Organic Compounds in Water and Wastewater NOM Characterization II - - PDF document

9/26/2014 1

CEE 697z

Organic Compounds in Water and Wastewater

NOM Characterization II

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Dave Reckhow - Organics In W & WW

Lecture #8

UV-Vis Absorbance Spectra

 Do we see “signatures of”

 Proteins (Bovine Serum Albumin – a typical one)  Lignin

Wavelength (nm)

200 250 300 350 400 450 500

Absorbance (cm-1)

0.00 0.05 0.10 0.15 0.20 0.25 Kensico January Ashokan January Cannonsville January Pepacton January Neversink January Lignin Bovine Serum Albumin

5 mg/L lignin 10 mg/L BSA

A 280 nm shoulder?

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Wavelength (nm)

200 250 300 350 400 450 500 550 600 650

• Sp. Abs. (L/m/mg-C)

0.1 1 10 Weak Hydrophobic Acids Hydrophilic Acids Humic Acid Fulvic Acid

Absorbance of Acid Fractions

Same DOC

Absorbance of Bases & Neutrals

Wavelength (nm)

200 250 300 350 400 450 500 550 600 650

• Sp. Abs. (L/m/mg-C)

0.1 1 10 Hydrophobic Bases Hydrophilic Bases Hydrophobic Neutrals Hydrophilic Neutrals

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UV absorbance vs TOC: raw waters

5

TOC (mg/L)

3 6 9 12 15

UV absorbance (cm-1)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Correlation Between TOC and UV absorbance for 53 samples of Grasse River Water (from Edzwald et al., 1985) SUVA = (0.7/15) * 100 = 4.7 L/mg-m

UV absorbance vs DOC: treated waters

Black Lake Fulvic Acid

DOC (mg/L) 1 2 3 4 UV Absorbance (/cm) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

 surrogate for many

• rganic parameters

 SUVA: specific UV absorbance, (UV/DOC)

Correlation Between DOC and UV absorbance for an Aquatic Fulvic Acid Subject to Coagulation at Various Alum Doses and various pHs (5-9) (from Reckhow, 1984)

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Specific UV Absorbance (SUVA)

7

 UV absorbance at 254nm (cm-1) divided by the DOC in mg/L

(usually multiplied by 100)

 Relates to character of NOM

 SUVA>4, water has a high humic character  high in hydrophobic organics, high MW, aromatic  SUVA=2-4, intermediate humic content  mix of hydrophobic and hydrophilic, medium MW  SUVA<2, mostly non-humic  hydrophilic organics, low MW, aliphatic

Some SUVA Values

8

Source SUVA (L/mg-m) Typical HA 6 Typical FA 4 Lake Manatee, FL 5.7 Grasse River, NY 4.6 Mississippi, R., LA 3.1 Wachusett Res., MA 2.5 Quabbin Res., MA 1.8 Colorado R., CA 1.5 Aysgarth Falls, Yorkshire Dales

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SUVA of NOM Fractions

9

Neutrals

• Sp. UV Abs (L/m/mg-C)

1 2 3 4 5 6 7

Hydrophobic

Bases Acids Neutrals Bases Weak Acids Humic Acid Fulvic Acid

Hydrophilic

9

Since treatment often results in preferential removal of humics, the SUVA in finished water is usually lower than in the raw water Bleaching of NOM by chlorine makes this even more pronounced

10

Surrogate Parameters/Correlations: (Normalized) THM Formation Potential (FP) versus SUVA (Croué)

from : Krasner & Am y

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Bulk NOM Absorbance Spectra

 What information can we extract from

this?

 Problem of particles

Wavelength (nm)

200 250 300 350 400 450 500

Absorbance (cm-1)

0.0 0.1 0.2 0.3 0.4 0.5 Kensico January Shoharie January Ashokan January Cannonsville January Pepacton January Neversink January

Problem with light scattering

Lignins

 Responsible for much of the tri-HAA?  Absorbance spectra of Coniferous Lignin

 Pew and Connors Tappi, 54 (1971), 245-251 Local Absorbance max at 280 nm

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Proteins

 Proteins generally exhibit a UVabs peak

near 280 nm.

 This absorption is due to the constituent amino

acids tyrosine, tryptophan, and phenylalanine (aromatic amino acids).

