In situ Visualization of Ferrous Ions Dissolved from Pure Iron Wire into Thin Frozen Aqueous Solution Films by Combination of Microscopy and Image Processing

Abstract

The dissolution of ferrous ions from pure iron into freeze-concentrated solutions (FCSs) formed in thin films of aqueous salt solutions was visualized by a combination of in situ diffusive-reflection microscopy and image processing. An iron surface in contact with an FCS was observed with a diffusive-reflection microscope. Ferrous ions dissolved from the iron surface were complexed with 1,10-phenanthroline doped in the ice film to develop reddish complexes. In situ observation enabled us to monitor the dissolution and migration behavior of ferrous ions in the FCS. Processing of the acquired microscopic images enabled quantitative mapping of the dissolved ferrous ions. The present approach has the potential for fast screening to assess the corrosion behavior of steel materials in contact with frozen aqueous electrolytes.

Dissolution Behavior of Iron in Contact with Frozen Electrolyte Solutions

“…To overcome this issue, our research group has reported a microscopic method for the evaluation of ferrous iron from pure iron wire dissolved in an FCS. 12) The ferrous ions dissolved from the wire were complexed with 1,10-phenanthroline doped in the FCS, and the resulting coloration was observed employing microscopy, followed by quantitative evaluation using an image processing tool. We successfully visualized the dissolution behavior of the ferrous ions in the FCS.…”