Monoterpenoid-Based Deep Eutectic Solvents/Natural Deep Eutectic Solvents: A Review on Its Characteristics and Applications

The use of deep eutectic solvents (DES) and natural deep eutectic solvents (NADES) as green extraction solvents holds significant potential for various industrial applications. This review aims to summarize recent studies (2020-2025) on the use of sustainable solvents such as DES and NADES based on monoterpenoids in extraction processes. It also covers their production and other applications found in the literature such as extraction of natural compounds from raw materials, biorefinery, and the combination with supercritical carbon dioxide. According to the literature data, the use of green solvents can be improved through its combination with green extraction methods (ohmic heating, ultrasound, microwave, and supercritical technology). DES and NADES can be prepared in specific molar proportions with the aid of energy sources (conventional heating, microwave reactor, and ultrasound). DES/NADES composed of monoterpenoids show significant potential for industrial applications, particularly in the extraction of bioactive compounds, antioxidants, and natural pigments from food matrices. These solvents also hold potential for innovation and application across various sectors, including health, pharmacy, chemistry, environment, petrochemicals, biorefinery, metallurgy, and supercritical technology. Unexplored areas, such as the combination of monoterpenoid-based DES/NADES with supercritical carbon dioxide, the study of their phase equilibrium, and investigation of their thermophysical properties under varying temperature and pressure conditions, present interesting opportunities from a technological point of view.