Scholarly Work - Chemical & Biological Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8718
Browse
3 results
Search Results
Item Scale-Up of a Two-Stage Cu-Catalyzed Alkaline-Oxidative Pretreatment of Hybrid Poplar(American Chemical Society, 2024-03) Dülger, Dilara N.; Yuan, Zhaoyang; Singh, Sandip K.; Omolabake, Surajudeen; Czarnecki, Celeste R.; Nikafshar, Saeid; Li, Mingfei; Bécsy-Jakab, Villő E.; Park, Seonghyun; Park, Sunkyu; Nejad, Mojgan; Stahl, Shannon S.; Hegg, Eric L.; Hodge, David B.A two-stage alkaline-oxidative pretreatment of hybrid poplar was investigated at scale (20 L reactor volume) with the goal of understanding how reaction conditions as well as interstage mechanical refining impact downstream process responses. The pretreatment comprises a first stage of alkaline delignification (alkaline pre-extraction) followed by a second delignification stage employing Cu-catalyzed alkaline hydrogen peroxide with supplemental O2 (O2-enhanced Cu-AHP). Increasing pre-extraction severity (i.e., temperature and alkali loading) and pretreatment oxidation (increasing H2O2 loading) were found to increase mass and lignin solubilization in each stage. Lignin recovered from the first stage was subjected to oxidative depolymerization and led to aromatic monomer yields as high as 23.0% by mass. Lignins recovered from the second-stage Cu-AHP pretreatment liquors were shown to exhibit aliphatic hydroxyl contents more than 6-fold higher than a typical hardwood kraft lignin, indicating that these lignins could serve as a biobased polyol for a range of polyurethane applications.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-Based Polyurethanes: Opportunities for Bio-Based Foams, Elastomers, Coatings and Adhesives(2019-07-19) Alinejad, Mona; Henry, Christian; Nikafshar, Saeid; Gondaliya, Akasha; Bagheri, Sajad; Chen, Nusheng; Singh, Sandip K.; Hodge, David B.; Nejad, MojganPolyurethane chemistry can yield diverse sets of polymeric materials exhibiting a wide range of properties for various applications and market segments. Utilizing lignin as a polyol presents an opportunity to incorporate a currently underutilized renewable aromatic polymer into these products. In this work, we will review the current state of technology for utilizing lignin as a polyol replacement in different polyurethane products. This will include a discussion of lignin structure, diversity, and modification during chemical pulping and cellulosic biofuels processes, approaches for lignin extraction, recovery, fractionation, and modification/functionalization. We will discuss the potential of incorporation of lignins into polyurethane products that include rigid and flexible foams, adhesives, coatings, and elastomers. Finally, we will discuss challenges in incorporating lignin in polyurethane formulations, potential solutions and approaches that have been taken to resolve those issues.