416509.0 The Forest Based Biorefinery: Chemical and Engineering Challenges and Opportunities (5cr) 3.-7.5.2010

Metals in Biorefineries5.5.2010: 13.15-14.15

Ari IvaskaProcess Chemistry CentreÅbo Akademi University

E-mail: ari.ivaska@abo.fi

Why are metals of importance ?

It is important to understand the natural existence and distribution of metal ions in tree material and the reactions of the metal ions with wood fibres and other chemicals in different stages of thepaper making process and in the energy conversion processes.

Chemical forms of metals in wood, pulp and process liquors varies from metal to metal Study on metals gives important

information to predict their behavior in different parts of paper making and energy conversion processes as well as their environmental impact.

The reasons to study

Objectives

Effects of metals on: Flows, Balances, Processes and products

Metals in wood= metals in fuels Important to understand because of: Fouling of equipment (K, Ca, Si) Corrosion of hot heat transfer surfaces

(K, Zn, Pb) Emission

(EU directive for heavy metals: As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Tl, Sb, V)

Metals are important for the growth of the tree and excist as natural components in tree material

Elemental distribution of different concentration ranges for stem woodof Scots pine (Pinus sylvestris) tree

Concentration range, Elementsppm (mg/kg)

1000 – 100 Ca, K, Mg100 – 10 F, Fe, Mn, Na, P, S10 – 1 Al, B, Si, Sr, Zn, Ti1 – 0.1 Ag, Ba, Cd, Cr, Cu, Ni, Rb, Sn0.1 – 0.01 Bi, Br, Ce, Co, I, La, Li, Pb, Se, W0.01 – 0.001 As, Eu, Gd, Hf, Hg, Mo, Nd, Pr, Sc, Sb

Elements in red are from the EU list of ”dirty dozen”.

Metals in wood are significant!

Metals in soil

Biofuelrefining

Chips

Mech. forestproducts

Ash

Paper

Recovery

Chem. pulping& bleaching

Mech. pulping& bleaching

Bark

Knots

Effluents

Fillers

Al Ink

DIP

Metal management is importantDegradationof bleachingagentsEnvironmental

effects

Soilpollution

Metals in soil

Biofuelrefining

Chips

Mech. forestproducts

Ash

Paper

Recovery

Chem. pulping& bleaching

Mech. pulping& bleaching

Bark

Knots

Effluents

Fillers

Al Ink

DIPCorrosionDepositsAshutilisation

Effects on fibrepropertiesand adverseeffects in food packaging

roundwood

stemwood

knots

chips

blackliquor

paper

com-bustion

----

gasifica-tion

ash

emissions

residuesheat power

synthesis gas

emissions

P

biofuels (l)

harvesting

recycling

debarking

chipping

extraction

pulping

synthesis

pulp

extraction

&

barkseparation

P P

P

pulpingchemicals

P P

pulpingchemicals

WP1

WP2

WP 4

WP5

WP7

WP8

extraction

WP6

Kraft Pulp Mill & Biorefinery WP3

WP5

WP5

WP5

WP5

Characterization of biofuel

Chemical fractionation

alkali sulfates/carbonates, chlorides

exchangeablesome CaCO3

carbonates, sulfatessilicates, insolublerest

all major ash elements

ammonium acetate

HCl

H2O

Analysis

Objective to investigate the forms of metal binding in

Scandinavian wood-fuels by sorption of a color dye

step-wise leaching in H2O, NH4Ac and HCl element analyzes of the leachates

ion-chromatography of the leachates

potentiometric titration

of the pure biomass from tree samples

Metals associated with fuel matrix

-COO-M 2+

-OOC-M+

-COO-

M 2+

-COO-

-COO-

Johan Werkelin, Maria Zevenhoven

Major Ash Forming Matter in Fuels

Organically associated ash forming matter

COO-K+COO-

-COO-Na+

Ca2+COO-

Water soluble ash-forming matter

Excluded minerals

Included minerals

Minor ash forming matter, heavy metals?

