Vermiculite as heterogeneous catalyst in electrochemical Fenton-based processes: Application to the oxidation of Ponceau SS dye
| Autor: | Carlos A. Martínez-Huitle, Enric Brillas, Ana Priscila Alves, Alexsandro Jhones dos Santos, Ignasi Sirés |
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| Rok vydání: | 2019 |
| Předmět: |
Depuració de l'aigua
Environmental Engineering Health Toxicology and Mutagenesis 0208 environmental biotechnology Kinetics 02 engineering and technology 010501 environmental sciences Vermiculite Electrochemistry Heterogeneous catalysis 01 natural sciences Catalysis Absorbance chemistry.chemical_compound Catàlisi Environmental Chemistry 0105 earth and related environmental sciences Water purification Chemistry Public Health Environmental and Occupational Health Oxidació electroquímica General Medicine General Chemistry Electrochemical Techniques Pollution 020801 environmental engineering Electrolytic oxidation Diazo Aluminum Silicates Leaching (metallurgy) Azo Compounds Nuclear chemistry |
| Zdroj: | Dipòsit Digital de la UB Universidad de Barcelona |
| ISSN: | 1879-1298 |
| Popis: | Modified sodium vermiculite, an iron-rich clay mineral, has been used in novel heterogeneous electrochemical Fenton-based treatments, so-called electro-Fenton (EF)-vermiculite, UVA photoelectro-Fenton (PEF)-vermiculite and solar photoelectro-Fenton (SPEF)-vermiculite. Tests were made with 130 mL of 0.150 mM Ponceau SS diazo dye in 0.050 M Na2SO4 at pH 3.0, in the presence of 1.0 g L-1 catalyst microparticles. The electrolyses were performed in an undivided cell with a boron-doped diamond anode (BDD) and air-diffusion cathode for H2O2 production, at 33.3 mA cm-2. Decolorization and mineralization were upgraded in the sequence: EF-vermiculite < PEF-vermiculite < SPEF-vermiculite. The removal of organics occurred by the combined action of ¿OH oxidant formed at the BDD surface and homogeneous and heterogeneous Fenton's reactions, along with the photolysis caused by UVA light or sunlight. The homogeneous Fenton's reaction resulted from iron ions leaching, but the heterogeneous mechanism was prevalent. Comparative treatments by anodic oxidation in the presence of H2O2 and homogeneous EF were less effective than EF-vermiculite. The diazo dye absorbance decays agreed with a pseudo-first-order kinetics. SPEF-vermiculite was the most powerful process, yielding total decolorization and 84.1% mineralization after 300 and 360 min, respectively. The influence of catalyst concentration, current density and diazo dye content on PEF-vermiculite performance was examined. Oxalic, oxamic, malic, tartronic and acetic acids were detected as final short-linear carboxylic acids. |
| Databáze: | OpenAIRE |
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