UV-photocatalytic oxidation

Tang, W.Z. and Hendrix, T., Development of QSAR models to predict kinetic rate constants for Ti02/UV photocatalytic oxidation, Water and Wastewater Industry and Sustainable Development, in honor of Prof. Xu Baojiu s 80th anniversary, Tsinghua Press, Beijing, China, 1998, pp. 427-439. 

Chemical oxygen demand Freshwaters UV irradiation for improving analyte degradation UV—Vis 0.5 mg L-1 Flow injection system manifold incorporating UV-photocatalytic oxidation instead of conventional heating [420]... 

D.-Z. Dan, R.C. Sandford, P.J. Worsfold, Determination of chemical oxygen demand in fresh waters using flow injection with on-line UV-photocatalytic oxidation and spectrophotometric detection, Analyst 130 (2006) 227. 

Option 1. Online UV-photocatalytic oxidation and spectrophotometric detection its application to the determination of COD in fresh waters using FIA. 

Tang WZ, An H (1995) UV/Ti02 photocatalytic oxidation of commercial dyes in aqueous solutions. Chemosphere 31 4157-4170... 

A further consequence of our photocatalytic oxidation cycle is the protective function which rutile pigments exert against UV degradation. This effect can be shown by several methods ... 

Choosing the most stable TiO modification. It has been shown that chalking is the result of two main processes UV degradation and the photocatalytic oxidation cycle. What can be done to stabilize Ti02 pigments in such a way that they cause as little chalking as possible A few possibilities have already been mentioned ... 

The ambient temperature and the possible use of solar UV are the advantages of photocatalysis moreover, Ti02 is not toxic. The reaction mechanisms of Ti02 photocatalytic oxidation of azo dyes was similar to the biodegradation process of oxidation of azo dyes with OH radical. 

The Adsorption Integrated Reaction (AlR-11) process is a destructive photocatalytic oxidation (PCO) process for the treatment of gas-phase waste streams that can operate successfully at low concentrations of contaminants and at a low energy cost. In the process, ultraviolet (UV) light illuminates a proprietary catalyst at room temperature, and produces hydroxyl radicals, which destroy organic compounds by oxidation. Very few by-products are created by the process, and many contaminants are broken down into harmless carbon dioxide and water. 

Ameen and Raupp examined photocatalytic regeneration following photocatalytic oxidation of o-xylene at 25 ppmv and 80% relative humidity [19]. Exposure to clean flowing air and UV illumination for 12 hr was found to restore the titanium dioxide photocatalyst activity to levels observed with fresh catalysts. 

Fig. 21. C MAS NMR spectra recorded during the photocatalytic oxidation of TCE (48pmol) on 170 mg of TiO2 in the presence of gaseous oxygen (60pinol). The UV irradiation time is indicated in minutes (right). Reproduced with permission from (190). Copyright 1997 American Chemical Society.

We report here results on the photocatalytic oxidation by oxygen of neat--liquid toluene, under UV-irradiation, by using unloaded and iron-loaded titania catalysts. Several experimental conditions have been selected to investigate parameters which can influence the chemical yields and the distribution of pro ducts particular attention has been devoted to investigate the evolution of chemical yields and selectivity by extending the irradiation times up to 12 h. 

On the other hand, the heterogeneous photocatalytic oxidation of toluene, in aqueous suspensions of TiO, has been studied with some details, by Fujihira et al. (refs.4-5). These authors have reported that, in aqueous media, up to 2 h of UV-irradiation, benzaldehyde was one of the main products benzyl alcohol was de tected as traces and benzoic acid was not detected (refs.4-5). However, in our experimental conditions using neat-liquid toluene, not only benzaldehyde but both benzyl alcohol and benzoic acid were detected as main products. 

Fig. 8.2 Principle of photocatalytic oxidation of various air pollutants under UV light illumination.

Photocatalytic oxidation by UV/Ti02 involves the excitation of Ti02 particles by UV light from the valance band of the solid to the conduction band. 

The photocatalytic reactions in acetonitrile were observed to have fewer primary products and a higher chemical yield of the desired sulfoxide (Fox et al., 1990). The photocatalytic oxidation of 2-chloroethyl methyl sulfide was found to be faster than the degradation of 2-chloroethyl ethyl. UV/ Ti02, in the presence of oxygen, yields the greatest amount of removal for the alkyl halides. The rate of alkyl halide removal was found to increase with increased concentrations of TiOz. 

---