High-temperature wall-tube cell Design, characterization and results of mass transport phenomena

Abstract

A high-temperature wall-tube electrode cell (WTE) for electrochemical studies in hydrothermal systems is described. The cell contains a jet impinging on a wall (electrode) where the hydrodynamics in the stagnation region is well defined and the WTE has uniform accessibility and is equivalent to a rotating disc electrode (RDE). The construction and testing of the high-temperature WTE is described and its performance tested using different redox couples such as hexacyanoferrate(II/III) and quinone/hydroquinone. Diffusion coefficients of iron(II)/iron(III) are reported at temperatures up to 142 °C in sulfate solutions and are analysed taking into account the speciation in the solution. The application of the Stokes–Einstein equation to describe the temperature dependence of the diffusion coefficients in systems with strong ionic association is discussed for iron(II)/iron(III) and other species.