## 3 Results and Discussion
### Intensification by Photocatalyst Formulation
In the case of MWCNT governing the film behavior (direct allowed transitions in composites), the calculated bandgap value is 3.27 eV. In the case of anatase governing the film behavior (indirect allowed transitions), the calculated bandgap value is 2.97 eV. It seems that the none of the transition types fully dominate, hence the average bandgap value of approximately 3.12 eV may be expected. Those values suggest that a considerable synergetic photocatalytic effect was achieved by preparing the composite--i.e., boding of the carbonaceous species to titania species (confirmed by [PERSON]) modifies the photoabsorption of the derived composites. Experiments of CT, HQ and RS photocatalytic degradation were performed in FPCR using both TiO\({}_{2}\)-GF and TiO\({}_{2}\)/CNT-GF films. Results are given in Figure 6a,b. The results showed the higher degradation extents when photocatalytic films were modified with CNT, confirming the hypothesis of intensification by sensitization. The extent of CT degradation in FPCR over irradiated TiO\({}_{2}\)-GF film reached 46%, while degradation over TiO\({}_{2}\)/CNT-GF film reached 52% after 180 min of treatment. The degradation extents of RS over irradiated TiO\({}_{2}\)-GF and TiO\({}_{2}\)/CNT-GF films after 180 min of treatment in FPCR were 56% and 72%, respectively. The sensitization effect of CNT was different for HQ where 58% and 47% of degradation, respectively, were obtained after 180 min of treatment in FPCR over irradiated TiO\({}_{2}\)-GF and TiO\({}_{2}\)/CNT-GF films. The possible adsorption of HQ on CNT on the film surface via the -OH group in para position could produce certain steric disturbance for eventual \(\bullet\)OH radical attack, which can explain the observed deviation and lack of sensitization effect in the case of HQ model solution. The positive sensitization effects were observed for binary mixtures. CT and RS degradation kinetics are shown as observed in the CT+RS mixture, while HQ degradation is presented as an exemplary compound for the CT+HQ mixture in Figure 6b. The extent of CT degradation in the CT+RS mixture in FPCR over irradiated TiO\({}_{2}\)-GF film reached 53%, while degradation over TiO\({}_{2}\)/CNT-GF film reached 84% after 180 min of treatment. The degradation extents of RS over irradiated TiO\({}_{2}\)-GF and TiO\({}_{2}\)/CNT-GF films after 180 of treatment in FPCR were 73% and 96%, respectively. HQ degradation in CT+HQ mixture reached only 40% after 180 min of treatment, while sensitization of photocatalytic film led to 77% of HQ degradation. In general, dihydroxybenzes degradation was faster in binary mixtures. With more of these substances on the photocatalyst surface, the pronounced hydroxylation,  
Figure 5: (a) DRS UV-VIS spectra (b) Tauc plot for the photocatalytic film constituents and photocatalytic composites on glass mesh. ring openings and radical ejection could self-catalyze the radical cycle reactions as an underlying mechanism of photocatalytic degradation. In the absence of catalytic reactions in the dark, as confirmed in control experiments, it is evident that all radical cycle reactions are initiated by the \(\bullet\)OH radical attack, formed on the surface of irradiated photocatalyst. Control experiments showed that the adsorption equilibrium of CT, HQ and RS on TiO\({}_{2}\)/CNT-GF was achieved in 10-15 min in the dark, and the respective concentration of each model pollutant remained the same afterwards. The adsorption of CT, HQ and RS on TiO\({}_{2}\)/CNT-GF in the dark led to only 1.7%, 4.6% and 0.8 % initial concentration decrease, which is different than zero as in the case of TiO\({}_{2}\)-GF but also negligible in terms of overall degradation extents. The better photocatalytic performance of TiO\({}_{2}\)/CNT composite can be explained by the formation of the Ti-O-C structure that can improve the transfer of photoinduced free electrons from TiO\({}_{2}\) to CNT, and overcome fast recombination of e-/h+ by formation of heterojunctions.