REFERENCE ELECTRODE

摘要

The present invention relates to a reference electrode, particularly, but not exclusively for use in the measurement of the electrochemical potential of metal in a hot caustic liquid. Preferably the reference electrode is for use in the measurement of electrochemical potential in the caustic solution used to extract aluminium from bauxite in industrial plants using the Bayer process. The reference electrode comprises a reference electrode cell, a first porous membrane, a salt bridge, a second porous membrane and a support for the second porous membrane, wherein the salt bridge is in liquid electrical contact with the reference electrode cell via the first porous membrane, and is in liquid electrical contact with the liquid to be sensed via the second porous membrane, characterised in that the second porous membrane is resistant to the chemical attack of the liquid and is of a porous structure, wherein the average size of the pores of the porous structure is sufficiently large to permit ionic conduction through the membrane, but not so large as to permit significant mass transport of ions therethrough.