Research on the water absorption diffusion model and kinetics of pretreated straw

To study the water absorption characteristics of corn, rice, and wheat straw after thermal pretreatment (120 ~ 200 °C). This work introduces an internal particle diffusion model for the moisture adsorption mechanism and measures the water contact angle to assess hydrophobicity, establishing a linear relationship between the water absorption kinetic parameters and temperature. The results show that when the temperature rises to 200 °C, the hygroscopicity reduction extent of corn straw, rice straw and wheat straw are 58.45%, 28.32% and 12.12%, respectively, significant increase in hydrophobicity. The three-stage internal particle diffusion equation can effectively describe the adsorption process of straw to moisture. At 70% humidity, the diffusion rate constant decreased and the boundary layer thickness increased. The ASABE equation can accurately predict the moisture content of corn straw; the water absorption process of rice and wheat straw conforms to the Peleg equation, which is significant for the subsequent large-scale high-quality utilization of straw.