Abstract
Photodegradation process of zinc pyrithione (Zn(PT)2) in aqueous solution was investigated using a photo spectroscopic technique. Three characteristic peaks were observed in ultraviolet and visible light absorption spectrum of Zn(PT)2. By xenon lamp irradiation, the spectrum rapidly changes to that of 2-pyridinsulfonic acid (PSA) and finally exhibits nearly flat with several very weak unknown peaks. Rate constants, obtained on a basis of the first order kinetics, do not depend on either the concentration between 0.03 and 3 mg/L or the temperature from 283 to 303 K, but are proportional to the intensity of irradiation light. The half life of Zn(PT)2 in water is estimated to be approximately 25 minutes under an average natural sun light intensity (188 W/m2) on the ocean surface.
