초록
<P><B>Abstract</B></P> <P>Paperboard mill sludge (PMS) composed of cellulose, hemicellulose, lignin and ash contents of 36.72±2.81, 32.91±1.75, 22.89±0.56, and 7.48±0.39%, respectively. Enzymatic hydrolysis process followed by fermentation of native PMS provided an ethanol yield of 0.36±0.01g/L which equivalent to net gain energy of −0.84±0.03kJ/g<SUB>PMS</SUB>. Choline acetate ionic liquid [Cho][OAc] IL was extensively used as a solvent for PMS to upgrade the performance. Pretreatment with [Cho][OAc] IL/PMS ratio of 10% (w/w) for 1.0h, at a temperature of 120°C exhibited hemicellulose and lignin removal efficiency of 5.05±0.52 and 14.71±1.22%, respectively with 89.19±5.62% cellulose recovery. This corresponded to net gain energy of 0.60±0.04kJ/g<SUB>PMS</SUB> based on ethanol yield from enzymatic saccharification process which was quite low due to a limited hemicellulose removal and glucose yield of 24.1±1.4g/L. [Cho][OAc] IL/PMS ratio of 10% (w/w) supplemented with 1% (v/v) HCl substantially improved the removal efficiency of hemicellulose (36.38±4.51%), lignin (17.42±1.19%) and cellulose (82.17±4.28%) which provided the maximum net energy of 5.36±0.30kJ/g<SUB>PMS</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Total reducing sugar concentration depends on [ChO][OAc] ionic liquid to biomass ratio. </LI> <LI> Acid-catalyzed ionic liquid significantly enhance pretreatment process. </LI> <LI> Prolonged pretreatment duration degraded sugars into furans compounds. </LI> <LI> Maximum net energy of 5.36±0.30kJ/g<SUB>PMS</SUB> obtained by using acid catalyst IL. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>