Degradation of highly chlorinated pesticide, lindane, in water using UV/persulfate: kinetics and mechanism, toxicity evaluation, and synergism by H2O2

초록

Sulfate radical-advanced oxidation processes (SR-AOPs) are emerging technologies for decomposing organic pollutants in water. This study investigated the efficiency of UV/persulfate (UV/S2O82-) process to degrade lindane in water, showing 93.2% lindane removal ([lindane]0 = 3.43 pM, [S2O82-](0) = 100 mu M) at a UV fluence of 720 mJ/cm(2). The lindane degradation followed first order kinetics and mechanistic studies suggested H-abstraction by SO4 center dot- and Cl removal via C-Cl bond cleavage by UV-C light. Toxicity assessment using ECOSAR program showed toxicity gradually decreased and eventually no significant toxicity remained when all byproducts vanished at high UV dose. Removal efficiency of lindane decreased from 93.2% to 38.4, 45.5, 56.0, 84.3 and 88.6%, by adding 1.0 mg/L humic acid or 1.0 mM CO32-, HCO3-, Clor SO42, respectively. Coupling of H2O2 with UV/S2O82- showed a significant synergistic effect with 99.0% lindane removal at a UV fluence of 600 mJ/cm(2), using [S2O82-](0) = [H2O2](0) = 50 mu M while UV/H2O2 resulted in only 36.6% lindane removal ([lindane](0) = 3.43 mu M, [H2O2](0) = 100 mu M) at a UV fluence of 720 mJ/cm(2). The results indicate that SR-AOP has potential for consideration as a remedial technology to treat persistent chlorinated pesticides such as lindane in contaminated water.

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