**3.1 Chemicals and experimental procedure**

The ILs [EMim][NTf2] and [HMim][NTf2] were supplied by IoLiTec GmbH. They were subjected to vacuum and moderate temperature (P = o.2 Pa, T = 343 K) for several days to eliminate water and volatile compounds that could be present. Cyclohexane, heptane and toluene were supplied by VWR Prolabo, and they were used without further purification. Mass purity of all chemicals was higher than 99%. In order to prevent water absorption, all chemicals were kept and manipulated under inert gas atmosphere.

**Figure 1** shows a representation of the quaternary systems studied in this work where grey surfaces represent the miscible areas on the top and the base of the tetrahedron. Due to the very negligible miscibility of these ILs in the aliphatic mixture (checked by <sup>1</sup> H-NRM), no IL is present in the aliphatic hydrocarbon phase. For the determination of liquid-liquid equilibrium data, samples of a mixture of the four components were prepared by weight using a Mettler AXE-205 Delta Range balance. In order to select the composition of the initial samples, a sectional plane (SP), in which the mole fraction of the ionic liquid is constant, was selected as it can be seen in **Figure 1**. This sectional plane is perpendicular to the tie lines, and the compositions of the other three compounds involved in the initial quaternary mixtures were selected in such a way that they cover the sectional plane.

The samples were vigorously stirred by using a magnetic stirrer for 6 hours and left to settle down overnight. Afterwards, a sample of each phase was withdrawn with a syringe, and it was analysed by gas chromatography.

The compositions of cyclohexane, heptane and toluene were analysed with a Hewlett-Packard 5890 Series II gas chromatograph with a Hewlett-Packard 5971 mass selective detector and a Hewlett-Packard-5MS capillary column (60 m × 0.250 mm × 0.25 μm). Because of the IL negligible vapour pressure, they cannot be analysed by gas chromatography; consequently, their composition was calculated through a mass balance. An empty precolumn was used to avoid the IL that could not be retained by the liner to go into the chromatograph. The temperature programme has initial temperature of 343.15 K for 10.30 min, ramp of 15 K min<sup>−</sup><sup>1</sup> and final temperature of 368.15 K for 4.30 min. The injector and detector were maintained at 553.15 K, and the helium carrier gas flow rate was kept constant at 1 mL min<sup>−</sup><sup>1</sup> in the column. Two analyses of each sample were performed to obtain a mean value.

**73**

**Table 1.**

*(1) + cyclohexane (2) + toluene (3) + [EMim][NTf2] (4).*

*Extraction of Aromatic Compounds from Their Mixtures with Alkanes: From Ternary…*

In order to determine the error in the composition, quaternary mixtures with known composition were analysed by chromatography, and their obtained compositions were compared with those obtained by weight. The error in the compositions

From experimental values, solute distribution coefficient, β, and selectivity, S,

*IIx*1+2 *<sup>I</sup>* /*x*<sup>3</sup> *I x*1+2

**Hydrocarbon-rich phase IL-rich phase β S**

0.778 0.151 0.018 0.010 0.062 0.87 28.97 0.717 0.123 0.020 0.010 0.133 0.83 23.28 0.639 0.182 0.021 0.015 0.147 0.82 18.73 0.522 0.167 0.019 0.014 0.242 0.78 16.25 0.445 0.149 0.018 0.014 0.294 0.72 13.44 0.367 0.153 0.017 0.015 0.329 0.69 11.14 0.196 0.180 0.010 0.022 0.405 0.65 7.63 0.561 0.241 0.03 0.024 0.153 0.77 11.48 0.408 0.264 0.014 0.024 0.249 0.76 13.42 0.351 0.226 0.014 0.022 0.301 0.71 11.41 0.255 0.254 0.010 0.026 0.341 0.69 9.82 0.143 0.271 0.007 0.031 0.392 0.67 7.29 0.604 0.326 0.029 0.029 0.057 0.81 13.06 0.423 0.352 0.013 0.031 0.183 0.81 14.33 0.317 0.357 0.011 0.033 0.248 0.76 11.65 0.264 0.328 0.010 0.033 0.295 0.72 9.95 0.523 0.427 0.014 0.031 0.041 0.82 17.31 0.340 0.427 0.011 0.037 0.191 0.82 13.10 0.229 0.444 0.004 0.039 0.246 0.75 11.77 0.165 0.403 0.005 0.041 0.313 0.72 8.95 0.436 0.501 0.009 0.036 0.052 0.83 17.19 0.322 0.510 0.012 0.049 0.138 0.82 11.20 0.247 0.511 0.007 0.045 0.190 0.79 11.44 0.350 0.589 0.024 0.072 0.052 0.85 8.34 0.241 0.587 0.004 0.066 0.138 0.80 9.49 0.150 0.623 0.006 0.071 0.182 0.80 8.05

*Experimental LLE data, solute distribution coefficients, β, and selectivity, S, for the quaternary system heptane* 

**II x3**

**II**

**II x2**

*II*/*x*<sup>3</sup>

*<sup>I</sup>* (1)

*II* (2)

*DOI: http://dx.doi.org/10.5772/intechopen.86229*

were calculated by the following equations:

*S* = *x*<sup>3</sup>

β = *x*<sup>3</sup>

**<sup>I</sup> x1**

was estimated to be ±0.004.

**3.2 Results and discussion**

**<sup>I</sup> x2**

**x1**

**Figure 1.** *Schematic representation of the quaternary system and the sectional plane (SP).*

*Extraction of Aromatic Compounds from Their Mixtures with Alkanes: From Ternary… DOI: http://dx.doi.org/10.5772/intechopen.86229*

In order to determine the error in the composition, quaternary mixtures with known composition were analysed by chromatography, and their obtained compositions were compared with those obtained by weight. The error in the compositions was estimated to be ±0.004.
