Replacing carbon cloth by nickel mesh as substrate for air-diffusion cathodes: H2O2 production and carbenicillin degradation by photoelectro-Fenton

Abstract

The development of air-diffusion electrodes (ADEs) that electrocatalytically produce H2O2 for its decomposition by Fenton's reaction is gaining relevance. However, attention has been paid to improve the catalytic layer using standard carbonaceous substrates like Ccloth. This work clearly proves the superior endurance of 3 cm2 ADEs fabricated with Nimesh as substrate, achieving stable H2O2 accumulation up to 60 mM at 100 mA for 48 h in an undivided cell. Consequently, the antibiotic carbenicillin could be totally degraded in 13 min by photoelectro- Fenton (PEF) process using the Nimesh|C-PTFE ADE at 20 mA in an acidic model solution. This high performance was confirmed by PEF treatment in urban wastewater, reaching total drug disappearance in 18 min with >80 % TOC abatement. The time course of ¿OH and toxicity was monitored, whereas chromatographic analysis of treated solutions revealed the formation of 32 aromatic and 16 aliphatic byproducts, including 7 linear carboxylic acids.