Colorimetric P Speciation Analysis Long Path Lengths and Model - - PowerPoint PPT Presentation

▶
colorimetric p speciation analysis
SMART_READER_LITE
LIVE PREVIEW

Colorimetric P Speciation Analysis Long Path Lengths and Model - - PowerPoint PPT Presentation

Mar 26, 2023 26 likes •191 views

Colorimetric P Speciation Analysis Long Path Lengths and Model Compounds D. Scott Smith, R. Gilmore, H. Gray, S. Goertzen, M. Robichaud Department of Chemistry, Wilfrid Laurier University August 12, 2011 1. Important Issues in P Analysis in

slide-1
SLIDE 1

Colorimetric P Speciation Analysis

Long Path Lengths and Model Compounds

  • D. Scott Smith, R. Gilmore, H. Gray, S. Goertzen, M.

Robichaud

Department of Chemistry, Wilfrid Laurier University

August 12, 2011

slide-2
SLIDE 2
  • 1. Important Issues in P Analysis in Waste Water

1 Low Levels:

regulatory requirements on TP potentially below detection using one cm light path Can long path lengths help?

2 Speciation:

to optimize P removal need to understand dynamics of P speciation across treatment technologies for example: DOP is resistent to traditional removal methods. Can it be converted to other (more treatable) forms? Does Standard Methods recover speciation of model compounds relevant to wastewater ?

slide-3
SLIDE 3
  • 2. Path length Study: Method

1

  • rthophosphate solutions

2

fixed concentrations to give absorbance of 0.4 for 10 cm or 1 m pathlengths

3

vary mixed reagent volume

4

vary colour development time

5

Standard Methods, 1998. Standard methods for the examination of water and wastewater, American Public Health Association, Washington, DC, USA, 20th ed.

slide-4
SLIDE 4
  • 3. Ascorbic Acid 10 cm

0.43 0.38 0.42 0.43 0.44 0.38 0.41 0.44 0.430.44 0.43 0.430.43 0.41

(a) Time (hr) Reagent Volume (mL) 2 4 6 0.5 1 1.5

1.8 0.4 0.5

(b) Time (hr)

0.3 0.2 0.8 1.2 0.1 0.3 0.3 1.0 0.7 0.3 0.9

Reagent Volume (mL) 2 4 6 0.5 1 1.5

Figure: Contour plot of absorbance (a) and relative (%) standard deviation (b) by the ascorbic acid method with 10 cm light path. Dashed line corresponds to the volume used in Standard Methods.

slide-5
SLIDE 5
  • 4. Ascorbic Acid 1 m

0.46 0.23 0.09 0.65 0.37 0.55 0.12 0.28 0.33 0.31 0.44 0.09 0.16 0.27 0.20 0.30 0.09 0.16 0.27 0.20 0.30

(a) Time (hr) Reagent Volume (mL) 5 10 15 20 25 0.5 1 1.5

1.50 1.50 1.67 1.67 20.5 27.1 27.1

(b) Time (hr)

30.5 30.5 1.66 1.66 50.1 29.2 9.90 1.61 5.63 31.6 43.9 50.6 67.1 49.0

Reagent Volume (mL) 5 10 15 20 25 0.5 1 1.5

Figure: Contour plot of absorbance (a) and relative (%) standard deviation (b) by the ascorbic acid method with 1 m light path. Dashed line corresponds to the volume used in Standard Methods.

slide-6
SLIDE 6
  • 5. Kinetic slice. Ascorbic Acid. 1 m

20 40 60 80 0.2 0.4 0.6 0.8 1 Time (hr) Absorbance (au)

Figure: 8 µg P/L standard, 0.5 mL mixed reagent volume.

slide-7
SLIDE 7
  • 6. Path length Study: Summary

1

no surprise = long path lengths work fine

2

reduced colour forming reagents = modest 10% increase in sensitivity

3

1 m pathlength requires long colour development for reproducible signal

4

suggests FIA would be useful !

slide-8
SLIDE 8
  • 7. Matrix Effects?

A B C 50 100 150 200

  • rthoP (µg P/L)

(a) D E F G H 1 2 3 4

  • rthoP (mg P/L)

(b)

Figure: Orthophosphate determinations using external calibrations (light gray bars) and standard addition calibration (dark gray bars). A. Grand River water, B. laboratory tap water, C. final treated wastewater

  • effluent. Subplot (b) correspond to 5 wastewater samples.
slide-9
SLIDE 9
  • 8. Anecdote for need to study speciation methods

50 100 150 200 250 20 40 60 80 100 120 Laurier (µg P/L) Other Lab (µg P/L) TP tAHPm sRP sAHPm tRP sTP

Figure: caption

slide-10
SLIDE 10
  • 9. P Speciation Study: Method

1

Both labs = Standard Methods, 1998. Standard methods for the examination of water and wastewater, American Public Health Association, Washington, DC, USA, 20th ed.

2

but different interpretations of Standard Methods!

3

Ascorbic acid method

4

Various digestion methods (always orthophosphate analysis at the end)

5

polyP

6

AMP

7

phospholipid

slide-11
SLIDE 11
  • 10. Recoveries

10 20 30 40 50 60 70 80 90 100 % recovery

  • rtho-P

acid hydrol. persulfate acid-acid polyP AMP PL AMP PL AMP PL polyP AMP PL

slide-12
SLIDE 12
  • 11. Persulfate Autoclave Program: AMP

L30 L50 L75 10 20 30 40 50 60 70 80 90 100 110 Phosphorus Recovery (%)

slide-13
SLIDE 13
  • 12. Persulfate Autoclave Program: Phospholipid

L30 L50 L75 10 20 30 40 50 60 70 80 90 100 110 Phosphorus Recovery (%)

slide-14
SLIDE 14
  • 13. Digestion Method and real waste water

persulfate acid−acid 10 20 30 40 50 60 70 80 90 100 110 Total Phosphorus Recovery (µ g/L)

slide-15
SLIDE 15
  • 14. P Speciation Study: Results

1

some model compounds are not recovered by typical methods

2

effect on TP results depends on actual speciation of sample

3

autoclave program needs optimization

4

analysis of model P compounds is important area for future research

5

analysis of real waste water by different digestion methods is important

slide-16
SLIDE 16
  • 15. P Acknowledgements

HQP current HQP past collaborators Holly Gray Rebecca Gilmore JB Neethling (HDR) Amanda Johnston Kelly Fisher April Gu (Northeastern) Petrease Patton Farah Ateeq Imre Takacs (Dynamita) Monique Robichaud Sudhir Murthy (DCWASA) Wayne Parker (Waterloo) Funding EnviroSim Associates Inc. NSERC OCE WERF Nutrient Challenge DCWASA