## 3 Results and Discussion
### Characteristics of Anb/C and Anb/AgNP/C Composites
One explanation can be related to the presence of two exocyclic nitrogens with lone pairs of electrons participating in binding silver. To study the influences of temperature and the nanometallic phase on the adenosine adsorption rate on the activated carbon RIAA, spectrophotometric spectra were measured. Figure 6 depicts registered spectra for the adenosine adsorption process from the one- (due to the great similarity only at 10 \({}^{\circ}\)C) (Figure 6A) or two-component solutions at 10, 25, and 40 \({}^{\circ}\)C (Figure 6B-D). Based on the maximum absorption values in given moments of the experiment, the profiles of concentration (c), \(\sim\) time (t), and (c) \(\sim\) square root of time (t\({}^{1/2}\)) were obtained. It should be explained that due to the invariability of the wavelength (259 nm) of the peak corresponding to adenosine (both in one- and two-component solutions), the kinetic curves are presented in the entire time range of the experiment. The peak corresponding to silver nanoparticles (in the two-component solution), depending on temperature, is shifted, widened, and even had its characteristics changed from mono- to bimodal, so the presented kinetic curves are truncated to approx. 1200 min. of the experiment to eliminate errors of temporary concentrations. Taking into account the complexity of the experimental systems (heterogeneity of nonuniform porous carbon, macromolecular structure of adenosine, and colloidal silver phase specificity), we assumed that the kinetics of adenosine on the activated carbon RIAA from the one- and two-component solutions may be well described by the multiexponential equation. So, first, an analysis of the kinetic curves using the m-exp. equation was carried out. In Figure 7A-D the experimental data and theoretical ones for the best-fitted parame  
Figure 6: The spectrophotometric spectra collected for the adenosine adsorption process on the activated carbon RIAA from one-(**A**) or two-component solutions (**B–D**) at 10, 25, and 40 \({}^{\circ}\)C.  
ters of the m-exp. equation are presented. One can see that the adenosine adsorption rate increases with the temperature (increase in kinetic energy of the adsorbate) and at higher temperatures, the equilibrium is achieved in a shorter time. This trend applies to both nitrogenous base adsorption from the one- and two-component solutions, although in the case of the latter systems, an additional significant effect of the colloidal silver phase on the adenosine adsorption rate is found. Undoubtedly, it is related to interactions between the metallic nanoparticles, adenosine, and activated carbon, visible in the absorption spectra of the metallic nanophase as a peak wavelength shift, widening, or differentiation of two separate peaks. All these changes can be explained by the decreased stability of nanoparticles, manifested in their shape and size alteration, or even the aggregation process. Based on the data in Table 3, it was found that the achievement of 50% efficiency for the adenosine adsorption from the one-component solution required times of 121, 138, and 222 min at 40, 25, and 10 \({}^{\circ}\)C, respectively. On average, to get the same efficiency (25, 50, or 75%) at 10 \({}^{\circ}\)C, as those at 40 \({}^{\circ}\)C, the process was prolonged by about 1.8 times (Figure 8). At 40 and 25 \({}^{\circ}\)C, the equilibrium was achieved after 12.5 and 16.5 h of the experiment, respectively. At 5 \({}^{\circ}\)C, the time of 19 h was not enough to reach an equilibrium state. A significant decrease of the adsorption rate of adenosine in the accompaniment of metallic nanoparticles was observed, though at 40 \({}^{\circ}\)C this effect is least meaningful (extension of time by average of 1.9 times, compared to an average of 2.4 and 2.6 at 10 and 25 \({}^{\circ}\)C, respectively). Taking into account that at 40 \({}^{\circ}\)C, the metal nanoparticles adsorption rate is greatest, one can assume a partially independent adsorption process of the metallic nanophase and adenosine.