significantly with the increase of pH from 5 to 8; the reactivation of aged S-nZVI weakened the PCP degradation due to the structural change of the material; however, the reactivation produced an FeS layer to restrain the surface passivation of nZVI and thus prolonged the life of S-nZVI. This research has implications for expanding the application of nanoscale zero-valent iron and contolling environmental pollutants.