## 3 Results
### Catalyst Reusability and Stability  
Exploring the reusability of heterogeneous catalysts is a key aspect of advanced research aimed at developing sustainable processes. To evaluate reusability of CuFeNPs@TWM, its performance in degrading a mixture of CECs was tested over multiple cycles under optimized conditions (Figure 10). As can be seen, the removal efficiency of CuFeNPs@TWM remained \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Catalyst** & **Contaminant** & **Process** & **Initial pH** & **Current** & **Remotion/Time** & **Reference** \\ \hline Waste green tea leaves & Phenol & Sono-adsorption & 3.5 & - & 92\% (60 min) & [91] \\ CuFe\({}_{2}\)O\({}_{4}\)/penicillin & Tetracycline & Fenton-like & 3-9 & - & \textgreater{}95\% (90 min) & [92] \\ Cu-adsorbed on & Methyl orange & Photo-Fenton catalyst & 3 & - & 96.9\% (200 min) & [43] \\ magnetite/tea waste & Rhodamine B (RB) & & Adsorption+ & & \\ ZnFe\({}_{2}\)O\({}_{4}\) adsorbed on & and reactive brilliant & & photo-Fenton & 3 & - & \textgreater{}99\% (60 min) & [77] \\  & red X-3B (RBR) & & & & \\ Cu-Fe-Fe\({}_{3}\) on & Amoxicillin & Electro-Fenton & 4 & 120 mA & 100\% (35 min) & [93] \\ nitrogen-doped biochar & Nano-Fe\({}_{3}\)O\({}_{4}\) & Amoxicillin & Electro-Fenton & 3 & 300 mA & 100\% (60 min) & [94] \\ CuFeNPs@TWM & Acetylsalicylic acid, & Electro-Fenton & 3 & 20 mA & 100\% (15 min) & This work \\ Ibuprofen, Naproxen & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the contaminant removal process using catalysts used in this work and other related catalysts. consistent for up to five catalytic cycles, achieving a complete elimination of the contaminants within each treatment cycle. This suggests good stability of the material under the studied conditions. For a more detailed assessment of the stability of the catalyst, the amount of Fe\({}^{2+}\) and Fe\({}^{3+}\) leached during each cycle were quantified (Figure S8). Stability tests showed that after the first cycle, the amount of Fe\({}^{2+}\) reached almost 0.02 mmol L\({}^{-1}\). This value decreased during the second cycle but progressively increased with the subsequent catalytic cycle. This behavior suggests that a portion of the catalyst is being affected by the oxidized species generated during the treatment. However, as demonstrated in Figure 10, this phenomenon does not significantly impact catalytic activity. Additionally, the concentration of Fe\({}^{3+}\) was found to be approximately one-third of the Fe\({}^{2+}\) concentration, indicating that the catalyst undergoes effective recovery during the treatment. As demonstrated in this research, tea waste has proven to be an excellent support material for magnetic nanoparticles, enhancing their stability, reactivity, and catalytic performance, particularly in the EF process. The porosity and functional groups of the  
Figure 10: Normalized concentration of the mixture of CECs in the function of time of treatment at different catalytic cycles. Each cycle considered 30 min of adsorption and 30 min of EF process. Experimental conditions: Catalyst, CuFeNPs@TWM; catalyst load, 20 mg L\({}^{-1}\); applied current, 20 mA; electrolyte, Na\({}_{2}\)SO\({}_{4}\) 50 mmol L\({}^{-1}\); pH, 3. Figure 9: Normalized concentration decay for each CEC in the function of different catalyst loads by heterogeneous EF process: (a) 10 mg L\({}^{-1}\) (b) 20 mg L\({}^{-1}\), and (c) 50 mg L\({}^{-1}\). Experimental conditions: Catalyst, CuFeNPs@TWM; applied current, 20 mA; electrolyte, Na\({}_{2}\)SO\({}_{4}\) 50 mmol L\({}^{-1}\); pH, 3.0.  
material facilitate the adsorption of contaminants and ease the generation of strong oxidants, for effective degradation of contaminants of emerging concern. The reuse of tea waste offers significant environmental and economic advantages by reducing organic waste and transforming it into a high-value material, aligning with circular economy principles.