Main Ash-forming Matter

0

2000

4000

6000

8000

10000

12000

14000

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

Si Al Fe Ti Mn Ca Mg P Na K

mg/

kg d

.s

Rest fraction, analysedLeached in HClLeached in AcetateLeached in H2O

© Maria Zevenhoven

0

50

100

150

200

250

300

350

400

450

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

bark

1ba

rk 1

for r

es.

woo

d1w

ood2

As Cd Co Cr Cu Hg Mn Ni Pb Sb Tl V Zn

mg/

kg d

.s.

Rest fraction, analysedLeached in HClLeached in AcetateLeached in H2O

Heavy Metals (EDD12+Zn)

© Maria Zevenhoven

Ash Elements in Spruce

© Johan Werkelin

Balance for Pine wood, bark & foliage

Johan Werkelin

Conclusion Metal binding in trees was determined

Metals: in wood: in bark: in foliage: as salts 5 – 10% 5 – 10% 10 – 30%

anionic gr 80 – 90% 20 – 50% 20 – 50%

as oxalate 0 – 10% 20 – 50% 10 – 40%

Chemical mode of ash-forming elements influence ash chemistry and deposit formation

Johan Werkelin

Metals in wood

Wood discs from 2 meters height of a ~40-year-old Norway spruce tree were used.

N

E

S

W

One annual growth ring

Annual growth rings in

different compass direction

Microtoming

Latewood Earlywood

Sampling for microanalysis

Andrey Pranovich

Wood

Microtoming

Thin sections (0.125 m)

Extraction GC (Extractives)

Acidmethanolysis

AcBrmethod

THM

GC UV-spectrometry GC-MSHemicellulosesPectin

Lignin content Lignin structureICP-MSMetals

Wood

Microtoming

Thin sections (0.125 m)

Extraction GC (Extractives)

Acidmethanolysis

AcBrmethod

THM

GC UV-spectrometry GC-MSHemicellulosesPectin

Lignin content Lignin structureICP-MSMetals

Scheme used for chemical microanalysis of wood samples

Andrey Pranovich

Earlywood Latewood

Annual growth ring

Distribution of analytes within annual growth ring

Analysis

Thin wood sections

sugars from hemicelluloses, uronic acidslignin

metals

Andrey Pranovich

Earlywood Latewood

Annual growth ring

0

200

400

600

800

1000

0 1 2 3 4

1994 WEST

mg/kg wood

mm

Ca

020406080

100120140160

Na

0100200300400500600700

K

Pb0,02 %

Cr0,01 %

Co0,01 %

Cd0,002%

Ni0,03 %

Zn0,7%

Sr0,4%

Fe0,3%

Cu0,1%Rb

0,1%

Other0,07 %

Al0,7%

Mg7,5%K

29,1%

Ca50,9%

Na6,9%

Mn2,2%

Ba1,1%

Metal content in spruce stemwood (average from 1989 and 1994 annual growth rings across

the stem)

Andrey Pranovich

Binding of metal ions to woodfibres

Ion-exchange equilibria inwood fibres

COO- H+

COO- H+

COO- H+

COO- H+

COO-

COO-

M2+

M2+ 2 H++ +

COO- H+

COO- H+

COO- H+

COO- H+

COO- H+

COO- H+

COO- H+

COO- M+

COO- H+

COO- H+

M++ H++ MH

MR HK

M HR

M HR MR H+ ++ +

222 2M HR MR H

2

22 22

MH

MR HK

M HR

Ion-exchange equilibria inwood fibres

MN

NR MK

N MR

N MR NR M+ ++ +

222 2X MR XR M

2

22 22

XM

XR MK

X MR

COO-M+

COO-M+

COO-M+

COO-M+

+ X2+

COO-M+

COO-M+

COO-N+

COO-M+

+ M+

COO-M+

COO-M+

COO-M+

COO-M+

COO-M+

COO-M+

COO-

COO-X2+

+ 2M+

+ N+

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

log

KC

a nK

n

0.001 M 0.005 M

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6

-0.8

-0.4

0.0

0.4

0.8

1.2

1.6

2.0

log

KM

g nK

n

0.0005M 0.005 M

Determination of stoichiometry of the ion exchange reaction

pH:4-10Mg - nKCa - nK

The column chromatographic methodStep 1Columnpacking

Step 2Removal of

natural ion content

Step 3 Loading of

pulp and rinsing

Step 4 Elution of metal ions

Pulp8 g or 18 g

- EDTA - HNO3- Deionized water

- Metal ion mixtures- Deionized water

Naturallycontainedmetal ions

Excess of metal ions(not bound)

