PHOTODEGRADATION OF QUINOLINE IN WATER

The photodegradation kinetics of quinoline have been studied at 313 nm and in sunlight in organic-free water, lake water, and water containing several different solutes. The half-life of sunlight photodegradation is slightly shorter in lake water than in organic-free water (4-8%, depending upon the season). In near-surface lake water at 40-degrees N latitude in summer, quinoline was predicted to degrade readily in sunlight, with a half-life of about 14 calendar days. The calculated half-life in winter was about 123 calendar days. The photodegradation of quinoline was accelerated significantly by NaNO3 and dissolved organic matter, two effective producers of hydroxyl radicals in aquatic environment. The rate was also faster at pH 4.5 than at pH 7.0. Two photoproducts were identified in low yield, 2-hydroxyquinoline and 8-hydroxyquinoline; prolonged irradiation appeared to destroy the aromatic nucleus.