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DOE OSTI2018

Processes and electron flow in a microbial electrolysis cell bioanode fed with furanic and phenolic compounds

We report that furanic and phenolic compounds are problematic compounds resulting from the pretreatment of lignocellulosic biomass for biofuel production. Microbial electrolysis cell (MEC) is a promising technology to convert furanic and phenolic compounds to renewable H 2 . The objective of the research presented here was to elucidate the processes and electron equivalents flow during the conversion of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; 4-hydroxybenzoic acid, HBA) compounds in the MEC bioanode. Cyclic voltammograms of the bioanode demonstrated that purely electrochemical reactions in the biofilm attached to the electrode were negligible. Instead, microbial reactions related to the biotransformation of the five parent compounds (i.e., fermentation followed by exoelectrogenesis) were the primary processes resulting in the electron equivalents flow in the MEC bioanode. A mass-based framework of substrate utilization and electron flow was developed to quantify the distribution of the electron equivalents among the bioanode processes, including biomass growth for each of the five parent compounds. Using input parameters of anode efficiency and biomass observed yield coefficients, it was estimated that more than 50% of the SA, FF, and HMF electron equivalents were converted to current. In contrast, only 12 and 9% of VA and HBA electron equivalents, respectively, resulted in current production, while 76 and 79% remained as fermentation end products not further utilized in exoelectrogenesis. For all five compounds, it was estimated that 10% of the initially added electron equivalents were used for fermentative biomass synthesis, while 2 to 13% were used for exoelectrogenic biomass synthesis. Finally, the proposed mass-based framework provides a foundation for the simulation of bioanode processes to guide the optimization of MECs converting biomass-derived waste streams to renewable H 2 .

09 BIOMASS FUELS↗

DOE OSTI2011

Recovery of phosphonate surface contaminants from glass using a simple vacuum extractor with a solid-phase microextraction fiber

Recovery of chemical contaminants from fixed surfaces for analysis can be challenging particularly if it is not possible to acquire a solid sample. A simple device is described that collects semivolatile organic compounds from fixed surfaces by creating an enclosed volume over the surface, then generating a modest vacuum. A solid-phase microextraction fiber is then inserted into the evacuated volume where it functions to sorb volatilized organic contaminants. The device is based on a syringe modified with a seal that is used to create the vacuum, with a perforable plunger through which the SPME fiber is inserted. The vacuum speeds partitioning of the semivolatile compounds into the gas phase, and reduces the boundary layer around the SPME fiber, which enables a fraction of the volatilized organics to partition into the SPME fiber. After sample collection the SPME fiber is analyzed using conventional gas chromatography/mass spectrometry. The methodology has been used to collect organophosphorus compounds from glass surfaces, to provide a simple test for the functionality of the devices. Thirty minute sampling times (deltaTvac) resulted in fractional recovery efficiencies ranged from 10(-3) to > 10(-1), and in absolute terms collection of low nanograms was demonstrated. Fractional recovery values were correlated to the vapor pressure of the compounds being sampled. Fractional recovery increased with increasing deltaTvac, and displayed a roughly logarithmic profile indicating that an operational equilibrium is being approached. Fractional recovery decreased with increasing time between exposure and sampling, however recordable quantities of the phosphonates could be collected three weeks after exposure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Methodology to determine printability criteria of highly concentrated pastes through rheological characterization

