Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2

Hydroxoaluminiumtricarboxymonoamide phthalocyanine (AlTCPc) adsorbed at different loadings on TiO2 Degussa P-25 was tested for Cr(vi) photocatalytic reduction under visible irradiation in the presence of 4-chlorophenol (4-CP) as sacrificial donor. A rapid reaction takes place in spite of the presuma...

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Autores principales: Rodríguez, Hernán Bernardo, Litter, Marta Irene
Publicado: 2009
Materias:
4 chlorophenol
benzoquinone
catechol
chromium 51
citric acid
dye
hydroquinone
phthalocyanine derivative
reactive oxygen metabolite
titanium dioxide
adsorption
article
bleaching
chemical reaction
electron
electron spin resonance
heavy metal removal
irradiation
kinetics
light irradiance
oxidation
photocatalysis
priority journal
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1474905X_v8_n5_p604_Meichtry
http://hdl.handle.net/20.500.12110/paper_1474905X_v8_n5_p604_Meichtry
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_1474905X_v8_n5_p604_Meichtry
record_format dspace
spelling paper:paper_1474905X_v8_n5_p604_Meichtry2023-06-08T16:17:49Z Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2 Rodríguez, Hernán Bernardo Litter, Marta Irene 4 chlorophenol benzoquinone catechol chromium 51 citric acid dye hydroquinone phthalocyanine derivative reactive oxygen metabolite titanium dioxide adsorption article bleaching chemical reaction electron electron spin resonance heavy metal removal irradiation kinetics light irradiance oxidation photocatalysis priority journal Hydroxoaluminiumtricarboxymonoamide phthalocyanine (AlTCPc) adsorbed at different loadings on TiO2 Degussa P-25 was tested for Cr(vi) photocatalytic reduction under visible irradiation in the presence of 4-chlorophenol (4-CP) as sacrificial donor. A rapid reaction takes place in spite of the presumable aggregation of the dye on the TiO2 surface. The removal of Cr(vi) is fairly negligible under visible-light irradiation, either without photocatalyst or in the presence of bare TiO2. The fast capture of conduction band electrons by Cr(vi), which forms a surface complex with TiO2, inhibits the formation of reactive oxygen species in the reductive pathway. This fact and the easier oxidation of 4-CP as compared to AlTCPc hinder the photobleaching of the dye and make feasible Cr(vi) reduction under visible irradiation. The consumption of Cr(vi) follows a pseudo-first order kinetics; the decay constant depends, in the studied range, on the photocatalyst mass, but it is barely affected by dye loading. The presence of 4-CP is essential, but its concentration has no effect on the Cr(vi) decay rate. Oxidation products of 4-CP, such as hydroquinone, catechol or benzoquinone, are not observed. Direct evidence of the one-electron reduction of Cr(vi) to Cr(v) was obtained by EPR spectroscopy using citric acid as Cr(v) trapping agent. In this case, disappearance of Cr(v) also follows a first order decay, but conduction band electrons do not seem to be involved. The fact that oxidation products of 4-CP are not observed is consistent with the fast dark removal of reaction intermediates by Cr(v), proved by EPR. © The Royal Society of Chemistry and Owner Societies 2009. Fil:Rodríguez, H.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Litter, M.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2009 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1474905X_v8_n5_p604_Meichtry http://hdl.handle.net/20.500.12110/paper_1474905X_v8_n5_p604_Meichtry
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic 4 chlorophenol
benzoquinone
catechol
chromium 51
citric acid
dye
hydroquinone
phthalocyanine derivative
reactive oxygen metabolite
titanium dioxide
adsorption
article
bleaching
chemical reaction
electron
electron spin resonance
heavy metal removal
irradiation
kinetics
light irradiance
oxidation
photocatalysis
priority journal
spellingShingle 4 chlorophenol
benzoquinone
catechol
chromium 51
citric acid
dye
hydroquinone
phthalocyanine derivative
reactive oxygen metabolite
titanium dioxide
adsorption
article
bleaching
chemical reaction
electron
electron spin resonance
heavy metal removal
irradiation
kinetics
light irradiance
oxidation
photocatalysis
priority journal
Rodríguez, Hernán Bernardo
Litter, Marta Irene
Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
topic_facet 4 chlorophenol
benzoquinone
catechol
chromium 51
citric acid
dye
hydroquinone
phthalocyanine derivative
reactive oxygen metabolite
titanium dioxide
adsorption
article
bleaching
chemical reaction
electron
electron spin resonance
heavy metal removal
irradiation
kinetics
light irradiance
oxidation
photocatalysis
priority journal
description Hydroxoaluminiumtricarboxymonoamide phthalocyanine (AlTCPc) adsorbed at different loadings on TiO2 Degussa P-25 was tested for Cr(vi) photocatalytic reduction under visible irradiation in the presence of 4-chlorophenol (4-CP) as sacrificial donor. A rapid reaction takes place in spite of the presumable aggregation of the dye on the TiO2 surface. The removal of Cr(vi) is fairly negligible under visible-light irradiation, either without photocatalyst or in the presence of bare TiO2. The fast capture of conduction band electrons by Cr(vi), which forms a surface complex with TiO2, inhibits the formation of reactive oxygen species in the reductive pathway. This fact and the easier oxidation of 4-CP as compared to AlTCPc hinder the photobleaching of the dye and make feasible Cr(vi) reduction under visible irradiation. The consumption of Cr(vi) follows a pseudo-first order kinetics; the decay constant depends, in the studied range, on the photocatalyst mass, but it is barely affected by dye loading. The presence of 4-CP is essential, but its concentration has no effect on the Cr(vi) decay rate. Oxidation products of 4-CP, such as hydroquinone, catechol or benzoquinone, are not observed. Direct evidence of the one-electron reduction of Cr(vi) to Cr(v) was obtained by EPR spectroscopy using citric acid as Cr(v) trapping agent. In this case, disappearance of Cr(v) also follows a first order decay, but conduction band electrons do not seem to be involved. The fact that oxidation products of 4-CP are not observed is consistent with the fast dark removal of reaction intermediates by Cr(v), proved by EPR. © The Royal Society of Chemistry and Owner Societies 2009.
author Rodríguez, Hernán Bernardo
Litter, Marta Irene
author_facet Rodríguez, Hernán Bernardo
Litter, Marta Irene
author_sort Rodríguez, Hernán Bernardo
title Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
title_short Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
title_full Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
title_fullStr Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
title_full_unstemmed Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2
title_sort photoreduction of cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on tio2
publishDate 2009
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1474905X_v8_n5_p604_Meichtry
http://hdl.handle.net/20.500.12110/paper_1474905X_v8_n5_p604_Meichtry
work_keys_str_mv AT rodriguezhernanbernardo photoreductionofcrviusinghydroxoaluminiumtricarboxymonoamidephthalocyanineadsorbedontio2
AT littermartairene photoreductionofcrviusinghydroxoaluminiumtricarboxymonoamidephthalocyanineadsorbedontio2
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