Hemicellulose content

The term alpha cellulose describes that part of cellulose which does not dissolve in 17.5% sodium hydroxide solution. Alpha cellulose can be determined according to Zellcheming Merkblatt IV/29 A. About 3 g (exactly weighed) of the sample (either pulp or holocellulose obtained from the raw material) are put in a porcelain beaker (250 ml), then 25 ml of 17.5% NaOH are added and the sample is left to swell for 4 minutes (time was exactly measured from the last drop), and then pressed with a glass rod for 3 minutes. After pressing, another 25 ml of sodium hydroxide are added and mixed thoroughly till a homogeneous paste is obtained (mixing for about 1 minute). The beaker is then covered and left for 35 minutes at 20°C. 100 ml of distilled water are then added and the material is quickly filtered under suction using a sintered glass funnel. The filtrate is then poured on the paste twice before washing with distilled water. After washing with distilled water till neutrality 100 ml of 10% acetic acid are added dropwise followed by distilled water.

Cellulose

This is calculated as:

Cellulose = 100% – (Hemicellulose + lignin + Ash)

Holocellulose estimation

Holocellulose is the total carbohydrate fraction (cellulose and hemicellulose) of the raw material as was estimated according to Wise et al., 1946.