Material extrusion is an additive manufacturing technique that enables the creation of reproducible and complex hardware by depositing a viscous, shear-thinning ink onto a substrate in a custom-pattern via extrusion through a syringe. Here, the ability of an ink to be extruded onto a substrate in many layers, and maintain the desired shape is what defines the printability. Printability is often investigated by formulating, printing, and postmortem analysis of final parts in an iterative manner. Investigations of printability through rheological characterization have often been concerned with inks that straddle the line between printable and too thin, leaving out an entire class of inks that are highly-filled pastes, where extrudability is the limiting factor. Highly-filled pastes continue to pose issues for researchers as the effect of filler morphology, size, loading, and packing fraction on the ink rheology and corresponding printability is not understood. While traditional rheological characterizations may be useful for some inks, we show that protocols utilizing steady-shear, or large-amplitude oscillatory shear are difficult and unreliable for highly-filled pastes. Through transient rheology paired with real-time images we show that each traditional protocol produces inhomogeneous deformations that violate the assumptions that underly common rheological definitions. Instead, we demonstrate metrics measured with small-amplitude oscillatory shear that are correlated to the printability of various ink formulations ranging in loading. The rheological measures that accurately predict the printability of the inks are the axial stress measured at small amplitudes, and the critical stress amplitude above which rheological characterizations become impossible. In addition, we estimate the maximum packing fraction for each filler, based on the exponent common to hard sphere models, and show that the printability of each ink can be predicted by the ratio of the packing fraction to the theoretical maximum. We show how small-amplitude oscillatory shear allows users to develop printability criteria for any ink to enhance the workflow in the development of new inks, increase the performance of material extrusion printing, and improve the stability of printed parts, with less wasted time and materials.

36 MATERIALS SCIENCE↗

DOE OSTI2019

CaloriSMART: Small-scale test-stand for rapid evaluation of active magnetic regenerator performance

We report operation of a device designed specifically for rapid experimental evaluation of performance of magnetocaloric materials in different magnetic fields using a compact active magnetic regenerator bed with a total volume of approximately 5 mL. Other features of the system include digital control of the rotating-permanent-magnet field source and custom dual-opposed syringe pump that enable precise tuning and coupling of the flow profile and the magnetic field profile. Performance of the device is demonstrated for flow volumes between 1 and 4 mL (utilization from 0.48 to 1.9), maximum magnetic fields of 1.13 and 1.45 T, and applied cooling powers from 0 to 20 W at frequencies from 0.5 to 4 Hz. A regenerator comprised of 25 g of 200 µm spherical Gd powder reached temperature spans of 19.3 K under no applied cooling load and 2.6 K under the maximum applied cooling load of 20 W. The device also achieves a very high specific exergetic cooling power of 73 W L -1 T -1 . Results obtained at two different maximum magnetic fields in the same device suggest a powerful new scaling for regenerator performance: the exergetic power quotient. The exergetic power quotient shows a simple scaling of device cooling performance with the amount of active material and the magnetic field strength. This suggests results from a small device correlate to expected performance of a larger regenerator, making the exergetic power quotient a well-suited parameter for evaluating functionality of active magnetic regenerators employing new magnetocaloric materials.

47 OTHER INSTRUMENTATION↗

DOE OSTI2022

Upcycling disposable face masks into fuel range iso-alkanes through hydropyrolysis coupled with vapor-phase hydrocracking

The COVID-19 pandemic has resulted in an alarming accumulation of plastic waste. Herein, an integrated hydropyrolysis and hydrocracking process was performed to upcycle disposable masks into fuel-range iso-alkanes over carbon supported ruthenium (Ru/C). Experimental results indicated that catalyst type significantly affected product distribution during the hydropyrolysis and vapor-phase hydrocracking of disposable masks. Compared with zeolites-induced catalytic cascade process where up to ~25.9 wt% yield of aromatic hydrocarbons such as toluene and xylenes were generated, a ~82.7 wt% yield of desirable iso-alkanes with a high C 5 –C 12 gasoline selectivity of 95.5% was obtained over Ru/C under 550 °C hydropyrolysis temperature and 300 °C hydrocracking temperature at 0.2 MPa H 2 . Further, the cascade hydropyrolysis and hydrocracking process also exhibited high adaptability and flexibility in upcycling single-use syringes, food packaging, and plastic bags, generating 79.1, 81.6, and 80.3 wt% yields of fuel range iso/n-alkanes, respectively. This catalytic cascade hydrotreating process provides an efficient and effective approach to convert pandemic-derived plastic waste into gasoline-range fuel products.

