Heterogeneous ozonation kinetics of 4-phenoxyphenol in presence of photosensitizer
Atmospheric Chemistry and Physics Discussions
In this work we have quantitatively measured the degradation of 4-phenoxyphenol adsorbed on silica particles following oxidative processing by gas-phase ozone. This was performed under dark conditions and in the presence of 4carboxybenzophenone under simulated sunlight irradiation of the particles surface. At the mixing ratio of 60 ppb which corresponds to strongly polluted ozone areas, the first order of decay of 4-phenoxyphenol is k 1 =9.95×10 −6 s −1 . At a very high ozone mixing ratio of 6
... mixing ratio of 6 ppm the first order rate constants for 4-phenoxyphenol degradation were the following: k 1 =2.86×10 −5 s −1 under dark conditions and k 1 =5.58×10 −5 s −1 in the presence of photosensitizer (4carboxybenzophenone) under light illumination of the particles surface. In both cases, the experimental data follow the modified Langmuir-Hinshelwood equation for surface reactions. The Langmuir-Hinshelwood and Langmuir-Rideal mechanisms for bimolecular surface reactions are also discussed along with the experimental results. Most importantly, the quantities of the oligomers such as 2-(4-Phenoxyphenoxy)-4-phenoxyphenol and 4-[4-(4-Phenoxyphenoxy)phenoxy]phenol formed during the heterogeneous ozonolysis of adsorbed 4-phenoxyphenol were much higher under solar light irradiation of the surface in comparison to the dark conditions.