Highly Efficient Iron Nanocatalyst Stabilized by Double-Walled Carbon Nanotubes and Mixed Metal Oxides for Degradation of Cationic and Anionic Dyes by a Fenton-like Process

In the present work, a three-dimensional iron nanocatalyst stabilized by double-walled carbon nanotubes and Mg-Al mixed metal oxides (Fe/DWCNTs-MMO) was directly generated by a facile catalytic chemical vapor deposition process, where Fe(CN)(6)(3-)-intercalated Mg-Al layered double hydroxide as catalyst precursor was utilized to catalyze the growth of DWCNTs. This preparation route did not require complex pretreatment of DWCNTs and subsequent immobilization of metal nanoparticles. The resulting Fe/DWCNTs-MMO was applied as a Fenton-like catalyst for the degradation of methylene blue and methyl orange dyes. The materials were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N-2 adsorption-desorption experiments, and Raman spectra. The results revealed that Fe/DWCNTs-MMO as Fenton-like catalyst showed superior catalytic activity in the degradation of model dyes to a traditional catalyst system derived from Fe(CN)(6)(3-)-intercalated Mg-Al layered double hydroxide, where iron nanoparticles were only deposited onto Mg-Al MMO flakes formed. The possible mechanism for the degradation of dyes was discussed. Moreover, as-formed Fe/DWCNTs-MMO possessed high structural stability under the reaction conditions and could be reused five times without remarkable activity loss.