Moisture Sorption Isotherm of Herbaceous and Agricultural Biomass

Abstract

The moisture sorption isotherm (MSI) is very useful for biomass drying and storage. In the present work, measured MSI data of herbaceous and agricultural biomass (HAB) were collected from the literature. The adsorption or desorption isotherms at the same temperatures (15, 20, 25, 30, 35, and 40 °C for adsorption and 20, 25, 30, and 35 °C for desorption) were compared, separately, to demonstrate the similarity, evaluate the difference in the MSI among HABs, and explore the feasibility of applying the similarity for MSI prediction. It was observed that the MSIs of HABs at the same temperature are similar, with most measurements falling within a range of ±20% from an average given by a Guggenheim, Anderson, and de Boer (GAB) model. The chemical composition and distinct sorption behaviors of the biomass components were identified as the major factors determining the similarity and defining the variation in the MSIs of HABs. Factors associated with the measurement, including the temperature of drying for sample preparation and uncertainty related to sample heterogeneity, may cause the variation of the MSI comparable to the range of ±20%. Considering the similarities among HABs, using the average to estimate the MSI of an unknown HAB has a relative error of < ±20%. Estimating the MSI based on the chemical composition and isotherms of the major components (cellulose, lignin, and hemicelluloses as well as the extractives) can achieve the same accuracy. Both may be acceptable for practical applications. Additionally, it was found from the comparison that HABs, on average, have evidently higher MSIs than wood species mainly as a result of their higher contents of hemicellulose and the extractives.

Review on Self-Heating of Biomass Materials: Understanding and Description

“…The determined DHS values in both desorption and adsorption seem to be biomass type-dependent although similarities were often reported for different species . The DHS values of herbaceous biomass are higher than those of most woody biomass particularly at low moisture contents (Figure b) probably because herbaceous biomass generally has higher moisture sorption capacity than woody biomass . However, some woody materials, that is, wood pellets and Babinga wood, have relatively higher DHS values, implying the complexity of the material–water interaction behavior.…”

“…The biomass type-dependence may be ascribed mainly to the difference in moisture sorption behavior between different materials, which depends significantly upon biomass composition and the sorption characteristics of the components . Moreover, the variations among various materials may be partially attributed to the determination method and associated measurement uncertainties, as highlighted by Leuk et al and Nopens et al…”

“…Nonetheless, using an empirical function to estimate the DHS values in desorption may still be plausible for most woody materials. In contrast, it may not be possible for herbaceous biomass (Figure b) because of their higher variations in the material–water interaction behavior . Considering the high variations in the DHS when the moisture content is less than 15–20%, the material dependence should be considered for relatively dry materials to avoid the error in calculating heat evolution of water exchange.…”

Torrefaction of Agricultural and Wood Waste: Comparative Analysis of Selected Fuel Characteristics

“…For example, the calculated M 0 values are 4.84% and 3.68% for raw and torrefied BS at 300 • C. This could be attributed to the increased cellulose crystallinity during torrefaction. According to Yao et al, [32], the monolayer moisture content decreases with increasing cellulose crystallinity.…”

Virtual Special Issue of 7th Sino-Australian Symposium on Advanced Coal and Biomass Utilisation Technologies

“…Jabeen et al (10.1021/acs.energyfuels.9b03156) develop an analytical procedure for the proximate analysis of algal biomass. Yao et al (10.1021/acs.energyfuels.9b02971) examine the moisture sorption isotherms of herbaceous and agricultural biomass, which are useful for operating biomass logistic processes (e.g., drying and storage). Kudo et al (10.1021/acs.energyfuels.9b02939) improve the pelletability of woody biomass by a combination of pressurized steam torrefaction and pelletization.…”