Rapid Removal of the Passivation on Iron Anode Surface by Oxalic Acid for Ferrate(VI) Generation

Abstract

A convenient anodic pretreatment was established based on the possibility of dissolution of passivation using oxalic acid. Then, X-ray photoelectron spectroscopy and scanning electron microscopy examinations were used to examine the composition and structure of anode surface, respectively. The high removal efficiency of passivation and the formation of porous structure on anode surface could be observed. These led to significant enhancement of the ferrate(VI) synthesis efficiency. The characteristics of ferrate(VI) solution such as stability and reproducibility were studied by flow-injection chemiluminescence method based on the chemiluminescence reaction of ferrate(VI)-luminol. The chemiluminescence signal was stable for a week. The relative standard deviation (RSD) was 2.41% for five runs of electrolysis.