Kinetics and mechanism for dye degradation with ionic Pd-substituted ceria

Deshpande, Parag A.; Jain, Disha; Madras, Giridhar

doi:10.1016/j.apcata.2011.01.020

“…Because of the sufficiently high H 2 O 2 concentration compared with the number of Ce(III) accessible sites, the excess H 2 O 2 (uncoordinated) can oxidise Ce(III) to Ce(IV) according to the reaction shown in step (3). At this point the reaction leads to the formation of a brown complex of Ce IV (O 2 ) 2− species, which was established from DR‐UV–vis and Raman data. These species are relatively stable at neutral pH, and cannot generate hydroxyl radicals.…”

Section: Resultsmentioning

confidence: 91%

Reactivity of ceria–zirconia catalysts for the catalytic wet peroxidative oxidation of azo dyes: reactivity and quantification of surface Ce(IV)‐peroxo species

Hamoud

¹

,

Azambre

²

,

Finqueneisel

³

2015

J of Chemical Tech & Biotech

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BACKGROUND: Doping nanoceria with zirconia often leads to improved catalytic properties due to enhanced concentration of structural defects in the resulting materials. This study aims to identify the parameters and mechanisms governing the reactivity of well-characterized commercial ceria-zirconia (Ce x Zr 1-x O 2 ) nanocatalysts with various Ce contents (x = 1, 0.80, 0.50, 0.21, 0) or surface area towards the degradation of Orange II dye in the presence of H 2 O 2 . RESULTS: Discoloration and mineralization kinetics were found to be strongly related both to the composition and surface area of the single or mixed oxides. Under standard conditions (23 ∘ C, dark, stoichiometric concentration in H 2 O 2 ), the best discoloration and mineralization performances were achieved for pure ceria (100% of color removal in 2 h and 65% mineralization in 8 h), but this arises mainly from its higher specific area by comparison with Zr-doped materials.For the first time, the amount of Ce IV (O 2 ) 2− surface species, intermediates in the production of hydroxyl radicals and generated from the reaction of H 2 O 2 with Ce(III) sites, was quantitated using TPD-MS in order to provide a rational basis to explain the catalytic performance. CONCLUSION: Doping ceria with Zr increases the surface density of defective Ce(III) sites that can be converted to Ce IV (O 2 ) 2− species in the presence of H 2 O 2 , but other parameters, such as the specific surface area and surface Ce content of the catalysts, are also important. An in-depth mechanism for the reaction of H 2 O 2 on the ceria-zirconia surface is discussed based on the experimental results.

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“…CeO 2 is also used as an additive or a promoter in commercial applications such as fluid catalytic cracking, ammoxidation and dehydrogenation processes [33][34][35][36][37]. Moreover, in the last years several ceriabased catalysts were investigated for CWAO (catalytic wet air oxidation) [38][39][40] and CWOP (catalytic wet peroxide oxidation) [41][42][43][44] techniques. The main purpose of this work is to investigate doped ceria materials in the treatment of landfill leachate by a heterogeneous Fenton process.…”

Section: Introductionmentioning

confidence: 99%

Potential of Ceria-Based Catalysts for the Oxidation of Landfill Leachate by Heterogeneous Fenton Process

2016

Sewage and Landfill Leachate

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In this study, ceria and ceria-zirconia solid solutions were tested as catalyst for the treatment of landfill leachate with a Fenton-like process. The catalysts considered in this work were pure ceria and ceria-zirconia solid solutions as well as iron-doped samples. All the catalysts were extensively characterized and applied in batch Fenton-like reactions by a close batch system, the COD (chemical oxygen demand) and TOC (total organic carbon) parameters were carried out before and after the treatments in order to assay oxidative abatement. Results show a measurable improvement of the TOC and COD abatement using ceria-based catalysts in Fenton-like process and the best result was achieved for iron-doped ceria-zirconia solid solution. Our outcomes point out that heterogeneous Fenton technique could be effectively used for the treatment of landfill leachate and it is worth to be the object of further investigations.

show abstract

“…CeO 2 is also used as an additive or a promoter in commercial applications such as fluid catalytic cracking, ammoxidation and dehydrogenation processes [33][34][35][36][37]. Moreover, in the last years several ceriabased catalysts were investigated for CWAO (catalytic wet air oxidation) [38][39][40] and CWOP (catalytic wet peroxide oxidation) [41][42][43][44] techniques. The main purpose of this work is to investigate doped ceria materials in the treatment of landfill leachate by a heterogeneous Fenton process.…”

Section: Introductionmentioning

confidence: 99%

Potential of Ceria-Based Catalysts for the Oxidation of Landfill Leachate by Heterogeneous Fenton Process

Aneggi

¹

,

Cabbai

²

,

Trovarelli

³

et al. 2012

International Journal of Photoenergy

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In this study, ceria and ceria-zirconia solid solutions were tested as catalyst for the treatment of landfill leachate with a Fenton-like process. The catalysts considered in this work were pure ceria and ceria-zirconia solid solutions as well as iron-doped samples. All the catalysts were extensively characterized and applied in batch Fenton-like reactions by a close batch system, the COD (chemical oxygen demand) and TOC (total organic carbon) parameters were carried out before and after the treatments in order to assay oxidative abatement. Results show a measurable improvement of the TOC and COD abatement using ceria-based catalysts in Fenton-like process and the best result was achieved for iron-doped ceria-zirconia solid solution. Our outcomes point out that heterogeneous Fenton technique could be effectively used for the treatment of landfill leachate and it is worth to be the object of further investigations.

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Kinetics and mechanism for dye degradation with ionic Pd-substituted ceria

Cited by 8 publications

References 49 publications

Reactivity of ceria–zirconia catalysts for the catalytic wet peroxidative oxidation of azo dyes: reactivity and quantification of surface Ce(IV)‐peroxo species

Reactivity of ceria–zirconia catalysts for the catalytic wet peroxidative oxidation of azo dyes: reactivity and quantification of surface Ce(IV)‐peroxo species

Potential of Ceria-Based Catalysts for the Oxidation of Landfill Leachate by Heterogeneous Fenton Process

Potential of Ceria-Based Catalysts for the Oxidation of Landfill Leachate by Heterogeneous Fenton Process

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