Production of lactobionic acid by means of a process comprising the catalytic oxidation of lactose and bipolar membrane electrodialysis

Abstract

Lactobionic acid (LBA) is a high value-added oxidation product of lactose with numerous potential applications in the food, pharmaceutical and chemical industries. This study aimed to investigate the viability of producing LBA from a sodium lactobionate (LBNa) solution obtained by the aerobic oxidation of lactose over gold nanoparticles supported on mesoporous silica, using a three-compartment bipolar membrane electrodialysis (BMED) stack with an effective area of 0.01m2. The results indicated that LBNa was continuously split in LB− (lactobionate anion) and Na+ ions during BMED, which formed LBA and NaOH in the acid and base compartments, respectively. A demineralization rate of about 50% was achieved after applying a voltage difference of 5.0V during 100min followed by 5.5V during 80min, while the LBA concentration increased about 2.5 times in the acid compartment. The specific energy consumption was 0.57kWhkg−1 over the whole stack. Although sodium was found in small amounts (17.5ppm) in the acid compartment, these results show for the first time the viability of producing LBA by means of an integral process comprising the catalytic oxidation of lactose and BMED, with the advantage that the NaOH could be efficiently recovered for its reutilization in further oxidation reactions.