Hot water extraction of hemicelluloses from inner and outer bark of ...
Hot water extraction of hemicelluloses from inner and outer bark of ...
Hot water extraction of hemicelluloses from inner and outer bark of ...
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<strong>Hot</strong> <strong>water</strong> <strong>extraction</strong> <strong>of</strong> <strong>inner</strong> <strong>and</strong> <strong>outer</strong><br />
<strong>bark</strong> <strong>of</strong> Norway Spruce (Picea abies)<br />
Jens Krogell<br />
COST FP0901 meeting<br />
21.08.2010<br />
1
Spruce <strong>bark</strong><br />
• Inner <strong>bark</strong> (~90 vol-%) <strong>and</strong><br />
<strong>outer</strong> <strong>bark</strong> (~10 vol-%)<br />
• Huge valuable side stream<br />
in wood industry<br />
• Chemical composition not<br />
completely known, differs<br />
<strong>from</strong> wood<br />
• Known composition <strong>of</strong><br />
<strong>bark</strong> → better utilisation<br />
2
Accelerated Solvent Extraction (ASE)<br />
• Automated <strong>extraction</strong><br />
with different times<br />
<strong>and</strong> pressures<br />
• Sequential <strong>extraction</strong>s<br />
with different solvents<br />
possible<br />
3
Hexane (90°C)<br />
Acetone/Water<br />
(100°C)<br />
Extraction scheme<br />
Water<br />
(100, 160 °C)<br />
Spruce <strong>bark</strong><br />
Pre-extracted<br />
<strong>bark</strong><br />
Bark residue<br />
Cellulose<br />
Extractives<br />
Monomeric sugars<br />
Hemicelluloses<br />
Monomeric sugars<br />
Tannins?<br />
Lignin<br />
4
Totally dissolved solids (TDS)<br />
mg/g <strong>bark</strong><br />
Gravimetrically determined<br />
700<br />
600<br />
500<br />
400<br />
300<br />
200<br />
100<br />
<strong>Hot</strong> <strong>water</strong> extract<br />
components<br />
(100+160°C)<br />
Hydrophilics<br />
Lipophilics<br />
0<br />
Inner <strong>bark</strong><br />
Outer <strong>bark</strong><br />
5
Hexane (90°C)<br />
Acetone/Water (100°C)<br />
Water<br />
(100, 160°C)<br />
Spruce <strong>bark</strong><br />
Pre-extracted<br />
<strong>bark</strong><br />
Bark residue<br />
Cellulose<br />
Extractives<br />
Hemicelluloses<br />
Lignin<br />
Acid<br />
hydrolysis<br />
Monomeric sugars<br />
HP-SEC<br />
Monomeric sugars<br />
Acid methanolysis<br />
“Klason-lignin”<br />
determination<br />
GC<br />
GC<br />
GC<br />
TMAH-GC-MS<br />
6
Extractives<br />
• Lipophilic <strong>and</strong> hydrophilic compounds extracted<br />
with hexane <strong>and</strong> acetone/<strong>water</strong><br />
• GC results gives both quantitative <strong>and</strong> qualitative<br />
results<br />
• Long or short column GC<br />
7
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
Lipophilics<br />
8<br />
Diglycerides<br />
Triglycerides<br />
Steryl esters<br />
Fatty acids<br />
Resin acids<br />
Sterols<br />
Diterpenoids<br />
Aliphatic alcohols<br />
mg/g<br />
Inner <strong>bark</strong><br />
Long column<br />
Outer <strong>bark</strong><br />
Short column
mg/g<br />
Long column<br />
Hydrophilics<br />
120<br />
100<br />
80<br />
60<br />
Inner <strong>bark</strong><br />
Outer <strong>bark</strong><br />
40<br />
Short column<br />
20<br />
0<br />
9<br />
Flavonoids<br />
Stilbenes<br />
Sugar monomers<br />
Steryl esters*<br />
Stilbene glucosides<br />
Triglycerides*<br />
* Components that eluates at the same time as steryl esters <strong>and</strong> triglycerides
Hemicelluloses <strong>and</strong> monomers<br />
• Mild depolymerization <strong>of</strong> <strong>hemicelluloses</strong><br />
• Adding 2 M HCl in methanol to freeze-dried sample <strong>and</strong> in 105 °C for 3<br />
hours cleaves <strong>hemicelluloses</strong> but not cellulose<br />
• Samples are further silylated with HMDS <strong>and</strong> TMCS<br />
• Good method for uronic acids determination (mild conditions)<br />
• Gives hemicellulose content in monomeric form<br />
• Methanolysis can be done on both solid <strong>and</strong> liquid samples<br />
• Monomers determined after direct silylation<br />
