Synthesis, characterization and re-activation of a Fe0/Ti system for the reduction of aqueous Cr(VI).

The conventionally employed zero-valent iron (Fe0) particles suffer a formation of surface oxides to lower their activity prior to use. During their using process for contaminant remediation, such oxide formation is also encountered, while the cumbersome handling of particles impedes the Fe0 recovery. To conquer the drawbacks, a Fe0 film was synthesized by electrodepositing ferrous ion cathodically on titanium (Ti) substrate to form a new Fe0/Ti system. X-ray diffraction (XRD) revealed that the freshly electrodeposited (FED) Fe0 film was free of oxides, which was attributed to the particularity of electrodeposition procedure. Reduction results of 10.0 mg/L chromium [Cr(VI)] indicated that the FED Fe0 film had higher activity than the oxide-covered counterpart. Further analysis of the pH-dependent Cr(VI) reduction reaction indicated that the Fe0/Ti system kept its activity and could be reused for further Cr(VI) reduction at pH 3.0 and 4.0, while it was inactivated at pH 5.0 and 7.0. Due to the easy handling of Fe0/Ti system, the inactivated Fe0 was recovered significantly through a cathodic reduction.