Hydrophobic deep eutectic solvents characterization and performance for efficient removal of heavy metals from aqueous media

Abstract

In this study, we successfully extracted copper, cobalt, and nickel metals from aqueous media using hydrophobic deep eutectic solvents (DESs). The DESs designed for this research consisted of a combination of carboxylic acids, namely Octanoic acid, Nonanoic acid, Decanoic acid, and Dodecanoic acid. Before and after the extraction process, the prepared DESs underwent comprehensive characterization using various analytical techniques. Viscosity measurements demonstrated that the prepared solvents exhibited low viscosity at room temperature, making them well-suited for extraction processes. Moreover, Karl Fischer Titration was employed to accurately determine the water content, which is crucial for evaluating hydrophobicity. We investigated the influence of various parameters on the metal extraction yield, including the initial concentration, temperature, and time. Under optimized conditions, using Dodecanoic acid + Octanoic acid as the most efficient DES, extraction yields of 85.61 % for Cu, 96.19 % for Co, and 76.54 % for Ni were achieved. Furthermore, through approximately three extraction steps, complete removal of metal ions from the aqueous medium was achieved. Due to its superior performance, the DES composed of Dodecanoic acid + Octanoic acid was selected for further investigations. The DESs exhibited favorable characteristics such as low viscosity and hydrophobicity, positioning them as promising for extraction in aqueous environments.