10
Chromatogram <strong>of</strong> sugar units in <strong>bark</strong> extract<br />
Inner <strong>bark</strong>, 160°C<br />
Std<br />
Ara<br />
Glc<br />
Man<br />
Gal<br />
Xyl<br />
Rha<br />
GalA<br />
11
mg/ <strong>bark</strong><br />
Bark <strong>water</strong> extract<br />
Inner <strong>bark</strong> 160 °C, 60 min<br />
80<br />
70<br />
60<br />
Total <strong>hemicelluloses</strong> ~150 mg/g <strong>bark</strong><br />
Total extracts<br />
~400 mg/g <strong>bark</strong><br />
50<br />
40<br />
Hemicelluloses <strong>and</strong> pectins<br />
30<br />
20<br />
Monomers<br />
10<br />
0<br />
Ara Xyl 4-O-<br />
MeGlcA<br />
GlcA Gal Man Glc Rha GalA<br />
12
Cellulose<br />
• Two step acid hydrolysis<br />
• 72 % sulfuric acid, 2 hours, room temp<br />
• Dilute with <strong>water</strong>, over night, autoclave 125°C<br />
90 min<br />
• Cleaves cellulose to glucose → cellulose<br />
content in sample<br />
13
“Klason-lignin”<br />
• Improved Klason-lignin method (gravimetrically)<br />
+ TMAH*-GC-MS<br />
• Py-TMAH-GC-MS milder conditions than py-GC-MS<br />
• Not all “Klason-lignin” is lignin, lot <strong>of</strong> long<br />
chained fatty acids probably originated <strong>from</strong><br />
suberin<br />
• 32% in <strong>inner</strong> <strong>bark</strong>, 45% in <strong>outer</strong> <strong>bark</strong><br />
* tetramethylammonium hydroxide<br />
Ref: Scwanninger, M., Hinterstoisser, B., 2002, Klason Lignin: Modifications to Improve the Precision <strong>of</strong> the St<strong>and</strong>ardized Determination,<br />
Holzforshung 56 161-166<br />
14
TMAH-GC-MS chromatogram<br />
Reference<br />
(lignin sample)<br />
Unextracted<br />
<strong>outer</strong> <strong>bark</strong><br />
15<br />
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27<br />
min
Metals by ICP-MS<br />
• Gives a detailed picture <strong>of</strong> the amount <strong>of</strong> inorganic elements in the<br />
<strong>bark</strong><br />
mg/kg <strong>bark</strong><br />
14000<br />
12000<br />
10000<br />
250<br />
200<br />
150<br />
100<br />
50<br />
250-10 mg/kg<br />
5<br />
4<br />
3<br />
2<br />
1<br />
< 10 mg/kg<br />
8000<br />
0<br />
Zn Al Na B Fe<br />
0<br />
Pb Mo Cu Ni Cr Cd<br />
6000<br />
4000<br />
Inner <strong>bark</strong><br />
Outer <strong>bark</strong><br />
2000<br />
0<br />
Ca K Mg Mn P S Zn Al Na B Fe Pb Mo Cu Ni Cr Cd<br />
16
Inner <strong>bark</strong><br />
Outer <strong>bark</strong><br />
Lipophilics<br />
Hydrophilics<br />
Lipophilics<br />
Hydrophilics<br />
Monosaccharides<br />
"Klason-lignin"<br />
Monosaccharides<br />
Polysaccharides,<br />
extractable<br />
(160 C, 60 min)<br />
Polysaccharides<br />
nonextractable<br />
Cellulose<br />
Polysaccharides,<br />
nonextractable<br />
Polysaccharides,<br />
extractable<br />
(160 °C, 60 min)<br />
"Klason-lignin"<br />
Cellulose<br />
Silylation + GC<br />
Methanolysis + silylation + GC<br />
Hydrolysis + silylation + GC<br />
Klason method + TMAH-GC-MS<br />
17
Conclusions<br />
• 15% <strong>of</strong> total weight <strong>of</strong> <strong>bark</strong> is extractable<br />
<strong>hemicelluloses</strong> <strong>and</strong> pectins<br />
• 91 % <strong>of</strong> dried <strong>inner</strong> <strong>bark</strong> characterized<br />
• 86 % <strong>of</strong> dried <strong>outer</strong> <strong>bark</strong> characterized<br />
• Important to get as much knowledge as possible<br />
<strong>of</strong> <strong>bark</strong> (valuable side chain)<br />
We need good <strong>extraction</strong> <strong>and</strong> analytical methods<br />
18
The future…<br />
• Purify the <strong>bark</strong> <strong>hemicelluloses</strong> (arabinans?)<br />
• Improve the <strong>extraction</strong><br />
• More work needed on industrial <strong>bark</strong><br />
• Develop existing <strong>and</strong> new analytical methods<br />
19
Applications<br />
• Platform chemicals<br />
• Animal feed<br />
• Specialty sugars<br />
• Bioethanol?<br />
20
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