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Surfactant effect on titanium dioxide photosensitized oxidation of 4-dodecyloxybenzyl alcohol

Paper ID Volume ID Publish Year Pages File Format Full-Text
26533 43960 2012 7 PDF Available
Title
Surfactant effect on titanium dioxide photosensitized oxidation of 4-dodecyloxybenzyl alcohol
Abstract

The TiO2 photosensitized oxidation of 4-dodecyloxybenzyl alcohol (1), water insoluble, was investigated in aqueous surfactant solutions. A variety of surfactants of different charge type was used and in some cases the pH effect was investigated. The considered surfactants are: cationic (cetyltrimethylammonium with various counterions, CTAX with X = Cl, Br and OMs), zwitterionic (dimethyldodecylamine oxide, DDAO, tetradecyltrimethylammonium propane sulfonate, SB3-14, and tetradecyltripropylammonium propane sulfonate, SBPr3-14) and anionic (sodium dodecylsulfate, SDS, sodium dodecylbenzenesulfonate, SDBS). The reaction, that is practically absent in water, is greatly enhanced by several surfactants at concentrations higher than cmc and the effect is strongly dependent on the nature of the surfactant. A rationale for that is suggested, with micellar aggregates rather than monomeric surfactants playing a main role. The effects of surfactant concentration on the conversion to the corresponding benzaldehyde were studied. We suggest that the increase of the surfactant concentration leads to an increase of the number of substrate molecules, solubilized (through co-micellization) in micelles, which can be transported close to the TiO2 particle surface where they react. After a certain concentration which varies with the nature of the surfactant, the presence of the competitive partition between the co-micellized substrate 1 adsorbed on TiO2 (where reaction occurs) and the co-micellized substrate in the bulk tends to limit more and more the beneficial kinetic effect of the surfactant. The surfactant that gives in water the best performance in terms of 4-dodecyloxybenzaldehyde yield (42%) is SB3-14 0.015 M. Moreover, a better yield (55%) is obtained in the presence of surfactant CTABr 0.05 M with added HCl 0.1 M.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► TiO2 photooxidation of 4-dodecyloxybenzyl alcohol in water does not happen. ► 4-Dodecyloxybenzaldehyde is obtained only in the presence of certain surfactants. ► The surfactants concentrations are higher than cmc. ► The reaction rate is dependent on the nature of the surfactant. ► Micellar aggregates and substrate comicellization play a main role.

Keywords
Titanium dioxide; Surfactants; Micelles; Oxidation; Photocatalysis
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Surfactant effect on titanium dioxide photosensitized oxidation of 4-dodecyloxybenzyl alcohol
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 229, Issue 1, 1 February 2012, Pages 53–59
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
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Online Support
Any Questions? feel free to contact us