Journal of Oil Palm Research Vol. 14 No 1  2002 June p.  9-14

Preparation of cellulose from oil palm empty fruit bunches via ethanol digestion: effect of acid and alkali catalysts

Author(s): ASTIMAR Abdul Aziz* ; MOHAMAD Husin*, Dr ; ANIS Mokhtar*

Ethanol digestion of oil palm empty fruit bunches (OPEFB) fibres at a temperature between 165ºC – 180ºC for 2 hr and at a solid-to-liquid ratio of 10:1, ethanol-to-water ratio of 1:1, and with or without 10% 1N HCl and 1.25 M NaOH as catalysts was studied in order to prepare cellulose via ethanol pulping. The pulp produced was studied for yield, moisture content, solubility in cold/hot water and 1% NaOH, lignin, holocellulose and α-cellulose content.
The highest yield of pulp (57%, oven dried weight basis) was from OPEFB fibres digested at 170ºC for 2 hr without addition of catalyst, whereas OPEFB fibres digested at 175ºC for 2 hr with acid catalyst gave the lowest yield of 45% (oven dried weight basis) pulp. Higher cooking temperature gave lower yield of pulp since the reaction hydrolyzed out the hemicellulose, lignin and part of the cellulose. The reactions at 165ºC, 170ºC and 175ºC with acid catalyst produced 56%, 50% and 45% of pulp yield, respectively. It was found that a temperature of 180ºC with or without catalyst was too high for pulping because it totally digested the fibre into a viscous soluble pulp.
On the effect of catalysts, acid catalyst was found to enhance the pulping of OPEFB fibres. Without the acid catalyst, at temperature of 165ºC, the fibres could not be fully cooked and would still be in the fibrous form. Reactions at 170ºC and 175ºC without catalyst gave 57% and 55% yield of pulp, respectively whereas with acid catalyst gave 50% and 45% yield of pulp respectively. The base catalyst could only fully pulp the OPEFB fibres at a temperature of 175ºC, but the fibres dissolved at temperature 180ºC.
Pulp produced at 175ºC for 2 hr with 10% 1.25 M NaOH gave the best quality pulp, which contained lowest lignin and highest holocellulose at 8.2% and 91.8% (based on the dry weight of pulp), resp ectively. The maximum yield of α-cellulose (isolated from the pulp) also was obtained from OPEFB digested with alkali catalyst at 175 ºC for 2 hr (64.3% based from dry weight of pulp; 34.1% based on dry weight of OPEFB).

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Author Information
* Malaysian Palm Oil Board, P.O. Box 10620, 50720 Kuala Lumpur, Malaysia.

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