## 3 Results
### Mechanistic Insights into Electrode Dissolution and Mass Loss  
Understanding electrode dissolution and mass loss mechanisms is crucial for optimizing electrochemical treatment processes. These phenomena directly impact the efficiency, longevity, and maintenance costs of the electrodes used. Figure 6 illustrates the changes in electrode mass for ECZ and ECZ-MAG processes at varying mixing speeds and durations. The consistent decrease in anode mass across all experiments clearly indicates anodic dissolution, a main EC mechanism that intensifies with longer contact times due to prolonged electrode exposure. Although most material loss occurs at the anode, dissolution of the cathode can also occur, mainly due to hydrogen evolution at the cathode. This process increases the local alkalinity and creates a high pH microenvironment that can chemically attack and dissolve the cathode surface, especially with prolonged treatment. However, the extent of cathode dissolution is significantly lower compared to anodic dissolution, confirming the dominance of anodic reactions in overall material loss. Specifically, for the 10 min experiments, the highest anode loss occurred in the ECZ-MAG process at 350 rpm, while the lowest in ECZ at 250 rpm. For 20 min experiments, the greatest anode loss was observed in ECZ-MAG at 250 rpm, and the lowest in ECZ at 350 rpm. For 30 min experiments, anode loss was highest in ECZ at 250 rpm and lowest in ECZ at 350 rpm. This observation is consistent with the fundamentals of electrode kinetics and [PERSON]'s laws of electrolysis, which state that the amount of dissolved Al electrode is directly proportional to the total electrical charge passed through the system. The process is therefore kinetically controlled, i.e., it depends primarily on the rate of the electrochemical  
Figure 6: Electrode mass loss after ECZ and ECZ-MAG processes at mixing speeds of 250 and 350 rpm for durations of (**a**) 10 min, (**b**) 20 min, and (**c**) 30 min. Note: standard deviation from the average value for electrode loss for anode is in the range \(\pm\)(0.003–0.019) g, while for cathode is in the range \(\pm\)(0.0005–0.0128) g.  
reaction (kinetic control) and not on mass transfer or diffusion of species in the solution. Although the magnetic field can improve the local conditions for mass transfer, it has no significant effect on the rate-limiting step, which is determined by the kinetics of electron transfer at the electrode surface. Therefore, the electrode loss under the tested parameters remains largely unaffected by the hydrodynamic conditions. The results of the electrode microscopic surface analysis carried out after each processes (at magnifications 100\(\times\), in bright field) are shown in Figure 7.  
Optical microscope images show progressive surface degradation of both anodes and cathodes with increasing treatment time (from 10 to 30 min) in the ECZ process at both 250 and 350 rpm. The anodes exhibit dominant general and pitting corrosion, more pronounced at longer times and at 250 rpm. The cathodes display dendritic, cracked layers at 250 rpm, while at 350 rpm, uniform dissolution occurs. Although the damage is slightly less at 350 rpm due to enhanced mixing, the overall trend indicates time-dependent deterioration in the absence of a magnetic field. In contrast, the ECZ-MAG process, which involves magnetic field assistance, shows a less consistent pattern. At 10 min, electrode surfaces display more severe damage compared to ECZ, likely due to intensified local turbulence and accelerated reactions. However, at 20 and 30 min, surface damage is notably reduced in ECZ-MAG compared to ECZ, suggesting that the magnetic field may promote a more uniform distribution of reactants and reduced corrosion attack on the surface over extended periods. The effect of the magnetic field in the ECZ-MAG process appears to be dual and time-dependent.