Investigation Effects of Phosphate Salt in the Extraction of Malic Acid Using Aqueous Two-Phase Systems

Novel separation methods that are necessary for the purification of biomolecules and carboxylic acids at industries, are expanding. Therefore, these methods should be fast, selective, and easy to scale up. The aqueous two-phase system is an effective separation procedure for the purification of materials. The purification of biomolecules and carboxylic acids is extremely selective by this method and also, the separation process is conducted in one step. This research aimed to investigate the effects of molecular weight of polyethylene glycol, pH, salt concentration, and salt type in polymer/salt aqueous two-phase systems. In this research, purification of malic acid in aqueous two-phase systems containing polyethylene glycol 4000 and 8000 g/mol, different concentration sodium di hydrogen phosphate, diammonium hydrogen phosphate, and di potassium hydrogen phosphate were studied. After investigating the effective factors, the best operation conditions for malic acid extraction was obtained in a system composed of  PEG4000, 0.25 (w/w) sodium di hydrogen phosphate at pH=5. The purification parameters such as partition coefficient of malic acid and yield were achieved 0.85 and 80%, respectively.