Deep eutectic solvents (DESs) have emerged as promising green alternatives to conventional organic solvents for the extraction of bioactive compounds from natural matrices because of their tunable physicochemical properties, low toxicity, and environmental compatibility. However, most existing reviews primarily focus on application-based results, with limited mechanistic and process engineering interpretations necessary for industrial applications. This review provides a comprehensive analysis of DES-based extraction from the perspective of separation and process engineering, emphasizing the relationships between DES composition, physicochemical properties, mass-transfer behavior, and extraction performance. Key parameters, including viscosity, hydrogen bonding interactions, solvent-to-feed ratio, temperature, and water content, are critically evaluated in terms of their influence on extraction efficiency, selectivity, and scalability. Furthermore, solvent recovery, process intensification strategies, and industrial implementation challenges are discussed to bridge the gap between laboratory research and large-scale application. By integrating mechanistic insights with process-level considerations, this review provides a systematic framework for the rational design and optimization of DES-based extraction processes as sustainable and scalable-separation technologies.

The aim of this study was to extract pomegranate peel waste, a by-product of the fruit juice industry, and enrich it with ellagic acid using cost-effective, scalable physical separation methods. To achieve this, ultrafiltration was employed as a pre-enrichment technique. The results showed that ellagic acid was selectively concentrated in the retentate fraction, with an 118% increase in purity when a 10 kDa cut-off membrane was used. Subsequently, the adsorption efficiency of two adsorbents, Amberlite XAD-4 resin and activated charcoal, was evaluated for ellagic acid enrichment. Adsorption experiments were performed using adsorbent concentrations of 0.5%, 1%, 2%, and 4%, followed by testing the desorption steps separately with 70% ethanol, methanol, and absolute ethanol for 24 h. Static adsorption tests revealed that 2% activated carbon and 4% Amberlite XAD-4 resin achieved the highest adsorption efficiencies, with 100% and 99.3% for ellagic acid, respectively. These cost-effective and environmentally friendly processes significantly enhanced the ellagic acid concentration in pomegranate peel-derived polyphenols, reaching 17.4 g/100 g dry weight (DW). This demonstrates their potential for the sustainable valorization of fruit waste. The methodology presented here offers an efficient and scalable approach for the recovery of ellagic acid, supporting the development of a circular bioeconomy by converting agricultural by-products into high-value bioactive compounds.