09 BIOMASS FUELS↗

DOE OSTI2017

Contribution of acidic components to the total acid number (TAN) of bio-oil

Bio-oil or pyrolysis oil — a product of thermochemical decomposition of biomass under oxygen-limited conditions — holds great potential to be a substitute for nonrenewable fossil fuels. But, its high acidity, which is primarily due to the degradation of hemicelluloses, limits its applications. For the evaluation of bio-oil production and treatment, it is essential to accurately measure the acidity of bio-oil. The total acid number (TAN), which is defined as the amount of potassium hydroxide needed to titrate one gram of a sample and has been established as an ASTM method to measure the acidity of petroleum products, has been employed to investigate the acidity of bio-oil. The TAN values of different concentrations of bio-oil components such as standard solutions of acetic acid, propionic acid, vanillic acid, hydroxybenzoic acid, syringic acid, hydroxymethylfurfural, and phenol were analyzed according to the ASTM D664 standard method. Our method showed the same linear relationship between the TAN values and the molar concentrations of acetic, propionic, and hydroxybenzoic acids. A different linear relationship was found for vanillic acid, due to the presence of multiple functional groups that can contribute to the TAN value. Furthermore, the influence of the titration solvent on the TAN values has been determined by comparing the TAN values and titration curves obtained from the standard method with results from the TAN analysis in aqueous environment and with equilibrium modeling results. Aqueous bio-oil samples with a known amount of acetic acid added were also analyzed. The additional acetic acid in bio-oil samples caused a proportional increase in the TAN values. These results of this research indicate that the TAN value of a sample with acids acting as monoprotic acids in the titration solvent can be converted to the molar concentration of total acids. For a sample containing acids that act as diprotic and polyprotic acids, however, its TAN value cannot be simply converted to the molar concentration of total acids because these acids have a stronger contribution to the TAN values than the contribution of monoprotic acids.

09 BIOMASS FUELS↗

DOE OSTI2018

Accelerated tert -butyloxycarbonyl deprotection of amines in microdroplets produced by a pneumatic spray

Protection and deprotection of organic compounds in multistep reactions using functional groups such as tert-butoxycarbonyl (Boc), is widely performed in synthetic organic chemistry. Reaction rate acceleration studies in spray-based ionization methods (electrosonic spray, paper spray, nanospray) have become increasingly common. In this report, we demonstrate reaction rate acceleration of Boc deprotection using easy ambient sonic-spray ionization (EASI), a pneumatic technique which does not involve an applied voltage, in a teaching laboratory setting. The goal of this laboratory exercise was to explore acceleration in a previously unexplored spray-based reaction, while emphasizing in a pedagogic setting the importance of protecting groups for multistep synthesis. Rate acceleration factors of more than an order of magnitude were observed in the uncharged micron-sized droplets generated by EASI. The effect of reaction conditions on reaction acceleration was examined including changes in the type of acid, reagent concentration ratios and syringe pump flow rates. Student knowledge was assessed by pre-laboratory assignments, post-laboratory reports and oral interviews.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

The Extent of Fermentative Transformation of Phenolic Compounds in the Bioanode Controls Exoelectrogenic Activity in a Microbial Electrolysis Cell

