Characterisation of industrial barks for their tannin contents for further green-wood based adhesives applications

F. BERTAUD1, S. TAPIN-LINGUA2, A. PIZZI3, P. NAVARRETE3, M. PETIT-CONIL1CTP Grenoble, 2FCBA Grenoble, 3LERMAB-ENSTIB Epinal

2010, August 20 – COST FP0901-Hamburg

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INTRODUCTION Context and motivations

WOOD PANELS & FIBREBOARDS INDUSTRY

� France : 6.7 Millions m3 of wood panels produced in 2005 (2d

largest production in EU) � 70-100 kg/m3 of adhesives in panels

� 5-12%, w/w (~500 000 T/y)� Usually based on urea-formaldehyde mixture (amino resin UF &

MUF)� Recently, formol has been classified as a probable human

carcinogen and its use could be limited in the near future

�Need to develop new and environmentally friendly adhesives

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INTRODUCTION Context and Motivations

WOOD PANELS & FIBREBOARDS INDUSTRY

� Alternatives of formol-based adhesives� Used of scavenger and lower the qty of formol in the formulation

(molar ratio F/U �)� Phenolic resin (phenol+ formol) => less formol released � Isocyanate-based adhesives (pMDI) but costly and could also

be restricted� Partial substitution by green chemicals :

Binder (protein) + Plasticizer (from bio-products)

� Natural phenols : tannins already used in few panel & board productions

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INTRODUCTION Context and motivations

TANNINS

� Wood adhesives from condensed flavonoid tannins (catechine) � Acacia (Mimosa), Quebracho, Pine (pinus radiata) tannins in

South Africa, South America and Australia, Japan …� Tannin-based adhesives : partial or total substitution of phenol in

phenol/formol formulation,» tannin/hexamine or tannin/iso-cyanate

� World production: 200 000 T/year � still too low for large industrial use

� Limitation : - not really industrial tannin extraction in Europe, - reactivity of tannin / nature (polymerisation duration, adhesive

properties)

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INTRODUCTION Context and motivations

TANNINS

� Tannin from wood-bark residues from pulp mill� Bark ~7-12 % w/w of the tree: std pulp mill (100 000 T/y pulp) � ~10 000 T/y barks

� In pulp mill : bark is used for energy recovering � Softwood barks are especially rich in condensed flavonoid

tannins

� Objectives� Study the potential of several industrial wood barks wastes

from pulp mills for tannin extraction, and further for their adhesive properties,

� Develop aqueous extraction of tannin,easy industrial scale-up

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INTRODUCTION Objectives

Tannin Extraction from pulp mill bark wastes

� Optimisation of aqueous extractions of condensed tannins� alkaline conditions or sulfite are the chemicals preferred for tannin

extraction

� urea as a nucleophile improves tannin extract quality

� A too high temperature increases extraction yield but leads to worse adhesives properties

�Therefore, extraction conditions, such as temperature, time, L/V ratio and bark pre-treatment need also to be set

� Analytical characterisation of tannin extracts using different spectrophotometric analyses and Pyr-GC/MS

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MATERIALS AND METHODS

Tannin Extraction and characterisation� Bark samples

� 5 different barks were sampled in pulp mills :

– spruce, maritime pine, aleppo pine, douglas fir and eucalyptus

� Dryness of fresh wood barks was between 40% to 70%.

� stored at –18°C, freeze dried and milled (particles Ø <1mm) before organic extraction.

� In case of large aqueous extraction: air-dried and ground (particles <3 mm

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MATERIALS AND METHODS

Tannin extraction and characterisation

� Extraction � Analytical organic extraction

– 250 mg of o.d. bark were extracted with 2x5 ml of acetone/water (70/30, v/v) in a ultra-sonic bath for 20 minutes at 20°C. After centrifugation, the supernat ant was collected.

� Aqueous extraction– 100 g of o;d. bark were extracted by 500 ml of aqueous

solution at 75°C during 1h, under reflux. The extra ct was filtrated on sintered glass N°1 before analysis.

– Four different aqueous solution were tested : » aqueous solution: tap water,» urea solution containing 2% of urea» urea/sulphite solution containing 2% urea and 2% sulphite» sulphite/carbonate solution containing 2% sulphite and

0.5% carbonate

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MATERIALS AND METHODS

Tannin extraction and characterisation

� Spectroscopic analyses� Phenolic compounds: Folin-Ciocalteu method

Tannic acid was used as standard. 0.5 ml of 1N Folin-Ciocalteureagent and 2.5 ml of 2% sodium carbonate solution are added to 0.05 – 1 ml of extract. Absorbance is measured at 725nm after 40 min of reaction

� Total phenols content: UV measurement at 280nm as described by Antoine et al. (2004) using mimosa tannin as standard.

