Preparation and characterization of xylan by an efficient approach with mechanical pretreatments

Abstract

Corn stalks, as an agricultural biomass resource, were generally burned or discarded, which not only leads to environmental pollution but also a waste of resources. To study the high-value use of resources, the extraction of xylan from corn stalks was carried out in this investigation. First, mechanical pretreatment was developed to change the internal structure of raw materials. And then the alkali-extractable xylan was isolated by a P-E method (adjusting the pH of the hydrolysate to separate lignin first, and then add ethanol to precipitate xylan). From the SEM, XRD, and sugar analysis, it was shown that the pretreatment materials with a more obvious displacement of fiber and lower crystallinity were easier to be hydrolyzed. And over 85 % xylan and about 80 % lignin could be removed from corn stalks under a lower alkali concentration. Besides, the yield of xylan increased from 45.80 % to 80.60 % by different mechanical pretreatment means. The structural properties of xylan were characterized by Ion Chromatography, FT-IR, thermo-gravimetric analysis, molecular weights, and NMR. Results proved that xylan had a backbone of d-xylp with a β-(1→4)-linkage attached with α-l-Araf and 4-O-Me-α-d-GlcpA. This work introduced a physic-chemical xylan extraction route from corn stalks, which is promising in the biorefinery process.