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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todo:paper_1474905X_v8_n5_p604_Meichtry2023-10-03T16:18:34Z Photoreduction of Cr(vi) using hydroxoaluminiumtricarboxymonoamide phthalocyanine adsorbed on TiO2 Meichtry, J.M. Rivera, V. Di Iorio, Y. Rodríguez, H.B. Román, E.S. Grela, M.A. Litter, M.I. 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. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar 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 Meichtry, J.M. Rivera, V. Di Iorio, Y. Rodríguez, H.B. Román, E.S. Grela, M.A. Litter, M.I. 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. |
| format |
JOUR |
| author |
Meichtry, J.M. Rivera, V. Di Iorio, Y. Rodríguez, H.B. Román, E.S. Grela, M.A. Litter, M.I. |
| author_facet |
Meichtry, J.M. Rivera, V. Di Iorio, Y. Rodríguez, H.B. Román, E.S. Grela, M.A. Litter, M.I. |
| author_sort |
Meichtry, J.M. |
| 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 |
| url |
http://hdl.handle.net/20.500.12110/paper_1474905X_v8_n5_p604_Meichtry |
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