Hydrogen peroxide, photolysis, effect

Einschlag FG, Feliz MR, Capparelli AL (1997) Effect of Temperature on Hydrogen Peroxide Photolysis in Aqueous Solutions, J. Photochem. Photobiol. A Chem. 110 235-242. 

Ultraviolet light without hydrogen peroxide is not very effective for the degradation of organics. When UV light and H202 are combined, the overall oxidative reaction potential is greatly enhanced even under ambient temperature and pressure. The efficiency of direct photolysis depends on (1) UV absorbance by substrates (2) quantum yield of photolysis (3) presence of other competitive UV absorbents and (4) intensity of UV sources. 

Another technique involving photolysis which is often effective involves exposure of a solid containing a trace of some photosensitive compound which absorbs in a region of lower energy than the onset of absorption by the solvent . Typically, dilute solid solutions of hydrogen peroxide in a wide range of solvents can be photolysed with a medium-pressure mercury arc. Early studies of this sort, described in Section III, involved the use of alcohols and it was shown that radicals characteristic of the alcohols were trapped. No evidence for trapped hydroxyl radicals was forthcoming and it was concluded that a secondary reaction occurred such as ... 

Figure 3. Effect of MWCNT on a) amount of hydroxyl radicals generated by photolysis of hydrogen peroxide, measured by ESR/spin trapping technique b) amount of superoxide radicals generated by a xantine/xantine oxidase system, measured by UV spectroscopy. Light gray bars no NT, dark gray bars in the presence of NT.31...

Noncatalytic remediation of aqueous solutions of a variety of aromatic compounds by microwave-assisted photolysis in the presence of hydrogen peroxide has recently been studied by Klan and Vavrik [187]. The combined degradation effect of UV and MW radiation was always larger than the sum of the isolated effects. 

In one of the first studies, Stepnowski Zaleska compared the effectiveness of three methods UV photodegradation, UV photolysis of hydrogen peroxide, and photocatalysis on UV-irradiated Ti02. For these investigations imidazolium ILs with different alkyl chain length were chosen (1-butyl-, l-hexyl-3-methylimidazolium, l-methyl-3-octylimidazolium, l-ethyl-3-ethylimidazolium chloride or tetrafluoroborate, methyl imidazole as reference). The stability of these compoxmds with respect to all the photodegradation methods used... 

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