## 3 Results
### Electrochemical Behavior of Ti Gr. 2 in Presence of Clays
2 electrode in contact with a 0.5 M NaCl solution reveals convinced values of \(i_{corr}\) equal to 0.0693 A/m\({}^{2}\), compared to values obtained for the clays where lower corrosion rates were observed, and equals to 0.0098, 0.0073, and 0.0522 A/m\({}^{2}\) for kaolinite, montmorillonite, and the mix 1:1 of both clays, respectively. These results suggest that the salt suspension with montmorillonite has the best protection against corrosion under the studied conditions. Furthermore, the \(i_{corr}\) value obtained for a NaCl solution is comparable to Ti-Ni alloy electrodes in NaCl solution [47] and close to that observed qualitatively for Ti samples in NaCl solutions [48; 49; 50], where an inapplicability of the Tafel law was reported. These values are further supported by the performance of the Tafel curve depicted in Figure 6b, as well as the electrochemical kinetic parameters for both ORR, HER, and TOR presented in Table 3. The corrosion rates are directly related to the electroflotation efficiency, where, as shown in Tables 2 and 3, lower electroflotation efficiencies were found for higher corrosion rates. This could be attributed to a competition between anodic titanium oxidation with oxygen evolution reaction and the interference of soluble ions from clays and their further combination with hydroxyl anions in solution, such as Al(OH)\({}_{3}\) formation. This last effect, associated with the dissolved ions from clays, can be verified by comparing the corrosion rates and electroflotation efficiencies between kaolinite and montmorillonite clays with their dissolution rates [51; 52], where a higher corrosion rate of the Ti Gr. 2 electrode in kaolinite slurry could be caused by a high Al/Si concentration relation (\(-0.85\) at pH = 4 [51]), compared to the Ti Gr. 2 electrode in montmorillonite slurry, where a low corrosion rate is attributed to a lower Al/Si concentration relation (\(-0.42\) at pH = 4 [52]). Figure 7 delineates the behavior of the first derivative (di/dE) concerning instantaneous current variation with potential from the cathodic to the anodic direction. The following three discernible regions emerge: (i) Within the potential range of \(-1100\) to \(-800\) mV/SHE, the experimental and fitted results confirm that the charge transfer is the rate-determining step for HER, which is corroborated by higher obtained Tafel slope values (\(|\,t_{H_{2}}|>200\) mV/dec), revealing faster HER kinetics for the 0.5 M NaCl solution without clays; (ii) from \(-800\) to \(-100\) mV/SHE, the cathodic subprocess for ORR only shows a planar plateau between \(-800\) and \(-650\) mV/SHE followed by a symmetric distribution between \(-650\) and \(-100\) mV/SHE with a maximum inflection point, indicating that the  
ORR is via a four-electron transfer pathway where a mixed control of charge and mass transfer is the rate-determining step, albeit decreasing the ORR kinetics in the presence of ultrafine clays in the saline solution; and from \(-100\) to \(200\) mV/SHE, the derivative values reveal different tendencies in the NaCl solution without and with the presence of clays, where for kaolinite clay, the results confirm a spontaneous passivation of the Ti Gr. 2 electrode through the observations of the first derivative values with potential, contrary to the tendency observed for the 0.5 NaCl solution, which reveals an increase in the di/dE values with potential. Similar results were observed for montmorillonite clay and the 1:1 mixture of both studied clays. The electroflotation results for kaolinite, montmorillonite, and their 1:1 mixture, in conjunction with the kinetic and corrosion parameters for Ti Gr. 2 electrodes, provide novel insights into the concentration process of clays with particle sizes less than 32 \(\upmu\)m in aggressive environments such as 0.5 M NaCl solution. Particularly, the kinetic parameters associated with the HER mechanism exhibit intriguing variability when the Ti Gr. 2 electrode interacts with different clay types.