Phenolic compounds in hydrolysate/pyrolysate and wastewater streams produced during the pretreatment of lignocellulosic biomass for biofuel production present a significant challenge in downstream processes. Bioelectrochemical systems are increasingly recognized as an alternative technology to handle biomass-derived streams and to promote water reuse in biofuel production. Thus, a thorough understanding of the fate of phenolic compounds in bioanodes is urgently needed. The present study investigated the biotransformation of three structurally similar phenolic compounds (syringic acid, SA; vanillic acid, VA; 4-hydroxybenzoic acid, HBA), and their individual contribution to exoelectrogenesis in a microbial electrolysis cell (MEC) bioanode. Fermentation of SA resulted in the highest exoelectrogenic activity among the three compounds tested, with 50% of the electron equivalents converted to current, compared to 12 and 9% for VA and HBA, respectively. The biotransformation of SA, VA and HBA was initiated by demethylation and decarboxylation reactions common to all three compounds, resulting in their corresponding hydroxylated analogs. SA was transformed to pyrogallol (1,2,3-trihydroxybenzene), whose aromatic ring was then cleaved via a phloroglucinol pathway, resulting in acetate production, which was then used in exoelectrogenesis. In contrast, more than 80% of VA and HBA was converted to catechol (1,2-dihydroxybenzene) and phenol (hydroxybenzene) as their respective dead-end products. The persistence of catechol and phenol is explained by the fact that the phloroglucinol pathway does not apply to di- or mono-hydroxylated benzenes. Previously reported, alternative ring-cleaving pathways were either absent in the bioanode microbial community or unfavorable due to high energy-demand reactions. With the exception of acetate oxidation, all biotransformation steps in the bioanode occurred via fermentation, independently of exoelectrogenesis. Therefore, the observed exoelectrogenic activity in batch runs conducted with SA, VA and HBA was controlled by the extent of fermentative transformation of the three phenolic compounds in the bioanode, which is related to the number and position of the methoxy and hydroxyl substituents.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2011

Combining Laser Ablation/Liquid Phase Collection Surface Sampling and High-Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid phase sample collection method for surface sampling and ionization with subsequent mass spectral analysis. A commercially available autosampler was adapted to produce a liquid droplet at the end of the syringe injection needle while in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collection was followed by either flow injection or a high performance liquid chromatography (HPLC) separation of the extracted components and detection with electrospray ionization mass spectrometry (ESI-MS). To illustrate the analytical utility of this coupling, thin films of a commercial ink sample containing rhodamine 6G and of mixed isobaric rhodamine B and 6G dyes on glass microscope slides were analyzed. The flow injection and HPLC/ESI-MS analysis revealed successful laser ablation, capture and, with HPLC, the separation of the two compounds. The ablated circular area was about 70 m in diameter for these experiments. The spatial sampling resolution afforded by the laser ablation, as well as the ability to use sample processing methods like HPLC between the sample collection and ionization steps, makes this combined surface sampling/ionization technique a highly versatile analytical tool.

Laser Ablation↗

DOE OSTI2019

Automated Nanoflow Two-Dimensional Reversed-Phase Liquid Chromatography System Enables In-Depth Proteome and Phosphoproteome Profiling of Nanoscale Samples

Two-dimensional reversed-phase liquid chromatography (2D RPLC) separations have enabled near-comprehensive proteome profiling of biological systems. However, large samples containing milligram amounts of protein are usually required due to the significant sample losses incurred during offline fractionation. The large sample requirements preclude the application of 2D RPLC to biological systems having sample availability in the nanogram to low-microgram range. To achieve in-depth proteomic studies of trace samples, we have developed an automated nanoflow 2D RPLC platform in which the first dimension high-pH fractionation was performed at 300 nL/min on a 75-µm i.d. capillary column.Each fraction was then fully transferred to a second-dimension nanoLC separation using an autosampler equipped with a custom-machined syringe. In addition to optimizing fractionation conditions, we found that the use of a plastic 96-well plate as collection device and the adding of n-Dodecyl ß-D-Maltoside (0.01%) in the collection buffer can significantly improve sample recovery. We have demonstrated the nanoflow 2D RPLC platform can achieve confident identifications of ~37,000–69,000 unique peptides, corresponding to ~5300–6900 protein groups using only 100 to 1000 ng of HeLa tryptic digest. Furthermore, by integrating phosphopeptide enrichment, the platform can identify as many as ~20,000 phosphopeptides from 100 µg of MCF7 protein digest. Because this platform is assembled from commercially available components, our approach can be readily adapted in other proteomics laboratories.

