3D Self-Supported Nitrogen-Doped Carbon Nanofiber Electrodes Incorporated Co/CoOx Nanoparticles: Application to Dyes Degradation by Electro-Fenton-Based Process

Ahmed Barhoum; Therese Favre; Syreina Sayegh; Fida Tanos; Emerson Coy; Igor Iatsunskyi; Antonio Razzouk; Marc Cretin; Mikhael Bechelany

doi:10.3390/nano11102686

3D Self-Supported Nitrogen-Doped Carbon Nanofiber Electrodes Incorporated Co/CoO_x Nanoparticles: Application to Dyes Degradation by Electro-Fenton-Based Process

Nanomaterials (Basel). 2021 Oct 12;11(10):2686. doi: 10.3390/nano11102686.

Authors

Ahmed Barhoum^{1

2

3}, Therese Favre², Syreina Sayegh^{2

4}, Fida Tanos^{2

4}, Emerson Coy⁵, Igor Iatsunskyi⁵, Antonio Razzouk⁴, Marc Cretin², Mikhael Bechelany²

Affiliations

¹ NanoStruc Research Group, Chemistry Department, Faculty of Science, Helwan University, Cairo 11795, Egypt.
² Institut Européen des Membranes (IEM), UMR 5635, Université Montpellier, École Nationale Supérieure de Chimie de Montpellier (ENSCM), Centre National de la Recherche Scientifique (CNRS), Place Eugène Bataillon, 34095 Montpellier, France.
³ School of Chemical Sciences, Fraunhofer Project Centre, Dublin City University, D09 V209 Dublin, Ireland.
⁴ Laboratoire d'Analyses Chimiques, Faculty of Sciences, LAC-Lebanese University, Jdeidet 90656, Lebanon.
⁵ NanoBioMedical Centre, Adam Mickiewicz University, 3, Wszechnicy Piastowskiej Str., 61-614 Poznan, Poland.

Abstract

We developed free-standing nitrogen-doped carbon nanofiber (CNF) electrodes incorporating Co/CoO_x nanoparticles (NPs) as a new cathode material for removing Acid Orange 7 (AO7; a dye for wool) from wastewater by the heterogeneous electro-Fenton reaction. We produced the free-standing N-doped CNF electrodes by electrospinning a polyacrylonitrile (PAN) and cobalt acetate solution followed by thermal carbonation of the cobalt acetate/PAN nanofibers under a nitrogen atmosphere. We then investigated electro-Fenton-based removal of AO7 from wastewater with the free-standing N-doped-CNFs-Co/CoO_x electrodes, in the presence or not of Fe²⁺ ions as a co-catalyst. The electrochemical analysis showed the high stability of the prepared N-doped-CNF-Co/CoO_x electrodes in electrochemical oxidation experiments with excellent degradation of AO7 (20 mM) at acidic to near neutral pH values (3 and 6). Electro-Fenton oxidation at 10 mA/cm² direct current for 40 min using the N-doped-CNF-Co/CoO_x electrodes loaded with 25 wt% of Co/CoO_x NPs led to complete AO7 solution decolorization with total organic carbon (TOC) removal values of 92.4% at pH 3 and 93.3% at pH 6. The newly developed N-doped-CNF-Co/CoO_x electrodes are an effective alternative technique for wastewater pre-treatment before the biological treatment.

Keywords: azo dyes; carbon nanofibers; electro-Fenton process; electrospinning; organic pollutants; self-supported electrodes; wastewater treatment.