Concerning the effect of temperature, ash removal increased
significantly from 21% at room temperature to 43% at 50 C. This is
also in agreement with the work of other groups who observed that
an increase in washing temperature was beneficial for the removal
of inorganics from biomass [15,19]. Pattiya et al. [21] also observed
increased ash removal at higher temperatures, for washing duration
longer than 12 h. It is likely that the increased temperature
facilitates the removal of inorganics by increasing their solubility in
the washing medium and/or by allowing the removal of inorganics
that are more strongly bound to the biomass matrix. In addition,
hot water may open up the biomass structure, allowing the
washing medium to penetrate deeper within the biomass particles
and remove inorganic matter; Nitsos et al. [26] reported a small
increase in the specific surface area of beech wood after washing
with water at 80 C for 80 min.