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Ethyl lactate is a hydrophilic green solvent which is bio-renewable and biodegradable with low toxicity towards humans and animals. For the first time, we report that aqueous solutions of ethyl lactate separate into two aqueous phases upon addition of salts. The performance of trisodium citrate, disodium tartrate and disodium succinate as salting-out media for the separation of natural organic compounds, such as caffeine and catechin, from their aqueous solutions was examined. In this respect, cloud points for the ternary solutions composed of ethyl lactate, water and salt were determined at ambient pressure (0.1 MPa) at 298.2 K. Partition coefficients of caffeine and catechin between two phases were determined by chemical analysis of phases in equilibrium for different initial compositions at 298.2 K. The obtained results clearly demonstrate the ability of the ternary mixture to phase separate, providing good salting-out media for the efficient and sustainable separation from aqueous solution. 1 H-NMR spectroscopy was employed to elucidate the mechanisms of phase splitting in the ternary (ethyl lactate + water + salt) systems at molecular level. The discovery of aqueous biphasic system (ABS) containing ethyl lactate as hydrophilic solvent opens a new and green platform for extraction of various compounds from aqueous solutions.

For the first time, we report on the performance of biphasic system composed of ethyl lactate, water and inorganic salt (K3PO4, K2HPO4 and K2CO3) for the separation of amino acids (Lphenylalanine, L-tryptophan and L-tyrosine) from their aqueous solutions. Cloud points (solubility curve) and tie-lines for three ternary (ethyl la ctate + water + inorganic salt) systems at 298.2 K and 313.2 K at atmospheric pressure were determined. For certain composition range, these mixture exhibit biphasic systemstop and bottom phases rich in ethyl lactate and salt, respectively. Partition coefficients of amino acids and their extraction efficiencies, as essential parameters for design of any separation process, were measured at two temperatures-298.2 K and 313.2 K. The maximum values of partition coefficients were observed for the system containing K3PO4: 3.5, 3.7 and 11.9 for L-phenylalanine at 313.2 K, L-tyrosine at 298.2 K and L-tryptophan at 313.2 K, respectively. The obtained results clearly showed that the biphasic systems based on ethyl lactate are suitable for the efficient and sustainable recovery of amino acids from solutions with water.

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