Modification of Citric Acid Technology Using Electrodialysis

Abstract

Modification of conventional citric acid technology has been proposed. Calcium citrate was converted into sodium citrate, which then went through electrodialysis with a bipolar membrane. The electrodialysis was carried out using the following membranes produced by Tokuyama Corporation (Japan): bipolar Neosepta BP, anion-exchange Neosepta ACM, cation-exchange Neosepta CMX; as well as the membranes produced by FumaTech GmbH (Germany): bipolar FBM, anion-exchange FAB and cation-exchange FKB. It was found that there are important relations between current efficiency, current density and energy consumption. The comparison of commercially available membranes shows that the FumaTech GmbH membranes are better - they have a higher efficiency and lower electric power consumption. Moreover, in case of the Tokuyama Corporation membranes, a considerable increase in solution temperature occurred when current density was high. After electrodialysis the acid solution went through crystallisation, which resulted in a product of chemical purity and granulometric composition meeting the criteria of food industry.