Avaliação da partição de corante de folhas de crajiru (arrabidaea chica) por sistemas aquosos bifásicos micelares

Abstract

The growing demand for natural dyes has driven the development of more sustainable extraction and purification technologies capable of replacing conventional processes based on organic solvents. In this context, Aqueous Biphasic Micellar Systems (ABMS) have emerged as a promising alternative for the separation of bioactive compounds due to their high water content, the properties imparted by surfactants, and their ability to operate under mild conditions. Accordingly, the objective of this study was to evaluate the potential of SABMs formed by polyethylene glycol (PEG), Triton X-114, and water in the partitioning of coloring compounds extracted from crajiru leaves (Arrabidaea chica). Therefore, extracts were prepared at a concentration of 40 mg.ml⁻¹ of leaf powder using three different methods (infusion, sonication, and maceration) and characterized in terms of colorimetric parameters, composition, and UV-Vis spectra. Partition tests in the SABM were conducted at 20 °C by varying the length of the tie-line length (TLL) and the molecular weight of the polymer (400 g·mol⁻¹ and 4000 g·mol⁻¹), the partition coefficient (k), the extraction efficiency (EE), and the Gibbs free energy change (ΔG) were evaluated. The extract obtained by maceration exhibited higher electromagnetic radiation absorption intensity, a colorimetric difference (ΔE* = 77.64 ± 0.08), antioxidant activity (DPPH = 1600.567 ± 47.808 and ABTS = 3723.44 ± 29.627), and anthocyanin content (46.5899 ± 2.0595 mg·L⁻¹). The SABMs demonstrated potential for separating the pigments present in crajiru, achieving a maximum extraction efficiency of 86.87% and a minimum of 70.80% of the dye were observed in the lower phase of the SABM formed by PEG400 in tie line 1 and PEG4000 in tie line 5, respectively. Furthermore, it was found that for all systems, k < 1 and ΔG > 0, indicating the greater difference in the physicochemical properties of the phases resulted in a greater distribution of the dye across the phases, as well as a reduction in the thermodynamic driving force for dye transfer to the upper phase. Thus, the systems studied proved to be a sustainable and efficient alternative for the recovery and concentration of natural dyes of industrial interest.