An Electro-Fenton-Like Reaction Pathway to Generate •Oh Avoiding O2-Aeration Using a Potential-Conversion Mode

Abstract

•OH generation via Electro-Fenton-like (EF-like) reactions mostly relies on O2-aeration, which results in a high energy consumption. Considering H2O2 generation during the anodic oxidation on graphite supported TiO2 composites (TiO2/C) anode and H2O2 decomposition to •OH via heterogeneous EF-like reaction on TiO2/C cathode, we designed a novel EF-like reaction pathway based on a potential-conversion mode. During this potential-conversion mode, the H2O2 and Ti-OH structure produced during the anode process was decomposed to •OH during the cathode process. The allocation of time and potential for potential-conversion mode was optimized as 1.0 V for 300 s and -0.6 V for 100 s, alternately. Under this condition, the •OH yield under potential-conversion mode (2.75 mg/L) was about three times higher than that under anode mode (0.8 mg/L). With cephalexin (CLN) as the target pollutant, the degradation efficiency reached 81.8% under potential-conversion mode and only 37.6% under anode mode within 90 min. When the EF-like device based on potential-conversion mode was used for simulating groundwater remediation, the CLN degradation efficiency were respectively 86.7%, 72.8% and 68.6% under the initial CLN concentration of 5, 10 and 20 mg/L within 8 h running at the hydraulic residence time (HRT) of 1 h. The HRT exhibited as a crucial parameter for the CLN degradation. The potential-conversion mode provides a new EF-like reaction pathway for the efficient •OH production without O2-aeration, offering a potentially cost-effective and eco-friendly method for water remediation.

Keywords: Non-aeration, TiO2, Hydroxyl radicals, Hydrogen Peroxide