Rc. Sun et al., Extraction and characterization of hemicelluloses and cellulose from oil palm trunk and empty fruit bunch fibres, J WOOD CH T, 19(1-2), 1999, pp. 167-185
The cell walls of oil palm trunk fibre and empty fruit bunch (EFB) fibre we
re initially extracted with 5% NaOH at boiling for 2 h, which removed 17.3%
and 15.2% hemicelluloses, respectively. Further extraction of the delignif
ied palm trunk and EFB fibre was conducted with 10% NaOH at 20 degrees C fo
r 16 h and 24% KOH-2% H3BO3 at 20 degrees C for 2 h This resulted in the re
lease of 11.9%, 13.5%, 12.7% and 14.9% residual hemicelluloses, respectivel
y. The cellulose content, isolated by 24% KOH-2% H3BO3 from the two fibre s
amples, was found to be 41.3-41.7%, most of which was relatively free of as
sociated lignin and hemicelluloses. The hemicelluloses, extracted with 5% N
aOH from the lignified palm trunk fibre and EFB fibre, contained relatively
high amounts of xylose, and minor arabinose and rhamnose than the hemicell
uloses, extracted with 10% NaOH and 24% KOH-2% H3BO3 from the delignified f
ibres. While the hemicelluloses, extracted with 10% NaOH and 24% KOH-2% H3B
O3 from the delignified palm trunk and EFB fibre, contained slightly more g
alactose, glucose, and mannose than the hemicelluloses, extracted with 5% N
aOH from the lignified fibres. Further studies implied that the hemicellulo
ses, extracted with 5% NaOH from the lignified fibres, were more linear and
acidic and had a large molecular size (weight-average, 17,400-22,900), tog
ether with comparatively high associated lignins (12.0-15.7%). Which were f
ound to be linked to hemicelluloses mainly via syringyl unit. On the other
hand, the hemicelluloses, extracted with 10% NaOH and 24% KOH-2% H3BO3 from
the delignified fibres, were more branched but less acidic and had a compa
ratively small molecular size (weight-average, 6,600-10,300), together with
trace amounts of associated lignin (0.3-1.1%). The hemicelluloses in the c
ell walls of palm EFB had a higher degree of polymerizaton than the hemicel
luloses in the bell walls of palm trunk fibre as indicated by the molecular
-average weights, ranging from 7,200 to 22,900, and from 6,600 to 17,400, r
espectively.