4/12/2008 Updated: 12 April 2008 CEE690K Lecture #16 1 Print version CEE 690K ENVIRONMENTAL REACTION KINETICS Lecture #16 Case Study: Nitrogenous Disinfection Byproducts Primary Literature as noted Introduction David A. Reckhow PROTEINS AS IMPORTANT REACTIVE COMPOUNDS IN DRINKING WATER TREATMENT Dave Reckhow University of Massachusetts - Amherst Junsung Kim, Guanghui Hua, Gladys g g y Makdissy, John McClellan, Cynthia Castellon, Darlene Buttrick MA WRRC Conference 8 April 2008 1
4/12/2008 Outline � Formation of N-DBPs from NOM N N � Occurrence � Characteristics � Chemistry of selected End Products � DHAN � DHAD � NDMA � Reactivity of Specific Nitrogenous Constituents � Amino Acids � Proteins & others � Key N-DBPs and Methods to be developed Reactions with Chlorine Oxidized NOM The Precursors! and inorganic chloride •Aldehydes HOCl + natural organics Chlorinated Organics (NOM) •TOX •THMs •HAAs The THMs Th THM Th THM The THMs Br Br Br Cl H Cl C H C H Br C C H Br Cl Cl Br Cl Cl Chloroform Bromodichloromethane Chlorodibromomethane Bromoform 2
4/12/2008 The Haloacetic Acids Br Br Cl Br COOH Cl C C COOH C COOH Br Cl C COOH Br Cl Cl Br Br Cl Cl Cl Cl Trichloroacetic Bromodichloroacetic Chlorodibromoacetic Tribromoacetic Acid Acid Acid Acid (TCAA) Br Br Cl H C COOH C COOH H C COOH H Cl Cl Br Dichloroacetic Bromochloroacetic Dibromoacetic Acid Acid Acid (DCAA) N-DBPs we know about: end products � Certain to come from N-organics when using free � Certain to come from N-organics when using free chlorine CNCl & CNBr � Major types: Br Cl Br � Cyanogen Halides H C C N H C N H C C N C Cl Br � Haloacetonitriles Cl Dichloroacetonitrile Bromochloroacetonitrile Dibromoacetonitrile � Halonitromethanes H l h (DCAN) (BCAN) (DBAN) Cl Cl NO Cl C Cl C C N 2 Cl Cl Special focus on these compounds because of large Trichloroacetonitrile Chloropicrin data set 9 species (TCAN) (CHP) 3
8 10 -6 Iodoacetamide CHO Cytotoxicity � Analytical chemistry is more complicated � Very little is known about N-DBPs � Some evidence that they are major contributors to � Can be enhanced by chloramination � Nitrogenous organics are generally quite reactive Why N-DBPs? � Work of Michael Plewa Bromoacetamide adverse human health effects of DBPs Dibromoacetonitrile IAA Bromoacetonitrile Iodoacetonitrile y CHO Cell Cytotoxicity as %C½ Values (~LC 50 ) D DBNM D DBCNM BNM B Log Molar Concentration (72 h Exposure) Bromochloroacetonitrile 10 -5 TBNM T BAA Dibromoacetamide BDCNM B 3,3-Di bromo-4-oxopentanoic Acid 3,3-Br romochloro-4-oxopentanoic Acid BCNM B 2-Iodo o-3-bromopropenoic Acid y Dichloroacetonitrile Tribromop yrrole Chloroacetonitrile Iodoform TBAA 10 -4 Chloroacetamide Trichloroacetonitrile 3-Iodo o-3-bromopropenoic Acid DBCAA MX 3,3-Di bromopropenoic Acid DIAA D DCNM DBAA C CNM T TCNM p BDCAA BIAA BCAA 10 -3 CAA Bromate Tribro mopropenoic Acid Dichloroacetamide 2-Brom mobutenedioic Acid Trichloroacetamide 2,3-Di bromopropenoic Acid TCAA DBP Chemical Class Bromoform EMS +Con ntrol 2-Brom mo-3-methylbutenedioic Acid Chlorodibromomethane July 2006 DCAA 10 -2 Chloroform Halonitromethanes Haloacetic Acids Haloacetonitriles Haloacetamides Halomethanes Other DBPs Halo Acids 4/12/2008 4
4/12/2008 Quantitative Structure-Toxicity Models � Lowest Observed Adverse Effect Level � AWWARF report by Bull et al., 2007 f halogenated DBPs 200 15 All Halo DBPs er of halonitriles Halonitriles 10 100 5 5 Numbe Number of 0 0 >1000 >100-1000 >10-100 >0.1-1 >0.01-1 >1-10 Distribution of estimated chronic LOAELs, mg/kg day -1 Chemistry of the end products 6.5 Surface Water 6.0 DCAN DCAN 5.5 5 5 5.0 hloroacetonitrile ( μ g/L) 4.5 4.0 3.5 3.0 2.5 2 0 2.0 Dich 1.5 Chlorine Dose 1.0 2.5 mg/L Loss of Residual 5 mg/L 0.5 10 mg/L 0.0 0 20 40 60 80 100 120 Time (hrs) 5
4/12/2008 H DCAN Cl C C N DHAN OCl Cl OH k 4 H k 2 N k 1 H H 2 O Cl C C N OCl Cl C C fast Cl OH H H Cl fast NH NCl � Key intermediate K i di Cl C C Cl C C H 2 O OH OH O N-Cl-DCAD Cl Cl � Concentrations are anion fast well known pKa = 3.7 N-Cl-DCAD DCAD H H NH 2 NHCl Cl(+II) Cl C C Cl C C S (+IV) O O Cl Cl k 1-2 k 1-1 OH HOCl H H NH 2 NHCl Cl C C OH Cl C C OCl O Cl fast OH Cl fast NH 3 H O NHCl 2 Cl C C OH Cl DCAA Proposed Rate Law for DCAN � Hydrolysis and oxidation � Hydrolysis and oxidation dC − = − + + + { k k OH [ ] k Cl [ ( I )]} C 1 2 3 dt k1 = 1.78 x10-7 ±0.35 x10-7 (s-1) k2 = 3.42 ±0.31 (M-1s-1) k3 = 1.30 x 10-1 ±0.08 x 10-1 (M-1s-1) 6
