## 3 Results
### Catalytic Performance of CuFeNPs@TWM for the Elimination of CECs
By comparing the apparent rate constants (k\({}_{\text{app}}\)), shown in Table 3, an increase in the initial kinetics of the electrochemical process were obtained when increasing the current, which is attributed to the higher generation of oxidants. After the first minutes of treatment, the electrogenerated species react with the oxidized forms of the CECs, decreasing the kinetics of the process. This effect is confirmed at the end of the EF process in Figure 8d. Therefore, 20 mA was selected as the optimal current for further applications. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Current (mA) \({}^{\bullet}\)** & **CEC** & **k\({}_{\text{app}}\) (min\({}^{-1}\))** & **R\({}_{2}\)** \\ \hline \multirow{3}{*}{10} & ASA & 0.12 & 0.99 \\  & NAP & 0.25 & 0.99 \\  & IBU & 0.22 & 0.99 \\ \hline \multirow{3}{*}{20} & ASA & 0.19 & 0.97 \\  & NAP & 0.66 & 0.99 \\  & IBU & 0.28 & 0.99 \\ \hline \multirow{3}{*}{50} & ASA & 0.39 & 0.99 \\  & NAP & 1.17 & 0.99 \\ \cline{1-1}  & IBU & 0.49 & 0.99 \\ \hline \hline \end{tabular}  
* The used catalyst was CuFeNPs@TWM and its dosage was 20 mg L\({}^{-1}\).  
\end{table} 
Table 3: Apparent rate constants of the CECs by applying different currents. Once the applied current was optimized, the effect of catalyst load was studied in the range of 10-50 mg L\({}^{-1}\). As seen in Figure 9, there is a dependence between the amount of the catalyst used and the elimination of the contaminants, which involves both the adsorption and electrochemical processes. When 10 mg L\({}^{-1}\) was used (Figure 9a), 4.1% (ASA), 12.3% (NAP), and 11.9% (IBU) were removed from the solution by adsorption after 30 min, achieving adsorption capacities of 4.01 \(\pm\) 0.01, 12.23 \(\pm\) 0.01, and 9.97 \(\pm\) 0.04 mg g\({}^{-1}\) for ASA, NAP, and IBU, respectively (Table 2). This dosage yielded high adsorption efficiency, particularly for NAP and IBU, suggesting that at lower dosages, the active sites are more concentrated and efficiently utilized, potentially reducing site competition between adsorbates [78,83]. For the same dosage, 29.1% (ASA), 29.9% (NAP), and 49.5% (IBU) were degraded after 30 min by the EF process. By using 20 mg L\({}^{-1}\) (Figure 9b), a significative increase in the elimination of the contaminants was observed. In this case, adsorption of 10.7% (ASA), 29.4% (NAP), and 19.8% (IBU) was reached, showing a higher retention capacity on the catalyst surface, achieving 5.32 \(\pm\) 0.01, 14.26 \(\pm\) 0.02, and 9.39 \(\pm\) 0.02 mg g\({}^{-1}\), for ASA, NAP, and IBU, respectively. These values show higher levels of adsorption capacity than that obtained using 10 mg L\({}^{-1}\) for ASA and NAP, while showing no significant variation for IBU [41,84]. After the equilibrium, a complete oxidation of the CECs was found at 15 min of electrochemical treatment, indicating that the increase in the amount of catalyst increases the number of active sites, not only for the adsorption but also for the oxidation process during the EF process. A different effect was observed for 50 mg L\({}^{-1}\) (Figure 9c) when an increase in remotion was only observed during the adsorption and not during the electrochemical process. After the first step, an elimination of 16.3% (ASA), 38.5% (NAP), and 20.5% (IBU) was found, favoring the remotion compared with that obtained using lower catalyst loads. However, if we compare by adsorption capacity, at 50 mg L\({}^{-1}\), the amount adsorbed decreased to  
Figure 8: Normalized concentration decay for each CEC in the function of different applied currents by heterogeneous EF process: (**a**) Adsorption (0 mA), (**b**) 10 mA, (**c**) 20 mA, and (**d**) 50 mA. Experimental conditions: Catalyst, CuFeNPs@TWM; catalyst load, 20 mg L\({}^{-1}\); electrolyte, Na\({}_{2}\)SO\({}_{4}\) 50 mmol L\({}^{-1}\); pH, 3.0. 3.26 \(\pm\) 0.01, 7.69 \(\pm\) 0.042, and 4.09 \(\pm\) 0.04 mg g\({}^{-1}\) for ASA, NAP, and IBU, respectively.