Research on the determination method of biomass dielectric properties based on mixing rules

Knowledge of the dielectric properties of a given biomass resource is essential for developing microwave-assisted thermochemical conversion of biomass. In this study, a promising strategy was developed to accurately determine the dielectric properties of biomass. The dielectric properties of four types of biomass materials (poplar wood, bamboo, corn straw, and rice straw), their main component model compounds (microcrystalline cellulose, xylan, and organosolv lignin), and starch were determined. The results showed that starch has the highest dielectric constant (4.76 and 4.44, at 915 MHz and 2450 MHz, respectively), and lignin has the lowest dielectric constant (3.18 and 3.09). The dielectric constants of the four biomass materials lie between those of starch and lignin, and their values are positively correlated with their cellulose content. The dielectric loss factors of all these biomass materials were less than 1. This work will provide a new way for measuring the dielectric properties of biomass materials and other porous media materials with complex structures.

Graphical abstract