Electro-Fenton degradation of the antibiotic sulfanilamide with Pt/carbon-felt and BDD/carbon-felt cells. Kinetics, reaction intermediates, and toxicity assessment

• Published in: Environmental science and pollution research international 2014, Vol.21 (14), p.8368-8378
• Main Authors: El-Ghenymy, Abdellatif, Rodríguez, Rosa María, Brillas, Enric, Oturan, Nihal, Oturan, Mehmet A
• Format: Article
• Language: English
• Subjects: Aliivibrio fischeri - drug effects; Aliivibrio fischeri - metabolism; Anodes; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibiotics; Antimicrobial agents; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bacteria; Benzoquinone; Boron; Boron - chemistry; Carbon; Carbon - chemistry; catechol; Chemicals; Chromatography; Degradation; Diamond - chemistry; Earth and Environmental Science; Ecotoxicology; Electrochemical Advanced Oxidation Processes for Removal of Toxic/Persistent Organic Pollutants from Water; Electrochemistry; Electrodes; Electrolysis; Electrolytic cells; Environment; Environmental Chemistry; Environmental Health; Experiments; Free radicals; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydroquinone; Hydroxyl Radical - chemistry; Hydroxyl radicals; Intermediates; Invertebrates; ions; Iron; Iron - chemistry; Kinetics; Liquid chromatography; Luminescence; Mineralization; Oxidation; Oxidation-Reduction; Persistent organic pollutants; Pharmaceuticals; Platinum; Platinum - chemistry; Pollutants; Resorcinol; reversed-phase liquid chromatography; Sodium sulfate; Statistical analysis; Sulfanilamide; Sulfanilamides - chemistry; Sulfanilamides - pharmacology; Toxicity; Vibrio fischeri; Waste Water Technology; Water Management; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - pharmacology; Water pollution; Water Pollution Control; Water treatment
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-014-2773-3

The degradation of 230 mL of a 0.6-mM sulfanilamide solution in 0.05 M Na₂SO₄ of pH 3.0 has been studied by electro-Fenton process. The electrolytic cell contained either a Pt or boron-doped diamond (BDD) anode and a carbon-felt cathode. Under these conditions, organics are oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between initially added (and then electrochemically regenerated) Fe²⁺ and cathodically generated H₂O₂. From the decay of sulfanilamide concentration determined by reversed-phase liquid chromatography, an optimum Fe²⁺ concentration of 0.20 mM in both cells was found. The drug disappeared more rapidly using BDD than Pt, and, in both cases, it was more quickly removed with raising applied current. Almost total mineralization was achieved using the BDD/carbon-felt cell, whereas the alternative use of Pt anode led to a slightly lower mineralization degree. In both cells, the degradation rate was accelerated at higher current but with the concomitant fall of mineralization current efficiency due to the greater increase in rate of the parasitic reactions of hydroxyl radicals. Reversed-phase liquid chromatography allowed the identification of catechol, resorcinol, hydroquinone, p-benzoquinone, and 1,2,4-trihydroxybenzene as aromatic intermediates, whereas ion exclusion chromatography revealed the formation of malic, maleic, fumaric, acetic, oxalic, formic, and oxamic acids. NH₄ ⁺, NO₃ ⁻, and SO₄ ²⁻ ions were released during the electro-Fenton process. A plausible reaction sequence for sulfanilamide mineralization involving all detected intermediates has been proposed. The toxicity of the solution was assessed from the Vibrio fischeri bacteria luminescence inhibition. Although it acquired its maximum value at short electrolysis time, the solution was completely detoxified at the end of the electro-Fenton treatment, regardless of the anode used.