Photochemical Fate of Organic Booster Biocides in the Aquatic Environment - Antifouling Paint Biocides - page 171

Photochemical Fate
of Organic Booster Biocides in the Aquatic Environment

Vasilios A. Sakkas · Ioannis K. Konstantinou · Triantafyllos A. Albanis ( )

Chemistry Department, Laboratory of Industrial Chemistry, Ioannina University,
45110 Ioannina, Greece
[e-mail]

1 I tr cti n ................................... 173

2 Photochemical Transformation Processes

of Pollutants in Aqueous Environment .................... 174

2.1 DirectPhotolysis ................................ 174

2.2 Sensitized / IndirectPhotolysis ......................... 175

3 Kinetics, Photoproducts, and Reaction Pathways

of Antifouling Booster Biocides ........................

176

3.1 Chlorothalonil.................................. 176

3.2 Dichlofluanid .................................. 178

3.3 Irgarol 1051 ................................... 180

3.4 Sea-Nine211................................... 183

3.5 Diuron ...................................... 186

3.6 ZincandCopperPyrithiones.......................... 188

3.7 Dithiocarbamates ................................ 190

3.7.1 ThiramandZiram................................ 190

3.7.2 ManebandZineb ................................ 191

3.8 TCMTB...................................... 192

3.9 Triphenylboron-pyridine ............................ 194

4 cl i g e ar s .............................. 195

References ....................................... 197

Abstract Considering the relevance and importance of photochemical processes in the
environmental fate and behavior of organic micropollutants, the present review describes
the state-of-the-art knowledge regarding the photodegradation of antifouling biocides in
the aquatic environment. It includes data on photodegradation rates, primary and end
photoproducts, and the pathways and mechanisms for most of the organic booster bio-
cides (i.e., irgarol 1051, Sea-Nine 211, dichlofluanid, diuron, chlorothalonil, TCMTB, zinc
and copper pyrithione, maneb, zineb, ziram, thiram, and triphenylboron-pyridine) used
in antifouling paints.
Light-induced degradation took place both with direct or indirect (photosensitized)
mechanisms via first-order kinetics. Direct photolysis in most cases seemed to be a mi-
nor event compared to photosensitized processes that usually enhanced the degradation.
The composition of the water matrix is a key factor for the photofate of biocides in var-
ious natural waters. Half-lives ranged from a few minutes (zinc / copper pyrithiones) to
several days (diuron and irgarol 1051) depending on the irradiation conditions as well as