Total degradation of p-hydroxybenzoic acid by Ru-catalysed wet air oxidation: a model for wastewater treatment

Catalytic wet air oxidation using heterogeneous catalysts is a promising technology for treatment of wastewaters. Wastewaters from olive oil mills are difficult to clean because effluents contain high levels of phenolic compounds that cannot be removed by biological treatment or incineration. Theref...

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Bibliographic Details
Published in:Environmental chemistry letters 2015-12, Vol.13 (4), p.481-486
Main Authors: Hammedi, Tijani, Triki, Mohamed, Alvarez, Mayra G, Chimentao, Ricardo J, Ksibi, Zouhaier, Ghorbel, Abdelhamid, Llorca, Jordi, Medina, Francisco
Format: Article
Language:English
Subjects:
4-hydroxybenzoic acid
air
Analytical Chemistry
biological treatment
Catalitzadors
Catalysts
Catalytic oxidation
Catalytic wet air oxidation
CeO2–TiO2
Desenvolupament humà i sostenible
Earth and Environmental Science
Ecotoxicology
effluents
Electromagnetisme
Enginyeria ambiental
Environment
Environmental Chemistry
Física
Geochemistry
hydrogen
leaching
nitrogen
olive oil
Original Paper
oxidation
oxides
Phenols
Pollution
Ruthenium
sol-gel processing
Sol–gel
Tractament de l'aigua
transmission electron microscopy
wastewater
wastewater treatment
Water treatment
X-ray diffraction
Àrees temàtiques de la UPC
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Summary:Catalytic wet air oxidation using heterogeneous catalysts is a promising technology for treatment of wastewaters. Wastewaters from olive oil mills are difficult to clean because effluents contain high levels of phenolic compounds that cannot be removed by biological treatment or incineration. Therefore, we tested the catalytic wet air oxidation of p-hydroxybenzoic acid, as model molecule of olive oil mills wastewaters, over Ru-supported CeO₂–TiO₂ mixed oxides. We focussed on the Ce/Ti molar ratio because this ratio modifies the properties of the Ru catalysts. Supports were prepared by using the sol–gel method. The Ru catalysts were prepared by impregnation. Those products were characterized by N₂ adsorption–desorption, X-ray diffraction, H₂ chemisorption, transmission electron microscopy and inductively coupled plasma. Catalytic wet air oxidation of p-hydroxybenzoic acid was performed in a batch reactor at 140 °C and 50 bar of air. Our results show that the most efficient catalyst was Ru with a Ce/Ti ratio of 1/5, which converted totally p-hydroxybenzoic after 7 h of reaction without Ru leaching. We explain this finding by an enhanced dispersion of Ru due to better structural properties of the CeO₂–TiO₂ support.
ISSN:1610-3653
1610-3661
DOI:10.1007/s10311-015-0529-z