## 3 Results
### Methylene Blue Removal by Adsorption and Photocatalytic Degradation
The rate constant \(k\) was higher for TiLAC-7/3 and TiLAC-9/1 samples, 0.377 and 0.276 min\({}^{-1}\) respectively, while the Ti sample yielded the lowest value of 0.182 min\({}^{-1}\). It can be noticed that the removal efficiencies, previously shown, are in  
Figure 8: Comparison of the experimental MB removal for (**a**) TiLAC-7/3 and; (**b**) TiLAC-9/1 with that predicted according to their individual components and contents. Figure 7: Methylene blue removal on Titania P25 (Ti) and TiLAC based catalysts; (**a**) under dark and UV-irradiation; (**b**) under UV-irradiation without the first phase of adsorption equilibrium; with C (MB) = 6.0 \(\times\) 10\({}^{-5}\) M, catalyst dosage = 1.25 g\(\cdot\)L\({}^{-1}\) at 25 \({}^{\circ}\)C.  
agreement with the constant rate value and strongly influenced by the content of LAC in each sample, since it seems to ensure a large interfacial surface available between titania particles and the dye molecules, as the BET specific surface areas confirm (see Table 1), providing abundant photoreactive sites and a developed porosity that facilitates the transfer of reactants and degraded products. Therefore, it seems that the higher the contact surface between _AdsCats_ particles and MB, the greater the degradation rate. Additionally, sample TiLAC-9/1 was treated at 250, 300, and 350 \({}^{\circ}\)C in a muffle furnace under air in order to investigate the influence of the oxidation state of Ti\({}^{m+}\) functional species present on the external surface of the composite. The results of the photocatalytic activity experiments are presented in Figure 9. It can be observed that, even though no phase transformations were discerned in the three XRD patterns after thermal treatment (not shown), some significant changes occurred from a catalytic point of view. In particular, the thermal treatment at 250 \({}^{\circ}\)C did not have any noticeable effect on the photocatalytic activity, while the activities of the samples treated at 300 and 350 \({}^{\circ}\)C are higher as the time required for the extensive MB degradation decreases. This improvement can be related to the enhancement in the crystallinity and the formation of larger crystals of titania particles as a result of the thermal effect in the air on the composite materials at temperatures above 300 \({}^{\circ}\)C, rather than the oxidation state [54]. Furthermore, heat treatment allowed the adsorption of more oxygen molecules on the surface of the composite by correlating with Ti\({}^{+4}\) ions. Thus, the presence of these oxygen molecules helps to trap photoexcited electrons and inhibit their recombination with holes. Hence, as the temperature increases, more superoxide anion radicals O\({}_{2}\) are formed and more hydroxyl radicals are stabilized by preventing combination [55], which is in agreement with Figure 9. \begin{table}
\begin{tabular}{c c} \hline \hline
**Sample** & **k (min\({}^{-1}\))** \\ \hline TiLAC-7/3 & 0.377 \\ TiLAC-9/1 & 0.276 \\ Ti (P25) & 0.182 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The rate constant k values for P25 and the TiLAC composites. Figure 9: Methylene blue removal on TiLAC catalysts, TiLAC-9/1, TiLAC-9/1–250 \({}^{\circ}\)C, TiLAC-9/1–300 \({}^{\circ}\)C, TiLAC-9/1–350 \({}^{\circ}\)C heat treated at different temperatures under dark and with UV-irradiation.