Distribution of Bound and Free Water in Anatomical Fractions of Pine Residues and Corn Stover as a Function of Biological Degradation

Abstract

Biomass quality is influenced by water’s abundance, distribution, and status in relation to other chemical species within the polymer matrix. Water interacts with polymers that make up the cell walls, and these interactions govern the physical and chemical changes that occur during the storage and preprocessing of biomass feedstocks. Time-domain nuclear magnetic resonance (TD-NMR) was employed to explore variations in the physical constraints of water within the lignocellulosic microstructure in distinct anatomical fractions of biomass and as a function of biological degradation. The Carr–Purcell–Meiboom–Gill sequence, when combined with knowledge of the chemical composition and physical structure of pine residues and corn stover anatomical fractions, gives an accurate measurement of the bound and free water. In this work, the impacts of storage and biological degradation were investigated to elucidate changes in the status and distribution of water within distinct plant tissues. We also investigate how degradation during storage affects water interactions in different pine residues (e.g., bark, branch, and needle) and corn stover (e.g., cob, leaf, and stalk) anatomical fractions using transverse relaxation times (T 2). As demonstrated herein, TD-NMR provides quantitative data on lignocellulosic biomass–water interactions within anatomical fractions, which can further aid in the investigation of preprocessing effects on feedstock quality. Our findings suggest that biological heating enhances biomass–water interactions at the cellular and macromolecular scale. In addition, analysis of three-dimensional scanning electron microscopy reconstructions indicates that surface roughness wavelengths align with microscale roughness, suggesting that pine forestry residue and corn stover particles have primarily hydrophobic exterior surfaces. This study offers multiscale insights into understanding the microstructure, wettability, and chemical environment that dictate diffusion, enzyme access, and recalcitrance of lignocellulosic biomass.

Image Analysis for Rapid Assessment and Quality-Based Sorting of Corn Stover

“…In contrast, variations in inorganic attributes, Si and S, corresponded to the extent of soil contamination and intrinsic inorganic content in the sample. Although a mechanistic understanding of the biological degradation (Groenewold et al, 2020;Ding et al, 2021a) and thermo-chemical oxidative reactions that alter biomass quality attributes during storage (Krigstin and Wetzel, 2016) is required to sort out confounding signals from the degradation and accumulation of inorganic species, qualitative results presented here show promise for developing rapid screening tools to deploy in-field or in-line for rapid assessment of quality (Ray et al, 2020).…”

“…Variations in lignocellulosic biomass material and quality attributes are often overlooked when assessing feedstock value and pathways for conversion to fuels, chemicals, and products (Ray et al, 2020). Variations in cell wall composition, extractives, moisture content, inorganic species, and soil contaminants have been identified as critical factors affecting biomass quality, process uptime, and product yields (Ray et al, 2020;Sievers et al, 2020;Ding et al, 2021a). Hoover et al (2019) developed several multiple regression models where five chemical characteristics could be used to estimate biochemical conversion performance.…”