Engineering topics

Ragauskas, Arthur

Publications and source records attributed to Ragauskas, Arthur.

15 records

DOE OSTI2024

Separation Process of Plant Fibers for Textile and Composite Application: A Review of Recent Advances

Plant fiber resources have gained significant attention for value-added utilization due to their renewability, sustainability, abundance, and widely acknowledged physical properties. The efficient and pragmatic separation of plant fibers is a critical process for their efficient utilization, yet a substantial gap persists between laboratory research advancements and their commercialization. To increase the possibility of research advancements for industrial application, this review summarizes the recent advances in different extraction methodologies of plant fiber research in textile and composite fields. It systematically outlines, compares, and contrasts physical (cryogenic, supercritical carbon dioxide, ultrasonic, steam explosion and microwave heating treatment), chemical (alkali, oxidation, organic solvents and deep eutectic solvents methods), and biological (natural retting, enzymatic and microorganism approaches) methods, addressing their respective mechanisms, strengths, limitations, research progress, and future prospects. In general, traditional chemical approaches have proven significantly effective but are accompanied by high pollution. Conversely, novel chemical treatments such as deep eutectic solvents and organic solvents offer a promising blend of efficiency and environmental friendliness but require deeper studies currently. Meanwhile, physical and biological treatments, though largely eco-friendly, tend to suffer from lower separation efficiencies. The research needs and future direction are also addressed to bridge the gap between scientific advancements and their widespread industrial application.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2024

Proton NMR spectra of lignin isolated from field grown transgenic poplar

Here we present a curated dataset of a series of 1H nuclear magnetic resonance (NMR) spectra of lignin isolated from transgenic monolignol 4-O-methyltransferase (MOMT4) engineered poplar. The transgenic poplar was collected from a 2-year-old rotation trees within a three-year field trial experiment. Two replicates were collected for each transgenic poplar for the 1H NMR analysis. The poplar samples were Soxhlet-extracted with toluene/ethanol to remove the extractives and the extractives-free poplar was then ball-milled in a Retsch PM100 planetary ball mill using a porcelain jar with ceramic balls at 600 rpm for 2 h. The ball-milled materials were subjected to enzymatic hydrolysis for 48 h followed by centrifugation and washing with deionized water. The solid residue was extracted twice with 96:4 (v/v) 1,4-dioxane/water mixture at room temperature overnight. The extracts were combined, rotary evaporated, and freeze-dried to recover lignin. The dry lignin samples were dissolved in deuterated dimethyl sulfoxide and transferred into a 5 mm NMR tube. 1H NMR experiments were performed in a Bruker Avance III HD 500 MHz NMR spectrometer operating at a frequency of 125.12 MHz for the 13C nucleus using a standard Bruker pulse sequence (zg) on a Prodigy platform cryoprobe. The NMR spectra were acquired with 16 ppm spectra width, 32k data points, 3s pulse delay, and 16 scans. All the data was processed using the Bruker’s TopSpin 3.6 software. Additional meta data is embedded in the raw spectra files.

1H NMR, lignin, poplar, field trial, MOMT4, CBI↗

DOE OSTI2024

Lignin molecular weights of Populus trichocarpa residues after CELF pretreatment

Here we present a dataset of molecular weights of lignin from a woody energy crop (Populus trichocarpa) residues after a series of co-solvent enhanced lignocellulosic fractionation (CELF) pretreatment. The natural poplar variant GW-9947 from the Center for Bioenergy Innovation (CBI) was used. The poplar was knife milled and passed through a 1 mm sieve and CELF pretreatment was performed in a Parr autoclave reactor with 7.5 wt % solids loading, 0.5 wt% H2SO4 as catalyst at 150°C with various time. Tetrahydrofuran was added in a 1:1 mass ratio with water as the pretreatment solvent. Lignin was isolated from the pretreated samples after ball-milling in a porcelain jar with ceramic balls via Retsch PM 200 at 580 rpm for 2.5 h followed by enzymatic hydrolysis in acetate buffer (pH 4.8, 50 °C) for 48 h. The solid residue was isolated by centrifugation and hydrolyzed again with freshly added buffer and enzymes for another 48 h. After filtration, the solid residue was extracted twice with 96% (v/v) 1,4-dioxane/water mixture at room temperature overnight. The extracts were combined, rotary evaporated, and freeze-dried to recover lignin. The lignin samples were then derivatized in an acetic anhydride/pyridine (1:1, v/v) mixture and stirred at room temperature for 24 h. Ethanol was added to the reaction mixture, left for 30 min and then removed with a rotary evaporator. The addition and removal of ethanol was repeated at least 3 times until all traces of acetic acid were removed. Acetylated lignin samples were then dissolved in tetrahydrofuran (THF) at a concentration of 1.0 mg/mL. The molecular weight of acetylated lignin was measured by a gel permeation chromatography (GPC) on a PSS-Polymer Standards Service (Warwick, RI, USA) GPC SECurity 1200 system featuring Agilent HPLC 1200 components equipped with four Waters Styragel columns (HR1, HR2, HR4 and HR6) and an UV detector (270 nm). Tetrahydrofuran was used as the mobile phase and flow rate was 0.3 mL/min. The Polymer Standards Service WinGPC Unity software (Build 6807) was used for data processing for all the samples. The data provides information about the effects of CELF pretreatment time at 150 ºC on lignin molecular weights.