0.005 M HNO3

Collection of fractions (bound

metal ions)

5 ml

65 c

m a

nd 1

20 c

m

20 mm

Determination of metal ion

concentrations in thefractions

Pingping Su, Kim Granholm

Study on metal ion affinities to oxygen delignified hardwood kraft pulp by a column

chromatographic methodProcedure: A column (65•2 cm and 120•2 cm) packed with pulp Natural ion content removal (EDTA, HNO3) and a rinsing

with deionized water Addition of mixtures of metal ions (loading) and washing

away the excess (unbound) of metal ions with deionized water

Elution of metal ions with 0.005 M HNO3

Collection of fractions (5 or 10 ml) during elution Determination of metal-ion concentrrations in the fractions

0 50 100 150 2000

5

10

15

20

25

pH Mg2+

V, ml

n,

mol

0

2

4

6

8

10

pH

Fig. 1. pH and the number of mikromoles (n) of magnesium ions as function of the volume (V) of eluate in the collected fractions.

22

22

22

2 )2(2

HMRMHRKHnMHRHnMR M

H

Pingping Su, Kim Granholm

100 120 140 160 180 200 2200

2

4

6

8

Sr2+

Mg2+

Ca2+

Ba2+

n,

mol

V, ml

Ba2+

Ca2+

Mg2+

Sr2+

Fig. 2. The number of mikromoles (n) of Ba2+ , Ca2+, Mg2+ and Sr2+ as function of the volume (V) of eluate in the collected fractions.

Pingping Su, Kim Granholm

0 50 100 150 200 2500

2

4

6

8

Fe2+

Mn2+

pH

V, ml

n,

mol

2

4

6

8

10

pH

Fig. 3. pH and the number of mikromoles (n) of Fe2+ and Mn2+ as functionof the volume (V) of eluate in the collected fractions.

Pingping Su, Kim Granholm

0 50 100 150 200 250200

300

400

500

600

321

mV pH

V, ml

Red

ox p

oten

tial,

mV

0

2

4

6

8

10

12

pH

Level

Redox

Potential

(mV)

pH Fe(III)

logFe(II)

Fe(III)

(%)

Fe(II)

(%) Fe(III)(OH)α Fe(II)(OH)α

Fe(III)

logFe(II)

Fe(III)

(%)

Fe(II)

(%)

1 290 8.2 -4.0 0.01 99.9 109.7 1 5.7 ~100 0

2 354 3.8 -2.9 0.1 99 101.2 1 -1.7 2 98

3 514 2.7 -0.25 36 64 100.2 1 -0.05 47 53

Table 1. Calculation of the Fe3+ /Fe2+ ratios from the mean values of the redox potentials and pH from the data presented in fig. 4.

Fig.4. The redox potential and pH plotted as function of the volume (V) of eluate for the sorption of Fe2+ and Mn2+.

oCell Cell

Fe(III)E =E +59.2mV log

Fe(II)

M(OH)

MM =

α

3+Fe(III)

2+Fe(II)

α FeFe(III)=

Fe(II) α Fe

n- MOH - M(OH)nM(OH) M,OH M,nOHα =1+ OH K + + OH K

Pingping Su, Kim Granholm

0 50 100 150 200 250 300 3500

2

4

6

8

n,

mol

V, ml

Fe3+

Mn2+

Fig. 5. The number of mikromoles (n) of Fe3+ and Mn2+ as function of the volume (V) of eluate in the collected fractions.

Pingping Su, Kim Granholm

Fig. 6. The number of mikromoles (n) of Ba2+, Cd2+, Cu2+, Mg2+, Mn2+, Na+, Pb2+ and Zn2+

as functionof the volume (V) of eluate in the collected fractions.

