Surface effects in photochemistry: an in situ cylindrical internal reflection-Fourier transform infrared investigation of the effect of ring substituents on chemisorption onto TiO[sub 2] ceramic membranes

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00038a030· OSTI ID:5845421

Tunesi, S; Anderson, M A ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States)

The role of phenyl substituent groups in the formation of surface complexes at the surface of titanium dioxide semiconducting ceramic membranes is investigated with cylindrical internal reflection-Fourier transform infrared (CIR-FTIR) spectroscopy. The CIR-FTIR study presented in this article allows for direct comparison between adsorption mechanisms derived from vibrational spectra at the semiconductor-liquid interface and surface structures influencing aqueous heterogeneous photochemical reactions. Therefore, chemisorption mechanisms we derived for benzoic acid and its substituted compounds could be used for the prediction of their photodegradation behavior. This IR investigation confirms that no adsorption is detectable on the rutile phase of TiO[sub 2], thus excluding the role of 5-fold coordinated Ti cations in the adsorption mechanisms. We observed that, for anatase surface, isolated carboxyl groups do not generate a favorable adsorption equilibrium (e.g., benzoic acid). It is proposed that amino and hydroxyl groups substituted in ortho position to a carboxyl group (e.g., salicylic, 3-chlorosalicylic, and anthranilic acids) may lead to a mononuclear bidentate coordination complex with 4-fold coordinated surface titanium cations. The higher adsorption level observed for phthalic acid is interpreted as due to its possibility of adsorbing on a greater number of anatase surface sites, by forming two different surface complexes, involving one or both carboxyl groups. A relationship between change in vibrational spectra of the carboxyl group, for substituted benzoic derivatives, and acidic dissociation constants is presented. 37 refs., 7 figs., 1 tab.

• OSTI ID: 5845421
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 8:2; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ADSORPTION
AMINO ACIDS
ANTHRANILIC ACID
BENZOIC ACID
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMISTRY
COMPLEXES
DICARBOXYLIC ACIDS
HYDROXY ACIDS
MATERIALS
MEMBRANES
MINERALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMISTRY
PHTHALIC ACID
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RUTILE
SALICYLIC ACID
SORPTION
THERMODYNAMICS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
WATER TREATMENT