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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Deliquescence of eutectic LiCl-KCl diluted with NaCl for interim waste salt storage

Molten eutectic LiCl-KCl salt is a widely used electrolyte for electrorefining uranium from spent nuclear fuel. Due to the hygroscopic nature of this salt, careful handling and storage of solidified waste electrorefiner (ER) salt is required to avoid deliquescence and corrosion of container materials. This study investigated a potential processing path for reducing the deliquescence through dilution with NaCl. The hydration behavior of LiCl-KCl salts diluted with NaCl was evaluated in terms of mass gain due to mass of water absorption, visual evidence of deliquescence, and visual evidence of corrosion to stainless steel containers in a humid air environment. Pure eutectic LiCl-KCl exhibited a 50 mass% increase due to water absorption and showed signs of deliquescence after 24 hours. 89 mass% NaCl was required in order to prevent deliquescence. Dilution with 89% NaCl was also found to protect corrosion to stainless steel crucibles. Corrosion, thus, appears to require deliquescence. While NaCl dilution greatly decreases steady state hydration and eliminated deliquescence, storage volume is increased ~10x.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Deep Eutectic Solvents: A Review of Fundamentals and Applications

Deep eutectic solvents (DESs) are an emerging class of mixtures characterized by significant depressions in melting points compared to those of the neat constituent components. These green materials are promising for applications as inexpensive ’designer’ solvents exhibiting a host of tunable physicochemical properties. Here, a detailed review of the current literature reveals the lack of predictive understanding of the microscopic mechanisms that govern the structure-property relationships in this class of solvents. Complex hydrogen bonding behavior is postulated as the root cause of their melt-ing point depressions and physicochemical properties; to understand these hydrogen bonded networks, it is imperative to study these systems as dynamic entities using both simulations and experiments. This review emphasizes recent research efforts in order to elucidate the next steps needed to develop a fundamental framework for understanding DESs. It covers recent developments in DES research, frames outstanding scientific questions, and identifies gainful research thrusts that would advance the field towards predictive models and fundamental understanding of these solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Improving Surface Quality of Titanium Electrodeposition from a Deep Eutectic Solvent with Organic and Inorganic Additives

Titanium electroreduction is desired for a variety of medical, electronic, and bonding applications but has not been possible until recently. Titanium electrodeposition with leveler and brightener additives in the deep eutectic solvent ethaline has been studied for effects on spectroscopic reflectance. Polymeric leveling agents and several small‐molecule brighteners produce level/bright films (respectively) with high values for both specular and diffuse reflectance. The application of these leveling and brightening agents can produce films with appearances and surface roughnesses that may be suitable for application in medical implants such as stents, corrosion protection of electronics for wearable technology, and as interlayers between dissimilar metals.

deep eutectic solvents↗
DOE OSTI2023

Investigation of the effects of ternary deep eutectic solvent composition on pretreatment of sorghum stover

Biomass‐derived deep eutectic solvents (DESs) have been introduced as promising pretreatment and fractionation solvents because of their mild processing conditions, easy synthesis, and green solvent components from biomass. In recent DES studies, solvent‐based third constituents like water, ethanol, and others improve the processibility of typical binary DESs. However, the impacts of these components are not well understood. Here, two solvent‐based constituents, including water and ethylene glycol, were applied to 3,4‐dihydroxybenzoic acid (DHBA)‐based DES system for improving the conversion efficiency of cellulose‐rich fraction and the properties of lignin fraction. Chemical composition, enzymatic digestibility, degree of polymerization of cellulose and physicochemical properties of lignin were used to evaluate the impact of each third constituent on biomass processing. Ternary ChCl‐DHBA DESs exhibited better performances in delignification, fermentable sugar production, and preservation of β‐O‐4 ether linkage in lignin compared with binary ChCl‐DHBA DES.

