Synthesis and Characterisation of Menthol-Based Hydrophobic Deep Eutectic Solvents

Hydrophobic deep eutectic solvents (HDESs) have found applications in water purification in recent years. The extent of their stability in aqueous media determines whether they are suitable materials for water purification or if they end up constituting a greater pollution load to the water they are to purify. This work sought to prepare HDESs from a monoterpene (menthol), and three long-chain organic acids (octanoic acid, decanoic acid, and dodecanoic acid). The physicochemical characteristics of the prepared HDESs were investigated. Thereafter, their moisture absorption capacity and stability in an aqueous medium were determined to ascertain whether or not they were hydrophobic as predicted.