THE CHARACTERISTICS OF CITRIC-ACID SEPARATION USING ELECTRODIALYSIS WITH BIPOLAR MEMBRANES

The conversion of salts into their corresponding acids and bases using electrodialysis with bipolar membranes shows specific characteristics . Considering for example the generation of HCL and NaOH from NaCl, th e process efficiency strongly decreases with increasing product concen tration, a process behaviour typical of strong acids. In this report t he separation and production of a (weak) organic acid, specifically:he conversion of sodium citrate into citric acid and NaOH in a three-com partment cell arrangement, will be described and characterized. Using model solutions, and varying the current density between 300 and 1000 A/m(2) the current efficiency, the conversion rate and the specific en ergy consumption were determined. Furthermore, by changing both the ba se concentration (1N-3.5N) and the acid content (20-60%), the resultin g effects upon the process behaviour were examined. In addition to the se experiments the product impurities and water transport were measure d and noted. Another goal was to investigate the highest attainable ac id concentration which was close to the saturation point.