09 BIOMASS FUELS↗

DOE OSTI2024

Cellulose molecular weight of corn stover with cotreatment

Here we present a dataset of cellulose molecular weights from corn stover after a cotreatment process. The corn stover sample was subjected to a combination of mechanical disruption (ball milling) and consolidated bioprocessing (CBP) process using the bacterium C. thermocellum at 60 grams/L solids loadings. Cellulose was isolated from control, no cotreatment control, and cotreatment corn stover. Cellulose was then derivatized using anhydrous pyridine and phenyl isocyanate over 48 h at 70 ºC. The reaction was quenched by anhydrous methanol. Methanol and water mixture (7:3, v/v) was added dropwise to promote precipitation of the cellulose derivative. The solids were collected by filtration and thoroughly washed with the methanol and water mixture followed by water. The cellulose derivative was dried overnight under vacuum at 40°C. The obtained cellulose tricarbanilates was then dissolved in tetrahydrofuran (THF) at 1.0 mg/mL and the solution was filtered through a 0.45 µm PTFE filter and placed in an auto-sampler vial. The molecular weight of cellulose was measured by Agilent GPC SECurity 1200 system equipped with four Waters Styragel columns (i.e., HR0.5, HR2, HR4, and HR6) and a UV detector (270 nm). THF was used as the mobile phase. Data collection and processing was performed by Polymer Standards Service WinGPC Unity software (Build 6807). The molecular weight was calculated relative to the polystyrene calibration curve. The data on molecular weights provided information about the effects of cotreatment on corn stover cellulose molecular changes.

Cellulose, molecular weights, corn stover, cotreat↗

DOE OSTI2024

Carbon-13 NMR spectra of lignin isolated from field grown transgenic poplar

Here we present a curated dataset of a series of 13C nuclear magnetic resonance (NMR) spectra of lignin isolated from transgenic monolignol 4-O-methyltransferase (MOMT4) engineered poplar. The transgenic poplar was collected from a 3-year field trial experiment. The poplar was Soxhlet-extracted with toluene/ethanol and the extractives-free poplar was then ball-milled in a Retsch PM100 planetary ball mill using a porcelain jar with ceramic balls at 600 rpm for 2 h. The ball-milled materials were then subjected to enzymatic hydrolysis for 48 h followed by centrifugation and washing with deionized water. The solid residue was extracted twice with 96:4 (v/v) 1,4-dioxane/water mixture at room temperature overnight. The extracts were combined, rotary evaporated, and freeze-dried to recover the lignin. The dry lignin samples were dissolved in deuterated dimethyl sulfoxide for NMR characterization. 13C experiments were performed in a Bruker Avance III HD 500 MHz NMR spectrometer operating at a frequency of 125.12 MHz for the 13C nucleus using a standard Bruker pulse sequence (zgpg) on a Prodigy platform cryoprobe. The NMR spectra were acquired under the following conditions: spectra width 229 ppm, 64k data points, 1s pulse delay, and 6k scans. All the data was processed using the Bruker’s TopSpin 3.6 software. Additional meta data is embedded in the raw spectra files.

