Quantification of the Primary Processes in Aqueous Heterogeneous Photocatalysis Using Single-Stage Oxidation Reactions

Davydov, Lev; Smirniotis, Panagiotis G.

doi:10.1006/jcat.1999.2777

Cited by 53 publications

(38 citation statements)

References 20 publications

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“…O 2 2 , and in turn the reactive oxygen species form in the aqueous suspension. 24,25 However, the Pt nanoparticle is itself an electron-hole recombination center. 26 Thus, at high Pt nanoparticle concentration the increased electron-hole recombination rate on Pt has a larger deleterious effect than the increased oxygen reduction on Pt, which enhances photoactivity.…”

Section: Resultsmentioning

confidence: 99%

Singlet oxygen photogeneration and 2,4,6-TCP photodegradation at Pt/TiO2 under visible light illumination

2012

RSC Adv.

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Pure and Pt nanoparticle-modified rutile TiO 2 were synthesized via hydrolysis of TiCl 4 in the absence or presence of Pt nanoparticles. HRTEM, XRD, and SEM were used to characterize the structure of the prepared catalysts. The resulting modified TiO 2 catalysts show extended visible light absorbance. Photodegradation of 2,4,6-trichlorophenol (2,4,6-TCP) over these photocatalysts was investigated under visible light illumination. The Pt nanoparticles facilitate the separation of photogenerated electron-hole pairs at low Pt content, then enhances the photodegradation rate of 2,4,6-TCP. 0.18Pt-TiO 2 achieved the best photocatalytic activity among the tested catalysts. It was found that singlet oxygen rather than ? OH acts as the main oxidative species for the degradation of 2,4,6-TCP according to the experimental results. The degradation intermediates of 2,4,6-TCP were identified and the degradation pathway was proposed.

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Section: Resultsmentioning

confidence: 99%

Singlet oxygen photogeneration and 2,4,6-TCP photodegradation at Pt/TiO2 under visible light illumination

2012

RSC Adv.

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“…However, distinct phenomena can also be involved; photocatalytic reactions may occur through direct electron transfer from the organic compounds to the semiconductor oxide and ultrasonic irradiation may selectively degrade less hydrophilic compounds through thermal degradation reactions (pyrolysis). The observed synergistic effect [20,22] may be justified by different reasons. In fact, for the ultrasonic treatment the presence of solid particles in the aqueous system enhances the cavitation phenomenon [23,24] as the microbubbles tend to break up into smaller ones thus increasing the total number of regions of high temperature and pressure.…”

Section: Ultrasonic Irradiationmentioning

confidence: 99%

The combination of heterogeneous photocatalysis with chemical and physical operations: A tool for improving the photoprocess performance

Augugliaro

Litter

Palmisano

et al. 2006

Journal of Photochemistry and Photobiology C: Photochemistry Re

406

178

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Heterogeneous photocatalysis is a process of great potential for pollutant abatement and waste treatment. In order to improve the overall performance of the photoprocess, heterogeneous photocatalysis is being combined with physical or chemical operations, which affect the chemical kinetics and/or the overall efficiency. This review addresses the various possibilities to couple heterogeneous photocatalysis with other technologies to photodegrade organic and inorganic pollutants dissolved in actual or synthetic aqueous effluents. These combinations increase the photoprocess efficiency by decreasing the reaction time in respect to the separated operations or they decrease the cost in respect of heterogeneous photocatalysis alone, generally in terms of light energy. Depending on the operation coupled with heterogeneous photocatalysis, two categories of combinations exist. When the coupling is with ultrasonic irradiation, photo-Fenton reaction, ozonation, or electrochemical treatment, the combination affects the photocatalytic mechanisms thus improving the efficiency of the photocatalytic process. When the coupling is with biological treatment, membrane reactor, membrane photoreactor, or physical adsorption, the combination does not affect the photocatalytic mechanisms but it improves the efficiency of the overall process. The choice of the coupling is related to the type of wastewater to be treated. A synergistic effect, giving rise to an improvement of the efficiency of the photocatalytic process, has been reported in the literature for many cases.

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“…The use of this molecule is suggested by Davydov and Smirniotis (2000) and Ito et al (1999). The formation of bicarbonate ion may be considered, although the air flow supplying oxygen to the solution is capable of stripping the carbon dioxide generated, keeping the bicarbonate concentration insignificant due to the shift in equilibrium (Equation 2).…”

Section: Test Molecule: Formic Acidmentioning

confidence: 99%

A comparison between bulk and supported TiO2 photocatalysts in the degradation of formic acid

Torres

Azevedo

Resende

et al. 2007

Braz. J. Chem. Eng.

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-The photocatalytic activity of bulk and supported TiO 2 catalysts were tested using formic acid as a probe molecule. The supported catalysts tested were prepared by impregnation using aluminum oxide (Al 2 O 3 ) as the support and the bulk catalysts by precipitation, both in sol-gel systems. For purposes of comparison, a photocatalyst supplied by DEGUSSA (P25) was also tested. The photolysis rate was found to be less significant than the photocatalytic rate. The Langmuir-Hinshelwood model was adopted and its constants were estimated and used to compare the various catalysts. The supported catalysts showed no significant activity, in spite of their high specific surface area. The bulk catalysts tested showed the highest photocatalytic rates. The adsorption constants determined experimentally were different from the ones estimated based on the kinetic experiments. The parameter estimation procedures tested were used to clarify this issue.

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Quantification of the Primary Processes in Aqueous Heterogeneous Photocatalysis Using Single-Stage Oxidation Reactions

Cited by 53 publications

References 20 publications

Singlet oxygen photogeneration and 2,4,6-TCP photodegradation at Pt/TiO2 under visible light illumination

Singlet oxygen photogeneration and 2,4,6-TCP photodegradation at Pt/TiO2 under visible light illumination

The combination of heterogeneous photocatalysis with chemical and physical operations: A tool for improving the photoprocess performance

A comparison between bulk and supported TiO2 photocatalysts in the degradation of formic acid

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