 Spectra from Shimadzu

Compare with NOM Spectra

 Do we see “signatures of”

 Proteins (Bovine Serum Albumin – a typical one)  Lignin

Wavelength (nm)

200 250 300 350 400 450 500

Absorbance (cm-1)

0.00 0.05 0.10 0.15 0.20 0.25 Kensico January Ashokan January Cannonsville January Pepacton January Neversink January Lignin Bovine Serum Albumin

5 mg/L lignin 10 mg/L BSA

A 280 nm shoulder?

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UV absorbance as a surrogate

15

 A good surrogate for DOC  especially when the character of

the DOC is reasonably constant

 A very good surrogate for THMFP,

HAAFP

 takes into account reactivity of

DOC as well as amount of DOC

 Oxidation processes (ozonation)

disrupt relationships between UV and DOC or THMFP

15

Commercial field probe

UV absorbance and THMFP

UV Absorbance (cm-1)

0.0 0.1 0.2 0.3 0.4

TTHMFP (g/L)

100 200 300 400 500 600

Correlation Between TTHMFP and UV absorbance for 31 samples of raw and treated water from the Oneida WTP (from Edzwald et al., 1985)

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UV absorbance and THMFP

Black Lake Fulvic Acid

UV Absorbance (cm-1) 0.00 0.04 0.08 0.12 0.16 0.20 THM Formation Potential (g/L) 50 100 150 200 250 300

Correlation Between TTHMFP and UV absorbance for an Aquatic Fulvic Acid Subject to Coagulation at Various Alum Doses and various pHs (5-9) (from Reckhow, 1984)

Algal Organics

18

Fang et al., 2010 extracellular intracellular Whole cells NOM Microsystis aeruginosa I: protein-like II: protein-like III: humic-like IV: protein-like V: humic-like

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Fluorescence - EEMs

19

Contour plots of 7 components identified from the complete F- EEMs dataset.

Baghoth et al., 2011 Terrestrial Humic Marine & Terrestrial Humic Terrestrial Humic Amino acid Terrestrial/ Anthro- pogenic Humic Amino Acid Marine & Terrestrial Humic

Excitation-Emission Matrices: Fluorescence intensity across the range of emission wavelengths while also scanning across excitation wavelengths

Correlates well with some NOM properties, but fundamental understanding is still not good

Assignment of EEM Regions

20

Location of EEM peaks (symbols) based on literature reports and

• perationally defined excitation and emission wavelength boundaries

(dashed lines) for five EEM regions

Chen et al., 2003

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NOM Characterization

 Analytical Tests

 elemental analysis  spectral properties  functional group chemistry

 Separation/Fractionation

 resin adsorption  size exclusion chromatography

 Combinations

Practical Characterization of NOM

 Two necessary components

 A set of useful, and accessible characterization tools (i.e.,

analytical methods)

 A means by which NOM characteristics can be translated into

information of practical importance (i.e., what does it all mean?)

 Progress is being made in both areas

 NOM characterization is still more “scientific” that “practical”

 exception: SUVA

 However, NOM characterization will become far more

important in the near future

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Most Useful Characterization Methods

 Current, accessible methods

 SUVA  Hydrophilic/hydrophobic  Absorbance at 272 nm???

 Future methods

 HPLC & spectral based methods  Deconvolution of UV/Vis Spectrum

 Research methods (require expensive equipment)

 Pyrolysis - GC/MS  13C-NMR  LC/MS

Pyrolysis GC/MS

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 high temperature, rapid thermal decomposition  followed by mass spectrometry for identification of pyrolysis byproducts  difficult, and not quantitative, or at best, semi-quantatitive  can attribute pyrolysis byproducts to starting structures .proteins (form pyrroles, indoles, phenol, p-cresol, nitriles) .amino sugars (form acetamide) .polyhydroxy aromatics (various phenolic derivatives) .carbohydrates (form furans, acetic acid, and many carbonyl compounds) .carboxylic acids  THMFP may be related to polyhydroxy aromatic content

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Fulvic Acid from Bruchet et al., 1990 (Sept. J.AWWA)

11 25 1 2 61 Miscellaneous Proteins Amino Sugars Hydroxy Aromatics Carbohydrates

HILIC - NMR

26 Woods et al., 2011 Figure 1. A) Chromatogram of HILIC separation. Blue line: DAD, 280 nm, units on left axis. Red line: fluorescence, 320/430 nm ex/em, units on right

