Monitoring Quality of Soda Black Liquor of Oil Palm Empty Fruit Bunch Fibers in Terms of Storage Time and Temperature

The quality of black liquor from oil palm empty fruit bunch fibers pulping was determined through direct isolation of soda lignin using 10% hydrochloric acid at three pH fractions, i.e. pH 2, pH 4 and pH 6. Destructive methods such as nitrobenzene oxidation and ash contents determination were used in the study. pH 2 was found to be the most preferable fraction due to the highest lignin yield. Nitrobenzene oxidation showed that the predominant compound was vanillin, which was in the range of 44.9-52.1% of the total product. Syringaldehyde was the second major compound (ca. 21.5-30.8%), followed by p-hydroxybenzaldehyde. The moisture and the ash contents of pH 6 fraction were the highest followed by pH 4 fraction and pH 2 fraction, especially at longer storage time. Soda lignin has to be isolated in less than 15 days of storage regardless of storage temperature to prevent high rate of biodegradation activities.