� Condensed tannins were determined according to butanol/HClmethod, using catechine and mimosa tannin as standards.

� Pyr-GC/MS analysis� 0.1 – 0.3 mg of dried extract� Pyrolab 2000, 500°C/4s,� GC/MS: HP1 (30 m x 0.25 mm, film thickness 0.25 µm),

Temperature prog: 50°C (1min) – 5°C/min – 300°C

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RESULTS: Tannin Extraction

ANALYTICAL EXTRACTION & CHARACTERISATION

Characteristic of acetone/water (70/30, v/v) extracts of wood barks

(g/100g of o.d. bark) Extraction yield Total phenols (UV 280nm)1

Phenolics (FC)2

Condensed tannins3

Spruce 26.6 26 ± 1 4,7 ± 0,1 11,0 Aleppo pine 30.1 5 ± 1* 7,5 ± 0,1 16,6 Douglas fir 22.8 11 ± 1 3,6 ± 0,1 6,7 Maritime pine 10.2 3 ± 1 0,8 ± 0,1 1,2 Eucalyptus 6.5 2 ± 1 0,2 ± 0,1 0,2 1eq. mimosa tannin , 2eq. tannic acid, 3eq. catechine * after 0.45µm glass membrane filtration

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RESULTS: Tannin Extraction

ANALYTICAL EXTRACTION & CHARACTERISATION

Highest extraction yields for aleppo pine, spruce and douglas fir barks

Characteristic of acetone/water (70/30, v/v) extracts of wood barks

(g/100g of o.d. bark) Extraction yield Total phenols (UV 280nm)1

Phenolics (FC)2

Condensed tannins3

Spruce 26.6 26 ± 1 4,7 ± 0,1 11,0 Aleppo pine 30.1 5 ± 1* 7,5 ± 0,1 16,6 Douglas fir 22.8 11 ± 1 3,6 ± 0,1 6,7 Maritime pine 10.2 3 ± 1 0,8 ± 0,1 1,2 Eucalyptus 6.5 2 ± 1 0,2 ± 0,1 0,2 1eq. mimosa tannin , 2eq. tannic acid, 3eq. catechine * after 0.45µm glass membrane filtration

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RESULTS: Tannin Extraction

ANALYTICAL EXTRACTION & CHARACTERISATION

Highest extraction yields for aleppo pine, spruce and douglas fir barksHighest phenol/phenolic contents in allepo pine, spruce and douglas fir

Characteristic of acetone/water (70/30, v/v) extracts of wood barks

(g/100g of o.d. bark) Extraction yield Total phenols (UV 280nm)1

Phenolics (FC)2

Condensed tannins3

Spruce 26.6 26 ± 1 4,7 ± 0,1 11,0 Aleppo pine 30.1 5 ± 1* 7,5 ± 0,1 16,6 Douglas fir 22.8 11 ± 1 3,6 ± 0,1 6,7 Maritime pine 10.2 3 ± 1 0,8 ± 0,1 1,2 Eucalyptus 6.5 2 ± 1 0,2 ± 0,1 0,2 1eq. mimosa tannin , 2eq. tannic acid, 3eq. catechine * after 0.45µm glass membrane filtration

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RESULTS: Tannin Extraction

ANALYTICAL EXTRACTION & CHARACTERISATION

Highest extraction yields for pine, spruce and douglas fir barksHighest phenol contents in spruce, douglas fir and allepo pine1/3 to 1/2 of bark extracts were constituted of condensed tannins (maritime pine and

eucalyptus contain much less condensed tannins)

Characteristic of acetone/water (70/30, v/v) extracts of wood barks

(g/100g of o.d. bark) Extraction yield Total phenols (UV 280nm)1

Phenolics (FC)2

Condensed tannins3

Spruce 26.6 26 ± 1 4,7 ± 0,1 11,0 Aleppo pine 30.1 5 ± 1* 7,5 ± 0,1 16,6 Douglas fir 22.8 11 ± 1 3,6 ± 0,1 6,7 Maritime pine 10.2 3 ± 1 0,8 ± 0,1 1,2 Eucalyptus 6.5 2 ± 1 0,2 ± 0,1 0,2 1eq. mimosa tannin , 2eq. tannic acid, 3eq. catechine * after 0.45µm glass membrane filtration

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RESULTS: Tannin extraction

OPTIMISATION OF AQUEOUS EXTRACTION

Highest extraction yield (10-15%): Aleppo pine & Douglas firUrea/sulphite

0

2

4

6

8

10

12

14

16

18

20

Spruce Douglas fir Aleppo pine Maritime pine Eucalyptus

Ext

ract

ion

yie

ldt

(g/1

00g

of

dry

bar

k)

