Solar photoelectro-Fenton degradation of the antibiotic metronidazole using a flow plant with a Pt/air-diffusion cell and a CPC photoreactor

Tzayam Pérez, Sergio GARCIA SEGURA, Abdellatif El-Ghenymy, José L. Nava, Enric Brillas

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The degradation of 10 dm3 of solutions of the heterocyclic antibiotic metronidazole in 0.10 mol dm-3 Na2SO4 of pH 3.0 has been comparatively studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Experiments were performed in a solar flow plant equipped with a Pt/air-diffusion cell and coupled to a compound parabolic collector (CPC) photoreactor. A very weak mineralization was found for the EF process in the dark, indicating a large recalcitrance of heterocyclic compounds to be destroyed by hydroxyl radicals formed at the Pt anode from water oxidation and mainly in the bulk from Fenton's reaction between added Fe2+ and cathodically generated H2O2. The quick photolysis of intermediates by UV radiation from sunlight enhanced largely the mineralization process by SPEF. The effect of applied current density and Fe2+ and drug contents on the SPEF treatment was examined. The best process was found for 1.39 mmol dm-3 metronidazole with 0.50 mmol dm-3 Fe2+ at 55.4 mA cm-2 giving 53% mineralization, 36% mineralization current efficiency and 0.339 kWh (g DOC)-1 in 300 min. Metrodinazole was completely removed and its decay obeyed a pseudo-first-order kinetics. LC-MS analysis allowed identifying five heterocyclic products and twelve hydroxylated derivatives. Ion-exclusion HPLC analysis revealed that final oxalic and oxamic acids were practically removed at the end of electrolysis due to the efficient photolysis of their Fe(III) complexes by sunlight. The initial N of metronidazole gave NO3 - ion as main inorganic ion. A large proportion of initial N remained in solution as unidentified N-products and their major part was lost as N-volatile species. Based on the detected products, a reaction sequence for metronidazole mineralization by SPEF is proposed.

Original languageEnglish (US)
Pages (from-to)173-181
Number of pages9
JournalElectrochimica Acta
Volume165
DOIs
StatePublished - Feb 28 2015
Externally publishedYes

Fingerprint

Metronidazole
Antibiotics
Photolysis
Anti-Bacterial Agents
Degradation
Ions
Air
Oxamic Acid
Heterocyclic Compounds
Electrolysis
Ultraviolet radiation
Anodes
Current density
Hydroxyl Radical
Derivatives
Oxidation
Kinetics
Acids
Water
Experiments

Keywords

  • Electro-Fenton
  • Metrodinazole
  • Oxidation products
  • Solar photoelectro-Fenton
  • Water treatment

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Cite this

Solar photoelectro-Fenton degradation of the antibiotic metronidazole using a flow plant with a Pt/air-diffusion cell and a CPC photoreactor. / Pérez, Tzayam; GARCIA SEGURA, Sergio; El-Ghenymy, Abdellatif; Nava, José L.; Brillas, Enric.

In: Electrochimica Acta, Vol. 165, 28.02.2015, p. 173-181.

Research output: Contribution to journalArticle

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abstract = "The degradation of 10 dm3 of solutions of the heterocyclic antibiotic metronidazole in 0.10 mol dm-3 Na2SO4 of pH 3.0 has been comparatively studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Experiments were performed in a solar flow plant equipped with a Pt/air-diffusion cell and coupled to a compound parabolic collector (CPC) photoreactor. A very weak mineralization was found for the EF process in the dark, indicating a large recalcitrance of heterocyclic compounds to be destroyed by hydroxyl radicals formed at the Pt anode from water oxidation and mainly in the bulk from Fenton's reaction between added Fe2+ and cathodically generated H2O2. The quick photolysis of intermediates by UV radiation from sunlight enhanced largely the mineralization process by SPEF. The effect of applied current density and Fe2+ and drug contents on the SPEF treatment was examined. The best process was found for 1.39 mmol dm-3 metronidazole with 0.50 mmol dm-3 Fe2+ at 55.4 mA cm-2 giving 53{\%} mineralization, 36{\%} mineralization current efficiency and 0.339 kWh (g DOC)-1 in 300 min. Metrodinazole was completely removed and its decay obeyed a pseudo-first-order kinetics. LC-MS analysis allowed identifying five heterocyclic products and twelve hydroxylated derivatives. Ion-exclusion HPLC analysis revealed that final oxalic and oxamic acids were practically removed at the end of electrolysis due to the efficient photolysis of their Fe(III) complexes by sunlight. The initial N of metronidazole gave NO3 - ion as main inorganic ion. A large proportion of initial N remained in solution as unidentified N-products and their major part was lost as N-volatile species. Based on the detected products, a reaction sequence for metronidazole mineralization by SPEF is proposed.",
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AU - GARCIA SEGURA, Sergio

AU - El-Ghenymy, Abdellatif

AU - Nava, José L.

AU - Brillas, Enric

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AB - The degradation of 10 dm3 of solutions of the heterocyclic antibiotic metronidazole in 0.10 mol dm-3 Na2SO4 of pH 3.0 has been comparatively studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Experiments were performed in a solar flow plant equipped with a Pt/air-diffusion cell and coupled to a compound parabolic collector (CPC) photoreactor. A very weak mineralization was found for the EF process in the dark, indicating a large recalcitrance of heterocyclic compounds to be destroyed by hydroxyl radicals formed at the Pt anode from water oxidation and mainly in the bulk from Fenton's reaction between added Fe2+ and cathodically generated H2O2. The quick photolysis of intermediates by UV radiation from sunlight enhanced largely the mineralization process by SPEF. The effect of applied current density and Fe2+ and drug contents on the SPEF treatment was examined. The best process was found for 1.39 mmol dm-3 metronidazole with 0.50 mmol dm-3 Fe2+ at 55.4 mA cm-2 giving 53% mineralization, 36% mineralization current efficiency and 0.339 kWh (g DOC)-1 in 300 min. Metrodinazole was completely removed and its decay obeyed a pseudo-first-order kinetics. LC-MS analysis allowed identifying five heterocyclic products and twelve hydroxylated derivatives. Ion-exclusion HPLC analysis revealed that final oxalic and oxamic acids were practically removed at the end of electrolysis due to the efficient photolysis of their Fe(III) complexes by sunlight. The initial N of metronidazole gave NO3 - ion as main inorganic ion. A large proportion of initial N remained in solution as unidentified N-products and their major part was lost as N-volatile species. Based on the detected products, a reaction sequence for metronidazole mineralization by SPEF is proposed.

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