4/12/2008 DCAN half-life based on pH & HOCl 100 At 20 C � 1 Hour 1 Hour 8 Hours From Reckhow, � 10 Minutes Platt, MacNeill & rine Residual (mg/L) 1 Day McClellan, 2001 10 OCl- � Aqua 50:1:1-13 3 Days Degradation in DS � observed to increase with 1 Week increasing pH 1 � ICR data: Chlor Obolensky & Frey, 2002 OH- H2O 0.1 3 Weeks 6 7 8 9 10 11 pH Halamides � Compounds � Compounds � Monohaloacetamides � Chloroacetamide, Bromoacetamide � Dihaloacetamides � Dichloroacetamide (DCAD) � Bromochloracetamide (BCAD) � Dibromoacetamide (DBAD) � T ih l � Trihaloacetamides t id � trichloroacetamide & analogues � Chlorination byproducts � Probably a bit less prevalent with chloramines � Pre-oxidation will probably reduce subsequent formation 7
4/12/2008 Haloacetamides Measureable by GC � Mostly from HANs: M l f HAN ⇒ ⇒ Haloaceton itriles Haloacetam ides Haloacetic Acids Free (f) Sulfite Chlorine N-Halogenated Forms Combined (c ) Total (t) DCAD Halflife 100 DCAD Stability 10 Minutes 1 Hour ual (mg/L) 8 Hours 10 Chlorine Residu 1 Day 1 Day 3 Days 1 HOCl 1 Week 3 Weeks 0.1 6 7 8 9 10 11 pH 6 7 8 9 10 11 3 Days 1 Hour OH- Reducing 1 Week 8 Hours Conditions 1 Day 3 Weeks 8
4/12/2008 Nitrosamines � NDMA: typically formed at greater levels with chloramination than with chlorination chloramination than with chlorination � Continues to form across DS? � other nitrosamines (beyond NDMA) have been reported in chloraminated water � Levels and mechanisms � Earlier work: Valentine & Weinberg � Earlier work: Valentine & Weinberg � New mechanism: Mitch Pathway to NDMA � Role of Dichloramine and oxygen � Role of Dichloramine and oxygen Monochloro Unsymmetric Dimethylhydrazine (UDMH-Cl) Dichloramine R Cl H CH 3 CH 3 Cl N N N R H N Cl CH 3 CH 3 Cl Dimethyl(xx)amine O O Oxygen O Based on recent work by Bill Mitch Cl and colleagues CH 3 H N O N N Cl PRODUCTS CH 3 Nitrosodimethylamine (NDMA) 9
4/12/2008 The Unnatural Precursor? 19 � Ranitidine (Zantac) � 63% conversion to NDMA � Schmidt et al., 2006 [WQTC] � Introduced in 1981, largest selling prescription drug by 1988 � Stomach ulcers and esophageal reflux � Mean concentration of 3000 ng/L estimated for raw municipal WW (national average) WW (national average) � Sedlak 2005 AWWARF report � 450 ng/L formation in raw WW expected � Unknowns: how much does this persist in treatment and in the environment? Reaction of UDMH Reaction of UDMH � Abbreviations � DMD: dimethyldiazene � TMT: tetramethyltetrazene � FMMH: formaldehyde monomethylhydrazone � FDMH: formaldehyde dimethylhydrazone � DMC: dimethylcyanamide � DMF: dimethylformamide From: Mitch & Sedlak, 2002 [ES&T, 36:588] 10
4/12/2008 THMs, THAAs The DBP Iceberg DHAAs ICR Compounds ICR Compounds ICR Compounds ICR Compounds 50 MWDSC DBPs 50 MWDSC DBPs Stuart Krasner ~700 Known DBPs ~700 Known DBPs Susan Richardson Halogenated Non Non- -halogenated halogenated Compounds Compounds Compounds Organic Nitrogen Abundance � Ratio to carbon � Ratio to carbon � Redrawn from Westerhoff & Mash, 2002 60 50 mg-C/mg-N) 40 DOC/DON (m 30 30 27 27 20 15 8.2 10 0 0 10 20 30 40 50 60 70 80 90 100 Percentile 11
4/12/2008 Ranges of Org-N by types � Estimates from literature surveys Order of magnitude estimates for organic nitrogen in surface waters (all values in µg-N/L) Classification 50%ile 90%ile 99%ile DON 350 800 2000 Free AA 20 50 200 Combined AA Combined AA 40 40 100 100 400 400 Nucleic acids 20 50 200 Amino Sugars 40 100 400 Humic-N 25 200 1000 Others Amino Acids and Proteins � Simple Amino Acids � some form THMs and HANs f M d AN NH 2 Alanine Alanine � Highest reactivity for activated AAs H 2 C C COOH � Tyrosine & Tryptophan: activated aromatic H � Cysteine: sulfhydryl group � Proteins NH 2 � many linked AAs; relatively HO C C COOH unreactive polypeptide bonds H 2 H � Reactions with proteins occurs Tyrosine Tyrosine most readily on AA side chains 12
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