13C NMR, lignin, poplar, field trial, MOMT4, CBI↗

DOE OSTI2023

The significance of biomass densification in biological-based biorefineries: A critical review

Replacing fossil fuels with renewable biofuels derived from lignocellulosic biomass is an important aspect of addressing environmental challenges and developing a sustainable industrial society. Densification overcomes the problems of low bulk density and poor flowability of biomass and has been commercialized for producing solid biofuels, but the overall impact of densification on biological-based biorefineries that primarily target liquid fuels (e.g., ethanol) is still under investigation. Herein, this review provides a thorough summary of the application of densified biomass in biological-based biorefineries. First, the effects of densification parameters as well as variables of biomass materials on the densified products’ quality are reviewed, and different commonly used densification technologies are also discussed and compared. Then, the discussion focuses on the physiochemical modifications of biomass caused by densification that may influence further pretreatment and/or enzymatic hydrolysis in biorefineries. Industrial pelleting has been generally shown to exhibit positive/neutral effects on the enzymatic hydrolysis of multiple biomass feedstocks after pretreatments, indicating the viability of using pellets as starting feedstocks in biorefineries. Densification causes structural disruption of biomass, which may facilitate further biochemical conversions. Integrating biomass densification in the feedstock supply chain is feasible for large-scale biorefineries to overcome the techno-economic barriers and become profitable. Suggestions are presented for the efficiency enhancement and cost reduction in densification-based biorefineries. To enable wider applications, it is now the time to employ more demo and full-scale activities in different regions of the world pushing the research and innovation of densification integrated within biorefining.

09 BIOMASS FUELS↗

DOE OSTI2023

Technical Lignin Fractionation: A Powerful Tool for Lignin Structure Homogenization and Its Application

Extracted lignin as a by-product of pulping and bio-refining processes is the main available bio-phenolic polymer. The structural complexity, polydispersity, and black color of lignin are the main limiting factors for its application. Preparation of lignin with lower structural complexity and polydispersity through lignin fractionation is one of the primary solutions to engineer lignin into a value-added material. Sequential lignin fractionation was developed based on pH reduction from alkaline to acidic using mineral acids and was recently optimized using carbon dioxide as a pH controller. The partial solubility of lignin in organic solvents is another promising method for lignin fractionation. Organic solvents with different polarity and solubility factors are able to fractionate lignin, yielding a more homogeneous chemical structure. As a modification of the lignin fractionation process, the use of solvents, water/organic solvent mixtures, such as alcohols, and acetic acid from room to high temperature has been proposed as a greener method for lignin fractionation. Using membrane technology is another promising method and current results indicate its good potential for lignin recovery and fractionation.

Sadeghifar, Hasan↗

DOE OSTI2023

Towards functionalized lignin and its derivatives for high-value material applications

In pursuit of low-carbon development, the production of diverse functional materials from renewable resources, especially lignocellulosic biomass, is of vital importance. Lignin is a major component of lignocellulose, and it is nature's only true high-volume aromatic polymer, which has the advantages of biodegradability, biocompatibility, and low acquisition cost. After modification by a variety of physicochemical strategies, it can be applied as an alternative to basic industrial materials, including polyurethanes, phenolic, and epoxy resins, which stands comparably to conventional synthetic polymers in terms of both performance and reduced cost. To further unlock the potential of lignin, an alluring opportunity is the exploitation of lignin for high-value materials, especially nanomaterials, that find extensive applications in energy and environment areas. This review provides a systematic summary and perspective of research that has been devoted to lignin transformation to high-value materials, ranging from industrially well-established engineering materials to the recently emerged nanomaterials that were used for energy and environment applications. Latest cutting-edge innovations on lignin modification, controlled depolymerization, and assembly during the last five years are summarized. Structure-function relationships of lignin materials in terms of their specific applications are analyzed. Furthermore, challenges and future opportunities for lignin conversion to high-value materials are also provided. We wish this review will stimulate further advances in lignin based high-value materials, and promote “waste” into “wealth”.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Towards the sustainable conversion of corn stover into bioenergy and bioproducts through biochemical route: Technical, economic and strategic perspectives

Corn stover (CS) is one of the most abundant agricultural wastes and is ubiquitous around the world that is left over after grain harvest and accounts for 47–50% dry mass of the total grain yield. The global CS yield is 1661.25 million tons/year, which is 27.2% of the total agricultural waste. CS consists of about 34.5% stems, 32.3% leaves, 14.3% husks, 12.3% cobs and 6.6% flowers, with up to 45% cellulose, 30% hemicellulose and 20% lignin. Further, due to its favorable economic and environmental potential, CS is considered an ideal raw material for producing biofuels and biobased chemicals, which can largely be divided into carbohydrate and lignin platforms. However, the techno-economic perspectives of CS-based biorefineries have remained questionable due to the inadequate supply chain logistics, lack of cost-effective conversion technologies, limited scale-up of the product-specific technologies, and lower competitiveness in the market compared to their counterparts, such as sugar and starch-based biorefineries. While CS is converted by thermochemical and biochemical approaches, the latter is considered to be more sustainable for its selective conversion under mild conditions using microorganisms. This review aimed to critically discuss the latest research and developments on the biochemical conversion of CS into biofuels and chemicals. In particular, this paper covers the market potential of biofuels and chemicals to which CS can make a significant contribution, technological developments in the microbial conversion of CS, major biofuels and chemicals produced from CS-derived carbohydrates and lignin, and the technoeconomic perspectives of CS-based biorefinery.