Mass spectrometry, multidimensional separations, n↗

DOE OSTI2015

Thermoreversible and Injectable ABC Polypeptoid Hydrogels: Controlling the Hydrogel Properties through Molecular Design

Here, a series of ABC triblock copolypeptoids [i.e., poly( N -allyl glycine)- b -poly( N -methyl glycine)-b-poly( N -decyl glycine) (AMD)] with well-defined structure and varying composition have been synthesized by sequential primary amine-initiated ring-opening polymerization of the corresponding N-substituted N -carboxyanhydride monomers (Al-NCA, Me-NCA, and De-NCA). The ABC block copolypeptoids undergo sol-to-gel transitions with increasing temperature in water and biological media at low concentrations (2.5–10 wt %). The sol–gel transition is rapid and fully reversible with a narrow transition window, evidenced by the rheological measurements. The gelation temperature ( T gel ) and mechanical stiffness of the hydrogels are highly tunable: T gel in the 26.2–60.0 °C range, the storage modulus (G') and Young’s modulus ( E ) in the 0.2–780 Pa and 0.5–2346 Pa range, respectively, at the physiological temperature (37 °C) can be readily accessed by controlling the block copolypeptoid composition and the polymer solution concentration. The hydrogel is injectable through a 24 gauge syringe needle and maintains their shape upon in contact with surfaces or water baths that are kept above the sol–gel transition temperature. The hydrogels exhibit minimal cytotoxicity toward human adipose derived stem cells (hASCs), evidenced from both alamarBlue and PicoGreen assays. Furthermore, quantitative PCR analysis revealed significant up-regulation of the Col2a1 gene and down-regulation of ANGPT1 gene, suggesting that the hydrogel exhibit biological activity in inducing chondrogenesis of hASCs. It was also demonstrated that the hydrogel can be used to quantitatively encapsulate water-soluble enzymes (e.g., horseradish peroxidase) by manipulating the sol–gel transition. The enzymatic activity of HRP remain unperturbed after encapsulation at 37 °C for up to 7 d, suggesting that the hydrogel does not adversely affect the enzyme structure and thereby the enzymatic activity. These results suggest that the polypeptoid hydrogel a promising synthetic platform for tissue engineering or protein storage applications.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Biotransformation of furanic and phenolic compounds with hydrogen gas production in a microbial electrolysis cell

In this study, furanic and phenolic compounds are problematic byproducts resulting from the decomposition of lignocellulosic biomass during biofuel production. This study assessed the capacity of a microbial electrolysis cell (MEC) to produce hydrogen gas (H 2 ) using a mixture of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as the sole carbon and energy source in the bioanode. The rate and extent of biotransformation of the five compounds, efficiency of H 2 production, as well as the anode microbial community structure were investigated. The five compounds were completely transformed within 7-day batch runs and their biotransformation rate increased with increasing initial concentration. At an initial concentration of 1,200 mg/L (8.7 mM) of the mixture of the five compounds, their biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode coulombic efficiency was 44-69%, which is comparable to wastewater-fed MECs. The H 2 yield varied from 0.26 to 0.42 g H 2 -COD/g COD removed in the anode, and the bioanode volume-normalized H 2 production rate was 0.07-0.1 L/L-d. The major identified fermentation products that did not transform further were catechol and phenol. Acetate was the direct substrate for exoelectrogenesis. Current and H 2 production were inhibited at an initial substrate concentration of 1,200 mg/L, resulting in acetate accumulation at a much higher level than that measured in other batch runs conducted with a lower initial concentration of the five compounds. The anode microbial community consisted of exoelectrogens, putative degraders of the five compounds, and syntrophic partners of exoelectrogens. The H 2 production route demonstrated in this study has proven to be an alternative to the currently used process of reforming natural gas to supply H 2 needed to upgrade bio-oils to stable hydrocarbon fuels.

