Removal of cresol contaminants from aqueous media using hydrophobic deep eutectic solvents

Cresols have distinct effects on the environment and human health. For example, o-cresol is considered a toxic isomer and can cause serious health problems. Cresol isomers generally have a negative impact on the environment as they can be hazardous to aquatic life and can accumulate in the food chain. The introduction of these chemicals has the potential to disrupt the balance of ecological systems by reducing oxygen concentrations in aqueous environments, thus affecting the viability and reproductive capacity of aquatic organisms. This work involves the use of six hydrophobic deep eutectic solvents (HDESs) for the extraction of m-cresol and o-cresol from wastewater. The HDESs include menthol:thymol, menthol:decanoic acid, thymol:decanoic acid, hydrocinnamic acid:decanoic acid, thymol:coumarin and thymol:camphor. All HDESs were prepared in a molar ratio of 1:1. The effects of various parameters such as contact time, mass ratio of HDESs to water, molar ratio of HDESs and initial concentration were investigated. The experimental results indicate excellent efficiency in the removal of cresols from wastewater using all HDESs. The extraction efficiency of > 94 % was achieved for the removal of cresol isomers from wastewater using all prepared HDESs. In addition, COSMO-RS was used to understand the extraction process.