## 3 Results and Discussion  
### Materials Characterization  
Structural information of the prepared materials was first obtained by means of X-ray diffraction (XRD) analysis. Figure 1 presents the diffraction patters of all materials. A typical diffraction pattern for the pure UiO-66 was observed [25; 45]. The PU composite presented the same diffraction pattern as the U sample. This observation verified that the presence of Pal did not affect the synthesis of UiO-66. No diffraction peak attributed to Pal was detected in the PU sample. Two reasons are probably responsible for this. Firstly, the amount of Pal in the composite was small. Secondly, there was an intense diffraction peak from UiO-66 in the ca. 8.5\({}^{\circ}\) region that overlapped with the main diffraction peak of Pal. TiO\({}_{2}\) presented the typical diffraction pattern of anatase. The PUT composite had a diffraction pattern that was a combination of the pure UiO-66 and TiO\({}_{2}\) sample, without any obvious differences compared with the patterns of their pure counterparts. The materials were further characterized using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, and the data are given in Figure 2a. The characteristic peaks of UiO-66 were observed in the materials containing this specific MOF (U, PU, and PUT) [46; 47; 48]. The symmetric and asymmetric stretch vibrations in the COO\({}^{-}\) group of the organic linker were observed at 1392 cm\({}^{-1}\) and 1582 cm\({}^{-1}\), while the vibrational mode of the C=C bond in the benzene ring was centered at 1510 cm\({}^{-1}\). Vibrational modes of the C-H, C=C, O-H, and OCO bonds were detected in the region 810-710 cm\({}^{-1}\). The broad peak at the beginning of the spectra (400-800 cm\({}^{-1}\)) was attributed to the presence of TiO\({}_{2}\)[44; 49]. Regarding the Pal sample, an intense peak was observed in the region 97-1060 cm\({}^{-1}\). This was not observed in the pure UiO-66 sample but was present in all composites bearing Pal (i.e., PU and PUT). This peak was attributed to the Si-O-Mg asymmetric stretching vibration [39; 46; 50] and verified the presence of Pal in the composite materials. It should be noted that the peak centered at 1582 cm\({}^{-1}\) in the UiO-66 sample was shifted to higher wavenumbers in the composite samples bearing Pal (Figure 2b). This is probably linked with the in-situ development of UiO-66 in the presence of Pal and suggests an interaction of the clay mineral with the carboxylate groups of the organic linker in the MOF structure. Overall, ATR verified the presence of UiO-66, Pal, and TiO\({}_{2}\) in the composite materials. In order to get information regarding the amount of the different parts in the composites, the prepared materials were subjected to thermogravimetric (TGA) analysis. The TGA profiles of all materials are illustrated in Figure 3. A smooth mass decrease was observed in the pure TiO\({}_{2}\) that ended at ca. 7% total mass loss at 550 \({}^{\circ}\)C. The mass loss was greater in the Pal sample (ca. 18% at 550 \({}^{\circ}\)C). In this temperature range, the mass loss in the Pal sample was attributed to both superficially adsorbed and loosely bound zeolitic water, as well as structural OH\({}_{2}\)[51, 52]. In the materials containing UiO-66, the small  
Figure 1: XRD patterns of the pure and composite materials. Figure 2: ATR spectra of all prepared materials (**a**); zoomed area of the COO\(-\)group vibration mode (**b**). weight loss in the temperature range 50-400 \({}^{\circ}\)C was due to the loss of guest molecules (DMF). The fast drop in mass loss at temperatures higher than 450 \({}^{\circ}\)C was attributed to the decomposition of the organic framework of UiO-66. This second drop in mass was observed at lower temperatures in the composite bearing TiO\({}_{2}\).