Abstract
Low-liquid aqueous ammonia (LLAA) pretreatment using aqueous ammonia was investigated to enhance enzymatic saccharification of corn stover. In this method, ground corn stover was simply contacted with aqueous ammonia mist (ammoniation step), followed by pretreatment at elevated temperature (90–150 °C) for an extended period (24–120 h) at different solid/liquid (S/L) ratios (0.29, 0.47 or 0.67), termed a pretreatment step. After that, excess (unreacted) ammonia was removed by evaporation, and the pretreated material was immediately saccharified by an enzyme without a washing step. The effects of key reaction parameters on both glucan digestibility and XMG digestibility were evaluated by analysis of variance (ANOVA). Under the best pretreatment conditions [S/L = 0.47, 0.16 (g NH3)/(g biomass), 90 °C, 24 h], LLAA pretreatment enhanced enzymatic digestibility from 23.1% for glucan and 11.3% for XMG (xylan + galactan + mannan) of untreated corn stover to 91.8% for glucan and 72.6% for XMG in pretreated solid.
Highlights
Limited supplies of fossil resources, climate change due to carbon dioxide accumulation in the atmosphere, and increased demand for fuels and chemicals have triggered an increase in utilization of diverse renewable feedstock
Cellulosic fuel ethanol, a second-generation biofuel, has the potential to solve several problems, including limited feedstock availability and food competition with fuel, that are currently associated with first-generation biofuels such as fuel ethanol from corn starch or sugarcane [1]
It was assumed that increasing the ammonia loading caused the breakdown of ester bonds in hemicellulose and lignin polymers at the elevated temperature; this situation can improve the enzymatic hydrolysis of hemicellulose (XMG)
Summary
Limited supplies of fossil resources, climate change due to carbon dioxide accumulation in the atmosphere, and increased demand for fuels and chemicals have triggered an increase in utilization of diverse renewable feedstock. In recent years has focused on the of effective pretreatment to make the lignocellulosic available for ethanol conversion. A washing acidisand alkali pretreatment methods removal of the remaining the step typically required in both acid for andthe alkali pretreatment methodschemical for the reagents removal from of the chemically treated biomass, thethe recovery and reuse of water andand chemicals significantly affectof the remaining chemical reagents and from chemically treated biomass, the recovery and reuse total and energy cost of significantly the biomass conversion process. InIn our present study, such problemsassociated associatedwith witha process a processusing using gaseous ammonia This pretreatment method consists such problems gaseous ammonia. Water).aqueous ammonia easy handle, requires low aqueous ammonia is is easy toto handle, making this method a more industrially adoptable process upcoming biomass-processing facility.
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