Two schemes of water extraction of bio-oil were adapted from a method
reported by B. Scholze and D. Meier [10]. The first scheme, shown in Figure 1 as
“Method A”, involved dropping bio-oil into ice-cooled distill water (1000 ml), while
the mixture was continuously stirred by a homogenizer. The desired volume of bio-oil
was added so as to give the water-to-oil ratios of 5:1, 10:1, 15:1 and 20:1 by volume.
The stirring continued after the bio-oil dropping finished. The mixture separated into
water-soluble and water-insoluble fractions (WSF and WIF, or pyrolytic lignin). The
fractions were separated and filtered to remove the water-soluble fraction and water.
The “wet” water-insoluble fraction (wet WIF) was left. Distilled water was then added
to the wet WIF and the mixture was stirred for 4 hours at room temperature and
subsequently dried in a rotary evaporator at 30 °C. The resulted “dry” pyrolytic lignin
was then analyzed. Similarly, the water-soluble fraction was dried at 40 °C. The second