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The objectivess of thisstudy were the determination of the second-order rate constants for the reactions ofpermanganate and chlorine with microcystin-LR (MC-LR) and cylindrospermopsin (CYL), and the formulation of a kinetic model topredict the toxin removal in drinking water treatment.Second-order rate constants for the reactions of MC-LR and CYL with permanganate andchlorine were determined in experiments performed in large excess of oxidant (first-orderconditions). The experiments started after addition of an aliquot of a concentrate stock oxidantsolution to a buffered toxin solution (10 mL). At fixed time intervals, 0.5 mL of sample wasrapidly transferred with a syringe into a HPLC vial containing tiosulphate to stop the reaction.The concentration of residual MC-LR and CYL was analyzed directly by HPLC.The elimination of MC-LR in surface water (pH=7.3, DOC=5.6 mg/L, [bicarbonate]=2.4 mM,[ammonia]=3.2 mM) was also investigated. Experiments were run with different initialoxidant doses, pH and temperature, covering well the conditions found in full-scale drinkingwater treatment. The initial MC-LR was very low (5 mg/L) as it is found in real samples.Experiments were performed by adding an aliquot of oxidant solution to the buffered naturalwater containing MC-LR. For each desired reaction time, oxidant and MC-LR concentrationswere analyzed. In these experiments, MC-LR concentration was measured by HPLC afterSPE enrichment. Includes 5 references, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 4File Size: 1 file , 270 KB