deposition of gums may also occur with time, primarily because of polymerization,
condensation, esterification, and etherification. This feature distinguishes
bio-oil from mineral oils, the properties of which do not change with time.
Bio-oil is not soluble in water, although it contains a substantial amount
of water. However, it is miscible in polar solvents, such as methanol and
acetone, but immiscible with petroleum-derived oils. Bio-oil can accept
water up to a maximum limit of 50% (total moisture). Any more water results
in phase separation. Table 9.3 shows that bio-oil has a heating value nearly
half that of conventional liquid fuels but has comparable flash and pour
points.