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Photochemical behaviour of phenylbenzoquinone at the surface of the clays: Kaolinite, bentonite and montmorillonite

Paper ID Volume ID Publish Year Pages File Format Full-Text
27823 44044 2009 5 PDF Available
Title
Photochemical behaviour of phenylbenzoquinone at the surface of the clays: Kaolinite, bentonite and montmorillonite
Abstract

The kinetics of direct photochemical transformation of phenylbenzoquinone (PhQ) was studied at the surface of clays, light absorbing and scattering supports. When compared to the spectrum in solution, the UV absorption of PhQ on clays shows a hyperchromic as well as a solvatochromic effects. In kaolinite, bentonite and montmorillonite, the shift was about Δλ = 30 nm and the molar absorption coefficient was roughly three times higher. For various layers of clays, the disappearance of PhQ, followed a pseudo-first order kinetics. The diffusion of the compound from the lower part to the illuminate one was found to be low toward photolysis within the range 15–70 μm. In these conditions, the first order rate constant at the surface of kaolinite, k0, was found equal 2.3 × 10−2 min−1 in aerated conditions. This was roughly constant for the two other tested clays, bentonite and montmorillonite, where k0 was estimated to be 2.1 × 10−2 min−1 and 1.8 × 10−2 min−1, respectively. The photocyclization was found to be oxygen concentration dependent: kvacuumz/kairz=Φvacuum/Φair≈3.5. Diffuse-reflectance experiments clearly show the implication of the triplet state excited state in the photolysis of PhQ.

Keywords
Phenylbenzoquinone; Photocyclization; Clays; 2-Hydroxydibenzofuran; Triplet state
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Photochemical behaviour of phenylbenzoquinone at the surface of the clays: Kaolinite, bentonite and montmorillonite
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 208, Issues 2–3, 15 December 2009, Pages 159–163
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Price was $35.95
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Price after discount Only $4.95
100% Money Back Guarantee
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