Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes
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Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.
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Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexesZhang, T.; Croué, Jean-Philippe (2014)Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by ...
Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidationZhang, T.; Li, W.; Croué, Jean-Philippe (2011)The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl ...
A non-acid-assisted and non-hydroxyl-radical-related catalytic ozonation with ceria supported copper oxide in efficient oxalate degradation in waterZhang, T.; Li, W.; Croue, Jean-Philippe (2012)Oxalate is usually used as a refractory model compound that cannot be effectively removed by ozone and hydroxyl radical oxidation in water. In this study, we found that ceria supported CuO significantly improved oxalate ...