# Electrodegradation of Selected Water Contaminants: Efficacy and Transformation Products
## 3 Results and Discussion
### Removal Efficiency, Kinetic Analysis, and Energy Consumption of Electrooxidative Treatment
#### 3.2.1 Removal Efficiency and Energy Consumption of EO Treatment
In contrast, the use of Na\({}_{2}\)SO\({}_{4}\) as an electrolyte promotes the formation of sulphate radicals, which also contribute to efficient oxidation but to a slightly lesser extent (see Supplementary Materials S3 Radical scavenger test). The relatively lower  
Figure 3: (**a**) Degradation of t-OPPE and t-OP at current density \(j\) = 5 mA/cm\({}^{2}\). (**b**) Removal efficiency of DBP in different supporting electrolytes at current density \(j\) = 10 mA/cm\({}^{2}\). efficiency observed with NaCl may result from the formation of chlorine-based oxidants (Cl\({}_{2}\) and HOCl), which are less reactive under the given conditions. These results are clearly illustrated in Figure 3b. In conclusion, H\({}_{2}\)SO\({}_{4}\) proved to be the most effective electrolyte for the electrochemical oxidation of DBP, followed by Na\({}_{2}\)SO\({}_{4}\), while NaCl showed the lowest efficiency. The energy consumption during the EO process varied based on the choice of supporting electrolyte. The lowest energy consumption was recorded when H\({}_{2}\)SO\({}_{4}\) was used as the electrolyte, amounting to 1378.8 kWh/kg\({}_{\text{DBP}}\), or 17.5 kWh/m\({}^{3}\) of treated water. Na\({}_{2}\)SO\({}_{4}\) showed a higher energy consumption of 1853.3 kWh/kg\({}_{\text{DBP}}\), while the highest energy consumption was observed with NaCl, totalling 1975.1 kWh/kg\({}_{\text{DBP}}\). In line with these findings, a study using an IrO\({}_{2}\)-Ta\({}_{2}\)O\({}_{5}\)/Ti electrode with Na\({}_{2}\)SO\({}_{4}\) as a supporting electrolyte (0.005 M) reported a similar removal efficiency of 90%, highlighting the crucial role of hydroxyl radicals (OH\({}^{\bullet}\)) in electrocatalytic oxidation processes [12]. A direct comparison of energy consumption between the present study and the findings of [PERSON] et al. [12] is challenging, as the two studies report energy metrics differently. In the present study, energy consumption is calculated per unit mass of the pollutant (kWh/kg\({}_{\text{DBP}}\)) and per unit volume (kWh/m\({}^{3}\)), while [PERSON] et al. [12] do not provide energy consumption in these standardized metrics. Additionally, [PERSON] et al. [12] reported an energy consumption of 0.046 kWh for a 0.5 L system with 10 mg/L DBP, which when standardized, corresponds to approximately 92 kWh/m\({}^{3}\). This value is notably higher than the energy consumption observed with H\({}_{2}\)SO\({}_{4}\) in the present study. In contrast, the degradation of DBP in printing wastewater via electrochemical methods achieved a lower efficiency (\(E\) = 45.8%) due to the complex wastewater matrix [43]. Additionally, the combined UV/NaClO process achieved faster degradation (\(E\) = 99.5% in 15 min) due to the significantly lower initial DBP concentration in tap water (0.1 mg/L) compared to our study (5 mg/L), but a direct comparison of energy efficiency is not possible since [PERSON] et al. did not provide standardized energy consumption metrics [44]. Alternative methods, such as the ultrasound/hydrogen peroxide system studied by [PERSON] et al., achieved approximately 90% DBP removal under optimal conditions but required chemical additions and longer treatment times [45]. Similarly, [PERSON] et al. [46] demonstrated 90% DBP removal using a hydrophobic Ti/TiO\({}_{2}\)NTs/PbO\({}_{2}\)-PTFE (polytetrafluoroethylene) anode after 8 h at a current density of 20 mA/cm\({}^{2}\), with higher energy consumption compared to the BDD system, which achieved complete degradation in under 30 min at a lower current density. The use of Ce-doped Ti/PbO\({}_{2}\) anodes resulted in high DBP removal (98.2%) but required longer reaction times (10 h) and higher energy consumption, especially at increased current densities [10]. In contrast, the BDD anode used in the present study achieved comparable or superior results with lower energy demand, highlighting its efficiency. Other approaches, such as the electro-Fenton process with a sacrificial iron anode [13], while effective, require additional chemicals and introduce potential issues with iron leaching.