Hydrogen peroxide-assisted UV photodegradation of Lindane

Aqueous solutions of gamma-hexachlorocyclohexane (Lindane) were photolyzed (lambda = 254 nm) under a variety of solution conditions. The initial concentrations of hydrogen peroxide (H2O2) and Lindane varied from 0 to 20 mM and 0.21 to 0.22 mu M respectively, the pH ranged from 3 to 11, and several concentration ratios of Suwannee River humic acid and fulvic acid were dissolved in the irradiated solutions. Lindane rapidly reacted. and the maximum reaction rate constant (9.7 x 10(-3) s(-1)) was observed at pH 7 and initial [H2O2] = 1 mM. Thus. 90% of the Lindane is destroyed in similar to 4 min under these conditions. In addition, within 15 min, all chlorine atoms were converted to chloride ion, indicating that chlorinated organic by-products do not accumulate. The reactor was characterized by measuring the photon flux (7.04 x 10(-6) E s(-1)) and the cumulative production of (OH)-O-center dot during irradiation. The cumulative (OH)-O-center dot production during irradiation was fastest at an initial [H2O2] = 5 mM (k = 0.77 mu M s(-1)). (c) 2008 Elsevier Ltd. All rights reserved.