Moisture content is an important feedstock quality in converting it into energy through biochemical or thermochemical platforms. Knowledge of moisture sorption relationship is useful in drying and storage to preserve the quality of feedstocks. Moisture sorption isotherms for potential feedstocks such as corn stover and big bluestem are missing. EMC values of corn stover and big bluestem were determined using static gravimetric technique with saturated salt solutions (ERH 0.12–0.89) at different temperatures (20, 30, and 40°C). Depending upon the ERH values, EMC values were ranged from 8.0 to 19.6 and 8.8 to 19.2% db for corn stover and big bluestem, respectively, and they followed typical type II isotherm found in food materials. Nonlinear regression was used to fit five commonly used three-parameter isotherm models (i.e., modified Oswin model, modified Halsey model, modified Chung-Pfost model, modified Henderson model, and the modified Guggenheim-Anderson-de Boer (GAB) model) to the experimental data. Modified Halsey emerged as the best model with high -statistic and values with low and and fairly random scattered residual plot for corn stover and big bluestem. These models can be used to predict the equilibrium moisture content of these feedstocks starting from harvesting, drying, preprocessing, transportation, storage, and conversion. 1. Introduction The search for a renewable fuel resource has become a global priority due to obvious reasons such as declining fossil fuel resources and economic and environmental concerns. According to Demirbas [1], lignocellulosic biomass appears to be an attractive feedstock due to its renewability, positive environmental impacts resulting in no net release of carbon dioxide, and very low sulfur content, and they are cheap (compared to corn/sugarcane) and abundant [2]. Corn stover is considered as one of the potential feedstock and most studied materials towards biofuel too. Perlack et al. [3] estimated that approximately 256 million dry tons of corn stover will be available for conversion into fuel in the year 2030 due to collection technologies improvement and a steady yield increase. Several studies have shown that big bluestem has a great potential as a feedstock in the biofuel arena harvest years [4–6]. Moreover, the United States Department of Energy has also listed big bluestem as one of the herbaceous energy crops. Based on the previous facts, corn stover and big bluestem were selected for this study. Moisture content is an important attribute of feedstocks in converting them in biochemical or thermochemical
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