Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description

The adsorption and photooxidation of salicylic acid on dispersed TiO 2 (Degussa P-25) particles was studied as a function of substrate concentration and pH. Salicylic acid chemisorbs at the particle interface, forming inner-sphere titanium(IV) salicylate surface complexes. The visible differential d...

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Autores principales: Regazzoni, A.E., Mandelbaum, P., Matsuyoshi, M., Schiller, S., Bilmes, S.A., Blesa, M.A.
Formato: JOUR
Materias:
Adsorption
Binding energy
Chemisorption
Interfacial energy
Isotherms
pH effects
Phase transitions
Substrates
Titanium dioxide
Metal charge transfer transition
Photooxidation
Salicylic acid
Carboxylic acids
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_07437463_v14_n4_p868_Regazzoni
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_07437463_v14_n4_p868_Regazzoni2023-10-03T15:38:31Z Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description Regazzoni, A.E. Mandelbaum, P. Matsuyoshi, M. Schiller, S. Bilmes, S.A. Blesa, M.A. Adsorption Binding energy Chemisorption Interfacial energy Isotherms pH effects Phase transitions Substrates Titanium dioxide Metal charge transfer transition Photooxidation Salicylic acid Carboxylic acids The adsorption and photooxidation of salicylic acid on dispersed TiO 2 (Degussa P-25) particles was studied as a function of substrate concentration and pH. Salicylic acid chemisorbs at the particle interface, forming inner-sphere titanium(IV) salicylate surface complexes. The visible differential diffuse reflectance spectra of the surface complexes present a band, with maximum absorption at 420 nm, which is assigned to the internal ligand to metal charge-transfer transition. The surface excess of salicylic acid increases with decreasing pH and levels off around pK a1 . At constant pH, the surface excess increases with the concentration of salicylic acid, the isotherm reflecting surface site heterogeneity. Photooxidation rates in air-saturated solutions, on the other hand, are independent of both pH and salicylic acid concentration, in the entire studied range. Chemisorption results are accounted for by a multisite surface complexation model in which two different surface titanium sites and three complexation modes are considered. The mismatch between salicylic acid surface excess values and photooxidation rates is interpreted in terms of the different reactivities of the titanium(IV) salicylate surface complexes and is attributed to the fastest hole capture by bidentate salicylate binding a single surface titanium ion. The advanced rationale illustrates the importance of the basic principles of coordination chemistry in the interpretation of apparent kinetic orders in photolyte concentration. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_07437463_v14_n4_p868_Regazzoni
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Adsorption
Binding energy
Chemisorption
Interfacial energy
Isotherms
pH effects
Phase transitions
Substrates
Titanium dioxide
Metal charge transfer transition
Photooxidation
Salicylic acid
Carboxylic acids
spellingShingle Adsorption
Binding energy
Chemisorption
Interfacial energy
Isotherms
pH effects
Phase transitions
Substrates
Titanium dioxide
Metal charge transfer transition
Photooxidation
Salicylic acid
Carboxylic acids
Regazzoni, A.E.
Mandelbaum, P.
Matsuyoshi, M.
Schiller, S.
Bilmes, S.A.
Blesa, M.A.
Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
topic_facet Adsorption
Binding energy
Chemisorption
Interfacial energy
Isotherms
pH effects
Phase transitions
Substrates
Titanium dioxide
Metal charge transfer transition
Photooxidation
Salicylic acid
Carboxylic acids
description The adsorption and photooxidation of salicylic acid on dispersed TiO 2 (Degussa P-25) particles was studied as a function of substrate concentration and pH. Salicylic acid chemisorbs at the particle interface, forming inner-sphere titanium(IV) salicylate surface complexes. The visible differential diffuse reflectance spectra of the surface complexes present a band, with maximum absorption at 420 nm, which is assigned to the internal ligand to metal charge-transfer transition. The surface excess of salicylic acid increases with decreasing pH and levels off around pK a1 . At constant pH, the surface excess increases with the concentration of salicylic acid, the isotherm reflecting surface site heterogeneity. Photooxidation rates in air-saturated solutions, on the other hand, are independent of both pH and salicylic acid concentration, in the entire studied range. Chemisorption results are accounted for by a multisite surface complexation model in which two different surface titanium sites and three complexation modes are considered. The mismatch between salicylic acid surface excess values and photooxidation rates is interpreted in terms of the different reactivities of the titanium(IV) salicylate surface complexes and is attributed to the fastest hole capture by bidentate salicylate binding a single surface titanium ion. The advanced rationale illustrates the importance of the basic principles of coordination chemistry in the interpretation of apparent kinetic orders in photolyte concentration.
format JOUR
author Regazzoni, A.E.
Mandelbaum, P.
Matsuyoshi, M.
Schiller, S.
Bilmes, S.A.
Blesa, M.A.
author_facet Regazzoni, A.E.
Mandelbaum, P.
Matsuyoshi, M.
Schiller, S.
Bilmes, S.A.
Blesa, M.A.
author_sort Regazzoni, A.E.
title Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
title_short Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
title_full Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
title_fullStr Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
title_full_unstemmed Adsorption and photooxidation of salicylic acid on titanium dioxide: A surface complexation description
title_sort adsorption and photooxidation of salicylic acid on titanium dioxide: a surface complexation description
url http://hdl.handle.net/20.500.12110/paper_07437463_v14_n4_p868_Regazzoni
work_keys_str_mv AT regazzoniae adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
AT mandelbaump adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
AT matsuyoshim adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
AT schillers adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
AT bilmessa adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
AT blesama adsorptionandphotooxidationofsalicylicacidontitaniumdioxideasurfacecomplexationdescription
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