Malic acid extraction from aqueous solution by using aqueous two-phase system method

Abstract

In this investigation malic acid extraction by aqueous two-phase system method (ATPS) was performed. ATPS are involved polymer (PEG 4000 and 8000) and various phosphate salts. Effect of PEG molecular weight, pH, temperature and concentration of salt were studied as independent parameters and the partition coefficient (D) and percentage of extraction(Y %) were considered as responses of the system. In order to the results, increasing all of the independent parameters cause to decrease the partition coefficient and percentage of extraction. As these parameters decrease, malic acid tends to move in the top phase (PEG-rich phase), and consequently separation will be occurred properly. In addition, van't Hoff equation was applied for discussing temperature effect on malic acid extraction. The obtained results show that increasing of temperature cause to increasing in Gibbs free energy. The best operation condition for malic acid extraction was obtained 4000, 25% w/w, 293 K and 5 for PEG molecular weight, Salt concentration, Temperature and pH, respectively.