Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “hydroxide anions”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Effect of Anions on the Delithiation of [Li–Al] Layered Double Hydroxides: Thermodynamic Insights

The utilization of lithium aluminum [Li–Al] layered double hydroxides (LDHs) is explored for direct lithium extraction (DLE) from geothermal brines and minerals. Following extraction, the Li + ions need to be removed from the LDH structure and converted into LiOH or Li 2 CO 3 products, making them suitable for battery applications. The research investigates the delithiation of [Li–Al-X] LDHs (where X = Cl – , OH – , and SO 4 2– ), which were synthesized and dried under different conditions. Herein the study aims to understand how the choice of anions and drying conditions affects the delithiation process. To determine the stability of these [Li–Al] LDHs, high-temperature oxide melt solution calorimetry is employed. The results reveal that the stability of LDHs varies significantly based on postdrying conditions, anion choice, and the water content in the interlayer. The order of stability, as indicated by the enthalpy of formation values, is found to be OH-LDH-O > OH-LDH-A > SO 4 -LDH-O > SO4-LDH-A > Cl-LDH-O > Cl-LDH-A. This trend is attributed to the interactions among the interlayer species and the metal hydroxide layers.

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

Impact of Anions and Water Content on [Li–Al] Layered Double-Hydroxide Stability

[Li–Al] layered double hydroxides (LDHs) are compounds with potential as sorbents for lithium extraction from brine solutions. Here, in this work, heat capacities were measured from approximately 2.5 to 300 K for six [Li–Al] LDHs with differing anions (Cl – , OH – , and SO 4 2– ) and water content (denoted A for air-dried and O for oven-dried). These measurements were used to calculate the standard entropy at 298.15 K, and the results were combined with previously performed enthalpy measurements to calculate Gibbs energies of formation from the binary compounds. The calculated order of stability based on Gibbs energies of formation was Cl-LDH-O > OH-LDH-O > Cl-LDH-A > SO 4 -LDH-O > SO 4 -LDH-A > OH-LDH-A. Results support previous findings that higher water content generally raises the Gibbs energy of the LDH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Synchrotron X-ray-induced Synthesis of Copper Hydroxide Nitrate Nanoplates on Cu Thin Films in an Ambient Atmosphere

Synchrotron X-rays are widely used for material characterizations. However, they can also ionize atoms and molecules to damage and manipulate probed materials. We report here an X-ray-induced growth of copper hydroxide nitrate, Cu 2 (OH) 3 NO 3 , on copper thin films in the ambient atmosphere without solvents and thermal treatment. In situ synchrotron X-ray diffraction measurements showed that the time-dependent growth process of the Cu 2 (OH) 3 NO 3 is accompanied by the consumption of Cu metal and can be described by a sigmoidal model. The growth rate was reduced after the initial fast growth period. Scanning electron microscopy (SEM) images show that the isolated islands of Cu 2 (OH) 3 NO 3 nanoplates formed in the beginning, which grew together with new nanoplates formed under continued X-ray irradiation. The result demonstrated that high-flux synchrotron X-rays may provide an unconventional approach to synthesizing and manipulating materials, which will inspire future investigation both experimentally and theoretically.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

LTE-P-6 AEM Conductivity

A procedure for measuring the hydroxide conductivity of an anion exchange membrane (AEM). A four-electrode In-plane conductivity is measured as a function of relative humidity (RH).

08 HYDROGEN↗
DOE OSTI2025

Unraveling Anion-Specific Inhibition and Structural Modulation of Gibbsite Crystallization: Implications for Aluminum Mobility in Natural and Engineered Systems

Gibbsite (α-Al(OH) 3 , sometimes designated as γ-Al(OH) 3 ) plays a crucial role in the chemistry of aluminum in the environment and industry, yet its crystallization behavior under multianionic conditions is not well understood. Here, in this study, we investigate how six common anions─fluoride (F – ), chloride (Cl – ), bromide (Br – ), nitrate (NO 3 – ), sulfate (SO 4 2– ), and phosphate (PO 4 3– )─influence the mineralization, structure, and morphology of gibbsite at room temperature. The results show that PO 4 3– , SO 4 2– , and F – strongly inhibit gibbsite formation, stabilizing amorphous or alternative crystalline phases such as nordstrandite and cryolite. On the contrary, Cl – , Br – , and NO 3 – allow partial to complete crystallization of gibbsite without significant morphological changes. Solid-state 27 Al magic angle spinning nuclear magnetic resonance provides crucial insight into aluminum coordination environments in both crystalline and amorphous phases, distinguishing between octahedral, pentahedral, and tetrahedral Al species. The density functional theory calculations reveal a direct correlation between the Al–X bond strength and the inhibition of crystallization, following the order: PO 4 3– > SO 4 2– > F – > NO 3 – > Cl – > Br – . These findings offer molecular-scale insights into anion-specific effects on aluminum hydroxide nucleation and transformation, improving the understanding of gibbsite formation and aluminum cycling in soils, phosphate retention, contaminant immobilization, and waste treatment strategies in nuclear and industrial settings. These insights can also guide the controlled synthesis of aluminum hydroxide materials with tailored crystallinity and morphology via liquid-assisted methods.

