Singlet oxygen indirect photolysis

Illustrative Example 16.2 Estimating the Indirect Photolysis Half-Life of Atrazine in a Shallow Pond Reactions with Singlet Oxygen ( 02)... 

Table 18.5 shows indirect photolysis half-lives of azo dyes in natural waters at 40°N at the surface and 1 meter depth using measured rate constants and singlet oxygen concentrations. They apply only if singlet oxygen and/or radical oxidation are the only mechanisms for degradation. 

Figure 7 Direct photochemical reaction pathway of Triclosan (5-chloro-2-(2,4-di-chlorophenoxy)phenol) in natural water (3-100 iM of Triclosan in pH-bujfered solutions), irradiated with a Hg-vapour lamp. Only the triclosan phenolate anion (present in water at pH >8) is susceptible to significant photochemical transformation and will also react through indirect photolysis (not shown) with singlet oxygen ( O2) and OH radicals to form 2,4-dichloro-phenol (2,4-DCP). The photoproduct 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) belongs to a notoriously persistent group of chemicals commonly referred to as dioxins ...

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