Hydrogen evolution in KF–2HF

This thesis describes an electrochemical investigation of the processes occurring at the hydrogen evolving cathode during the industrial production of fluorine in molten KF–2HF. A 1A laboratory cell, designed for the purposes of the project, is described. Observations of the operation of this cell are reported. A comparison of a range of electrode materials is given, both with regard to electrochemical overvoltage and the bubbling releasing characteristics, for which photographic evidence is presented. In addition, measurements of the ohmic potential drop, caused by the presence of bubbles, were made for different bubble types. Included in the above is a description of any effects of metallic impurities present in the melt both on overvoltage and bubble release. A mechanistic study of hydrogen evolution on platinum is described and compared with the reaction at a mild steel electrode. A preliminary investigation into the use of parallel strand expanded metal electrodes was made and further photographic evidence presented.