Electrochemistry in Near-Critical and Supercritical Fluids. 3. Studies of Br(-), I(-), and Hydroquinone in Aqueous Solutions

摘要

A new type of apparatus has been constructed for carrying out electrochemistry in nearcritical and supercritical aqueous solutions. The following systems have been studied at a platinum electrode: H2O/O2, I(-)/I2, Br(-)/Br2, and hydroquinone/benzoquinone. The compact, alumina flow-cell can be heated or cooled quickly, and can be recharged with fresh electrolyte solution while at high temperature and pressure. A large reduction in the potential required for the electrolysis of water was observed. Diffusivities have been measured for iodide ions and hydroquinone. General agreement with the Stokes-Einstein model was observed in the temperature range 25 C to 375 C.