09 BIOMASS FUELS↗
DOE OSTI2025

Thermodynamic Water Activity Explains the Unusual Electrochemical Stability of Aqueous Deep Eutectic Solvents

The presence of water in nonaqueous deep eutectic solvent (DES) electrolytes has been debated in recent years, with efforts ranging from its complete removal to willful addition. It was shown that controlled amounts of water can be beneficial, as it not only enhances the physicochemical properties of these electrolytes but also has no significant detrimental effects on their electrochemical stability. Despite these advantages, there is still limited understanding of how water interacts with DES systems at the molecular level. This study examines the water activity in ethylene glycol and glycerol, as well as their binary mixtures with choline chloride to form the DESs ethaline and glyceline, respectively. In this work, we show that the high electrochemical stability of glyceline is related to its lower water activity compared to ethaline and can be attributed to the robust H-bonding network formed by the three hydroxyl groups of glycerol. Its 3D H-bond network effectively integrates water molecules within its solvent structure, reducing degradation and maintaining stability at higher water contents. The deviations from the ideal Raoult's law behavior are reflected in the water activity and activity coefficients, which highlight the intricate H-bond interactions within DES-water mixtures. Water acts like a lubricant within the more viscous DES mixtures without being detrimental to their electrochemical performance. The presented results emphasize the necessity of customizing DES-water compositions to enhance their performance as electrolytes, especially in flow battery applications where electrochemical stability, ionic conductivity, and fluidity are of utmost importance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Bis(1,2,4-oxadiazolyl) Furoxan: A Promising Melt-Castable Eutectic Material of Low Sensitivity

A scalable synthesis of bis(1,2,4-oxadiazoyl) furoxan, C 6 H 2 N 6 O 4 , its physical properties, and its theoretical performance values are described herein. Previous attempts to synthesize this compound required expensive reagents, and/or time-consuming synthesis processes and low overall yields. In addition to disclosing a streamlined synthesis of bis(1,2,4-oxadiazolyl) furoxan, we report its molecular configuration and crystal structure, as well as its correct melting point. Bis(1,2,4-oxadiazolyl) furoxan exhibits a very insensitive behavior to impact, friction, and electrostatic discharge, with a calculated detonation pressure 20 % higher than that of TNT. Given its physical properties and theoretical performance values, this material can be classified as a promising ingredient in the development of melt-castable eutectic technology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Deep Eutectic Solvent Extraction of High-Purity Lignin from a Corn Stover Hydrolysate

Here, a lactic acid/chlorine chloride-based deep eutectic solvent (DES) was used for the extraction of high-purity lignin (up to 94.7%) in high yield (up to 75%) from the hydrolysis/fermentation residue corn stover hydrolysate (CSH), which was generated from a pilot-plant-scale biorefinery. A range of extraction conditions were investigated, which involved varying reaction temperature, time, and DES composition. The relationship between lignin yield, purity, and structural characteristics with DES treatment conditions was determined. The extraction of high-purity lignin from hydrolysis/fermentation residues presents a promising approach for enhancing the economic feasibility of a lignocellulose biorefinery. It was also determined that DES extraction can produce lignin with a controlled range of molecular weight and functional group content.

09 BIOMASS FUELS↗
DOE OSTI2025

Genetically engineered poplar wood effectively enhances the efficiency of deep eutectic solvent-mediated one-pot processing

Although lignocellulosic biomass is a renewable resource with the potential to replace fossil-derived fuels and chemicals, its recalcitrance, largely due to lignin, limits its utilization. Recent advancements in genetic engineering have produced transgenic trees with reduced lignin content and/or modified lignin structure without compromising growth traits. Here, three engineered poplar varieties are evaluated as feedstocks using a biocompatible one-pot deep eutectic solvent-mediated process that integrates biomass fractionation and enzymatic saccharification within a single reactor, eliminating water washing and reconditioning. All transgenic poplars exhibit higher fermentable sugar yields than wild-type (WT) trees. Notably, QsuB poplar, incorporating 3,4-dihydroxybenzoate in lignin, achieves the highest glucose conversion yield of 91.3% (vs. 73.0% from WT). AT5 and MdCHS3 poplars, incorporating ferulate esters and naringenin, also demonstrate improved glucose yields (86.7 and 84.7%, respectively), confirming reduced biomass recalcitrance. Additionally, residual lignins are valorized via hydrogenolysis into phenolic compounds, with comparable alkylphenol production across all lines. These findings demonstrate that the transgenic poplar lines not only serve as superior feedstocks for sugar conversion but also provide a rich resource for phenolic compound production, enhancing the operational and economic viability of integrated biorefinery processes.

