Enhanced enzymatic hydrolysis of corncob by ultrasound-assisted soaking in aqueous ammonia pretreatment
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Ultrasound-assisted soaking in aqueous ammonia (USAA) pretreatment with 15 wt% aqueous ammonia under low temperature (~ 60 °C) and short-time (< 12 min) low-frequency (20 kHz, 60–650 W) ultrasound has been investigated for enhancement of enzymatic hydrolysis of corncob. Operational parameters of energy density (2.93–17.07 W/mL) and sonication time (0.34–11.66 min) that affect cellulose recovery, delignification, and sugar recovery yield were studied and optimized. The maximum cellulose recovery, delignification and sugar recovery yield determined at the optimum conditions (energy density 10 W/mL, sonication time 11.66 min) were 83.8, 84.7, and 77.6%, respectively. The corncob pretreated using USAA has a lower hemicellulose content (28.9% vs 31.8%), a slightly lower crystallinity index value (42.7% vs 43.7%), and a larger surface cavity diameter (> 36 μm vs < 20 μm) than that pretreated using soaking in aqueous ammonia (SAA) pretreatment. The USAA pretreatment was proved to be a reliable and effective method for corncob pretreatment.
KeywordsCorncob Ultrasound Enzymatic hydrolysis SAA USAA
This research was supported by the Research Project of Chongqing Education Commission (No. KJ1500632), Chongqing Technology and Business University (No. 1556035 and 20145601), and the Natural Science Foundation of China (No. 21776212).
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Conflict of interests
The authors declare that they have no conflict of interests.
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