Biysk, Barkaul, Russian Federation
We carry out the preliminary processing of oat husk biomass by autohydrolysis. There was a change in the process temperature in the range of 160-220 °C, the processing time in the range of 5-60 minutes and the treatment hydromodule 1:10. To characterize the pre-treatment conditions, we use the autohydrolysis severity factor, which varied from 2.50 to 5.37. We assessed the effectiveness of the autohydrolysis performed by changing the chemical composition of the solid phase of the treated oat husk. The auto-hydrolysis of oat husk biomass with increasing hardness of the treatment conditions leads to a significant decline of hemicelluloses in the solid phase when the severity factor reaches 4.17 at the first stage and to a subsequent almost complete removal. Also, at the first stage, there is a slight change in the concentration of lignin and an increase in the proportion of cellulose in the solid fraction. A further increase in the severity of the conditions at the second stage with a change in the severity factor from 4.7 to 5.37 leads to the accumulation of lignin in the solid residue up to a maximum value of 45.7% as a result of the lignin condensation reaction. Due to the increase in the lignin content, the proportion of cellulose in the solid fraction decreases. The authors assessed the effectiveness of the pretreatment by the final accumulation of reducing substances obtained as a result of enzymatic hydrolysis using an enzyme complex consisting of the preparations "Cellolux-A" and "Bruzime BGX. At the first stage, with a decrease in the concentration of hemicelluloses, the availability of cellulose for enzymes significantly increases and the yield of reducing substances reaches a maximum value of 66.7% with a severity factor of autohydrolysis of 4.17. At the second stage, an increase of the severity of the processing conditions to a value of a factor of 5.37 leads to the accumulation of lignin in the fixed residue, which limits the effect of enzymes. It reduced the yield of substances during enzymatic hydrolysis to 30.0%.
oat husk, pretreatment, auto-hydrolysis, hydrothermal treatment, cellulose, enzymatic hydrolysis
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