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Counterion effect of cationic surfactants on the oxidative degradation of Alizarin Red-S photocatalysed by TiO2 in aqueous dispersion
- Source :
- Journal of Photochemistry and Photobiology A: Chemistry. 332:546-553
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- The TiO 2 photocatalyzed degradation of a hazardous texile dye, 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt (Alizarin Red-S, ARS), has been assisted by various cationic surfactants and examined in air-equilibrated aqueous medium under UV light irradiation. Absorption spectral analysis showed that ARS degrades slowly via a pH-dependent process in TiO 2 dispersions containing no surfactant. The photodegradation efficiency of the dye was significantly enhanced, especially in alkaline media, by the addition of surfactants such as cetyltrialkylammonium salts (CTRAX). Since both ARS and the TiO 2 surface are negatively charged in basic conditions, the addition of cationic surfactants has effectively allowed the mutual interaction among the dye, CTRAX and TiO 2 . The cooperation between the inorganic and organic components, which is very likely realized through the formation of cationic surfactant bilayers on the TiO 2 particles, permitted an improvement in the coadsorption of ARS onto the TiO 2 particles and thus rendering ARS more available to the action of the photo-yielded oxidative species formed on the semiconductor surface. The crucial influence of the surfactant adsorption was clearly pointed out by the investigation of the counterion effect on the degree of ARS photodecomposition as a function of the cetyltrimethylammonium salt (CTAX) concentration. Two particularly significant aspects have emerged from this investigation: the almost complete degradation of ARS was achieved, for all surfactants used, at a concentration close to 1 mM (value well above the cmc in the experimental conditions); also, by increasing the surfactant concentration, the photocatalytic reaction became less and less efficient and significantly dependent on the counterion nature. These results have allowed to gain insight and a better understanding of the surfactant-assisted photocatalytic degradation mechanism of the dye.
- Subjects :
- General Chemical Engineering
Inorganic chemistry
General Physics and Astronomy
Salt (chemistry)
02 engineering and technology
010402 general chemistry
Photochemistry
01 natural sciences
Catalysis
chemistry.chemical_compound
Adsorption
Pulmonary surfactant
Alizarin Red-S
Photodegradation
Surfactant
Alizarin Red-S, Catalysis, Photodegradation, Surfactant, Titanium dioxide
chemistry.chemical_classification
Cationic polymerization
General Chemistry
021001 nanoscience & nanotechnology
0104 chemical sciences
chemistry
Titanium dioxide
Absorption (chemistry)
Counterion
0210 nano-technology
Subjects
Details
- ISSN :
- 10106030
- Volume :
- 332
- Database :
- OpenAIRE
- Journal :
- Journal of Photochemistry and Photobiology A: Chemistry
- Accession number :
- edsair.doi.dedup.....1910f3ff3bad460055a5c9eac65d7f78