08 HYDROGEN↗

DOE OSTI2016

Inhibitory Effect of Furanic and Phenolic Compounds on Exoelectrogenesis in a Microbial Electrolysis Cell Bioanode

Furanic and phenolic compounds are 20 lignocellulose-derived compounds known to inhibit to H2- and ethanol- producing microorganisms in dark fermentation. Bioelectrochemical conversion of furanic and phenolic compounds to electricity or H2 has recently been demonstrated as a productive method to use these compounds. However, potential inhibitory effect of furanic and phenolic compounds on exoelectrogenesis in bioelectrochemical systems is not well understood. This study systematically investigated the inhibitory effect of furfural (FF), 5-hydroxymethylfurfural (HMF), syringic acid (SA), vanillic acid (VA), and 4-hydroxybenzoic acid (HBA) on exoelectrogenesis in the bioanode of a microbial electrolysis cell. A mixture of these five compounds at an increasing initial total concentration from 0.8 to 8.0 g/L resulted in current decrease up to 91%. The observed inhibition primarily affected exoelectrogenesis, instead of non-exoelectrogenic biotransformation pathways (e.g., fermentation) of the five compounds. Furthermore, the parent compounds at a high concentration, as opposed to their biotransformation products, were responsible for the observed inhibition. Tests with individual compounds show that all five parent compounds contributed to the observed inhibition by the mixture. The IC50 (concentration resulting in 50% current decrease) was estimated as 2.7 g/L for FF, 3.0 g/L for HMF, 1.9 g/L for SA, 2.1 g/L for VA and 2.0 g/L for HBA. Nevertheless, these compounds below their non-inhibitory concentrations jointly resulted in significant inhibition as a mixture. Catechol and phenol, which were persistent biotransformation products of the mixture, inhibited exoelectrogens at high concentrations, but to a lesser extent than the parent compounds. Recovery of exoelectrogenesis from inhibition by all compounds was observed, except for catechol, which resulted in irreversible inhibition. The reversibility of inhibition, as well as the observed difference in recovery rates, suggest different modes of exoelectrogenesis inhibition, related to the hydrophobicity of the inhibiting compounds.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2024

Building a Simplistic Automatic Extruder: Instrument Development Opportunities for the Laboratory

This work presents an automatic extruder as a research experience for undergraduate students. The system offers a user-friendly approach to preparing vesicles, such as liposomes or polymersomes, with a defined size and polydispersity properties crucial for research in biology and macromolecules. It comprises two syringe pumps connected by a membrane filter. The setup is controlled by software. Compared to manual extrusion, this automated system provides advantages, such as precisely controlled variables. The project describes a tool to enhance undergraduate learning in science and engineering laboratories. Building an automatic extruder serves as a simplified model of a complex industrial process. It offers a clear advantage: automating a well-understood manual extrusion process. To make this project accessible, it is broken down into three manageable tasks: software development, hardware assembly, and testing procedures. This breakdown describes the software created, the hardware components used, and the testing procedures conducted for this project. All project data, including software code, testing data, and procedures, are freely available online. This allows undergraduate students to not only begin their own projects but also contribute to this educational instrument’s ongoing development.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Liquid–Solid Mixtures of Ga Metal Infused with Cu Microparticles and Nanoparticles for Microscale and Nanoscale Patterning of Solid Metals at Room Temperature

This paper demonstrates and characterizes a simple ink for nanopatterning of solid metallic structures under ambient conditions by taking advantage of the low melting point of gallium and its affinity to form intermetallics with other metals. Bare copper micro- and nanoparticles readily mix with liquid gallium near room temperature to form a paste that ultimately amalgamates into a dense solid when mixed at the appropriate concentration ratios. The paste has sufficient shelf life that can be extruded from a nozzle at modest temperatures to form solid three-dimensional (3D) shapes. Additionally, the paste can be molded at room temperature to replicate feature sizes ranging from a few millimeters down to hundreds of nanometers. In situ X-ray diffraction (XRD) and thermo-mechanical analysis (TMA) data show gallium and copper readily interdiffuse to form the thermodynamically expected intermetallic phase. We describe the capabilities and limitations of a simple way to pattern solid metals in an additive fashion (syringe-based extrusion) and with high resolution (molding) at or near room temperature. Here, the use of a paste that solidifies provides a novel route for 3D printing of solid metals at ambient temperatures as well as the creation of micro- and nanostructured metallic surfaces that may be useful for optics, non-wetting surfaces, or electronic microcomponents.

