## 3 Result and Discussion
Thus the decomposition of M, M/Cu\({}_{2}\)O and M/Cu ended at the temperatures of 594, 579 and 554 \({}^{\circ}\)C, while the decomposition of G, G/Cu\({}_{2}\)O and G/Cu terminated at the temperatures of 641, 591, and 518 \({}^{\circ}\)C, respectively. Interestingly, as regards the number of transformations (four stages) only the decomposition of M/Cu in air (Figure 1b) resembled the decomposition of M alone. As described in detail in our previous paper [30], the reference material, i.e., the macroreticular anion exchanger (M), decomposed in four stages which was due to water evaporation, functional group decomposition, benzene ring elimination from the styrene/divinylbenzene copolymer and the ultimate destruction (burning and incineration) of the polymeric matrix. In the case of M/Cu, the second stage of decomposition (the splitting off of the functional groups) proceeded at a relatively low temperature (in the range of 131-271 \({}^{\circ}\)C at the maximum decomposition rate of 4.2%/min at 201 \({}^{\circ}\)C, with a weight loss of 27%). As the functional groups of M/Cu were in the ascorbate form, it was concluded that the organic acid salt form (similarly as the OH\({}^{-}\) form) accelerated (as opposed to the mineral acid salt form Cl\({}^{-}\), SO\({}_{4}\)\({}^{2-}\)) the splitting off of the functional groups shifting this transformation by almost 100 \({}^{\circ}\)C towards higher temperatures [31]. This phenomenon could also have been the result of the catalytic (accelerating) action of Cu\({}^{0}\) as the final two stages of the thermal decomposition of M/Cu also proceeded at a lower temperature in comparison with M alone. The TG/DTG curves under air for M/Cu\({}_{2}\)O, G/Cu\({}_{2}\)O and G/Cu (Figures 1a and 2a,b) had a similar but unconventional shape, very different than for M/Cu (Figure 1b). At the temperature above 275 \({}^{\circ}\)C, after the functional groups have split off, one can see four transformations instead of two. The large number of small-area peaks indicates that the decomposition of the hydrocarbonaceous matrix was complicated due to the oxidation of Cu\({}_{2}\)O and Cu\({}^{0}\) to CuO. An XRD analysis (Figure 3) showed CuO to be present in the products of the combustion of all the samples. The set of reflections at 20 = 32.68, 35.73, 38.89, 48.91, 53.70, 58.29, 61.71, 66.04 and 68.25 was consistent with ICSD Card No. 16025. Then the TG/DTG curves recorded during pyrolysis (thermal decomposition under inert atmosphere) were analyzed. Figures 4 and 5 show that the pyrolysis of all the samples proceeded similarly and typically for this process, i.e., in three stages: dehydration, the cleavage of the functional groups, and the decomposition of the polymer matrix [11; 30; 31]. The pyrolysis of all the samples would end at a temperature considerably lower than their combustion (about 450 \({}^{\circ}\)C vs. about 550 \({}^{\circ}\)C). Moreover, differently than in air, under nitrogen the presence of fine particles did not accelerate, but slightly slowed down the decomposition of the polymer matrix. Thus the effect of Cu\({}^{0}\) and Cu\({}_{2}\)O on the pyrolysis of both the macroreticular anion exchanger and the gel-like one was to a large extent similar to the effect of CuO [31]. The most interesting aspects of the pyrolysis of the investigated materials were connected with the composition and amount of the solid residue (Table 2). The residue remaining after the pyrolysis of the HIXs (pyrolysate) had a much larger mass than the post-combustion residue (ash) since besides a mineral phase it contained an organic phase (char). More precisely, the pyrolysate contained char (a mixture of various high molecular weight organic compounds constituting a product of the decomposition of the polymer's hydrocarbonaceous matrix in oxygen-free conditions) and inorganic matter (mainly deriving from the deposit). Our previous study showed that during pyrolysis the CuO particles contained in the HIXs had undergone reduction to Cu\({}^{0}\)[31]. Therefore we expected a similar result in this study.