## 3 Results and Discussion
### Impregnation Methodology
#### 3.1.3 Effect of the Time and Contact Method on TiO\({}_{2}\) Impregnation  
The effect of time and type of contact (mixing) between the Leca and the TiO\({}_{2}\) suspension in ethanol are relevant parameters in synthesizing the supported catalyst. The type of contact is crucial to guarantee the turbulence of the solution to enhance the TiO\({}_{2}\) impregnation over all the surface of Leca particles. In this way, an ultrasonic bath and the shaker were used. These tests were carried out for 10 g of Leca in contact with 3.6% TiO\({}_{2}\). Different contact times were considered in these experiments, from 15 to 120 min, and compared with no mixing, consisting only of adding Leca with TiO\({}_{2}\) suspension without any kind of mixing. It should be noted that the times in question are not cumulative. Regarding the shaker method, the incorporations did not show promising results, ranging from about 12 to 14 mg of TiO\({}_{2}\)/g of Leca, which reveals that impregnation was lower than without any mixing. This is due to the type of movement used, causing TiO\({}_{2}\) aggregation and some degree of sedimentation. Thus, a fraction of TiO\({}_{2}\) will not be available to adhere to the surface of Leca. The best results were obtained with an ultrasonic bath, with a TiO\({}_{2}\) impregnated mass for 15 and 120 min of about 22 to 23 mg/g Leca, respectively (Table 1). The ultrasound waves can enhance the dispersion of nanoparticles of TiO\({}_{2}\) P25 onto the Leca surface and reduce the agglomeration of the nanoparticles, uniformizing the immobilization onto the support. This improvement can be related to the acoustic cavitation created by ultrasound waves which will create nanobubbles and collapse them to generate solvent microjets [34]. These microjets will drive the nanoparticles against the Leca support improving its immobilization [34; 35]. [PERSON] et al. [35] immobilized TiO\({}_{2}\) onto clinoptiolite support, and the presence of ultrasound guaranteed a uniform morphology and a more homogeneous dispersion. [PERSON] et al. [36] have highlighted the effect of increased ultrasonic amplitude in improving the stability of suspensions and uniformity in the glass coating process. It can be inferred that the frequency with which the ultrasonic waves are emitted promotes vibrations that allow for better dispersion of TiO\({}_{2}\) in ethanol. However, in the ultrasonic contact method, it was noted that no significant differences in the amounts of impregnated TiO\({}_{2}\) occurred as the agitation time increased. According to [PERSON]'s test, the \(p\)-value is 0.1055 \(>\) 0.05, and it can be concluded that there are no significant differences between the average of the replicates of the samples in question. This fact demonstrates that 15 min of ultrasound is suitable and was adopted in the further stages of the impregnation  
Figure 1: (**a**) TiO\({}_{2}\) impregnated as a function of the Leca amount used in the preparation procedure; (**b**) TiO\({}_{2}\) impregnated yield as a function of the S/L ratio (using as TiO\({}_{2}\) load in the suspension 500 mg and 19.5 mL of solvent volume). method. Higher exposure times to ultrasounds will increase the preparation costs without relevant benefits. Effect of contact time and type of agitation on the amount of TiO\({}_{2}\) impregnated. Effect of the Solvent Type  
For obtaining a stable suspension of TiO\({}_{2}\) for the preparation of the photocatalysts, it is indispensable the utilization of a solvent. A homogeneous dispersion is crucial to achieving an effective impregnation of the porous ceramic material due to the small size of TiO\({}_{2}\) nanoparticles. In the present work, ultrapure water and ethanol were tested as solvents. Ethanol as a solvent can enhance the nanoparticle's dispersion since these nanoparticles tend to agglomerate, reducing the impregnation yield. The water was considered due to the widespread usage to disperse powders and the cost availability.