Order of affinities to the pulp:

Fe3+>>Pb2+>>Cu2+>>Cd2+>Zn2+>Ba2+>Ca2+>Mn2+>Fe2+>Sr2+>Mg2+>K+>Rb+>Na+

200 300 400 500 6000

5

10

15

20

25

Na+

Cd2+

Cu2+

Pb2+

n,

mol

V, ml

Ba2+

Cd2+

Cu2+

Mg2+

Mn2+

Na+

Pb2+

Zn2+

Pingping Su, Kim Granholm

R.F. Generator

Interface Quadrupole

Ion lense

Detector

Vacuum pumps

Computer

MCS

AmplifierGascontrol

Plasmatorch

Laserablation

LA-ICP-MS for element analysis

Analysis of single wood fiberAnalysis of single wood fiber

Pingping Su, Paul Ek

Pingping Su, Paul Ek

0 20 40 60 80 100 120 140 160 180

0

50

2000

4000

6000

8000

10000

12000

14000

The distribution of the metals in the single fibre of the unbleached kraft softwoodTh

e in

tens

ity /

cps

Time / s

K Fe Mn

LA-ICP-MS scan along a single wood fiber

0 40 80 120 160 200 240 280 320 360distance, m

Pingping Su, Paul Ek

Distribution of metal ions in tree

Detailed localisation of metals in different wood species (spruce, aspen, birch, larch) and tissues (sapwood, heartwood, EW, LW) by chemical microscopy

Objectives

Elena Tokareva

ToFToF--SIMS imaging of radial sectionSIMS imaging of radial sectionfrom spruce sapwood.from spruce sapwood.

Ca, Na, Mg, K, Fe dominate in Ca, Na, Mg, K, Fe dominate in bordered pit bordered pit toritori..Only little lignin was observed in the same regions.Only little lignin was observed in the same regions.

100m

Total ion Ca

Lignin

Na

Mg Fe

Elena Tokareva

LA-ICP-MS of radial section from spruce sapwood

Elena Tokareva, Paul Ek

Spruce Spruce sectionssections No treatmentNo treatment

Alkali treatment Alkali treatment (pH 12, 60(pH 12, 60°°C)C)

Acid treatmentAcid treatment(pH 2, 20(pH 2, 20°°C)C)

SrClSrCl22 / MgCl/ MgCl22impregnationimpregnation

ToFToF--SIMSSIMS

Labelling of anionic groups

-- CHCH33OHOH

NaOH, t°C O

OO

O

OH

OOH

COO OH

OH

COO

OH

COO OH

OHO

OO

O

OH

O

COOCH3Elena Tokareva

Original spruce section

Sr2+ impregnated section

Total ion

100 100 mm

SrCa

Total ion

100 100 mm

SrCa

ToF-SIMS images

Elena Tokareva

Speciation of calcium in black liquor

Construction of all-solid-state Ca2+ ISE(= ion-selective electrode)

Glassy carbon

PVC

PEDOT

Ca2+ cocktail

Ca2+ membrane

1

2 3

1. Electrosynthesis of poly(3,4-ethylenedioxythiophene) (PEDOT)= electically conducting polymer

2. Drop-casting of Ca2+ selective cocktail3. All-solid-state Ca2+ ISE

Galvanostatic Electropolymerization:- 0.01 EDOT+ 0.1 M NaPSS- +0.0014 mA (0.2mA/cm2), 714 s- Condition in 0.1 M CaCl2, 24 h

Drop-casting:- 4.65 mg ETH 1001,1.62 mg KTpClPB,

3.73 mg ETH 500, 161 mg PVC, 325 mg o-NPOE, 3ml THF

- Condition in 0.01 M CaCl2, 24 h

Kim Granholm

3 % dry matter, diluted with waterOriginal, evaporated sample, 78% dry matter

Kim Granholm

0 10 20 30 40 50-120

-100

-80

-60

-40

-20

E / m

V

time / h

-4.0-3.6-1.7-1.8After 48 h

-4.3-3.8-2.2-1.8Before

lg KCa,Allg KCa,Mglg KCa,Klg KCa,Na

-6 -5 -4 -3 -2 -1

-40

-20

0

20

40

60

80

100

120

E / m

Vlog CCa2+ / M

Before black liquor After 48h in black liquor

Selectivity coefficients

Calibration curves48h in black liquor (3.3%)

