For some model molecules (methanoic and ethanoic acids, methane,and phenol), systematic investigations of quantum yields were carried out in the present paper, as a function of concentration and of absorbed radiant power. Quantum yields Φ∞,calculated from rates, followed an apparently Langmuirian function of initial concentration C0, by which Φ∞ values at "infinite" concentration could be obtained. By having thus established that quantum yields of photomineralisation Φ∞ are independent of radiation wavelength, within the absorption range of semiconductor, but depend on radiant power, such a dependency was experimentally investigated. For all the investigated molecules, the maximum allowable values reached in the low radiant power range clearly appeared as a plateau. On the contrary, at high radiant power values, another plateau, at a value of about 1/4-1/5 with respect to the maximum value, was evident. This was interpreted on the basis of a competition kinetics of hydroxyl radicals with themselves, leading to hydrogen peroxide formation, other than with substrate or intermediate molecules leading to full mineralisation.Modelling of quantum yields as a function of concentration and radiant power thus allows a fully consistent and trustworthy design of photoreactors. Copyright © 2006 Ignazio Renato Bellobono et al.
Bellobono, I. R., De Martini, G., Tozzi, P. M., Canevali, C., Morazzoni, F., Scotti, R., & Bianchi, R. (2006). Modelling of quantum yields in photocatalytic membrane reactors immobilising titanium dioxide. International Journal of Photoenergy, 2006. https://doi.org/10.1155/IJP/2006/26870