Partition of Chlorogenic and Nicotinic Acids Using Eco-Friendly ATPSs Containing Ethyl Lactate at 298.15 K and 0.1 MPa

Biowaste, particularly food waste, could provide an alternative and more sustainable source for biomolecules such as antioxidants, allowing delays in the final treatment steps of these residues (e.g., fertilizer production and incineration) and even reduction of the amount of final waste. Furthermore, the application of green solvents such as ethyl lactate in aqueous two-phase systems (ATPSs) provides a biocompatible medium with high water content and promising scale-up potential. Nevertheless, a preliminary lab-scale evaluation of the extraction of each antioxidant using ATPSs is vital for the success of pilot-scale operations. In this work, partition studies were carried out for chlorogenic acid (ChloA) and nicotinic acid (NicoA) at 298.15 K and 0.1 MPa in the ATPSs {ethyl lactate (1) + NaKTartrate or Na₃Citrate or K₃Citrate (2) + water (3)}. The largest performance indicators of extraction for ChloA were obtained using Na₃Citrate, achieving a maximum partition coefficient (K) of 10 ± 1 and a maximum extraction efficiency (E) of 90.4 ± 0.9% in the longest tie-line [tie-line length (TLL) = 69.68%], while for NicoA, the most successful extraction, with K = 6.5 ± 0.5 and E = 86.8 ± 0.8%, was observed for the ATPS with K₃Citrate (TLL = 77.66%). The obtained partition coefficients and extraction efficiencies were checked by calculating the mass losses in quantification (L_s), which were lower than 4%, validating the analytical method and allowing to conclude that the studied ATPSs could provide an efficient and eco-friendly extraction medium for NicoA and ChloA.