An overview of hydrophobic deep eutectic solvents driven liquid-phase extraction: Applications and prospects

Deep eutectic solvents (DESs) are a type of emerging green solvent. They are simple to prepare, cost-effective, highly atom-efficient, exhibit extremely low toxicity, and are biodegradable. Since their discovery, DESs have attracted significant interest from the scientific community across various fields. In recent years, these solvents have been extensively studied by researchers as extraction media. Hydrophobic deep eutectic solvents (hDESs) first appeared in the literature in 2015 and represent a group of DESs that meet the requirements of green chemistry. hDESs have great potential in the fields of separation and extraction and are considered effective alternatives to replace hydrophilic DESs and other hydrophobic organic solvents for the extraction of lipophilic natural products. This review summarizes pioneering and innovative work on hDESs, including the latest research progress regarding their applications, extraction techniques, and recycling methods. It also highlights issues that need to be addressed in the future. The results of hDESs in natural product extraction and the extraction of other compounds have revealed their significant potential as alternative green solvents in industrial separation processes.