Matching Biochar Characteristics with Metals-C i d S il Eff i l R d M lContaminated Soil to Effectively Reduce Metal

Bioavailability at Mining Sites

Mark G. JohnsonResearch Soil ScientistResearch Soil Scientist

Clu-In SeminarNovember 7, 2017

Outline of Presentation• What is biochar?

• How is biochar made?• Biochar propertiesBiochar properties• Biochar and metal sorption• Why EPA and biochar?

Bi h d t f t l• Biochar as an amendment for metal contaminated spoil soils

• Tuning biochar properties to address spoil soil limitationslimitations• Insuring a good match between site conditions

and soil amendments• Field StudiesField Studies

• Target soils• Monitoring site conditions

• SummarySummary• Outlook for the future

2

What is Biochar?

•Carbon-rich solid produced by heating biomass in theby heating biomass in the absence of oxygen (pyrolysis)

•Residual product of bio-penergy production

•Porous solid with a number Biochar from Wood Chips

of beneficial properties•Properties depend upon f d k lfeedstock, pyrolysis conditions and possibly other modificationsmodifications

Biochar from Wood Pellets3

What is Biochar?

Ponderosa Pine Biochar Poultry Litter Biochar

4

Ponderosa Pine Biochar Poultry Litter Biochar

Charcoal being added to Willamette Valley soil following a grass field fire

6

Making Biochar via Pyrolysis:Energy Extraction from BiomassEnergy Extraction from Biomass

Concept diagram of low-temperature (350 to 500 °C) pyrolysis based bio-energy production with biochar storage in soil. Typically, between 20 and 50% of the initial biomass carbon is converted

into biochar and can be returned to soil (Lehmann, 2007). 7

Comparison of Pyrolysis Processes for Syngas (Energy) and Biochar Production(Energy) and Biochar Production

http://www.csiro.au/files/files/poei.pdf 8

Pyrolyzers: Heating Biomass Without Oxygen

Old School Highly Controlled Lab-Scale

Industrial Portable9Slide - D. Crowley

Modern Slow Pyrolysis Unit: Prineville, OR

Beehive, Teepee or Wigwam Burner –Historically used to

burn sawmill wastes

10

Feedstock Hopper

Pyrolysis Retort

BiocharProduct

11

Examples of Biochar FeedstocksPine ChipsSwitchgrass Pine ChipsSwitchgrass

Swine Solids Poultry LitterSwine Solids Poultry Litter

12

Energy Extraction and Biochar Production

Wood Chip

Saw Mill Waste Coarse Wood Chips Wood Chips Feed Into Gasification Retort

Wood ChipAugerRetort

FineBi h

CoarseBiochar

Retort Volatile Gases Boiler

Biochar

13

Volatile Gases From Retort Feed Into Boiler

Hot Water From Boiler Heats 5 Acres of Greenhouses

“Waste Product” = High Quality Biochar

Biochar has a Range of Structural Properties that Depend Upon Pyrolysis Temperature and ConditionsDepend Upon Pyrolysis Temperature and Conditions

(Keiluweit et al, 2010) 14

Adsorption, Leaching, and Distribution of Simazine in Soils Amended with Biochar

Control Control

D.L. Jones et al. / Soil Biology & Biochemistry 43 (2011) 804-81315

Weed control of barnyard grass with Diuron herbicide applied at different concentrations to soil amended with varying y g

concentrations of wheat straw biochar. (Yang 2006)

16

Key Biochar PropertiesKey Biochar Properties• pH

• Ash content• Ash content• Proximate carbon

• Volatile matteri d b• Fixed carbon

• Surface area• PorosityPorosity

• Pore size distribution• Chemistry

• Total elemental• Total elemental• Nutrients

• Cation exchange capacity (CEC)

17

SEM Images of Douglas-fir Wood Chip Feedstock and Biochar

300 °CRaw Feedstock 400 °C

500 °C 600 °C 700 °C18

Proximate Carbon Analysis

• Quantify three constituents of biochar

l il

ProcedureAdapted from ASTM Method D1762-84:

Chemical Analysis of Wood Charcoal

• Volatile matter• Low molecular weight carbon• Labile carbon fraction

Fi d b

Weigh Dry Biochar into Inconel Crucibles (A)

Heat Biochar in Covered • Fixed carbon

• Stable forms of carbon• Biopolymer (lignin, cellulose,

hemicellulose etc )

Crucibles at 950°C for 6 minutes.

Reweigh when cool. (B)hemicellulose, etc.)

