## 3 Results  
The vapor sorption isotherm curves on SGs had similar patterns at all measurement temperatures (298 K, 313 K, 333 K). They were of mixed type III and IV (IUPAC recommendation) (Figure 10) and were characteristic of weak adsorption interactions. This type of isotherms is characteristic of mesoporous materials. According to this type, sorbed water molecules become sorption sites for subsequent sorbate molecules. As reported by [PERSON] et al. [59], the process then takes on an island character and the so-called clusters are formed, indicating multi-particle adsorption. The samples sorption capacity to water vapor varied as a function of measurement temperature. As the temperature increased, the sorption capacity decreased, which agrees with fluid sorption research [60]. In the SG1 samples, the vapor sorption isotherms in the range of 0% < RH < 40% (298 K) and in the range of 0% < RH < 60% (313 K and 333 K) had a nearly linear course, almost proportional to the increase in moisture content, while they flattened out above these values (Figure 10). The SG1 sorption capacity to vapor at 0.1 MPa at 298 K, 313 K, and 333 K was 31.1 wt.%, 26.8 wt.%, and 29.1 wt.%, respectively. When CNTs were added, lower values of the total sorption capacity parameter were obtained in the SG1/CNT mixtures. H2-type hysteresis loops with different areas were noted in all samples. The difference between the adsorption and desorption equilibrium points at different RH points was from 3.6% to 8.9%. The distribution of hysteresis loops for each sample is included in Figure 11.  
Figure 9: Multiwall carbon nanotubes CNT, (**a**) magn. 8000\(\times\); (**b**) magn. 50,000\(\times\); (**c**) magn. 100,000\(\times\); (**d**) chemical composition determined by an X-ray dispersion energy spectrometer (EDS). In the SG2 samples, the almost linear vapor adsorption isotherm was in the range of 0% to 40% relative humidity (Figure 12). From 60% < RH < 70% the isotherm curve bent and for 70% < RH < 80% the increase in adsorption was smaller and tended to plateau. A vapor total sorption capacity in the range of 23.8% wt.-35.0 wt.% was achieved. Different shapes of adsorption/desorption curves and different areas of hysteresis loops were noted in these samples, which were up to 9% (Figure 13). Figure 11: The difference between the isotherms of adsorption and desorption-hysteresis loop area in SG1 in temperatures: (**a**) 298 K; (**b**) 313 K; (**c**) 333K. Figure 10: Adsorption-desorption isotherms of silica gel SG1 in the temperatures of: (**a**) 298 K, (**b**) 313 K, (**c**) 333 K.  
The use of SG/CNT mixture resulted in a decrease in the sorption capacity to vapor. As presented in Figure 14a, the ratio of change in mass in the mixture \(Q_{SG1}/CNT\) to pure \(Q_{SG1}\) was less than 1. The ratio of parameter \(Q_{SG1}/CNT/Q_{SG1}\) in the pressure of 0.1 MPa at 298 K and 313 K were at a very similar level of 0.88-0.89, while at 333 K it had the lowest value equal to 0.69. In the case of the SG2 silica gel, the \(Q_{SG2/CNT}/Q_{SG2}\) ratio, for measurements at 298 K and 333 K, were also below 1, while at 313 K in the relative humidity range of 10% \(\rm{RH}<60\%\) it was above 1 (Figure 14b). At RH = 100% at all three temperatures, the \(Q_{SG2/CNT}/Q_{SG2}\) ratio was below 1 with values in the range of 0.80-0.89, and the lowest value was obtained at 333 K.  
It was observed that the amount of adsorption increases with vapor concentration. The result was interpreted using BET isotherm. Based on the sorption equilibrium points, in the range of 0.05% \(<\) RH \(<\) 0.3%, the structural parameters were determined (Table 3). At a pressure of 0.1 MPa, the specific surface area in the SG1 sample available for vapor was in the range of 561-674 m\({}^{2}\)/g. In the SG2, this value was at a lower level, in the range of 359-459 m\({}^{2}\)/g. The addition of CNTs increased the vapor accessible specific surface area in the SG1/CNT mixture to 641-997 m\({}^{2}\)/g and in SG2/CNT to 425-743 m\({}^{2}\)/g.