09 BIOMASS FUELS↗

DOE OSTI2023

Recent advances in biomass pretreatment using biphasic solvent systems

The complexity and recalcitrance of lignocellulosic biomass seriously hinder its subsequent conversion to liquid fuels. To achieve high-value utilization of lignocellulosic biomass, the physical–chemical barrier should be overcome through appropriate pretreatment techniques to improve the accessibility of cellulose for efficient enzymatic hydrolysis. With the rapid emergence of novel pretreatment solvents, biphasic solvent pretreatments represent a nascent and green pretreatment method that has shown outstanding advantages and broad application prospects in the biorefinery of lignocellulosic substrates due to its ability to provide economically viable biomass upgrading, the separation process for products in the solvent phase, and the reutilization of solvents. Herein, different types of biphasic solvents (e.g., 2-methyltetrahydrofuran, methyl isobutyl ketone, 1-butanol, phenoxyethanol, ionic liquids, and deep eutectic solvents) were reviewed systematically, including the fundamental designs of biphasic solvents for biomass pretreatment, their effect on the fractionation of individual biomass components (e.g., carbohydrate and lignin) and the enzymatic hydrolysis performance, and the coproduction of furan and hydroxymethylfurfural. Finally, the main pros and cons of these different biphasic solvent systems are summarized, and the future development direction is also proposed. Finally, this review can provide a reference for designing and selecting effective biphasic pretreatment methods for various types of lignocellulosic biomass.

09 BIOMASS FUELS↗

DOE OSTI2022

Green synthesis of cellulose formate and its efficient conversion into 5-hydroxymethylfurfural

5-hydroxymethylfurfural (HMF) production from cellulose is a hot topic, while the rigidity of cellulose limits its efficient conversion into HMF. Cellulose formate has exhibited the great potential for HMF production but it’s synthesis via direct formylation of cellulose in formic acid is difficult. We reported a green synthetic route of cellulose formate and its efficient conversion into HMF. Ball milled cellulose formate (BCF) was synthesized via ball milling followed by formylation in formic acid at 80 °C for 0.5 h. The structure of BCF was thoroughly characterized and BCF was subsequently converted to HMF catalyzed by AlCl3 and HCl in dimethyl sulfoxide (DMSO)-H 2 O media. Results showed that ball milling of cellulose for 1–1.5 h efficiently deconstructed its crystallinity and degree of polymerization, boosting its further formylation and catalytic conversion. An overall 66.9% HMF yield from cellulose was achieved at 150 °C for 20 min using BCF derived from cellulose ball milled for 1.5 h as the substrate. BCF exhibits high reactivity toward HMF due to its excellent solubility and accessibility in DMSO-H 2 O media, and the release of formic acid in reaction further facilitates HMF production. BCF synthesized with different ball milling times shows different degrees of substitution of formyl groups, which could serve as an indicator and regulate the HMF production. The green synthesis of cellulose formate creates an efficient pathway for HMF production.

5-hydroxymethylfurfural↗

DOE OSTI2022

Lignin as a bioactive polymer and heavy metal absorber- an overview

As a pulping and bio-refinery by-product with phenolic chemical structure, lignin indicated high potential as natural antioxidant activity, UV blocker, antibacterial and toxic material absorbent properties. Presence of phenolic hydroxyl groups in lignin structure plays the main role of its antioxidant activity. However, lignin antioxidant power can change depending on its other structural features and functional groups like ortho-methoxy groups, –OCH 3 groups, the α-CH 2 groups, the aliphatic carbonyl groups, and the size of π-conjugated systems. Lignin in mixture with synthetic polymers, improved their thermal stability. Lignin has high UV light absorbing potential in broad-spectrum (UVA, UVB). Adding 1–5% of lignin into hand cream indicated excellent range of sun protection factor (SPF) with more than 95% UV light absorption. Lignin also indicated strong UV light protection when applied in different transparent film and protect paint, oil, and varnish from UV degradation. Further, lignosulfonate and other modified lignin including chemically modification, nano-particles and lignin hydrogel indicated high potential as heavy metal absorber.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Revealing the mechanism of lignin re-polymerization inhibitor in acidic pretreatment and its impact on enzymatic hydrolysis

