Hydrophobic deep eutectic solvents as extraction agents of nitrophenolic pollutants from aqueous systems
Olalla G. Sas, Lorena Villar, Ángeles Domínguez, Begoña González, Eugénia A. Macedo
Abstract
Nitrophenolic compounds are hazardous substances, listed as priority pollutants by World Health Organization, due to their toxicity on both the environment and human health. They are used in agriculture as insecticides and fungicides substances, and they can contaminate water reserves by filtering through the soil into groundwater. Therefore, these substances must be removed from agricultural wastewater before being discharged. In this work, several Deep Eutectic Solvents, based on menthol, thymol and organic acid, are used as separation agents in liquid–liquid extraction to remove 2-nitrophenol and 4-nitrophenol from water. The optimal extraction conditions were studied and the better extraction yields were obtained using: (1:1) VDES:VW ratio and 30 min of stirring time. All extraction experiments were carried out at 298.15 K and 30 min of centrifugation time at 6000 rpm. As the results show, these deep eutectic solvents based on menthol can be used to extract both nitrophenolic compounds, while those based on thymol can only be applied for the removal of 4-nitrophenol. All studied solvents present high extraction efficiencies, over to 90%, assuring their capability as extraction agents in aqueous systems.