## 3 Results and Discussion
### Adsorbents Characteristics
#### 3.1.2 Structure of Nano-Sized Materials by XRD and Small-Angle X-ray Scattering
The intensity of the scattering effect of the carbons C1-C4 (Figure 7A) differs in the initial phase of the SAXS curve. This may suggest various proportions of the scattering objects with mesoporous dimensions depending on the carbon type (in particular on the type of polymer matrix and the thermal treatment time during their synthesis), (inset in Figure 7A). This is supported  
Figure 6: XRD patterns of mesoporous carbon (C1–C4) and polymeric materials (P1, P2). by the porosity of the materials described by nitrogen adsorption/desorption data (Table 4). Here, sample C4 shows the highest share of porosity in the range of mesopores (pore sizes of 4.05 and 3.74 nm for D\({}_{\mathrm{BH}ads}\) and D\({}_{\mathrm{BH}ads}\), respectively). The second highest SAXS intensity is demonstrated by the sample C2. Similarly, the pore sizes of 3.43 and 3.24 nm (Table 4) for D\({}_{\mathrm{BH}ads}\) and D\({}_{\mathrm{BH}ades}\) distributions remain consistent with SAXS observations. Moreover, the SAXS curve for C4 runs at most up to the scattering vector value of 0.2 A\({}^{-1}\). When the observed feature of momentum transfer q is correlated with the length scale d probed in an X-ray scattering experiment by \(\mid\) q\(\mid\) = 2\(\pi\)/d, the size of inhomogeneity (d [A]) can be calculated. Here, the position of q = 0.2 A\({}^{-1}\) corresponds to the d \(\sim\)3.1 nm. From the above, sample C4 can contain objects with sizes above 3.1 nm in larger quantities than in other samples. Similarly, carbon C3 shows the fewest objects with such characteristics. Another feature of the tested porous carbons is the heterogeneity of the SAXS scattering curve. Some fluctuations in the curve may indicate characteristic structural elements. In all cases, the SAXS curves reveal the presence of inhomogeneities at position q = 0.025 A\({}^{-1}\). This corresponds to the objects of theoretical size \(\sim\)25 nm. Taking into account the complex porous structure formed during carbon preparation (especially during the removal of the silica matrix when the extended porosity is formed), it is possible to obtain a hierarchical porous structure with elements of similar sizes. This can be confirmed by TEM images, which show extensive porosity with such characteristics [60]. Taking into account the course of the scattering curve, carbon materials differentiate into two groups. Taking into account the type of polymer matrix used for the synthesis of carbons (PE9400 for C1 and C3 and PE6400 for C2 and C4), they can determine the formation of porosity with different characteristics. Differences in the porous structure translate directly into the nature of the interaction of the nanostructure with X-ray radiation at low angles and determine the shape and course of the experimental curve (Figure 7A). In the case of carbon materials, these differences are quite significant. By analysing the shape and extent of X-ray scattering in Figure 7, it can be found that the scattering effect of the carbon (Figure 7A) and polymer materials (Figure 7B) is quite different. Polymer materials generate a significant SAXS effect in the range of small diffraction angles, which suggests the presence of nano-objects involved in this phenomenon. They exhibit a polydispersive nature that highlights the absence of any structural ordering or enhanced heterogeneity features. The scattering intensities are significant, although the shape of the experimental curves is very similar. A characteristic feature of the polymer samples (Figure 7B) is the intersection of the SAXS curves at the position q = 0.025 A\({}^{-1}\). This could indicate the differentiation of the proportion of objects with sizes of 25 nm. In the initial region of the SAXS curve, i.e., below the value q = 0.025 A\({}^{-1}\), the scattering  
Figure 7: SAXS patterns of the investigated carbon C1–C4 (**A**), and polymer (**B**) materials. intensity for the sample P1 is higher, while after passing this point the intensity of the SAXS curve for the sample P2 is slightly higher.