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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: [email protected]
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