Process for the concentration of sulfuric acid

摘要

A process is described for increasing the sulfuric acid concentration of solutions containing an alkali metal sulfate, sulfuric acid and alkaline earth metal ions. The solutions to be worked up are introduced into the anode compartment of an electrolysis cell. The anode compartment and the cathode compartment of the cell are each bounded by a cation exchange membrane. A center chamber is located between the two membranes. This center chamber is filled with an aqueous solution containing alkali metal ions. The concentration of alkaline earth metal ions in the solution in the center chamber must be kept below 5 mg/l during the electrolysis.