• axis. Dashed lines: HPLC fraction intervals. Arrow:

signal predominated by tryptophan. B) PCA plot of the scores for the NMR data. C) Major structural groups with increasing polarity; assignments explained in the main text. Correlations have a significance of p < 0.0005 except aromatics (p = 0.578). (avg%) indicates average percentage of NMR signal for all fractions

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The Future??: Higher MW ID

 NOM research

 ESI with Ultra High-

Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

 Benefits

 Unambiguous molecular

formulae

28 m/z

900 800 700 600 500 400 300

Abundance

12 11 10 9 8 7 6 5 4 3 2 1

Raw Water - Winnipeg

0.00E+00 5.00E+01 1.00E+02 1.50E+02 2.00E+02 2.50E+02 3.00E+02 3.50E+02 4.00E+02 150 250 350 450 550 650 m/z Intensity

• ve ion

+ ve ion

ESI -TOF MS ESI -FTI CR MS

Same: comparison side-by-side

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29

m/z

425 420 415 410 405 400 395 390

Abundance

7 6 5 4 3 2 1

Chlorinated Water + Br Winnipeg

m/z

409.436 409.354 409.272 409.19 409.108 409.027 408.945 408.863

Abundance

7 6 5 4 3 2 1

Ultra-high resolution MS

30 Area of predicted fulvic acid molecules in a C- vs molecular mass diagram for the mass range m/z 310-370 (marked by the lines) and fulvic acid molecules detected by SEC-FTICR- MS in the river isolate (dots (island no. 24) and triangles (island no. 25)).

Reemtsma et al., 2006 [ES&T: 40:19:5839]

Zone of low solubility

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31



Van Krevelen diagram for the Dismal Swamp DOM, compound classes are represented by the circles

• verlain on the plot. The distinctive lines in the plot denote the following chemical reactions: (A)

methylation/demethylation, or alkyl chain elongation; (B) hydrogenation/dehydrogenation; (C) hydration/condensation; and (D) oxidation/reduction.

Sleighter & Hatcher, 2007 [J. Mass Spec. 42:559]

Elemental Ratios

32

 Van Krevelen Plot

From: Perdue & Ritchie, 2004

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How to measure NOM

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 Identify and quantify individual compounds

 expensive and may only account for 10%  not practical

 Fractionate, extract and weigh

 comprehensive, but time-consuming  doesn’t tell us precisely what the stuff is

 Use a collective or “gross” measurement

 TOC, UV absorbance, DBP precursors  easiest method, useful for engineering purposes

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NOM Characterization

34

 Analytical Tests

 elemental analysis  spectral properties  functional group chemistry

 Separation/Fractionation

 resin adsorption  size exclusion chromatography

 Combinations

34

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NOM Characterization

35

 Elemental Analysis

 TOC/DOC  TKN or TN  TOD or COD  CHON analysis

 Size

 UF  Size Exclusion  FFF

 Absorbance

 Color  UV abs  Fluorescence

 Acidity  Hydrophobicity  Pyrolysis-GC/MS  FTIR  NMR (13C or H)  LC/ESI-MS

 Disinfectant Reactivity

– THM/HAA FP – Aldehyde formation – Oxidant demand

 Coagulatability  Biodegradability

– BDOC – AOC

Composition Structural Reactivity Light blue background signifies a “research method”

Adapted from Kornegay et al., 2000

Summary and Conclusions

 Humic and Fulvic Acids

 relatively hydrophobic, significant aromatic content, strong UV

absorbance, moderate negative charge

 they will be reactive with disinfectants, but easy to remove by

coagulation

 contain aromatic structures indicative of tannin and lignin

residues

 largely allochthonous

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Summary (cont.)

 Non-humics

 include hydrophilic acids, bases and neutrals and some hydrophobic

materials

 may be highly charged, or uncharged, lower MW, weak UV

absorbance

 they will be more soluble and difficult to remove by coagulation,

but less reactive with disinfectants

 many aliphatic structures indicative of a lipid hydrocarbon source  may be heavily autochthonous (algal derived)

Summary (cont.)

 DBP formation

 most identified halogenated products result from free

chloriation

 concentrations of majors (THMs, HAAs) increase with

reaction time, unless biodegradation occurs

 pH and temperature play a significant role  bromide results in brominated forms of the DBPs  all disinfectants form oxygenated byproducts

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Dave Reckhow - Organics In W & WW

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