Dechlorination of carbon tetrachloride by Nanoscale Nickeled Zero-Valent Iron @ Multi-Walled Carbon Nanotubes: Impact of reaction conditions, kinetics and mechanism

摘要

The nanoscale nickeled zero-valent iron @ multi-walled carbon nanotubes (NF@MWCNTs) were synthesized, characterized and used to dispose carbon tetrachloride (CT) in aqueous solution. Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) gas sorptometry measurements were conducted to characterize the microstructure of the NF@MWCNTs. And batch experiments under different operation parameters were conducted to investigated the activity of NF@MWCNTs on degrading CT, including the content of NF@MWCNTs composites, temperature, catalyst dosage, initial pH and different anions. The experimental results showed that 4% nickel content of Ni/Fe bimetal and 2:1 doping ratio of Fe/MWCNTs were the wise choices in this study, which provided excellent degradation efficiency of CT when compared with nanoscale zero-valent iron (nZVI) (97.44% and 55.28%, respectively). That was benefited from the fact that MWCNTs as an excellent support material could reduce the activation energy of 7.952 kJ/mol, and the nickel metal further reduced the reaction activation energy of 11.022 kJ/mol as presented in the conceptual model. Beyond that, NF@MWCNTs showed good reusability after five times consecutive reaction. Based on these, the reaction mechanism and degradation pathway also had been discussed.