Hydrogen peroxide-assisted UV photodegradation of Lindane

Aqueous solutions of γ-hexachlorocyclohexane (Lindane) were photolyzed (λ = 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 μM, 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 × 10−3 s−1) was observed at pH 7 and initial [H2O2] = 1 mM. Thus, 90% of the Lindane is destroyed in ∼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 × 10−6 E s−1) and the cumulative production of OH during irradiation. The cumulative OH production during irradiation was fastest at an initial [H2O2] = 5 mM (k = 0.77 μM s−1).