## 3 Results and Discussion
### Study of the Multicomponent Extraction Capability  
Regarding the study of the extraction capability of these solvents to remove a mixture of phenols, an aqueous solution of these three phenolic compounds--phenol, o-cresol, and 2-chlorophenol (using equal amount of each one)--was prepared, and the extraction yield was determined following the same experimental procedure. The results plotted in Figure 3 show that high extraction efficiencies were obtained with all studied solvents, except when [1P1 Mpyr][Nf2] is used to extract phenolic compounds at low concentration.  
Figure 2: Extraction efficiency (E%) versus initial concentration of phenolic compounds (C\({}_{i}\)), (**A**) for the extraction of 2-chlorophenol using [1P1 Mpip][NTf2] (—) and [1P3 Mpy][NTf2] (—); (**B**) for the extraction of o-cresol using [1P1 Mpip][NTf2] (—) and [1P1 Mpyr][NTf2] (—).  
The extraction efficiency remains practically constant when the initial concentration of phenol mixture is higher than 0.05 g\(\cdot\)L\({}^{-1}\), being above 90% (Table S4).  
In spite of the presence of more than one phenolic compound, the extraction capability of these solvents was not affected, presenting high extraction efficiency values comparable with the results obtained to remove only one phenolic compound. Attending to the final concentration of the phenolic compound mixtures (Table S5), the legal limit was reached in only one cycle for initial concentrations below 50 mg\(\cdot\)L\({}^{-1}\) for all studied ILs, following the same behavior as when only one phenolic compound was studied. Consequently, it is possible to conclude that all these studied solvents are also good extraction agents for removing phenolic compounds from water when a mixture of them is present.  
In industrial wastewaters, not only different phenolic compounds are present, but also other kind of substances, such as salts or other pollutant agents, can be found. Different studies about the influence of the presence of salts in aqueous solution on the extraction of phenolic compounds have been published. The effect of the NaCl in the extraction of resorcinol, phenol, guaiacol, o-cresol, and p-nitrophenol whit [C\({}_{4}\)C\({}_{11}\)OHim][BF\({}_{4}\)] as extraction agents was carried out by [PERSON] et al. [14]. Experimentally, it was observed that the presence of this salt increases significantly the extraction efficiency, being more remarkable when the concentration of salt increases. This behavior was explained through the salt ions attracting water molecules (salting-out effect), and thus decreasing the water free molecules concentration [14].  
In general, good extraction efficiencies were obtained for all studied systems. The [\({}^{1}\)P\({}^{1}\)Mpyr][Nf\({}_{2}\)] ionic liquid presents good results even at low initial concentrations for individual phenolic compounds. These observations are in agreement with the results obtained in previous studies of this group, where the capability of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (C\({}_{2}\)mim)FSI to remove phenols from water were studied. High extraction efficiencies, greater than 90%, were also obtained for all initial concentrations of phenol, o-cresol, and 2-chlorophenol [7].