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Thisresearch examined the influence of natural organic matter (NOM) and bromide on the loss of chlorpyrifos (CP) in thepresence of free chlorine. The effect of bromide on CP degradation was examined at twodifferent free chlorine concentrations ([FC]subT/sub = 10 and 50 M), bromide concentrations from 0-10mM, over the pH range 7-9. A model NOM source, Suwannee River fulvic acid (SRFA), wasused to provide a potential sink for active oxidants in the aqueous system. Results are presentedas observed first order rate coefficients (ksubobs/sub).Experiments were conducted at 25 ¿¿¿¿ 1C in 128 mL amber batchreactors. Free chlorine was added to the aqueous system containing 0.5 M CP, 10 mMcarbonate buffer, and with or without the presence of bromide and/or NOM. Details of theexperimental procedures have been discussed elsewhere. A stock solution of NOM wasprepared from lyophilized Suwannee River fulvic acid (SRFA). The SRFA (50 mg) was dissolved in 500 mL of de-ionizedwater for 24 hours, filtered through a 0.45 micron filter to remove lyophilized SRFA that did notreconstitute, and the pH was adjusted to 9.0 with NaOH. UV/Vis spectra were obtained on aPerkin Elmer Lambda 900 spectrophotometer. Total organic carbon (TOC) concentration was analyzed with aShimadzu TOC 5050A analyzer with normal sensitivity platinum catalyst. Includes 8 references, table, figures.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 6File Size: 1 file , 230 KB