• High degree of aromaticity• Ash content

• Residual mineral matter

Heat Biochar in Uncovered Crucibles at

750°C for 6 hours.• Residual mineral matter

Reweigh when cool. (C)

Volatile matter = B – A; Fixed carbon = B – C; Ash content = C

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Ternary Plot of Proximate Carbon FractionsFormosa Mine Extract Study - Summer 2014

Arundo donax - 300 C° Arundo donax - 500 C° Arundo donax - 700 C° Anaerobically Digested Fiber - 300 C° Anaerobically Digested Fiber - 500 C°

†

90

1000

10

Anaerobically Digested Fiber 500 C Anaerobically Digested Fiber - 700 C° ARS Char #1ARS Char #2ARS Char #3ARS Char #4ARS Char #5

% Ash

70

80

90

rbon

20

30

40

ARS Char #5ARS Kentucky Bluegrass Seed ScreeningsARS Rice Seed ScreeningsARS Tall Fescue Seed ScreeningsARS WoodDouglas fir - 300 C° sh Content

40

50

60

% F

ixed

Car 40

50

60

Douglas fir - 500 C° Douglas fir - 700 C° Dairy Manure Biochar (Enchar)Elymus - 300 C° Elymus - 500 C° Elymus - 700 C°

10

20

3070

80

90

yGranulated Activated CharcoalHazelnut Shells - 300 C° Hazelnut Shells - 500 C°Hazelnut Shells - 700 C°Miscanthus - 300 C°Miscanthus 500 C°

300 °C700 °C

% Volatile Matter0 10 20 30 40 50 60 70 80 90 100

0

10

100

Miscanthus - 500 CMiscanthus - 700 C°Oregon White Oak - 300 C°Oregon White Oak - 500 C°Oregon White Oak - 700 C°Spent Brewer's Grain - 300 C°500 °CSpent Brewer's Grain - 500 C°Spent Brewer's Grain - 700 C°Sorghum - 300 C°Sorghum - 500 C°Sorghum - 700 C°†ASTM Method D-1762 20

Physical Properties of Biochar from y pDifferent Feedstocks: GrassGrass†† vs. WoodWood‡‡

Pyrolysis Temperature

(°C)

Yield(wt%)

Yield (wt%)

CarbonContent

(wt%)

Carbon Content

(wt%)

Volatile Matter (wt%)

Volatile Matter (wt%)

Fixed Carbon (wt%)

Fixed Carbon (wt%)

Ash* (wt%)

Ash* (wt%)

Surface Area

(m2g-1)

Surface Area

(m2g-1)

100 99.9 99.8 48.6 50.6 69.6 77.1 23.5 21.7 6.9 1.2 1.8 1.6

200 96.9 95.9 47.2 50.9 70.7 77.1 23.6 21.4 5.7 1.5 3.3 2.3

300 75.8 62.2 59.7 54.8 54.4 70.3 36.2 28.2 9.4 1.5 4.5 3.0

400 37.2 35.3 77.3 74.1 26.8 36.4 56.9 62.2 16.3 1.4 8.7 28.7

500 31.4 28.4 82.2 81.9 20.3 25.2 64.3 72.7 15.4 2.1 50 196

600 29.8 23.9 89.0 89.0 13.5 11.1 67.6 85.2 18.9 3.7 75 392

700 28 8 22 0 94 2 92 3 9 1 6 3 71 6 92 0 19 3 1 7 139 347700 28.8 22.0 94.2 92.3 9.1 6.3 71.6 92.0 19.3 1.7 139 347

††Tall Fescue,Tall Fescue, ‡‡Ponderosa pinePonderosa pine

*Ash = Metal and non-metal oxides, chlorides, phosphates, and carbonate residue

(From Keiluweit et al, 2010)21

Physical Properties and pH of Douglas-fir Biochar: A Function of Pyrolysis Conditions and Feedstock

Property 300 °C 400 °C 500 °C 600 °C 700 °C

A Function of Pyrolysis Conditions and Feedstock

Production Yield (%) 49.9 36.6 31.3 28.8 27.2

Volatile MatterVolatile Matter (%) 46.90 32.35 20.54 11.80 7.96

Fixed C (%) 52.70 67.16 78.87 87.51 89.12

Ash Content (%) 0.40 0.48 0.59 0.69 2.93

Surface Area 3 7 13 7 353 6 391 3 379 9(m2g-1) 3.7 13.7 353.6 391.3 379.9

pH 4.67 5.95 6.68 7.48 8.22

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Fourier Transformed Infrared (FTIR) Spectra of Douglas fir Biochar and FeedstockFourier Transformed Infrared (FTIR) Spectra of Douglas-fir Biochar and Feedstock

O-H Aliphatic C-Hs700°C

C=OC=C C-O

banc

e

600°C

500°C Aromatic C-Hs

C=C C-O

C-O fromPolysaccharides

lativ

e A

bsor

b

400°C

Rel 300°C

Feedstock

Wavenumbers (cm-1)

400600800120014001600180022002400260028003200340036003800 1000200030004000

Transmission FTIR: 0.5 % material in pressed KBr pellet

Wavenumbers (cm )

23

Early Research: First Study

Mine spoil “soil” from Leadville, COSi l d i (S ) i• Simulated Rainwater (SRW) extraction (pH 4.5)

• 25 mls of filtered SRW added to 0.25 g of Douglas-fir biochar

• 24 hour contact time• Biochar separated from SRW solutionBiochar separated from SRW solution• Characterization of SRW solution with

ICP AESICP-AES24

% Change in Initial Metal Concentration of Simulated Rainwater Extract of Leadville CO Mine Spoil after 24 Hour Contact with

