posted on 2017-05-17, 00:00authored byZhanying Zhang, William O. S. Doherty, Ian M. O’Hara
In
this study, salt-induced phase separation was integrated with n-propanol-based pretreatment for clean fractionation of
sugar cane bagasse. First, biomass solid residue and pretreatment
hydrolysate were separated by filtration following pretreatment. Lignins
with high molecular weights (HMWs) were separated through precipitation
and filtration after diluting hydrolysate with water. The filtrate
was added with (NH4)2SO4 at a saturated
concentration, which induced the formation of a biphasic solution:
the top layer was n-propanol phase containing sugar
degradation products and lignins with low molecular weights (LMWs);
the bottom layer was aqueous phase, rich in salt and soluble sugars.
The solvent phase was directly reused for pretreatment, while the
aqueous phase was distilled to recycle both salt and water. Direct
recycling solvent phase for pretreatment four times only led to a
slight decrease in glucan digestibility from 100% (fresh solvent)
to 96%. Direct reuse of solvent phase also led to a significant increase
in furfural concentration from 2.4 g/kg to 15.1 g/kg, while recycling
water and salt in aqueous phase by distillation led to a substantial
increase in xylose concentration from 3.2 g/kg to 13.5 g/kg after
five batches of pretreatments. In addition, the total yield of HMW
lignins increased gradually from 38% to 49%.