## 3 Swelling of the spatial high molecular scaffold of adsorbent. In our case, the most likely cause may be the first one. To calculate the parameters of synthesized NC, the obtained isotherms were analyzed using the Quantachrome TouchWin program. In particular, to determine the specific surface area, the multipoint BET method [30] was applied, using the experimental data approximation by a straight line in the range of the relative pressure \(P/P_{0}=0.05\div 0.35\), cf. Figure 9. The coefficient of correlation with the model was 0.996 for all nanocomposites. As the result of calculations, the values of specific surface area and pore volume were obtained, as presented in Table 5. The obtained values of the specific surface area for samples NC1_10 and NC1_5 are slightly smaller than the values calculated by SAXS patterns. This difference is significantly bigger for the NC2 sample. These facts indicate that a significant part of the porous space of the samples NC1_10 and NC1_5 is open and accessible to adsorbed molecules, which is not the case for NC2 nanocomposite. The nature of adsorption isotherm behavior shows a significant effect of micropores in the studied nanocomposites. This allows using the density functional theory (DFT) method for modelling, which is based on quantum mechanical calculations with the use of fundamental molecular parameters characterizing gas-gas and gas-solid interactions in the adsorption system. We have chosen a model of slit-like pores with perfectly flat graphene walls [31]. The results of calculating the pore distribution are shown in Figure 10, and the specific surface area and volume of micropores are presented in Table 5. The behavior of curves in Figure 10 completely follows the behavior of the curves calculated on the basis of SAXS patterns (Figure 8), only with a shift to the area of micropores, because the DFT method gives the best results precisely for this part of the porous structure of  
Figure 9: Isotherms of nitrogen adsorption at 77 K by synthesized nanocomposites, 1—NC1_10; 2—NC1_5; 3—NC2. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{3}{c}{**Multipoint BET Method**} & \multicolumn{2}{c}{**DFT Method**} \\ \cline{2-5}  & \(\mathbf{S}\)**, m\({}^{2}\)/g** & \(\mathbf{V}\)**, cm\({}^{3}\)/g** & \(\mathbf{\widetilde{r}}\)**, nm** & \(\mathbf{S}\)**, m\({}^{2}\)/g** & \(\mathbf{V}\)**, cm\({}^{3}\)/g** \\ \hline NC1\_10 & 224.5 & 0.148 & 1.32 & 187.8 & 0.128 \\ NC1\_5 & 218.8 & 0.145 & 1.33 & 184.3 & 0.127 \\ NC2 & 296.7 & 0.167 & 1.16 & 329.2 & 0.146 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Parameters of the porous structure of synthesized nanocomposites according to nitrogen adsorption/desorption data. samples. Thus, the nickel chloride activator promotes the development of the carbonaceous materials' surface, especially by the two-stage synthesis. The activation efficiency is not as significant as with FeCl\({}_{3}\)[32], but the activation mechanisms are probably similar. Hysteresis loops of the synthesized Ni/C nanocomposites are shown in Figure 11, and the values of coercive force (\(H_{\rm c}\)), specific saturation magnetization (\(\sigma_{\rm s}\)), and relative residual magnetization (\(\sigma_{\rm r}\)/\(\sigma_{\rm s}\)) are given in Table 6. Table 6 shows that the values of the specific saturation magnetization of composites NC1_10 and NC1_5 significantly exceed the magnetization of previously synthesized Fe/C composites [22], where the carrier of the magnetic moment was Fe\({}_{3}\)O\({}_{4}\) oxide. Slightly lower and close to the values of Fe/C is the value of the specific saturation magnetization of the nanocomposite NC2. However, the previously given values of the specific saturation magnetization are sufficient, for example, for the use of composites as magnetically controlled adsorbents. Figure 11: Hysteresis loops of the magnetic moment of composites: 1—NC1_10; 2—NC1_5; 3—NC2. In insets: range of small values of the magnetic field strength.