Manufacture of gluconic acid: A review towards process intensification for green production

• State-of-the-art of gluconic acid manufacture reviewed.
• Major drawbacks of the conventional processes examined.
• Recent developments towards green processes highlighted.
• Membrane-integrated hybrid processes observed as potential candidates.

In view of the huge application potential of gluconic acid and its derivatives, this manuscript critically reviews literature of the last thirty years on evolution of production processes of this important organic acid for the purpose of directing further research towards process intensification for innovative green processes. Fermentative process and catalytic oxidation are found to be the two basic approaches in production of gluconic acid. In both the approaches, downstream purification involves several steps such as centrifugation, carbon adsorption, evaporation, crystallization and ion-exchange. Cost-effective and eco-friendly production of high purity gluconic acid has remained a challenge, mainly due to involvement of multiple downstream processing units and their associated energy consumption and cost factors. In the recent years, possibility of integration of tailor-made and highly selective membranes and modules with fermenter in downstream purification of gluconic acid appears to have brightened the prospects of gluconic acid manufacture. This paper through a comprehensive review of the critical aspects of production of gluconic acid suggests ways towards development of green processes through process intensification leading to the prospects of sustainable business.