36 MATERIALS SCIENCE↗

DOE OSTI2018

A Wearable Microfluidic Sensing Patch for Dynamic Sweat Secretion Analysis

Wearable sweat sensing is a rapidly rising research area driven by its promising potential in health, fitness, and diagnostic applications. Despite the growth in the field, major challenges in relation to sweat metrics remain to be addressed. These challenges include sweat rate monitoring for its complex relation with sweat compositions and sweat sampling for sweat dynamics studies. Here, we present a flexible microfluidic sweat sensing patch that enhances real-time electrochemical sensing and sweat rate analysis via sweat sampling. The device contains a spiral-patterned microfluidic component that is embedded with ion-selective sensors and an electrical impedance-based sweat rate sensor on a flexible plastic substrate. The patch is enabled to autonomously perform sweat analysis by interfacing the sensing component with a printed circuit board that is capable of on-site signal conditioning, analysis, and transmission. Progressive sweat flow in the microfluidic device, governed by the pressure induced by the secreted sweat, enhances sweat sampling and electrochemical detection via a defined sweat collection chamber and a directed sweat route. The characteristic of the sweat rate sensor is validated through a theoretical simulation, and the precision and accuracy of the flow rate is verified with a commercial syringe pump and a Macroduct sweat collector. On-body simultaneous monitoring of ion (H + , Na + , K + , Cl – ) concentration and sweat rate is also demonstrated for sensor functionality. This sweat sensing patch provides an integrated platform for a comprehensive sweat secretion analysis and facilitates physiological and clinical investigations by closely monitoring interrelated sweat parameters.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Oxidative Catalytic Fractionation of Lignocellulosic Biomass Using a Co-N-P-C Catalyst and One-Step Isolation of Aromatic Monomers via Centrifugal Partition Chromatography

Methods for catalytic fractionation of biomass provide a means to convert lignin directly into monomers while generating a high-quality cellulosic stream, contrasting conventional biomass pretreatment strategies that prioritize the cellulosic fraction. Here, a nonprecious-metal Co-N-P-C catalyst is identified for aerobic oxidative catalytic fractionation (OCF) of poplar feedstock in dimethyl carbonate that achieves significantly higher yields of aromatic monomers (24 wt %) relative to those obtained with a recently reported Co-N-C catalyst in acetone solvent (15 wt %). Mechanistic studies indicate that the acidic properties of the catalyst contribute to its improved performance by promoting extraction of lignin from insoluble polysaccharides. This OCF process is complemented by the development of a new centrifugal partition chromatography (CPC) method that supports isolation of all five major aromatic monomers (syringic acid, syringaldehyde, vanillic acid, vanillin, and para-hydroxybenzoic acid) in a single liquid–liquid extraction purification step. Furthermore, this OCF/CPC sequence has important implications for future lignin valorization efforts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Oxidative Catalytic Fractionation of Lignocellulosic Biomass under Non-alkaline Conditions

Biomass pretreatment methods are commonly used to isolate carbohydrates from biomass, but they often lead to modification, degradation, and/or low yields of lignin. Catalytic fractionation approaches provide a possible solution to these challenges by separating the polymeric sugar and lignin fractions in the presence of a catalyst that promotes cleavage of the lignin into aromatic monomers. In this work, we demonstrate an oxidative fractionation method conducted in the presence of a heterogeneous non-precious-metal Co-N-C catalyst and O 2 in acetone as the solvent. The process affords a 15 wt% yield of phenolic products bearing aldehydes (vanillin, syringaldehyde) and carboxylic acids (p-hydroxybenzoic acid, vanillic acid, syringic acid), complementing the alkylated phenols obtained from existing reductive catalytic fractionation methods. The oxygenated aromatics derived from this process have appealing features for use in polymer synthesis and/or biological funneling to value-added products, and the non-alkaline conditions associated with this process support preservation of the cellulose, which remains insoluble at reaction conditions and is recovered as a solid.

09 BIOMASS FUELS↗