## 3 Results and Discussion
### The Influence of n-Hexane and Ethanol on the Viscosity, Density and Surface Tension of Canola Oil
The extraction of some substances from canola oil to the ethanol phase is confirmed by the data presented in Figure 4. The viscosity of ethanol being in contact with canola oil is larger than that of pure ethanol. The viscosity increase is caused by the substances from the canola oil dissolved in ethanol. The presence of n-hexane in the oil phase results in the decrease in ethanol viscosity. This indicates that n-hexane is in the ethanol phase. However, the volume of the ethanol phase is decreased after the contact with canola oil. Thus, there is mutual dissolution of n-hexane and ethanol as well as dissolution of some substances from canola oil in the ethanol phase. To show the mutual influence of n-hexane and ethanol dissolution on viscosity, ethanol was contacted with n-hexane. After the contact the viscosity of ethanol phase decreased from 1.22 to 1.049 mPa\(\cdot\)s and that of n-hexane increased from 0.3102 to 0.5748 mPa\(\cdot\)s. As follows from the data, there is large mutual dissolution of n-hexane and ethanol. Contrary to viscosity the changes of the density of the canola oil, n-hexane and ethanol mixture from zero to 20% of n-hexane content are insignificant (Figure 5). The density values of this mixture differ only slightly from those of diesel fuel. The changes of the density of ethanol phase after its contact with the canola oil and n-hexane mixture confirm the above conclusions about the mutual dissolution of the mixture and ethanol (Figure 6). Figure 4: The plot of the viscosity (\(\eta\)) of the ethanol phase contacted with the canola oil + n-hexane mixture vs. the n-hexane concentration (\(C_{p}\)). Apart from viscosity and density, the surface tension of canola oil is an important parameter concerning application as a diesel fuel. The surface tension of canola oil is about \(5\) mN/m larger than that of diesel fuel (Table 1) [45]. It should be remembered that the value of the surface tension of liquid decides about the size of the drops which is important in the diesel engines. The surface tension of the liquid decides also about the wetting properties of the solid [27]. According to the viscosity the contact of ethanol with the canola oil and n-hexane mixture causes a greater decrease in the canola oil surface tension than the addition of only n-hexane to oil (Figure 7). The decrease in the ethanol phase surface tension is also observed (Figure 8). However, the value of the surface tension of ethanol phase after the contact with canola oil without n-hexane is only slightly larger than for pure alcohol (Table 1) [46; 47]. This indicates that the substances from canola oil having smaller surface tension than basic components are dissolved in ethanol. As a matter of fact, the presence of the n-hexane in the canola oil reduces the surface tension of the ethanol phase. This is due to the dissolution of n-hexane in the ethanol phase. The surface tension of this phase at the concentration of n-hexane in the canola oil equal to 20 volume percent is equal to 21 mN/m (Figure 8). To determine the maximal influence of n-hexane dissolution on the ethanol surface tension the n-hexane phase was contacted with the ethanol one. It appeared that the surface  
Figure 5: The plot of the density (\(\rho\)) of the canola oil + n-hexane + ethanol mixture vs. the n-hexane concentration (\(C_{p}\)). Figure 6: The plot of the density (\(\rho\)) of the of ethanol phase contacted with canola oil + n-hexane vs. the n-hexane concentration (\(C_{p}\)). tension of the n-hexane phase was equal to 19.9 mN/m and that of the alcohol was equal to 20.4 mN/m. This fact suggests that at the concentration of n-hexane in the oil phase equal to 20%, the ethanol phase being in the contact with the canola oil and n-hexane mixture is saturated by n-hexane. The mutual dissolution of ethanol and n-hexane is important when the substances are used for changes of the physical and chemical properties of the canola oil regarding its application as the diesel fuel.