“…Nevertheless, a further increase of the H 2 O 2 dose (up to 200% of the theoretical stoichiometric amount) led to a decrease of the azole pesticides conversion rate (e.g., TEB conversion was reduced to 88%). The concentration of H 2 O 2 was then in clear excess so the oxidant itself could compete with the micropollutants for the available active sites at the catalytic surface, leading to an inefficient consumption of H 2 O 2 and slower degradation of the pesticides (Farzaneh Kondori et al 2018 ; Huaccallo-Aguilar et al 2021a , b ). Furthermore, H 2 O 2 could also act as an autoscavenger for oxidizing radicals (mainly HO· and HOO·), leading to termination reactions, as the following ones (Eqs.…”
Section: Resultsmentioning
confidence: 99%
“…Furthermore, H 2 O 2 could also act as an autoscavenger for oxidizing radicals (mainly HO· and HOO·), leading to termination reactions, as the following ones (Eqs. 5 – 6 ) (Farzaneh Kondori et al 2018 ; Pera-Titus et al 2004 ): Fig. 4 Impact of the H 2 O 2 initial concentration ( a : 3.6 mg L −1 ; b : 6.7 mg L −1 ; c : 10.0 mg L −1 ; d : 13.4 mg L −1 ) on the oxidation of the three azole pesticides ([TET] 0 = [TEB] 0 = [PEN] 0 = 500 µg L −1 ; τ = 16 g cat min mL.…”
The global occurrence of micropollutants in water bodies has raised concerns about potential negative effects on aquatic ecosystems and human health. EU regulations to mitigate such widespread pollution have already been implemented and are expected to become increasingly stringent in the next few years. Catalytic wet peroxide oxidation (CWPO) has proved to be a promising alternative for micropollutant removal from water, but most studies were performed in batch mode, often involving complex, expensive, and hardly recoverable catalysts, that are prone to deactivation. This work aims to demonstrate the feasibility of a fixed-bed reactor (FBR) packed with natural magnetite powder for the removal of a representative mixture of azole pesticides, recently listed in the EU Watch Lists. The performance of the system was evaluated by analyzing the impact of H2O2 dose (3.6–13.4 mg L−1), magnetite load (2–8 g), inlet flow rate (0.25–1 mL min−1), and initial micropollutant concentration (100–1000 µg L−1) over 300 h of continuous operation. Azole pesticide conversion values above 80% were achieved under selected operating conditions (WFe3O4 = 8 g, [H2O2]0 = 6.7 mg L−1, flow rate = 0.5 mL min−1, pH0 = 5, T = 25 °C). Notably, the catalytic system showed a high stability upon 500 h in operation, with limited iron leaching (< 0.1 mg L−1). As a proof of concept, the feasibility of the system was confirmed using a real wastewater treatment plant (WWTP) effluent spiked with the mixture of azole pesticides. These results represent a clear advance for the application of CWPO as a tertiary treatment in WWTPs and open the door for the scale-up of FBR packed with natural magnetite.
“…Nevertheless, a further increase of the H 2 O 2 dose (up to 200% of the theoretical stoichiometric amount) led to a decrease of the azole pesticides conversion rate (e.g., TEB conversion was reduced to 88%). The concentration of H 2 O 2 was then in clear excess so the oxidant itself could compete with the micropollutants for the available active sites at the catalytic surface, leading to an inefficient consumption of H 2 O 2 and slower degradation of the pesticides (Farzaneh Kondori et al 2018 ; Huaccallo-Aguilar et al 2021a , b ). Furthermore, H 2 O 2 could also act as an autoscavenger for oxidizing radicals (mainly HO· and HOO·), leading to termination reactions, as the following ones (Eqs.…”
Section: Resultsmentioning
confidence: 99%
“…Furthermore, H 2 O 2 could also act as an autoscavenger for oxidizing radicals (mainly HO· and HOO·), leading to termination reactions, as the following ones (Eqs. 5 – 6 ) (Farzaneh Kondori et al 2018 ; Pera-Titus et al 2004 ): Fig. 4 Impact of the H 2 O 2 initial concentration ( a : 3.6 mg L −1 ; b : 6.7 mg L −1 ; c : 10.0 mg L −1 ; d : 13.4 mg L −1 ) on the oxidation of the three azole pesticides ([TET] 0 = [TEB] 0 = [PEN] 0 = 500 µg L −1 ; τ = 16 g cat min mL.…”
The global occurrence of micropollutants in water bodies has raised concerns about potential negative effects on aquatic ecosystems and human health. EU regulations to mitigate such widespread pollution have already been implemented and are expected to become increasingly stringent in the next few years. Catalytic wet peroxide oxidation (CWPO) has proved to be a promising alternative for micropollutant removal from water, but most studies were performed in batch mode, often involving complex, expensive, and hardly recoverable catalysts, that are prone to deactivation. This work aims to demonstrate the feasibility of a fixed-bed reactor (FBR) packed with natural magnetite powder for the removal of a representative mixture of azole pesticides, recently listed in the EU Watch Lists. The performance of the system was evaluated by analyzing the impact of H2O2 dose (3.6–13.4 mg L−1), magnetite load (2–8 g), inlet flow rate (0.25–1 mL min−1), and initial micropollutant concentration (100–1000 µg L−1) over 300 h of continuous operation. Azole pesticide conversion values above 80% were achieved under selected operating conditions (WFe3O4 = 8 g, [H2O2]0 = 6.7 mg L−1, flow rate = 0.5 mL min−1, pH0 = 5, T = 25 °C). Notably, the catalytic system showed a high stability upon 500 h in operation, with limited iron leaching (< 0.1 mg L−1). As a proof of concept, the feasibility of the system was confirmed using a real wastewater treatment plant (WWTP) effluent spiked with the mixture of azole pesticides. These results represent a clear advance for the application of CWPO as a tertiary treatment in WWTPs and open the door for the scale-up of FBR packed with natural magnetite.
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