All-fatty acid hydrophobic deep eutectic solvents towards a simple and efficient microextraction method of toxic industrial dyes

A simple and efficient microextraction method using fatty acid-based hydrophobic deep eutectic solvent (HDES) mixtures for the removal of several toxic industrial dyes malachite green, methyl violet, and methylene blue in aqueous solution was developed. The phase diagrams of the C12:C8, C12:C9, and C12:C10 HDES mixtures were first determined and the mole fractions corresponding to their eutectic points were used for the liquid-liquid microextractions. It was observed that the performance of the HDES mixtures varied across different dye contaminants and changing the HDES dose, dye concentration, and contact time further improved or decreased the performance of the HDES extractant. Very high extraction efficiencies of 99% were achieved for malachite green and methyl violet, while 95% efficiency was achieved for methylene blue. This study demonstrates a green and sustainable method for the microextraction of toxic industrial dyes using fatty acid-based HDES mixtures. (C) 2020 Elsevier B.V. All rights reserved.