Monitoring Photo-Fenton and Photo-Electro-Fenton process of contaminants emerging concern by a gas diffusion electrode using Ca10-xFex-yWy(PO4)6(OH)2 nanoparticles as heterogeneous catalyst.

The catalytic performance of modified hydroxyapatite nanoparticles, Ca 10-x Fe x-y W y (PO 4) 6 (OH) 2 , was applied for the degradation of methylene blue (MB), fast green FCF (FG) and norfloxacin (NOR). XPS analysis pointed to the successful partial replacement of Ca by Fe. Under photo-electro-Fenton process, the catalyst Ca 4 FeII 1·92 W 0·08 FeIII 4 (PO 4) 6 (OH) 2 was combined with UVC radiation and electrogenerated H 2 O 2 in a Printex L6 carbon-based gas diffusion electrode. The application of only 10 mA cm−2 resulted in 100% discoloration of MB and FG dyes in 50 min of treatment at pH 2.5, 7.0 and 9.0. The proposed treatment mechanism yielded maximum TOC removal of ∼80% and high mineralization current efficiency of ∼64%. Complete degradation of NOR was obtained in 40 min, and high mineralization of ∼86% was recorded after 240 min of treatment. Responses obtained from LC-ESI-MS/MS are in line with the theoretical Fukui indices and the ECOSAR data. The study enabled us to predict the main degradation route and the acute and chronic toxicity of the by-products formed during the contaminants degradation. [Display omitted] • New modified hydroxyapatite nanoparticles as catalysts to produce.●OH in the MB, FG dyes and NOR degradation; • High recyclability of the heterogeneous catalyst was verified due to magnetic properties. • MB, FG dyes and NOR reached high degradation rate by Photo-Electro-Fenton process using GDE. • Acute and chronic theoretical toxicological was evaluated to NOR. • The by-product identification study resulted in low toxicity compounds. [ABSTRACT FROM AUTHOR]