Phenolic additives, including 2-naphthol, 2-naphthol-7-sulfonate, and resorcinol were evaluated for their impact on the lignin re-polymerization and subsequent hydrolysis of bamboo residues. Low surface lignin concentration (65.68%) of the substrate and high Tg value (185 °C) of lignin was observed for 2-naphthol-7-sulfonate assisted pretreatment, leading to the most significant increase (14%) in enzymatic hydrolysis efficiency of pretreated bamboo residues. Meanwhile, physicochemical properties of lignin revealed that the introduced sulfonic acid groups increased the surface charge, decreased the molecular weight, promoted the cleavage of β-O-4 linkages, and prevented the re-condensation of lignin. Even though resorcinol-assisted pretreatment, by contrast, was found to be an inhibitor for enzymatic hydrolysis. NMR analysis of modified lignin showed that resorcinol led to a higher amount of non-condensed phenolic OH groups and promoted the cleavage of β-O-4 linkages, acting as an inhibitor in lignin re-polymerization during the dilute acidic pretreatment. In short, the above findings present a detailed view of suppressing lignin re-polymerization for boosting the utilization of bioresources with acidic pretreatment.

09 BIOMASS FUELS↗

DOE OSTI2022

Epoxy as Filler or Matrix for Polymer Composites

Epoxy is a widely used polymer because of its ease of processing, high adhesiveness, and high chemical resistance. Epoxy-based composites are commonly used in aerospace, automotive, and marine applications. The epoxy type, function, curing agent, and curing process are discussed in this chapter. Epoxy is used as either a filler or polymer matrix in composite applications. As a filler, the epoxy modification on the fiber is discussed. As a polymer matrix, the epoxy is reinforced by natural and synthetic fibers. The manufacturing process and the fabricated epoxy-based composites’ performance (e.g., mechanical and thermal properties) are investigated. The advantages and disadvantages of epoxy’s function are discussed and summarized. Epoxy modification is an effective approach to improve the composites’ performance.

Zhao, Xianhui↗

DOE OSTI2021

Lignin-enzyme interaction: A roadblock for efficient enzymatic hydrolysis of lignocellulosics

Efficiently producing second-generation biofuels from biomass is of strategic significance and meets sustainability targets, but it remains a long-term challenge due to the existence of biomass recalcitrance. Lignin contributes significantly to biomass recalcitrance by physically limiting the access of enzymes to carbohydrates, and this could be partially overcome by applying a pretreatment step to directly target lignin. However, lignin typically cannot be completely removed, and its structure is also significantly altered during the pretreatment. As a result, lignin residue in the pretreated materials still significantly hindered a complete conversion of carbohydrate to its monosugars by interacting with cellulase enzymes. The non-productive adsorption driven by hydrophobic, electrostatic, and/or hydrogen bonding interactions is widely considered as the major mechanism of action governing the unfavored lignin-enzyme interaction. One could argue this type of interaction between lignin residue and the activated enzymes is the major roadblock for efficient enzymatic hydrolysis of pretreated lignocellulosics. To alleviate the negative effects of lignin on enzyme performance, a deep understanding of lignin structural transformation upon different types of pretreatments as well as how and where does lignin bind to enzymes are prerequisites. In the last decade, the progress toward a fundamental understanding of lignin-enzyme interaction, structural characterization of lignin during pretreatment and/or conformation change of enzyme during hydrolysis is resulting in advances in the development of methodologies to mitigate the negative effect of lignin. Here in this review, the lignin structural transformation upon different types of pretreatments and the inhibition mechanism of lignin in the bioconversion of lignocellulose to bioethanol are summarized. Some technologies to minimize the adverse impact of lignin on the enzymatic hydrolysis, including chemical modification of lignin, adding blocking additives, and post-treatment to remove lignin were also introduced. The production of liquid biofuels from lignocellulosic biomass has shown great environmental benefits such as reducing greenhouse gas emissions and mitigate climate change. By addressing the root causes of lignin-enzyme interaction and how to retard this interaction, it is our hope that this comprehensive review will pave the way for significantly reducing the high cost associated with the enzymatic hydrolysis process, and ultimately achieving a cost-effective and sustainable biorefinery system.

09 BIOMASS FUELS↗