Characteristic modification of alkalized corn stalk and contribution to the bonding mechanism of fuel briquette

In this paper, corn stalk was alkalized by gradient concentrations of sodium hydroxide and briquetted with anthracite coal. The bonding mechanism was explored by a combined analysis of physicochemical, microstructure and mechanical properties. Alkaline treatment had a large effect on decomposing most of lignin and dissolving the carbohydrates in corn stalk even at a low concentration of 1%. With the increase in alkaline concentration (for 1%–2%), the degree of decomposition of hemicellulose and amorphous cellulose increased gradually. When the concentration of alkaline reagent was higher than 3%, more than 40% of hemicellulose was degraded. A complete surface structure of a spatial network was achieved when corn stalk was treated by 2% alkaline, which mainly contributed to the bonding performance of compound briquette. Under this condition, the ratio of cellulose to hemicellulose to lignin was approximately 7.0:2.5:0.5, and it also exhibited a good pyrolysis performance for energy conversion.