Chromium(VI) reduction in aqueous medium by means of catalytic membrane reactors
| Autor: | Francisco Medina, A. Dafinov, Jesús E. Sueiras, Verónica Pinos |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Chromate Reduction
Inorganic chemistry 0211 other engineering and technologies chemistry.chemical_element 02 engineering and technology 010501 environmental sciences 01 natural sciences Pd And Pd/Ceo2/Fe2o3 Active Phases law.invention Catalysis Chromium law Chemical Engineering (miscellaneous) Calcination Waste Management and Disposal Incipient wetness impregnation 0105 earth and related environmental sciences 021110 strategic defence & security studies Chromate conversion coating Chemistry Process Chemistry and Technology Catalytic Membrane Reactors Selective catalytic reduction Pollution Membrane Palladium |
| Zdroj: | Journal of Environmental Chemical Engineering Repositorio Universidad de Cuenca Universidad de Cuenca instacron:UCUENCA |
| DOI: | 10.1016/j.jece.2016.03.008&partnerID=40&md5=0cef906bc2a632a3a07ee416543feeeb |
| Popis: | A novel method for catalytic reduction of chromium(VI) to chromium(III) in model and real water is proposed in this work. Hydrogen was used as a reducer. Three different catalytic membrane reactors were prepared and employed in the studied reaction. The catalytic membrane reactors were prepared using commercial corundum hollow fiber membranes. The active phases, palladium, cerium oxide, iron oxide or combinations of them, were incorporated by incipient wetness impregnation of the corresponding water-soluble salts followed by calcination and reduction. The catalytic tests were performed in semi-batch mode at ambient conditions. A mass flow controller was used to supply hydrogen to one end of the membrane whilst the other end was kept closed. The reactors were submerged into a vessel containing the chromate solution. The concentration of the chromate was continuously monitored following a standard analytical method. The initial chromate concentration was varied between 0.5 and 18 mg L −1 . In order to completely reduce the Cr(VI) to Cr(III), it was necessary to decrease the pH of the solution to 3. In the end of the tests the final solutions were neutralized to pH 8 and filtered. The content of chromium in the final solutions and in the precipitates was determined by inductively coupled plasma (ICP) technique. It was demonstrated that for the studied reaction the presence of palladium is essential. In all experiments, with synthetic and real water adjusted to pH 3, the catalytic membrane reactors containing palladium (0.3–0.9 w/w%) effectively reduced the chromium to levels below 0.03 mg L −1 without losing activity in repetitive runs. The results from ICP analyses demonstrated that the chromium can be completely eliminated from the water after neutralization and filtration. |
| Databáze: | OpenAIRE |
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