Heterogeneous ozonation kinetics of 4-phenoxyphenol in presence of photosensitizer

• Published in: Atmospheric chemistry and physics discussions Vol. 9; no. 5; pp. 21647 - 21668
• Main Authors: Net, S, Nieto-Gligorovski, L, Gligorovski, S, Wortham, H
• Format: Journal Article
• Language: English
• Published: 15.10.2009
• ISSN: 1680-7367; 1680-7375

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 presence of 4-carboxybenzophenone under simulated sunlight irradiation of the particles surface. At mixing ratio of 60 ppb which corresponds to strongly ozone polluted areas, the first order decay of 4-phenoxyphenol is k sub(1)=9.9510 super(− 6) s super(− 1). At very high ozone mixing ratio of 6 ppm the first order rate constants for 4-phenoxyphenol degradation were the following: k sub(1)=2.8610 super(− 5) s super(− 1) under dark conditions and k sub(1)=5.5810 super(− 5) s super(− 1) in presence of photosensitizer (4-carboxybenzophenone) under light illumination of the particles surface. In both cases the experimental data do follow the modified Langmuir-Hinshelwood equation for surface reactions. Langmuir-Hinshelwood and Langmuir-Rideal mechanisms 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.