biomasses↗
DOE OSTI2018

Measurement of the Kinematic Viscosity of Melted Mixtures of Sodium, Lithium, and Beryllium Fluorides and the Effect of the Eutectic Additive Cerium Trifluoride on the Viscosity

Experimental data on the kinematic viscosity and liquidus temperature of certain fused mixtures of sodium, lithium, and beryllium fluorides were obtained, by the method of damping of torsional oscillations of a cylinder with the experimental melt, in validation of the concept of molten-salt incinerator reactors for incinerating transuranium elements from spent nuclear fuel from light-water reactors. The measurements were conducted from the liquidus temperature to 800°C. The effect of the addition of cerium trifluoride on the viscosity of the eutectic melt 58NaF–15LiF–27BeF{sub 2} was studied. It was shown that the additive appreciably reduces the viscosity at low temperature and also lowers the liquidus temperature. The parameters characterizing the temperature dependence of viscosity were determined for the experimental melts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Dynamic Analysis of Recalescence Process and Interface Growth of Eutectic Fe{sub 82}B{sub 17}Si{sub 1} Alloy

By employing the glass fluxing technique in combination with cyclical superheating, the microstructural evolution of the undercooled Fe{sub 82}B{sub 17}Si{sub 1} alloy in the obtained undercooling range was studied. With increase in undercooling, a transition of cooling curves was detected from one recalescence to two recalescences, followed by one recalescence. The two types of cooling curves were fitted by the break equation and the Johnson–Mehl–Avrami–Kolmogorov model. Based on the cooling curves at different undercoolings, the recalescence rate was calculated by the multi-logistic growth model and the Boettinger–Coriel–Trivedi model. Both the recalescence features and the interface growth kinetics of the eutectic Fe{sub 82}B{sub 17}Si{sub 1} alloy were explored. The fitting results that were obtained using TEM (SAED), SEM and XRD were consistent with the changing rule of microstructures. Finally, the relationship between the microstructure and hardness was also investigated.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Studying the Wettability and Reactivity of Liquid Si-Ti Eutectic Alloy on Glassy Carbon

The contact heating sessile drop method was applied for a fundamental study concerning the wettability and reactivity of liquid Si-16.2 at.%Ti (eutectic composition) in contact with glassy carbon. The evolution of the contact angle behaviors and spreading kinetics were evaluated at three different temperatures. A strong temperature dependence was found by analyzing the spreading kinetics in determining the achievement of the equilibrium at the interface. Different spreading stages with different slopes depend on whether the diffusion of reacting phases (liquid Si and C) through the growing reaction layer (SiC) starts to be the rate-limiting factor. On the contrary, the final contact angle value seems not affected by the temperature. The solidified Si-Ti eutectics/GC samples were examined both at the top of the drop and at the cross section by SEM/EDS. The presence of C pockets of dissolution and a SiC layer at the interface confirmed the reactive nature of the interaction mechanisms. In addition, a thicker layer of SiC at the triple line was detected and most probably responsible for pinning the alloy drop at a measured final value of contact angle of 43° ± 2.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Enzymatic synthesis of 1-caffeoylglycerol with deep eutectic solvent under continuous microflow conditions