Durability test of Ca2+-ISE in black liquor

Kim Granholm

Calcium distrubution at the membrane surfaceLA-ICP-MS

No conditioning After Ca2+-conditioning After in black liquor

0.48 mm

8.5 mm

Scan rate: 6 µm/s Laser: spot size = 15 µm, effect = 45 %, 5 Hz

LA-ICP-MS LA-ICP-MSLA-ICP-MS

Kim Granholm

LA-ICP-MSSodium distrubution at the membrane surface

No conditioning After Ca2+-conditioning After black liquor

LA-ICP-MS

Scan rate: 6 µm/s Laser: spot size = 15 µm, effect = 45 %, 5 Hz

LA-ICP-MSLA-ICP-MS

Kim Granholm

Depth profile of Calcium in the membrane

After black liquor

LA-ICP-MS

Membrane thickness: ~200 µm

Laser: spot size = 40 µm, effect = 35 %, 5 Hz

After Ca2+-conditioning

Kim Granholm

Depth profile of Sodium in the membrane

After black liquor

LA-ICP-MS

After Ca2+-conditioning

Membrane thickness: ~200 µm

Laser: spot size = 40 µm, effect = 35 %, 5 hz

Kim Granholm

Titration of Ca2+-solution with EDTA using Ca2+ ISE

0 2 4 6 8 10-140

-120

-100

-80

-60

-40

-20

0

20

40

E / m

V

0.005 M EDTA / ml0 2 4 6 8 10

0

1

2

3

4

5

3.8*0.005M = 0.019 mmol Ca2+

Linear fit:y=4.11-1.08xy=0: x=3.810

^(E/

30)

0.005 M EDTA / ml

Titration curve: Gran’s Plot:

(100 ml of 2*10-4 M CaCl2 0.02 mmol Ca2+)

Kim Granholm

Potentiometric titrations with EDTA using Ca2+-ISE

0 2 4 6 8 10-130

-120

-110

-100

-90

-80

-70

-60E

/ mV

0.005 M EDTA / ml

BL (100 ml)

Kim Granholm

Potentiometric titrations with EDTA using Ca2+-ISE

0 2 4 6 8 10-130

-120

-110

-100

-90

-80

-70

-60E

/ mV

0.005 M EDTA / ml

BL (100 ml) BL (100 ml) + 0.01 mmol Ca

Kim Granholm

0 1 2 3 4 5 6 7 8 9 100

2

4

6

8

10

Black liquor Black liquor + 0.01 mmol Ca2+

1000

*10^

(E/3

0)

0.005 M EDTA / mlFreeCa2+

TotalCa2+

TotalCa2+

FreeCa2+

Potentiometric titrations with EDTA using Ca2+-ISE(Grans´s Plot)

Kim Granholm

0 1 2 3 4 5 6 7 8 9 100

2

4

6 Black liquor Black liquor + 0.01 mmol Ca2+

1000

*10^

(E/3

0)

0.005 M EDTA / mlFreeCa2+

TotalCa2+

TotalCa2+

FreeCa2+

0.01 mmol0.02 mmol

0.02 mmol

0.03 mmol

Free Ca2+ = 0.01 mmolBound Ca2+ = 0.01 mmol

Free Ca 2+ = 0.02 mmolBound Ca2+ = 0.01 mmol

Kim Granholm

Conclusions The Ca2+-ISE can be ”conditioned” in black liquor to

eliminate the potential drift It is possible to measure Ca2+ ions in diluted black

liquors The selectivity coefficients for the Ca2+-ISE remains

high after black liquor measurments A speciation of complexed Ca2+ ions and uncomplexed

Ca2+ ions seems to be possible