WATER+ 2% UREA+2% UREA + 2% SULPHITE+ 2% SULPHITE + 0.5% CARBONATE

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RESULTS : Tannin extraction

OPTIMISATION OF AQUEOUS EXTRACTION

Urea/sulphite extracts : high total phenol contentsHighest phenolic contents : aleppo pine and douglas fir

0

2

4

6

8

10

12

14

16

18

20

spruce douglas f ir aleppo pine maritime pine eucalyptus

To

tal p

hen

olic

tan

nin

- U

V 2

80 n

m(%

o.d

. bar

k)

WATER

+ 2% UREA+2% UREA + 2% SULPHITE

+2% SULPHITE + 0.5% CARBONATE

0

1

2

3

4

5

6

7

8

9

10

spruce douglas f ir aleppo pine maritime pine eucalyptus P

hen

olic

co

nte

nts

(F

C)

(% o

.d. b

ark)

WATER

+2% UREA

+2% UREA + 2% SULPHITE

+2% SULPHITE + 0.5% CARBONATE

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RESULTS: Tannin extraction

OPTIMISATION OF AQUEOUS EXTRACTION OF INDUSTRIAL BARKS

Urea/sulphite in favor of condensed tannins extraction

0

20

40

60

80

100

120

140

160

180

200

spruce douglas fir aleppo pine maritime pine eucalyptus

Co

nd

ense

d t

ann

in i

n t

he

extr

act

(mg

/ml o

f ex

trac

t)

WATER

+2% UREA

+2% UREA + 2% SULPHITE

+2% SULPHITE + 0.5% CARBONATE

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RESULTS: Pyr-GC/MS

Pyr-GC/MS : structural elucidation of tannins

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RESULTS: Pyr-GC/MS

Pyr-GC/MS of a reference sample

condensed tannin structure

fura

nedi

one

dériv

é du

pyr

anon

eB

enzè

ne d

iol

Res

orci

nol

bi-f

uran

Ben

zène

-trio

l

1

2

3

(1) catechol � A ring(2) Resorcinol � B ring (3) pyrogallol� A ring

�Tannin structures :as Catechine et/ou Epicatechine

(catechol B ring and resorcinol A ring) and Epigallocatechine (pyrogallol B ring and resorcinol A ring).

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RESULTS: Pyr-GC/MS

Aleppo pine extracts04-Dec-2008

500 deg 4 s500 deg 4 s 15:52:36Extr H2O Alep 150mcg sur HP1

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC1208_17 Scan EI+

1.09e71.07

1.57

6.37

4.663.07

5.47

12.27

8.72

8.46

7.08

11.10

14.56

12.49

12.58 16.34

16.87

22.7218.23 20.43

met

hyl-p

heno

l

cate

chol

Eth

yl-p

hen

ol M

eth

ylbe

nzè

ne-

diol

phe

nol

Water extract

Phenol A ringCatechol B ring

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RESULTS: Pyr-GC/MS

Aleppo pine extracts04-Dec-2008

500 deg 4 s500 deg 4 s 15:52:36Extr H2O Alep 150mcg sur HP1

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC1208_17 Scan EI+

1.09e71.07

1.57

6.37

4.663.07

5.47

12.27

8.72

8.46

7.08

11.10

14.56

12.49

12.58 16.34

16.87

22.7218.23 20.43

met

hyl-p

heno

l

cate

chol

Eth

yl-p

heno

l Met

hylb

enzè

ne-d

iol

phe

nol

01-Apr-2009500deg 4 s500deg 4 s 15:02:56

Alep extr. HCO3 CPsil 6CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC0904_06 Scan EI+

5.00e61.77

8.13

5.97

4.793.23

10.75

10.16

14.23

11.1416.65

met

hoxy

-phe

nol

cate

chol

Met

hylb

enzè

ne-d

iol

phen

ol

26-Mar-2009500deg 4 s500deg 4 s 11:00:45

Alep eau + uree CPsil 6CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC0903_37 Scan EI+

8.13

1.69

4.413.22

10.75

10.44

14.31

13.3416.65

met

hyl-p

heno

l

cate

chol

Met

hylb

enzè

ne-d

iol

phen

ol

06-Apr-2009500deg 4 s500deg 4 s

Alep extr. Uree + SO3 CPsil 5CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC0904_25

