ELECTROCHEMICAL REGENERATION OF CERIC SULFATE IN AN UNDIVIDED CELL

Ceric sulphate (0-0.5 M) was generated electrochemically from cerous s ulphate slurries (0.5-0.8 M total cerium) in 1.6 m sulphuric acid, at 50-degrees-C, using a bench scale differential area undivided electroc hemical cell with an anode to cathode ratio of eleven. A cell current efficiency for Ce(IV) of 90% was obtained at an anode current density of 0.25 A cm-2. An empirical model illustrates an increase in overall current efficiency for Ce(IV) with an increase in electrolyte velocity , an increase in total cerium concentration, and a decrease in the cel l current. From separate kinetic studies on rotating electrodes, both, anode and cathode kinetics were found to be affected by cerium sulpha te adsorption processes. Anode adsorption of cerous sulphate species l eads to inhibited mass transfer and negatively affected current effici encies for Ce(IV). Cathode adsorption of cerium sulphate is thought to be responsible for high cathode current efficiencies for hydrogen (93 -100%). The dissolved cerous sulphate concentration increased with inc reasing ceric sulphate and total cerium sulphate concentrations result ing in slurries with a stable dissolved cerous sulphate concentration of as high as 0.85 M in 1.6 M H2SO4 at room temperature.