1-caffeoylglycerol (1-CG) is a hydrophilic ester with a high solubility, and has a strong activity to prevent skin cancer caused by ultraviolet. However, the current preparation process to synthesize 1-CG via transesterification from methyl caffeate (MC) and glycerin was not economic due to long reaction time or adding extra field. Therefore, an enzymatic synthesis with deep eutectic solvent chloride-urea (ChCl-urea) in a microreactor was firstly applied under continuous microflow condition to improve the productivity. A maximum 1-CG yield of 96.49% was obtained under the optimized conditions: temperature of 65 degrees C, flow rate of 2 $μ$L/min, MC concentration of 50 g/L. Compared to the batch reactor, the reaction time reduced by 75%, the $K_m$ value decreased by 5/6, the reuse times of lipase increased by 2.29-fold, the external mass and transfer coefficients increased 10 times, which process was verified by numerical simulation. In addition, the produced 1-CG of 2 mg/mL has a high UV damage remediation ability of 75.16% using HaCaT cell model, which reveals 1-CG can repair the damage of cells radiated by the UV. Thus, this approach represents a convenient and cost-saving method to produce 1-CG using microfuidic biocatalysis.

09 BIOMASS FUELS↗
DOE OSTI2021

Facilitating enzymatic hydrolysis with a novel guaiacol-based deep eutectic solvent pretreatment

In this work, we established a novel deep eutectic solvent (DES) using lignin-derived guaiacol as hydrogen bond donor (HBD). The sole ChCl/guaiacol system was found to be inefficient for the fractionation of wheat straw (WS), while the incorporation of trace AlCl 3 significantly facilitated the degradation of hemicellulose and lignin, resulting in a complete enzymatic digestibility of the pretreated WS. Further, this study revealed that the DES-degraded lignin was readily precipitated during the washing process, and thus hindered the enzymatic hydrolysis of poplar and bamboo (with hydrolysis yield of 42.03% and 71.67%, respectively). Alkali washing offers a possible approach to remove the precipitated lignin, after which a near 100% hydrolysis yield was also obtained for poplar and bamboo.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Alkali-facilitated deep eutectic solvent for effective bamboo saccharification

In this report, a Na 2 S promoted deep eutectic solvent (DES) was established to reduce the natural recalcitrance of moso bamboo (MB) and improve the subsequent enzymatic saccharification. It was found that the addition of Na 2 S (Choline chloride/Ethylene glycol/Na 2 S) dramatically promoted the deconstructions of lignin with highest removal of 74.67 %, but at the same time preserved glucan and hemicellulose to the maximum extent. With the fractionation, the enzymatic saccharification yield of pretreated MB can reach 100 % under the pretreatment condition of 140 °C, and lignin could be readily recovered with a high yield of 81.47 %. The proposed DES is superior to normal alkaline DES in terms of the higher lignin removal and recovery yield, carbohydrate preservation and enzymatic digestibility, which indicated Na 2 S as a novel and powerful reinforcer enhancing the DES fractionation efficiency.

09 BIOMASS FUELS↗
DOE OSTI2020

Synergistic effect of dual Brønsted acidic deep eutectic solvents for oxidative desulfurization of diesel fuel

Deep eutectic solvents (DESs) are generally used as attractive solvents or extractants rather than catalysts in the field of synthesis and separation. Herein, dual Brønsted acidic DESs were prepared by mixing sulfonated quaternary ammonium and oxalic acid as extractants and catalysts for deep oxidative desulfurization. Compared to the DESs with single acidic group, the dual acidic DESs exhibited much higher catalytic activity likely due to the synergistic effect. The 1 H NMR study indicated that the weak interaction between DES and sulfur compounds led to a low extraction capacity. However, the sulfur removal could reach 97.7% under optimized reaction conditions. Density functional theory (DFT) calculations demonstrated that sulfonic group and carboxylic group are of equal importance to desulfurization performance. Further, the desulfurization efficiency was also strongly affected by the viscosity of DESs. Here, we put forward a new strategy that the reaction time could be sharply shortened to 40 min and 100 min by adding low viscous acetonitrile and polyethylene glycol into DES to form mixing reaction system, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

A tailored deep eutectic solvent for high-yield conversion of poplar residues to bio-based building blocks at mild conditions

