Liquid-liquid extraction of chlorophenols from wastewater using hydrophobic ionic liquids

In this work, liquid-liquid extraction of 3-chlorophenol, 2, 5-dichlorophenol, 2, 4, 6-trichlorophenol and pentachlorophenol from wastewater was conducted using five hydrophobic ionic liquids (ILs). Moreover, the impact of key parameters like molecular structure, pH, temperature, phase ratio and initial concentration of feed on the removal of the chlorophenols (CPs) from their aqueous solution were studied. The results showed that the molecular structure of the IL has an important impact on the removal of CPs. Generally, the evaluation of different ILs with the same CPs revealed that piperidinium and pyridinium based ILs have greater extraction efficiency than sulfonium and imidazolium based ILs. It was found that the extraction efficiency decreased with the decrease of IL:wastewater mass ratio, with a maximum extraction at a ratio of 1:1. The results showed that temperature and initial concentrations in the range of 25–45 °C and 4–1000 mg/L, respectively had no significant impact on the extraction for all studied systems.