Separation of α-ketoglutaric acid by salting-out extraction coupled with solar-driven distillation

Alpha-ketoglutaric acid (alpha-KG), as an essential intermediate in biosynthesis and drug synthesis, has a broad application prospect. However, the lower product concentration and impurities in the alpha-KG production make the downstream separation more complex and costly. In this study, alpha-KG was separated from biotransformation broth by salting-out extraction (SOE) combined with solar-driven distillation. First, the aqueous two-phase system (ATPS) consisting of acetone/(NH4)(2)SO4 was selected by comparison. The effects of acetone/(NH4)(2)SO4 concentration, temperature, alpha-KG concentration, and pH on the distribution behavior of alpha-KG in ATPS were investigated. Under the optimized conditions, higher extraction efficiency and purity of alpha-KG were obtained in the actual biotransformation broth. In addition, solar evaporation was used to achieve preconcentration of the organic phase and salt recovery, significantly reducing energy consumption. The method is environmentally friendly and easy to operate, providing a new idea for separating low concentration products in biosynthesis.