A
hybrid electrodialysis –ion exchange (EDIX) method was investigated for
the recovery of cesium from cesium-sorbed ammonium
molybdophosphate-polyacrylonitrile (AMP-PAN) ion exchange resin.
Concentration polarization was studied by observing current –voltage
(I–V) characteristics of a three compartment electrodialysis cell
containing AMP-PAN in the middle compartment. The effect of process
parameters such as flow rates of electrolytes and anolyte concentration
on the current –voltage behavior was examined. Limiting currents,
determined using Cowan plots, increased with electrolyte flow rates and
anolyte concentration. In the present study, limiting current density
(LCD) was measured for the electrodialysis system as a function of
linear velocity and anolyte concentration using the equation ilim=aCub. Coefficients a and b
for relating limiting current density and flow velocity were evaluated
for different anolyte concentrations and electrolyte flow rates.
Application of overlimiting currents resulted in lower recovery of
cesium from AMP-PAN. During continuous operation of the cell, the onset
of concentration polarization was detected by observing the pH of the
acidic catholyte which turned to alkaline.