| abstract |
Formate salts such as sodium formate are removed from a pentaerythritol solution in an electrodialysis unit divided by a stack of alternating cation and anion permselective membranes into an anode compartment, a series of alternating concentration and dilution compartments, and a cathode compartment. The anode compartment is contiguous to a concentration compartment and, preferably, the cathode compartment is contiguous to a dilution compartment. The impure pentaerythritol solution passes through the dilution compartments; an electrically conductive liquid, preferably a dilute solution of the impurity in the pentaerythritol solution, passes through the concentration compartments; and an electrolyte containing a salt, preferably one with the same cation as the formate salt in the pentaerythritol solution, is circulated from a common tank through the anode and cathode compartments and back to the tank. |