Initial Metal

Extract of Leadville, CO Mine Spoil after 24 Hour Contact with Douglas-fir Biochar

Metal Concentration (mg kg-1 biochar)

300 °C 400°C 500°C 600°C 700°C

Al 247 3.8 21.8 68.2 92.9 98.6

Ca 57922 -0.4 -0.8 -1.0 -2.4 -2.6

Cd 101 3.7 3.9 5.0 5.3 6.4

Cu 204 8.4 17.5 65.1 87.1 97.4

Mg 8441 3.8 3.4 2.8 2.1 5.9

Mn 2364 4 5 4 2 3 7 3 2 7 4Mn 2364 4.5 4.2 3.7 3.2 7.4

Pb 198 11.2 21.1 54.8 72.5 95.3

Zn 8720 3.6 2.9 3.1 3.6 5.5

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Early Research: Second Study

Cu sorption on biochar• 25 mls of a 5 mM Cu(NO3)2·2.5 H2O

solution added to 0.25 g of Douglas-fir biochar

• 24 hour contact time• Biochar separated from Cu solution,

washed with MeQ water and driedQ• Cu sorption characterized with X-Ray

Absorption SpectroscopyAbsorption Spectroscopy

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Micro X-ray Absorption Spectroscopy (µXAS): ALS Beamline 10.3.2

Samples Mounted with Kapton tapeKapton tape

X-ray Beam

Sample Support

5 mm

X-ray beam spot size: 3 – 10 µm27

Biochar FluorescenceChemistry Maps

300 °C Douglas-fir Biochar treated

with 5mM CuC C K 200μmCuCaK 200μm

500 °C Douglas-fir Biochar treated

200μmwith 5mM Cu

CuCaK

700 °C

200μm

Douglas-fir Biochar treatedwith 5mM Cu

CuCaK 28

X-ray Absorption Fine Structure (XAFS)X ray Absorption Fine Structure (XAFS)of Cu on Douglas-fir Biochar

1.4

1.6

XANES

µ(E) 1.0

1.2 EXAFS

sorb

ance

- µ

0.6

0.8

XANES = X-ray Absorption Near Edge Structure

Abs

0.2

0.4

300 °C - Spot 2500 °C - Spot 1

EXAFS = Extended X-ray Absorption Fine Structure

E ( V)9000 9200 9400 9600

-0.2

0.0p

700 °C - Spot 2

Cu K-edge = 8979 eV

Energy (eV)

29

XANES of Cu(II) Standards

ance

- µ(

E)ze

d A

bsor

baNo

rmal

iz

Cu AcetylacetonateCu(II) on GraphiteCu on DF Feedstock

Cu Acetate Cu HydroxideCu CarbonateCu Oxide - 1Cu Oxide - 2

y

Energy (eV)8950 9000 9050 9100 9150

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X-ray Absorption Near Edge Structure (XANES)X ray Absorption Near Edge Structure (XANES)of Cu on Douglas-fir Biochar

1.4

1.6µ(

E) 1.0

1.2

Peak &

sorb

ance

- µ

0.6

0.8

Pre-edge

Peak & Post-edge

Ab

0.2

0.4

300 °C - Spot 2500 °C - Spot 1

g

E ( V)8950 9000 9050 9100 9150

-0.2

0.0p

700 °C - Spot 2

Cu K-edge = 8979 eV

Energy (eV)

31

XANES f C 300 °C D l fi Bi h d C St d dXANES of Cu on 300 °C Douglas-fir Biochar and Cu Standards

1.2

1.4- µ

(E)

0.8

1.0

bsor

banc

e -

0.4

0.6

Ab

0.0

0.2300 °C - Spot 2Cu AcetateCu(II) on DF Feedstock

Energy (eV)8950 9000 9050 9100 9150

-0.2

Cu Acetylacetonate

Energy (eV)

32

XANES of Cu on 500 and 700 °C Douglas-firXANES of Cu on 500 and 700 C Douglas firBiochar and Graphite

1.4

1.6

µ(E) 1.0

1.2

sorb

ance

- µ

0.6

0.8

Abs

0.2

0.4

500 °C - Spot 1

E ( V)8950 9000 9050 9100 9150

-0.2

0.0Cu(II) on Graphite

p700 °C - Spot 2

Energy (eV)

33

Observations and Conclusions from Early Studies

• Biochar from Douglas-fir (DF) has the potential for remediating metal contaminated soils and waters for certain metals

• For some metals sorption is a function of the pyrolysis temperature

• Pyrolysis temperature↑ metal sorp on↑

• Metal sorption in low temperature (≤ 400 °C) DF biochar appears to be controlled by oxygen-containing functional groups and appears to be relatively weak association for Cu(II)

• In contrast, metal sorption in higher temperature (> 400 °C) DF biochars does not appear to be controlled by oxygen-containing functional groupsg p

• Possible explanations for sorption in the high temperature biochar include physisorption of metals in micropores and/or pi-bonding with aromatic p systems that form during pyrolysis.pi bonding with aromatic p systems that form during pyrolysis. The mechanism for this sorption still needs to be resolved.

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