Isotope effects in solid Li2SO4 at 600-790 °C

Three different isotope fractionation processes have been studied in the same experiment, when solid Li2SO4 was electrolysed in a Vycor cell using a liquid zinc cathode and a gold anode. The main object was to study the enrichment of 7Li at the anode due to the difference in ion mobility. For this electromigration process the mass effect (i. e. relative difference in ion mobility/relative difference in mass) was µ = - 0,14, independent of temperature. The mass effect is thus about the same as in molten lithium halides. The principal difference between electromigration experiments in solid and molten salts is that in the former the salt lattice forms the « separation column », which is gradually consumed during the run, while for a melt the hydrostatic forces produce a counterflow which keeps the separation column filled with salt.