8.13

0.89

1.79

2.90

4.77

10.73

14.23

13.32

16.51

met

hoxy

-phe

nol

cate

chol

Met

hylb

enzè

ne-d

iol

phen

ol

water + sulfite/carbonate

+ urea + urea/sulfite

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RESULTS: Pyr-GC/MS

Douglas fir extracts

water + sulfite/carbonate

+ urea + urea/sulfite

04-D ec-2008500 deg 4 s500 deg 4 s 14:51:13

Extr H2O Doug las 200mcg sur HP 1

5 .00 10.00 15.00 20 .00 25.00 30 .00 35.00 40 .00 45 .000

100

%

PC1208_16 Scan EI+ 1.05

1.16

1.559.10

8.75

6.30

4.652.287.45

11.50

11.10

12.18

18.6214.62 18.03

20.3022.74

met

hoxy

-phe

nol

cate

chol

phen

ol

Ben

zène

-met

hyl-

prop

enyl

Cyc

lohe

xen-

ol-m

ethy

l-m

ethy

leth

ylpr

open

yl

02-Apr-2009500deg 4 s500deg 4 s

Douglas extr. HCO3 CPsil 5CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.000

100

%

PC0904_09

10.73

1.60

8.11

5.915.0110.04

14.14

11.41

16.64

met

hoxy

-phe

nol

cate

chol

phen

ol M

ethy

lben

zène

-dio

l

Ben

zene

-met

hyl-

prop

enyl

27-Mar-2009500deg 4 s500deg 4 s 10:35:45

Douglas + uree CPsil 5CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00Time0

100

%

PC0903_44 Scan EI+

5.00e6

10.73

8.131.60

9.8016.6513.81

met

hoxy

-phe

nol

phen

ol

07-Apr-2009500deg 4 s500deg 4 s

Douglas extr. Uree + SO3 CPsil 5CB

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.000

100

%

PC0904_29

14.3810.73

8.15

0.89

1.88

2.90 6.904.41

13.87

14.53

16.67

20.21

17.46

19.11

20.58

24.19

met

hoxy

-phe

nol

cate

chol

phen

ol

Met

hylb

enzè

ne-d

iol

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RESULTS: Pyr-GC/MS

Summary

condensed tannin structure

In all aqueous extracts, but especially urea+sulfite

Douglas bark tannin ()phenol type A ring (R1 = H)catechol type B ring (R1 = OH) rich

Aleppo pine bark (all aqueous extracts)phenol type A ring (R1 = H)catechol type B ring (R1 = OH) rich

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RESULTS: Adhesives properties

ADHESIVE PROPERTIES (LERMAB)

Water : Euca, spruce, douglas firUrea : Aleppo pineUrea/sulphite : spruce, douglas, aleppo pineSulphite/carbonate : aleppo pine, maritime pine

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RESULTS: Adhesives properties

ADHESIVE PROPERTIES (LERMAB)

Water : Euca, spruce, douglas firUrea : Aleppo pinesUrea/sulphite : spruce, douglas, aleppo pineSulphite/carbonate : aleppo pine, maritime pine

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LARGE SCALE STUDY

LARGE-SCALE EXTRACTION� Large Aqueous Extraction

� 10 kg eq.sec, L/V = 5 L / 1 kg� coarse milled bark + extraction 2% urea + 2% sulphite� agitated thermo-regulated reactor 75°C/1h� centrifugation : tannin extract + extracted barks

� Aleppo pine, spruce and ‘mill blend’ (20% black pine + 20% maritime pine + 30% norway pine + 10% aleppo pine + 15% spuce + 5% douglas fir)� tannin extracts for the preparation of adhesive

formulations and production of wood panels at pilot-scale

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LARGE SCALE STUDY

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LARGE SCALE STUDY: Preliminary results

�Higher amount of extract at large scale>> Lab-scale≥≥≥≥ Acetone/water extraction

?? Quality and Reactivity

2.833%84.7%Mill Blend

2.546%83.5%Aleppo pine

2.827%95.6%Spruce

Preparedextract(kg)

Extract Yield (%)Dryness (%)

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CONCLUSIONS

BARK EXTRACTION : TANNIN UTILISATION in ADHESIVES

� Aqueous extraction are well suitable and easily to up-scaleWater + 2% urea + 2% sulphite

� Softwood species : Spruce, Allepo pine, Douglas firExtraction yield of 10-15%

� An aqueous extraction of softwood barks in pulp mill before heat recovering can be realistically foreseen

� Economical Evaluation � Adhesives 300 $/ T,Tannin extract 600 $/ T� Bark / Heating recovery : 20 €/T

� Tannin recovery =10 % of initial bark � � 1 000 T/y tannin

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ACKNOWLEDGEMENTS

� ADEME financial support (French Environment and EnergyManagement Agency)

� TEMBEC R&D Kraft (now FIBRE EXCELLENCE)

� ENCE-Pontevedra