## 3 Results and Discussion  
Figure 1 shows the FTIR spectrum of the ACCS, which shows a rather simple course. The spectrum contains only two well-defined peaks at 3463 cm\({}^{-1}\), corresponding to the -OH vibrations of the phenolic group; and at 1635 cm\({}^{-1}\), which can be attributed to the C=O  
stretching vibrations of aldehydes, ketones, and carboxylic acids [40; 41]. A similar course was observed in the case of the activated carbon used for the phosphate removal presented by [PERSON] et al. [42] and the activated carbon used for the synthetic dye removal presented by [PERSON] and [PERSON] [43]. The relatively low number of observed peaks may indicate a high conversion temperature, which unfortunately was not declared by the producer. According to [PERSON] [44], the intensity of the bands between 1234 and 1153 cm\({}^{-1}\) decreases with increasing temperatures used for the activated carbon preparation. The SEM images taken at different magnifications are presented in Figure 2. As the micrographs taken at lower magnifications show, the activated carbon particles had a regular shape and a rather smooth surface without the cracks, crevices, and large holes noticed previously, for example, by [PERSON] [45]. The images taken at greater magnifications showed the visibly porous morphology of the activated carbon surface. This seems to be advantageous because high porosity indicates a high formaldehyde adsorption capacity [46]. The results of the EDS analysis showed mainly carbon and trace amounts of oxygen, sodium, magnesium, and potassium (Table 1). This is consistent with the results presented by [PERSON] and [PERSON] [47], who showed that the carbon content ranged between 97.39 and 93.58%, depending on the production temperature. Alkaline metal oxides such as K\({}_{2}\)O, MgO, Na\({}_{2}\)O, and CaO are usually the source of the inorganic elements found in trace amounts, and their presence can affect, for example, the hydrophilicity of activated carbon [48]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{3}{c}{**Weight (\%)**} \\
**C** & **O** & **Na** & **Mg** & **K** \\ \hline
97.6 & 2.0 & 0.1 & 0.1 & 0.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Elemental composition of activated carbon. Figure 1: FTIR spectra of activated carbon. Figure 2: SEM images of activated carbon at different magnifications: (**a**) 100\(\times\), (**b**) 500\(\times\), (**c**) 1400\(\times\). The results of the properties of the adhesive mixtures, which are crucial for particle-board production technology, are presented in Table 2. It was found that the addition of activated carbon in the amounts up to 1% did not cause any statistically significant changes in the gel time. However, the maximum addition of 1.5% resulted in a significant acceleration of the gel time by approx. 15% when compared to the non-modified adhesive. This is particularly important because it is the most fundamental property when the pressing technology, i.e., pressing time and pressing temperature, is set, which in turn may affect the production costs and financial efficiency in a considerable way [49; 50]. [PERSON] et al. [30] found that small loadings of activated carbon can contribute to a slight increase in curing reaction enthalpy, which is an indication of improved reactivity as well. The reason could be the ability of ACCS to absorb water both in the surface and subsurface pores [51; 52]. As a result, the curing process of the UF adhesive is promoted. This is particularly beneficial because increasing reactivity could potentially shorten the pressing time, which in turn, taking into account the energy consumption of this process, could increase the financial efficiency of production. Furthermore, the addition of activated carbon in an amount exceeding 0.25% resulted in a statistically significant increase in viscosity. In the variant with the maximum modifier content, the viscosity increased by approx. 11%. For comparison, in another study, the addition of 1.5% of ACCS resulted in increased viscosity by approx.