# TiO2 Modified Geopolymers for the Photocatalytic Dye Decomposition
## 3 Results and Discussion
### Characterization of the Studied Materials
colloid (see Figure 2), were not observed here and thus were broken during incorporation into the GP matrix. Figure 4 also shows the successful incorporation of TiO\({}_{2}\) into the geopolymer structure. In contrast to the work of [PERSON] et al. (2019), where the authors found TiO\({}_{2}\) nanoparticles of different sizes in their respective GP matrices, we observed homogenous material without traces of agglomerated TiO\({}_{2}\). The geopolymer source materials contain impurities such as titanium dioxide (see Table A1), and the prepared parent geopolymer matrix contains the TiO\({}_{2}\) (0.94 wt.%)--see Table 3. The studied materials with the industrially produced TiO\({}_{2}\) powder incorporated into the GP matrix were prepared by mixing 5 g of TiO\({}_{2}\) powder, 100 g of the clay material Mefisto L05, 33 g of the BFS material and the corresponding amounts of alkalis. The chemical composition of the prepared samples was checked using an XRF analysis, which detected 3.42, 2.93 and 3.31 wt.% of TiO\({}_{2}\) in GP-CG100, GP-CG300 and GP-P25 materials, respectively (Table 3). The elemental maps obtained from the electron microscopy also show the homogenous distribution of titanium dioxide over the entire volume of the studied geopolymer with the incorporated TiO\({}_{2}\). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample Name** & **GP** & **GP-CG100** & **GP-CG300** & **GP-P25** \\ \hline Ti (wt.%) & 0.61 \(\pm\) 0.06 & 1.57 \(\pm\) 0.19 & 1.57 \(\pm\) 0.17 & 1.64 \(\pm\) 0.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The EDS control analysis of titanium content (the surface area of 0.1 mm\({}^{2}\)) on grind samples (the average of the four measurements). Figure 4: The representative SEM image for the GP-P25 sample. Figure 3: The box plot of the Ti/(Al+Si) ratio for the milled photocatalysts incorporated into the geopolymer matrix obtained by EDS analysis formed from the minimum and maximum values (whiskers), the standard deviation (SD) values (box) and the arithmetic mean (open squares in the box). Powder X-ray diffraction patterns of the milled geopolymers are shown in Figure 5. The parent geopolymer (GP) contains, aside from a large quantity of amorphous geopolymers, quartz (JCPDS No. 00-046-1045), calcite (JCPDS No. 00-047-1748), gehlenite (JCPDS No. 00-035-0755) and anatase (JCPDS No. 04-014-5762). Diffraction lines of these phases have also been observed in the case of geopolymers with added TiO\({}_{2}\). The intensity of the (101) line of anatase at about 25.3\({}^{\circ}\) in the diffraction pattern of GP-CG300 seems to be similar to that of the GP, whereas in the case of GP-P25 and GP-CG100, the intensity of this diffraction line increases. To confirm this, the peak areas of the most intensive diffraction lines of anatase, calcite and quartz in the diffractograms were determined; they are shown in Table 4. As evident from Table 4, the anatase/quartz and anatase/calcite peak-area ratios for GP-P25 and GP-CG100 samples are about three times larger than in the case of the parent GP, which is in accordance with the increase in theTiO\({}_{2}\) content. On the other hand, the values of the peak-area ratios for the GP-CG300 sample remained practically the same as in the untreated GP, although the TiO\({}_{2}\) content in GP-CG300 also increased to about 3 wt.%. Furthermore, if we compare the proportion of the amorphous phase in the individual samples, it is clear that in the case of GP-CG100 and GP-P25 it was reduced in comparison with the parent geopolymer matrix by the addition of TiO\({}_{2}\). On the other hand, the proportion of the amorphous phase in the GP-CG300 sample is comparable to the parent geopolymer. Based on these data, we can assume that the added TiO\({}_{2}\) CG300 (probably due to the smaller particle size and thus larger surface area (see Table A4)) reacts with the geopolymer matrix and therefore the addition of CG300 does not lead to an increase in the anatase content in the material.