ALKALI EXTRACTION OF HEMICELLULOSE FROM DEPITHED CORN STOVER AND EFFECTS ON SODA-AQ PULPING

Heli Cheng, Huaiyu Zhan, Shiyu Fu, Lucian A. Lucia

Abstract


A biorefinery using the process of hemicellulose pre-extraction and subsequent pulping provides a promising way for the utilization of straw biomass and resolution of problems related to silicon. In this work, hemicellulose was extracted from depithed corn stover with sodium hydroxide solution before soda-AQ pulping. Components of the extracts were quantified by ion chromatography. The parameters (alkali concentration and temperature) affecting hemicellulose pre-extraction were optimized. The main constituent of hemicellulose in corn stover was xylan, which accounted for 18.1% of the depithed raw material. More than 90% of the xylan can be extracted under the optimal conditions: NaOH concentration of 10%, temperature of 75ºC, and time of 2h. Solid fractions after extraction were subjected to soda-AQ pulping. In comparison with control pulp obtained without extraction, it was found that alkali pre-extraction could improve the brightness and decrease kappa number of the subsequent pulp, causing a slight loss of yield, viscosity, density, and burst strength, but an obvious improvement of tear strength. Moreover, the silicon content was decreased by 79.8% when the extraction conditions were set at 75 ºC with alkali concentration of 8%, suggesting that pre-extraction of hemicellulose is a potential way to solve silicon problems associated with alkaline pulping of stover.

Keywords


Corn stover; Alkali pre-extraction; Hemicellulose; Silica removal; Soda-AQ pulping

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Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucian.lucia@gmail.com URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126