A novel cleaning process for industrial production of xylose in pilot scale from corncob by using screw-steam-explosive extruder.

Abstract

Steam explosion is the most promising technology to replace conventional acid hydrolysis of lignocellulose for biomass pretreatment. In this paper, a new screw-steam-explosive extruder was designed and explored for xylose production and lignocellulose biorefinery at the pilot scale. We investigated the effect of different chemicals on xylose yield in the screw-steam-explosive extrusion process, and the xylose production process was optimized as followings: After pre-impregnation with sulfuric acid at 80°C for 3h, corncob was treated at 1.55MPa with 9mg sulfuric acid/g dry corncob (DC) for 5.5min, followed by countercurrent extraction (3 recycles), decoloration (activated carbon dosage 0.07g/g sugar, 75°C for 40min), and ion exchange (2 batches). Using this process, 3.575kg of crystal xylose was produced from 22kg corncob, almost 90% of hemicellulose was released as monomeric sugar, and only a small amount of by-products was released (formic acid, acetic acid, fural, 5-hydroxymethylfurfural, and phenolic compounds were 0.17, 1.14, 0.53, 0.19, and 1.75g/100g DC, respectively). All results indicated that the screw-steam-explosive extrusion provides a more effective way to convert hemicellulose into xylose and could be an alternative method to traditional sulfuric acid hydrolysis process for lignocellulose biorefinery.