Recovery of biomolecules in sustainable ATPSs (298.15 K) and solubility determination in pure water and ethyl lactate (283.15, 298.15 and 313.15 K)

Abstract

Biowaste is considered to hold an immense potential as a source of bioactive compounds, such as vitamins and antioxidants, which constitute important value-added chemicals for the food and pharmaceutical industries. Moreover, the valorisation of biowaste could help fight resource depletion and forward a more circular economy. Therefore, the study of green extraction techniques is crucial for the effective retrieval of these biomolecules, with Aqueous Two-Phase Systems (ATPSs) standing out due to their high scale-up potential and use of harmless materials. In this work, sustainable ATPSs composed of water, ethyl lactate and the organic salts disodium succinate (Na2Succinate), tripotassium citrate (K3Citrate) and trisodium citrate (Na3Citrate) were used in a lab scale extraction of cyanocobalamin (B12), catechin (Cat) and nicotinic acid (NiA), at 298.15 K and 0.1 MPa. To assess extraction performance, the partition coefficient (K) and the extraction efficiency (E) were calculated, with catechin presenting the most promising results: a maximum K of (5 f 1) center dot 101 and maximum E of (94.2 f 0.9)%, for the longest tie-line of the ATPS composed of Na3Citrate. Conversely, the ATPSs based on Na2Succinate presented the worst results, only achieving a maximum K of 7.33 f 0.04 and a maximum E of (75.8 f 0.6)%, for the longest tie-line in the extraction of cyanocobalamin. Considering the promising results for the extraction of cyanocobalamin observed in several ATPSs, as reported in previous works of the research group, an additional study was conducted on the limiting effect of the solubility of this biomolecule in water or ethyl lactate on its partitioning in ATPSs. The solubilities in water and ethyl lactate were found to be extremely higher (over 40 and 300 times, respectively) than the concentration of cyanocobalamin in the phases of the ATPS, indicating that solubility was not a limiting factor.