Degradation mechanisms of Microcystin-LR during UV-B photolysis and UV/HO processes: Byproducts and pathways.

The removal and degradation pathways of microcystin-LR (MC-LR, [M+H] = 995.6) in UV-B photolysis and UV-B/HO processes were examined using liquid chromatography-tandem mass spectrometry. The UV/HO process was more efficient than UV-B photolysis for MC-LR removal.

Degradation mechanisms of geosmin and 2-MIB during UV photolysis and UV/chlorine reactions.

We conducted chlorination, UV photolysis, and UV/chlorin reactions to investigate the intermediate formation and degradation mechanisms of geosmin and 2-methylisoborneol (2-MIB) in water. Chlorination hardly removed geosmin and 2-MIB, while the UV/chlorine reaction at 254 nm completely removed geosmin and 2-MIB within 40 min and 1 h, respectively, with lesser removals of both compounds during UV photolysis. The kinetics during both UV photolysis and UV/chlorine reactions followed a pseudo first-order reaction.