Cleaning Phenolic Compounds Present in Water Using Salting-Out Effect with DCA-Based Ionic Liquids

Abstract

Water is an essential natural resource, and its contamination is an important issue at present. This study aimed to increase the techniques that can be used to clean and reuse industrial wastewater by studying the feasibility of an aqueous two-phase system to eliminate phenolic compounds from aqueous systems. The system was prepared using two hydrophilic ionic liquids based on dicyanamide anion, 1-ethyl-3-methylimidazlium dicyanamide [EMim] [DCA], and 1-butyl-3-methylimidazolium dicyanamide [BMim][DCA], and one inorganic salt, K3PO4, at three different concentrations (20, 30, and 40%). The process was tested for the removal of phenol, o-cresol, 2-chlorophenol, and a mixture of them (PCM) at initial concentrations from 0.003 to 15 g·L−1 in water. The extraction efficiencies for all the studied systems were calculated. The influence of the structure of the cation, the concentration of salt, and the initial concentration of the extracted compounds in the extraction yields were recorded. In general, the obtained results were high for all the studied systems, with extraction efficiencies of more than 90% representing the highest removal of the 2-chlorophenol compound using [EMim] [DCA] at the highest concentration of salt.