Tom HolmMike Machesky

John Scott

PYRENE SORPTION TO AND EXTRACTION FROM

CORN STOVER CHAR

Corn stover Pyrolysis

450°C 550°C 750°C

N2 atmosphere

BIOCHAR PREPARATION

0.0

0.1

0.2

0.3

450° 1.4

Co

nte

nt

(mg

/kg

)

SPAH

USEPA-16 PAH CONTENT OF CORN STOVER CHAR

See John Scott’s Poster!!

0.01 0.1 1 101E+04

1E+05

1E+06

1E+07

Dissolved Pyrene (mg/L)

Sorb

ed

Pyre

ne (

mg

/kg

)SORPTION ISOTHERM 450° CHAR

r2 0.96

0.001 0.01 0.1 1 101E+04

1E+05

1E+06

1E+07

450°550°750°

Dissolved Pyrene (mg/L)

Sorb

ed

Pyre

ne (

mg

/kg

)SORPTION ISOTHERMS, FRESH

CHAR

Mild extractions with 2-hydroxypropyl-b-

cyclodextrin (HPCD)

HPCD-extractable PAHs correlate well with

Bioavailability

Biodegradation

Poor correlation with total PAH content

BIOAVAILABILITY-RELATED EXPERIMENTS

20 30 40 50 60 70 80 900%

5%

10%

15%

20%

Added Pyrene (mg/kg)

Extr

acta

ble

Pyre

ne

HPCD-EXTRACTABLE PYRENE450° CHAR

Native pyrene

Hale et al. (2011)

40% field capacity (moisture)

Incubate 1 month Freeze/Thaw 60°C 110°C

ARTIFICIAL AGING

0.001 0.01 0.1 11E+04

1E+05

1E+06

1E+07

FreshFrz-Thaw60 C110 C

Dissolved Pyrene (mg/L)

Sorb

ed

Pyre

ne (

mg

/kg

)SORPTION ISOTHERMS,

AGED AND FRESH 750° CHAR

10 20 30 40 50 60 70 80 900%

5%

10%

15%

20%

FreshFrz-Thaw60 C110 C

Added Pyrene (mg/kg)

Extr

acta

ble

Pyre

ne

HPCD-EXTRACTABLE PYRENE450° CHAR, FRESH & AGED

0 100 200 300 400 500 600 7000%

5%

10%

15%

20%

FreshAged 60Aged 110

Added Pyrene (mg/kg)

HP

CD

-Extr

acta

ble

Pyre

ne

HPCD-EXTRACTABLE PYRENE550° CHAR, FRESH & AGED

PAHs sorb strongly to corn stover char Freundlich isotherm 6 < Log K < 7 for fresh char For native PAHs, solubility << 1 ng/L

CONCLUSIONS, PAH SORPTION

Small fraction of pyrene is bioavailable (HPCD-extractable) 10-15% 450° char 1-3% 550°, 750° chars

CONCLUSIONS, PAH BIOAVAILABILITY

(Artificial) aging has small effects on PAH sorption DLog K for pyrene ≤ 0.5

Aging effect on PAH bioavailability 450° char: decrease 550° char: large decrease (?) 750° char: no effect

CONCLUSIONS, CHAR AGING

WATER-SOLUBLE BLACK CARBON

DOC 9.8 mg/LpH 9.2

ABSORBANCE SPECTUM,WATER EXTRACT OF CS450

250 350 450 5500

0.1

0.2

0.3

0.4CS450 Water

Extract

Wavelength (nm)

Ab

sorb

an

ce

250 350 450 5500

0.05

0.1

0.15

0.2

0.25Groundwater, Champaign Co.

Wavelength (nm)

FLUORESCENCE EXCITATION-EMISSION SPECTRA

CS450 Water Extract Groundwater, Champaign Co.

BASE TITRATION, WATER EXTRACT OF CS450

4 5 6 7 8 9 10

0.00

0.05

0.10

0.15

0.20

0.25

0.30m

eq O

H- /g

C

pH

Carboxylic Phenolic

Net extract base titration curve (after sparging with N2(g) at pH 4)

Initial extract pH was 9.16

Will Gillespie, ISWS, for corn stover B. K. Sharma & Wei Zheng for biochar pyrolysis

Jill O’Connell for assistance with experiments

Illinois Sustainable Technology Center for project support

AKNOWLEDGEMENTS