Harnessing the power of natural deep eutectic solvents (choline chloride/sucrose) and polypropylene glycol in the formation of aqueous biphasic systems and the application of these systems in drug extraction

Abstract

In recent times, there has been considerable interest in utilizing aqueous biphasic systems (ABSs) containing natural deep eutectic solvents (NADESs) for the extraction of various substances. In this study, we focused on investigating the phase behavior of ABSs composed of poly(propylene) glycol 400 and NADESs (specifically, choline chloride/sucrose with molar ratios of 2 : 1 and 1 : 1). By analyzing the compositions of tie-lines, it was observed that these ABSs, which consist of four components, exhibit characteristics similar to ternary systems. To examine the influence of molar ratios on phase separation, the binodal model was applied to the obtained binodal data. The NRTL and UNIQUAC models were employed to establish correlations for the tie-lines. Moreover, we examined the extraction capabilities of the aforementioned ABSs for three commonly used drugs: diclofenac potassium, acetaminophen, and salicylic acid. To assess the efficiency of extraction, partition coefficients and extraction efficiencies were calculated for each drug. The results revealed that the extraction efficiency of these drugs into the polymer-rich top phase is dependent on their hydrophobicity. Furthermore, we employed the Diamond–Hsu equation, along with its modified version, to establish correlations between the experimental partition coefficients of the drugs and NADES overall concentrations.