Application of hydrophobic solvents based on L-menthol, as greener alternatives to classical solvents for Pb(II) ions extraction.

Deep eutectic solvents (DESs) as a new-generation of solvents are receiving increasing attention as environmentally friendly solvents in various analytical techniques. These solvents are new generation solvents, and based upon what they are derived from, they can be the safest, cheapest, and most effective extraction methods available. With DES, the extraction efficiency and metal ion recycling are significantly improved. In this work, the potential application of these solvents for the extraction of Pb(II) ions was investigated. For that purpose, hydrophobic DESs (HDESs), based on L-menthol as H-acceptor and decanoic acid as H-donor, were prepared at molar ratios of acceptor to donor of 1:1 and 1:2. In the optimized extraction procedure, the Pb(II) ions were extracted into the organic phase with the efficiency of 94.3% and 97.3% for 1:1Men:DecA and 1:2 Men: Dec A, respectively. The results also showed that unlike of classical liquid-liquid extraction methods, in the original solutions, counterions are not required to transfer the analyte to the hydrophobic phase. Furthermore, no ligands were required to transfer the analyte ions to the HDES phase: the results show that the extraction efficiency of 1:1 HDES decreased to 88.65% in the presence of 18C6, and to 96.5% for 1:2 HDES. Comparable results for HDES (1:1 Men: DecA) extraction efficiency in the proposed method with the efficiency of 1,2- dichloroethane and chloroform in classical methods (96.7% and 92%, respectively), without counterions and without the requirement for ligands as carriers, make this HDES-based extraction method simpler, less expensive, and most importantly, more environmentally friendly. [ABSTRACT FROM AUTHOR]