Iopamidol as a Precursor to Iodinated Disinfection Byproduct (DBP) Formation as a Function of NOM concentration, pH, and Chlorinated Oxidants

The objective of this study was to investigate the formation of regulated and unregulated iodinated disinfection by-products (iodo-DBPs) in the presence of iodinated x-ray contrast media (ICM), natural organic matter (NOM), and chlorinated oxidants.The ICM chosen for these experiments was iopamidol, because it is a known source of iodine in the formation of iodo-DBPs.The experiments were conducted with either aqueous chlorine or monochloramine as the chlorinated oxidant.The pH range used to conduct these experiments was pH 6.5 -9.0.Also, the NOM and iopamidol concentration were varied to assess their impact on DBP formation.The formation of the regulated DBP chloroform was highest at pH 9.0 for chlorine (up to 2500 nM) and pH 6.5 for monochloramine (up to 55 nM).This trend also held true for dichloroiodomethane, an iodinated THM, where the chlorine experiments formed up to 462 nM and the monochloramine experiments formed up to 48 nM.The formation of the regulated DBPs proved to be a function of iopamidol concentration as well as a function of NOM concentration.The formation of dichloroiodomethane also proved to be a function of NOM concentration, but was significantly impacted by the concentration of iopamidol present.No reliable trends were determined with respect trichloroacetic acid formation.The expected trend of decreased DBP formation with decreased NOM present was observed in all experiments with respect to chloroform, dichloroiodomethane, and trichloroacetic acid.The exception to this was dichloroiodomethane formation in monochloramine experiments, were formation was higher in lower NOM experiments.With respect to iv the varied iopamidol experiments, iopamidol showed to be significant in both chloroform and dichloroiodomethane formation.Additionally, a statistical model was created to identify an interaction term.This greatly improved the statistical analysis of the data and was able to demonstrate that iopamidol and NOM both significantly impacted the formation of regulated and unregulated iodo-DBPs.v ACKNOWLEDGMENTS I would like to thank my advisor Dr. Duirk for guiding me through my master's and helping to place me into my Ph.D. program.I would also like to thank Dr. Cutright for all of her guidance through my undergraduate and graduate degree, both personally and professionally.There have also been countless experiences with my friends and family that have brought me to where I am now.Reaching this point would have been impossible without them.With the support they've given me, success is guaranteed.