The generation of condensed compounds in a deep eutectic solvent (DES) pretreatment has become a paramount factor that inhibits the further conversion of pretreated cellulose-rich substrate. Here, this study proposed a novel three-constituent DES system for the value-added utilization of poplar residues by efficiently suppressing hemicellulose derived condensation reactions. The results showed that adding ethanol into the DES system could effectively deconstruct the recalcitrant structure of poplar residues, simultaneously hindering the condensed composition formation. Under optimum ethanol addition (30%), the maximum xylan and lignin removal of 87.94% and 90.99% could be achieved, with more than 90.47% of glucan being preserved. With this, the glucan enzymatic hydrolysis efficiency was remarkably improved to 100% under the pretreatment conditions of 100 °C for 60 min, which was 84.69 times higher than the regular DES-pretreated poplar residues (1.17%). The working mechanism of relieving condensation reactions was characterized by Py-GC–MS, NMR, SEM, FTIR, and others. The results demonstrated that the addition of ethanol could regulate the degradation/conversion pathway of hemicellulose and lignin precipitation, thus inhibit the formation of condensed compounds during the pretreatment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Process strategies for recovery of sugars, lipids, and lignin from oilcane bagasse using natural deep eutectic solvents (NADES)

Sugarcane is being enhanced as a bioenergy crop by engineering it to accumulate and store lipids along with polymeric sugars in vegetative tissues. However, there is no existing process that allows for processing this new crop to recover both lipid and cellulosic sugars from the oilcane bagasse. Therefore, a comprehensive investi- gation of two pretreatment methods—natural deep eutectic solvents (NADES) and chemical-free hydrothermal pretreatment (HT) was conducted to judge their suitability for recovering fermentable sugars, lipids, and lignin from bagasse. Two NADES, i.e., choline chloride: lactic acid (ChCl:LA) and betaine: lactic acid (BT:LA) were prepared using a 1:2 M ratio and were evaluated for pretreatment of oilcane bagasse at 10, 20, and 50 % (w/w) solids, followed by enzymatic hydrolysis at 10 % (w/w) solids. Notably, ChCl:LA NADES treatment at 10 % (w/ w) solids at 140 °C for 2 h, solubilized 78.8 % of lignin and 80.4 % of hemicellulose and allowed 82.7 % enzymatic conversion of glucans to glucose. In contrast, HT pretreatment removed approximately 87.6 % of the hemicellulose and provided an enzymatic glucose yield of 69.7 %. Furthermore, ChCl:LA operated at 50 % solids loading the enriched lipids 2.6-fold (9.2 wt%) in recovered solids compared to HT (6.4 %) and BT:LA (5.1 %) pretreatment processes. NMR-HSQC and GPC analysis showed that ChCl:LA also cleaved the most lignin β–O–4 linkages and demonstrated lower molecular weight compared to HT. As a result, this study demonstrates that NADES pretreatment is an effective green processing method for recovering lipids, sugars, and lignin from bioenergy crops at high solid loading (50 % w/w) within the context of an integrated biorefinery.

09 BIOMASS FUELS↗
DOE OSTI2020

Deep eutectic solvents in separations: Methods of preparation, polarity, and applications in extractions and capillary electrochromatography

Deep eutectic solvents (DESs) have emerged as alternatives to conventional organic solvents and ionic liquids (ILs). Their tunable and designer physio-chemical properties, low cost, and ease of preparation make them attractive solvent systems for use in extractions and additives to chromatographic separations. However, due to the diverse range of hydrogen bond acceptors and donors that comprise DESs, choosing the appropriate solvent for separations can be challenging. This work discusses all methods of DES preparation and details their advantages and disadvantages. Since polarity is an important aspect in their use in separations, the classification of DESs based on the betaine dye and nile red scales as well as Kamlet-Taft parameters is also discussed. Finally, a summary of applications of DESs in various extraction processes (phenolics, fuels, metals, proteins, carbohydrates), solid-phase extraction, solid-phase microextraction, as well as capillary electrochromatography is provided.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