Cationic balance and current efficiency of a three-compartment bipolar membrane electrodialysis system during the preparation of chitosan oligomers

Chitosan oligomers, known for their specific biological properties, were produced by an alternate method using a three-compartment bipolar membrane electrodialysis (BMED) system. The three main products (i.e. an acidified chitosan solution, a basified chitosanase solution and a demineralized chito-oligomer solution) were analyzed by inductively coupled plasma (ICP) for their cationic content as a function of BMED duration. It was found that sodium and potassium were the main cations present in the solutions. Using a current density of 10 mA/cm2 for BMED, these cations were removed from the diluate compartment with constant migration rates of 0.30 and 0.37 mequiv. L−1 min−1, respectively for sodium and potassium. The cationic balance showed that all cations were preserved during the electrodialysis treatment, and that 80% of the cations were distributed between the basified and the diluate compartments. In addition, a current efficiency of 80%, constant during all the process, was calculated from the total cations migrated in the basified compartment, confirming the energetical performance of the system.