Anions effect↗
DOE OSTI2020

An Exceptionally Stable Metal–Organic Framework Constructed from Chelate-Based Metal–Organic Polyhedra

In this paper, we report the rational design and synthesis of a new, water-stable metal-organic framework (MOF), Fe-HAF-1, constructed from supramolecular, Fe3+-hydroxamate-based polyhedra with mononuclear metal nodes. Owing to its chelate-based con-struction, Fe-HAF-1 displays exceptional chemical stability in organic and aqueous solvents over a wide pH range (pH 1-14), including in the presence of 5 M NaOH. Despite the charge-neutrality of the Fe 3+ -tris(hydroxamate) centers, Fe-HAF-1 crystals are negatively charged above pH 4. This unex-pected property is attributed to the formation of defects during crystallization that results in uncoordinated hydroxamate ligands or hydroxide-coordinated Fe centers. The anionic na-ture of Fe-HAF-1 crystals enables selective adsorption of pos-itively charged ions in aqueous solution, resulting in efficient separation of organic dyes and other charged species in a size-selective fashion. Fe-HAF-1 presents a new addition to a small group of chelate-based MOFs and provides a rare framework whose 3D connectivity is exclusively formed by metal-hydroxamate coordination.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of relative humidity on the interlayer spacing of phosphate intercalated Mg, Al layered double hydroxide (hydrotalcite‐like) crystals

Abstract The availability of water and the type of interlayer anions present affect the arrangement and interlayer spacing of layered double hydroxide (LDH). A systematic study of the effect of relative humidity (RH) on the basal spacing of phosphate intercalated, magnesium aluminum LDHs (MgAl–PO 4 LDH) was conducted, confirming that MgAl‐PO 4 LDH exhibit distinct interlayer spacing corresponding to separate low‐ and high‐hydration states produced when exposed to low and high humidity conditions. The transition from the low‐ to high‐hydration form begins when RH exceeds 33% and is accompanied by the transition from one to two interlayers of water. An improved understanding of the effect of RH on MgAl–PO 4 LDHs will enable more accurate atomistic modeling and experimental characterization of MgAl–PO 4 LDHs and may lead to improvements in the tunability of MgAl‐PO 4 LDHs for commercial applications such as slow‐release fertilizer.

Reed, Titus↗
DOE OSTI2023

Chloride Insertion Enhances the Electrochemical Oxidation of Iron Hydroxide Double-Layer Hydroxide into Oxyhydroxide in Alkaline Iron Batteries

Rechargeable alkaline iron batteries that constitute environmentally benign electrolytes and earth-abundant industrial materials are desirable green solutions for large-scale energy storage. As one of the most abundant metal elements in the earth’s crust, iron (Fe) can satisfy nearly all criteria for low-cost and safe battery electrodes. However, challenges in achieving reversible Fe redox impede their extensive implementation in modern energy supply systems. Here, this study revealed that Cl-anion insertion into Fe(OH) 2 layered double hydroxide (LDH) formed a green rust intermediate phase with the formula [Fe 2 2+ Fe 1 3+ (HO – ) 6 ] + [Cl] – , which assisted a high Fe(OH) 2 /FeOOH conversion reaction (64.7%) and improved cycling stability. This new iron redox chemistry was validated by operando X-ray diffraction, electrochemical testing, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) analysis, scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy (STEM-EDS) mapping, and molecular dynamics (MD) simulations. Our study provides new insight into designing LDH materials for high-capacity alkaline iron batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Purification and Concentration of 99 Mo from a UREX raffinate

The medical isotope 99m Tc ( t ½ = 6.0 h) accounts for over 80% of isotopes used in diagnostic nuclear medicine today and is normally derived from its transient equilibrium parent 99 Mo ( t ½ = 66 h). To reduce U.S. dependence on 99 Mo derived from HEU by foreign suppliers, the NNSA/M3 program—under the American Medical Isotope Production Act—has been tasked with facilitating the work of domestic 99 Mo suppliers that do not utilize HEU. Superconducting electron linear accelerators with high-Z converter targets can generate bremsstrahlung photons and neutron fluxes that can induce photonuclear reactions and LEU fission. After sufficient production intervals, targets can be rotated out and processed while another batch is irradiated. The process flow chemistry is shown in Figure 1. The irradiated U 3 O 8 targets are retrieved and dissolved in HNO 3 ; the volatile fission products are expelled and captured during this step. The HNO 3 liquor bearing the uranyl, fission and activation products is injected into the UREX suite of liquid-liquid extraction banks. The uranyl is partitioned in typical fashion using tri-$\textit{n}$-butyl phosphate (TBP) in a hydrocarbon diluent. The raffinate—comprising mainly 99 Mo and fission products—is then injected into the MoLLE (Molybdenum Liquid-Liquid Extraction) flowsheet, where the Mo is selectively extracted by an organophosphorous acid extractant such as di-(2-ethylhexyl phosphoric acid) (HDEHP). Trace amounts of Nb, Zr, Np, I, and Te are co-extracted. The Mo is stripped using acetohydroxamic acid (AHA) and fed onto an anion exchange column. Following a series of hydroxide, HCl, and oxalic acid wash steps, the Mo can be recovered in NaOH/NaCl. A manuscript describing this process chemistry in more detail was recently published.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

