Publications by Colleges and Departments (MSU - Bozeman)
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Item Effect of Dilute Acid Pretreatment and Lignin Extraction Conditions on Lignin Properties and Suitability as a Phenol Replacement in Phenol-Formaldehyde Wood Adhesives(American Chemical Society, 2022-12) Saulnier, Brian K.; Siahkamari, Mohsen; Singh, Sandip K.; Nejad, Mojgan; Hodge, David B.Corn stover was subjected to dilute sulfuric acid pretreatment to assess the impact of pretreatment conditions on lignin extractability, properties, and utility as a phenol replacement in wood phenol-formaldehyde (PF) adhesives. It was identified that both formic acid and NaOH could extract and recover 60–70% of the lignin remaining after pretreatment and enzymatic hydrolysis under the mildest pretreatment conditions while simultaneously achieving reasonable enzymatic hydrolysis yields (>60%). The availability of reaction sites for the incorporation of lignins into the PF polymer matrix (i.e., unsubstituted phenolic hydroxyl groups) was shown to be strongly impacted by the pretreatment time and the recovery. Finally, a lignin-based wood adhesive was formulated by replacing 100% of the phenol with formic-acid-extracted lignin, which exhibited a dry shear strength exceeding a conventional PF adhesive. These findings suggest that both pretreatment and lignin extraction conditions can be tailored to yield lignins with properties targeted for this co-product application.Item Lignin properties and cell wall response to deconstruction by alkaline pretreatment and enzymatic hydrolysis in brown midrib sorghums(Elsevier BV, 2022-04) Singh, Sandip K.; Saulnier, Brian K.; Hodge, David B.Lignin has an adverse impact on the deconstruction of plant cell wall biopolymers in biorefining processes and its reduction and/or alteration during biosynthesis is one target for decreasing plant cell wall recalcitrance. In this work, the impact of two brown midrib mutations (bmr6 and bmr12) in two sorghum background lines (the commercial hybrid Atlas and near-isogenic BTx623) on lignin properties and the plants’ response to cell wall deconstruction to monomeric sugars via alkaline pretreatment and enzymatic hydrolysis is investigated with the goal of assessing how differences in lignin content and properties impact the plant’s response to pretreatment. We identify that both bmr sorghum lines show significantly lower abundance of water-extractable sugars (glucose, sucrose, and fructose) and alkali-saponifiable p-coumarate. Furthermore, both these properties exhibited identical trends across both background lines. Next, both untreated and mild alkali-pretreated bmr sorghums were shown to exhibit higher glucose hydrolysis yields following enzymatic hydrolysis than the control lines. Following pretreatment, the Atlas bmr sorghums exhibited more lignin solubilization and the solubilized lignin was of lower molar mass than the background control line suggesting that differences in the lignin response to pretreatment resulted these differences. Finally, significant differences were observed in the lignin content, lignin monomer distribution, and inter-unit linkages in the Atlas bmr line relative to the control line with key differences including lower syringyl monomer content in both bmr lines, higher relative abundance of β-O-4 linkages in the bmr6 line, and the presence of 5-hydroxy guaiacyl monomers and benzodioxane (α-O-5/β-O-4) linkages in the bmr12 line.