The polysaccharide degradation products were obtained by precipitation of the corresponding neutralized black liquors with 3 vols of 95% ethanol, respectively. After evaporation of the ethanol, the lignin fractions were reprecipitated from the corresponding supernatants of the black liquor by acidification to pH 2.0, adjusted with 9.68 N H2SO4, respectively.
The precipitated lignins were thoroughly washed with acidified water (pH 2.0) to remove co-precipitated ash and silicon. After being dried in air, the lignin fractions were extracted with pentane in a Soxhlet apparatus for 6 h to remove lipophilic non-lignin matters such as wax and lipids and finally air-dried (Fig. 1).