Total Organic Halogen Formation in the Presence Of
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TOTAL ORGANIC HALOGEN FORMATION IN THE PRESENCE OF IOPAMIDOL AND CHLORINATED OXIDANTS WITH AND WITHOUT NATURAL ORGANIC MATTER. A Thesis Presented to The Graduate Faculty of The University of Akron In Partial Fulfilment of the Requirements for the Degree Master of Science Nana Osei Bonsu Ackerson May, 2014 TOTAL ORGANIC HALOGEN FORMATION IN THE PRESENCE OF IOPAMIDOL AND CHLORINATED OXIDANTS WITH AND WITHOUT NATURAL ORGANIC MATTER. Nana Osei Bonsu Ackerson Thesis Approved: Accepted: ____________________________ ____________________________ Advisor Department Chair Dr. Stephen E. Duirk Dr. Wieslaw Binienda _____________________________ ____________________________ Committee member Dean of the College Dr. Christopher C. Miller Dr. George K. Haritos _____________________________ ____________________________ Committee member Dean of Graduate School Dr. Lan Zhang Dr. George R. Newkome ____________________________ Date ii ABSTRACT The objectives of this study were to investigate the transformation of ICM as a function of pH (6.5 to 9.5) and time (up to either 72 or 168 hr) in the presence of chlorinated oxidants. Total organic iodide (TOI) loss was used as a surrogate for the ICM. Experiments were performed with and without natural organic matter (NOM). Degradation of TOI in the absence of NOM was carried out at low and high concentrations of iopamidol and aqueous chlorine. Also, the effect of NOM variation on iodate formation was investigated. The TOI degradation and iodate formation at low reactant and buffer concentrations were greatest at pH 7.5 and least at pH 9.5. TOI degradation followed observed first-order kinetics at all pH except pH 6.5, which exhibited bi-phasic degradation kinetics. Iodate formation did not follow either first or second order observed formation and was the predominant iodine-containing species after 24 hr. Furthermore, disinfection by-products (DBPs) formed at pH 6.5 – 8.5 were chloroform, trichloroacetic acid and chlorodiiodomethane. In the presence of monochloramine and in the absence of NOM, the loss of TOI was insignificant and no iodate formation was observed. At high concentrations of iopamidol and aqueous chlorine, TOI loss and iodate formation at pH 6.5 and 8.5 was rapid for the first 24 hr and ceased afterwards. The formation of total organic chloride (TOCl) was initially observed at 6 hr and 2 hr for pH 6.5 and 8.5 respectively. Also, chloroform, dichloroiodomethane, chlorodiiodomethane, dichloroacetic acid and trichloroacetic acid was observed. iii About 99% of the remaining TOI formed at each discrete time was contained in unidentified iopamidol transformation products. When TOI was monitored in the presence of NOM and aqueous chlorine, source waters from Akron, Barberton and Cleveland respectively recorded 68 to 74%, 62 to 72% and 68 to 77% loss of TOI. However, no iodate was formed in any of the source water experiments. No significant degradation of TOI was observed in the presence of NOM and monochloramine. Iodate was not formed in varying NOM concentrations in Barberton and Cleveland source waters. iv ACKNOWLEDGEMENTS I thank my God Almighty who has brought me this far and blessed me with wisdom and understanding in my academic pursuits. I would like to express my profound appreciation to my advisor, Dr. Stephen E. Duirk for his guidance, assistance and time. His patience, constructive criticisms and dedication were vital to the success of this thesis. Also, my gratitude goes to Dr. Christopher C. Miller and Dr. Lan Zhang for their time, advice and insightful comments. To my laboratory colleagues, both graduate and undergraduate students, I say thank you for your unflinching support. My sincere thanks to all and sundry who supported me in diverse ways. Finally, my deepest appreciation goes to my wife Irene Ackerson and my daughter Nana Onomaa Ackerson for their prayers, love, support, patience and understanding during my busy schedules and throughout my studies. v TABLE OF CONTENTS Page LISTS OF TABLES ...................................................................................................... ix LIST OF FIGURES ....................................................................................................... x CHAPTER I INTRODUCTION ...................................................................................................... 1 1.1 Background .............................................................................................................. 1 1.2 Problem Statement ................................................................................................... 5 1.3 Specific Objectives .................................................................................................. 7 II LITERATURE REVIEW .......................................................................................... 9 2.1 Introduction .............................................................................................................. 9 2.2 Iodinated X-ray Contrast Media .............................................................................. 9 2.2.1 Occurrence and Concentration of ICM in Water and Wastewater .................. 11 2.2.2 Transformation of ICM ................................................................................... 13 2.3 Reactions of Chlorinated Oxidants Used in Water Treatment .............................. 14 2.3.1 Chlorine ........................................................................................................... 14 2.3.2 Chlorine Dioxide ............................................................................................. 17 2.3.3 Chloramines .................................................................................................... 18 2.4 Chemistry and Reactions of Iodine ........................................................................ 19 2.5 Total Organic Halogen Formation ......................................................................... 22 vi 2.6 Toxicity of Halogenated Disinfection By-Products ............................................... 26 III MATERIALS AND METHODS ........................................................................... 29 3.1 Chemicals and Reagents ........................................................................................ 29 3.2 Source Water Characterization .............................................................................. 30 3.3 Experimental Methods ........................................................................................... 38 3.3.1 Experiments with Deionized Water ................................................................ 38 3.3.2 Experiments with Source Waters .................................................................... 42 3.4 Analytical Procedures ............................................................................................ 44 3.4.1 Total Organic Halogen .................................................................................... 44 3.4.2 Disinfection By-product .................................................................................. 45 3.5 Analyses of TOX, Iodate and Iodide ..................................................................... 47 3.6 Analyses of DBPs .................................................................................................. 55 IV RESULTS AND DISCUSSION ............................................................................ 71 4.1 Introduction ............................................................................................................ 71 4.2 Transformation of Iopamidol in the Absence of NOM ......................................... 71 4.2.1 Transformation at Low Concentration ............................................................ 71 4.2.2 Transformation at High Concentration ........................................................... 83 4.3 Transformation of Iopamidol in the Presence of Chlorine and NOM ................... 96 4.4 Transformation of Iopamidol in the Presence of Monochloramine and NOM .... 104 4.5 Iodate Formation as a Function of Dissolved Organic Carbon ........................... 110 V CONCLUSIONS AND RECOMMENDATIONS ............................................... 112 vii 5.1 Introduction .......................................................................................................... 112 5.2 Conclusions .......................................................................................................... 112 5.3 Recommendations ................................................................................................ 115 REFERENCES .......................................................................................................... 116 viii LISTS OF TABLES Table Page 2.1 Aqueous Iodine species..........................................................................................20 2.2 Reactions forming TOX and iodate........................................................................25 3.1 Source water characteristics from Akron, Barberton and Cleveland water...........32 3.2 Florescence EEM regions proposed by Chen et al. (2003)....................................34 3.3 Florescence regions for Akron, Barberton and Cleveland source waters for 1 mg/L C...................................................................................................................................34 3.4 Comparison of recovery at 4°C and room temperature using 2,4,6- trichlorophenol, 2,4,6-tribromophenol and 4-iodophenol. [TCP] = 25 – 100 μM, [TBP] = 5 –