Citric acid production by electrodialysis with bipolar membranes

Production of citric acid from sodium citrate was carried out by electrodialysis (ED), using bipolar membranes (BP) prepared from poly(phenylene oxide) (PPO). The process feasibility was tested using a laboratory ED-cell with an effective area 20 cm2. Based on the configuration of BP-cation membranes (C)-BP, the performances of various sodium sulfate concentrations and sodium citrate concentrations are compared and discussed in terms of ionic transport and ion exchange. It is suggested that, in such an operation, the optimum concentration range be 0.5–1.0 M for sodium citrate and 0.25–1.5 M for sodium sulfate from the viewpoint of energy consumption, current efficiency and acid concentration.