Solvo-Surfactant Properties of Dialkyl Glycerol Ethers: Application as Eco-Friendly Extractants of Plant Material through a Novel Hydrotropic Cloud Point Extraction (HCPE) Process

Six dialkyl glycerol ethers with short alkyl chains have been synthesized, and their solvo-surfactant properties have been compared to those of the mono- and trisubstituted isomers. The dialkyl ethers are completely miscible with water at room temperature, and some of them show a cloud point. In aqueous solution, they are much better solubilizers of Disperse Red 13 hydrophobic dye than the trialkyl ethers. They also have much lower boiling points than the isomeric monosubstituted counterparts. These features make the dialkyl glycerol ethers attractive for aqueous extraction of hydrophobic material. Their volatility allows an easier recovery of solute compared to when nonvolatile nonionic surfactants are used, as in the standard cloud point extraction (CPE) process. The effectiveness of the novel hydrotropic cloud point extraction (HCPE) method proposed in this work is illustrated by extraction of piperine from black pepper using an aqueous solution of 1-butyl-3-methyl glycerol ether that is an attractive candidate in the series because of its ease of synthesis, volatility, middle-range cloud point, and high solubilizing power.