Reverse Pluronic 10R5-Based Aqueous Biphasic Systems with Ammonium Salts: A Novel Platform for Phenolic Compound Partitioning

The valorization of lignocellulosic biomass is essential for developing sustainable bioprocesses and producing high-value compounds such as phenolics. However, the efficient separation of these compounds remains challenging due to their structural diversity. This study explored the use of aqueous biphasic systems (ABS) composed of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), Pluronic 10R5, and different biodegradable ammonium salts (acetate, tartrate, and citrate) for the extraction of phenolic compounds. Phase diagrams were constructed at three temperatures (289.2, 298.2, and 313.2 K) and characterized by the binodal curve, tie-line length, and slope of the tie-line, with phase inversion phenomena observed for the first time in reverse Pluronic-based systems. The system with ammonium citrate exhibited the best performance in terms of extraction efficiency, biodegradability, and pH compatibility, resulting in stable phenolic compound stability. Five model compounds were evaluated, yielding partition coefficients ranging from 3.5 to 6.5 and extractions exceeding 80% in the polymer-rich phase. These findings demonstrate the potential of sustainable ABS as an effective platform for selective recovery processes in lignocellulosic biorefineries.