Comparative electro-Fenton and UVA photoelectro-Fenton degradation of the antibiotic sulfanilamide using a stirred BDD/air-diffusion tank reactor

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• 作者：Abdellatif El-Ghenymy ; Nihal Oturan ; Mehmet A. Oturan ; Jos茅 Antonio Garrido ; Pere Llu铆s Cabot ; Francesc Centellas ; Rosa Mar铆a Rodr铆guez ; Enric Brillas
• 关键词：Boron-doped diamond ; Electro-Fenton ; Oxidation products ; Photoelectro-Fenton ; Sulfanilamide ; Wastewater treatment
• 刊名：Chemical Engineering Journal
• 出版年：December, 2013
• 年：2013
• 卷：234
• 期：Complete
• 页码：115-123
• 全文大小：657 K

文摘

Here, the degradation of 100 mL of sulfanilamide solutions of pH 3.0 has been comparatively studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) using a stirred tank reactor equipped with a 3 cm² boron-doped diamond (BDD) anode and a 3 cm² air-diffusion cathode. In both treatments, organics are destroyed by hydroxyl radicals formed at the BDD surface and in the solution bulk from Fenton鈥檚 reaction between cathodically generated H₂O₂ and initially added Fe²⁺, whereas in PEF, additional photolysis of intermediates under UVA radiation is also feasible. The influence of applied current density and substrate concentration on antibiotic decay, degradation rate and mineralization degree was examined. The sulfanilamide decay always followed a pseudo-first-order reaction, as found by reversed-phase liquid chromatographic monitoring, being faster for PEF. The EF process led to large mineralization of sulfanilamide concentrations up to 2390 mg L^鈭?. Nevertheless, the PEF process was much more potent and allowed achieving total mineralization (>99% of dissolved organic carbon removal) of all the solutions tested. Results showed that the application of this treatment is preferable at low current densities and high substrate concentrations to obtain the best mineralization current efficiencies. Ion-exclusion liquid chromatography revealed that oxalic and oxamic acids were the most persistent generated carboxylic acids. Their Fe(III) complexes were slowly removed by hydroxyl radical in EF and much more quickly photolyzed by UVA light in PEF. Ion chromatography confirmed the main release of and ions, and ion in relatively smaller extent, during all the mineralization processes.