Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter
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University of Akron / OhioLINK
2013
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ndltd-OhioLink-oai-etd.ohiolink.edu-akron13721655692021-08-03T05:24:22Z Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter Kumkum, Pushpita Environmental Engineering Environmental Science TOX ICM iodo-DBPs The aim of this study was to investigate iodinated pharmaceuticals as potential precursors to total organic halogen (TOX) formation in the presence of chlorinated oxidants (i.e., aqueous chlorine and monochloramine) and without NOM present. The reaction mechanism of aqueous chlorine and monochloramine with iopamidol, an iodinated x-ray contrast media (ICM), as a primary contributor of iodide in the formation of total organic iodide (TOI), the precursor to the formation of extremely toxic iodinated-DBPs, was evaluated. Reaction with other ICM with chlorinated oxidants was also investigated. The traditional TOX method was modified to measure total organic chloride (TOCl), total organic bromide (TOBr), as well as TOI.The aqueous chlorination of iopamidol, iomeprol, iopromide, iohexol and Na-diatrizoatewas studied in the pH range 6.5-9 and at 25±1 °C. Under these conditions, iopamidol was transformed releasing iodide into aqueous phase. Once in the aqueous phase, iodide is rapidly transformed to hypoiodous acid (HOI). HOI is a very reactive species with organic material and almost exclusively participates in electrophilic substitution reactions forming iodide containing transformation products. However, HOI can also be oxidized by residual aqueous chlorine to form iodate in absence of natural organic matter (NOM). Transformation of iopamidol was monitored as the loss of total organic iodide (TOI) and the formation of iodate. The observed loss in TOI concentration appears to be the greatest at pH 7.5, least at pH 6.5, and approximately the same for pH 8.5 and 9. The degradation of TOI can be described by observed first-order kinetics in the presence of excess aqueous chlorine over the pH range of 7.5-9; however, TOI degradation at pH 6.5 appears to be bi-phasic indicating a more complex reaction mechanism is responsible for TOI degradation in the presence of aqueous chlorine. Iodate formation from the degradation of iopamidol transformation products does not echo iodate formation due to iodide oxidation in the presence of aqueous chlorine, and it does not appear to be described by observed first or second order kinetics. Therefore, it is being proposed that both chlorine species (i.e., HOCl and OCl-) are responsible for in the degradation of TOI in aqueous systems containing iopamidol and chlorine. The other ICM were also investigated in the presence of aqueous chlorine over the pH range of 6.5-8.5. It was assumed that they were not reactive since the TOI concentration did not change regardless of pH over 72 hours and no other inorganic iodide containing species were identified.Monochloramine experiments with iopamidol result in an insignificant degradation of TOI degradation over the pH range of 6.5-8.5. Similar results were observed in a previous study that in the absence of other reactants, HOI is very stable in the presence of monochloramine and does not result in iodate formation. 2013-09-20 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1372165569 http://rave.ohiolink.edu/etdc/view?acc_num=akron1372165569 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Environmental Engineering Environmental Science TOX ICM iodo-DBPs |
| spellingShingle |
Environmental Engineering Environmental Science TOX ICM iodo-DBPs Kumkum, Pushpita Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| author |
Kumkum, Pushpita |
| author_facet |
Kumkum, Pushpita |
| author_sort |
Kumkum, Pushpita |
| title |
Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| title_short |
Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| title_full |
Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| title_fullStr |
Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| title_full_unstemmed |
Iodinated Pharmaceuticals as Precursors to Total Organic Halogen Formation in the Presence of Chlorinated Oxidants and Absence of Natural Organic Matter |
| title_sort |
iodinated pharmaceuticals as precursors to total organic halogen formation in the presence of chlorinated oxidants and absence of natural organic matter |
| publisher |
University of Akron / OhioLINK |
| publishDate |
2013 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=akron1372165569 |
| work_keys_str_mv |
AT kumkumpushpita iodinatedpharmaceuticalsasprecursorstototalorganichalogenformationinthepresenceofchlorinatedoxidantsandabsenceofnaturalorganicmatter |
| _version_ |
1719419660729843712 |