Physicochemical properties of corn stalk after treatment using steam explosion coupled with acid or alkali.

The aim of this study was to evaluate comparatively the effects of different pretreatments including steam explosion, acid, and alkali, alone or in combination, on the structural properties and thermal stability of corn stalk. All of the treated treatments decreased the contents of hemicellulose and lignin and thereby increased the content of cellulose in corn stalks. But the combined treatments with alkali and steam explosion under 0.4-0.6 MPa were better as compared with other treatments based on the removals of hemicellulose and lignin, and about 71.58-79.59% of hemicellulose and 64.32-71.83% of lignin were removed. Treatment with steam explosion coupled with acid or alkali changed the bonding distribution and surface morphology and increased the crystallinity and thermal stability of corn stalks, and the degradation temperature reached over 350 °C. These results suggest that steam explosion coupled with alkali is a better method for the depolymerization of corn stalk polymer.