## 3 Result and Discussion
Indeed, the XRD pattern (Figure 6) revealed that the inorganic load consisted mainly of metallic copper (peaks at 20 = 43.44 and 50.57, ICSD Card No. 43493). Figure 3: XRD patterns of the residues in air of (**a**) M/Cu\({}_{2}\)O, (**b**) G/Cu\({}_{2}\)O, (**c**) M/Cu, (**d**) G/Cu. X-ray diffraction method provides a very simple possibility for estimating the crystallite size from the broadening of the XRD reflections via the Scherrer equation:  
\[D_{\rm hkl}=K\lambda/(\rm B_{\rm hkl}cos\theta), \tag{1}\]  
where \(D_{\rm hkl}\) is the crystallite size in a direction perpendicular to the reflection planes (hkl); \(\lambda\) is the X-ray wavelength (0.15418 nm); \(K\) is the Scherrer constant related to crystallite shape, normally taken as 0.94; \(\rm B_{\rm hkl}\) is the full-width at half-maximum in radians; and \(\theta\) is the Bragg angle. The most intensive diffraction peaks (111) of Cu and and (002) of CuO were analyzed to determine the particle size. The mean crystallites size of copper and copper oxide were determined as 48 nm and 58 nm correspondingly. The residue remaining after the pyrolysis of M/Cu\({}_{2}\)O, M/Cu, G/Cu\({}_{2}\)O and G/Cu amount to respectively about 31.2, 28.5, 26.8 and 24.3% of the original sample. As reported in our previous paper [31], the residue remaining after the pyrolysis of the reference materials (the anion exchangers with no copper deposit) amounted to respectively  
Figure 4: TG/DTG curves in N\({}_{2}\) of (**a**) M/Cu\({}_{2}\)O, (**b**) M/Cu. 11.2 (M) and 14.1% (G) of the original sample. A comparison of the above values provides interesting information about the essence of the pyrolysis of the HIXs. If one adds up the residue remaining after the pyrolysis of the reference material and the predicted (on the basis of the data presented in Table 1) metallic copper content in the product of the pyrolysis of a given material, one gets a result lower than the actual experimentally determined amount of residue. In the previous study we suggested a mechanism according to which an additional amount of char formed as a result of hydrogen expenditure for the reduction of cupric compounds (whereby there had been a hydrogen deficit in the reaction medium and the alkyl radicals, instead of generating volatile decomposition products, underwent condensation into products with larger non-volatile particles). In the present study the residue remaining after the pyrolysis of M/Cu\({}_{2}\)O and G/Cu\({}_{2}\)O (where the reduction of Cu\({}_{2}\)O to Cu\({}^{0}\) had taken place) was larger than the residue remaining after the pyrolysis of M/Cu and G/Cu (where no reduction had taken place) but was clearly smaller than the residue remaining after the pyrolysis of M/CuO and G/CuO (where two-step reduction had taken place) [31]. Figure 5: TG/DTG curves in N\({}_{2}\) of (**a**) G/Cu\({}_{2}\)O, (**b**) G/Cu. The following comparisons lead to interesting conclusions concerning the pyrolysis of the HIXs doped with copper containing deposit. The solid residues determined by us for the samples M/CuO, M/Cu\({}_{2}\)O, M/Cu and M form the series 34.1, 31.2, 28.5 and 11.2% respectively, while the series for G/CuO, G/Cu\({}_{2}\)O, G/Cu and G is 39.5, 26.8, 24.3 and 14.7% (Scheme 2). The data indicate that the higher the oxidation state of the copper atoms present in the deposit was, the greater was the amount of the solid residue formed as a result of pyrolysis. In other words, since under N\({}_{2}\) the transforming organic phase is capable of reducing the inorganic deposit, more of the latter condenses into products with large non-volatile particles than in the case of pure resin. The above observations do not fully explain the char formation mechanism as there was a significant difference in the amount of solid residue between M/Cu and M (and also between G/Cu and G), where no deposit reduction took place.