Chemical Characterization Results for Tank 40 Sludge Batch 10 Waste Acceptance Product Specifications (WAPS) Sample

A 3-L sample (HTF-40-23-24) obtained from Tank 40 following transfer of Tank 51 to achieve the final Sludge Batch 10 processing composition was received by Savannah River National Laboratory (SRNL). SRNL was tasked with characterization of the sample in accordance with requirements for reporting the Waste Acceptance Product Specifications. A representative subsample, approximately 500 mL, was prepared by continuously agitating the 3-L sample via a mixing blade inserted into the bottle. This subsample was then used for the chemical and physical characterization reported here. This characterization includes the following: (1) Supernate and slurry density; (2) Weight percent solids; (3) Mercury Analysis (supernate and slurry); (4) Anions; (5) Total Organic/Inorganic Carbon; (6) Free Hydroxide; (7) Other Base; (8) Elementals; (9) Volatile Organic Analysis and Semi-volatile Organic Analysis; and (10) Fissile Radionuclides and Uranium Enrichment. The results of this physical and chemical characterization of the sample are documented in this report.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Dissolution of poorly soluble uranyl phosphate phases in the Metaautunite Subgroup under uranyl peroxide cage cluster forming conditions

Uranyl phosphate minerals are widespread in uranium deposits and usually exhibit very low solubility in aqueous systems. Uranyl phosphates of the autunite group and metaautunite subgroup impact the mobility of uranium in the environment and have inspired groundwater remediation strategies that emphasize their low solubility. The importance of soluble uranium-bearing macro-anions, including nanoscale uranyl peroxide cage clusters, is largely unexplored relative to solubilization of normally low-solubility uranium minerals. Eight synthetic analogs of metaautunite subgroup minerals have been prepared and placed in various alkaline aqueous solutions containing hydrogen peroxide and tetraethylammonium hydroxide. Each uranyl phosphate studied has a topologically identical anionic sheet of uranyl square bipyramids and phosphate tetrahedra combined with various cations (Li + , Na + , K + , Rb + , Cs + , Mg 2+ , Ca 2+ , Ba 2+ ) and water in the interlayer. Uranyl peroxides formed under many of the experimental conditions examined, including solid studtite [(UO 2 )(O 2 )(H 2 O) 2 ](H 2 O) 2 and soluble uranyl peroxide cage clusters containing as many as 28 uranyl ions. Uranyl phosphate solids in contact with solutions in which uranyl peroxide cage clusters formed dissolved extensively or completely. The greatest dissolution of uranyl phosphates occurred in systems that contained cations with larger hydrated radii, Li + and Na + . The details of the uranium speciation in solution depended on the pH and counter cations provided from the interlayers of the uranyl phosphate solids.

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

Surprising Relationship between Silicon Anode Calendar Aging and Electrolyte Components in a Localized High-Concentration Electrolyte System

Although localized high-concentration electrolytes (LHCEs) have been shown to improve the calendar lifetime of silicon anodes, the roles of the electrolyte constituents in calendar aging are not well understood. Here, in this work, we utilize a voltage hold protocol and an LHCE with varying molar ratios of lithium bis(fluorosulfonyl)imide (LiFSI), tetramethylene sulfone (TMS), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) to probe the component roles during aging. Interestingly, the estimated calendar lifetime and irreversible lithium losses from the V-hold experiments are independent of the electrolyte formulations. Contrarily, the solid electrolyte interphase (SEI) composition depends on the electrolyte formulation. X-ray photoelectron spectroscopy shows that TMS-coordinated species decompose to form insoluble alkanes and lithium hydroxide (LiOH), while lithium fluoride (LiF) originates from the anion-coordination complex. The SEI composition does not appear to play a significant role in the silicon anode passivity, as measured by parasitic current, suggesting that the SEI-electrolyte interactions dictate the calendar aging mechanisms.

Si anode↗
DOE OSTI2023

Theoretical Examination of the Hydroxide Transport in Cobaltocenium-Containing Polyelectrolytes

Polymers incorporating cobaltocenium groups have received attention as promising components of anion-exchange membranes (AEMs), exhibiting a good balance of chemical stability and high ionic conductivity. In this work, we analyze the hydroxide diffusion in the presence of cobaltocenium cations in an aqueous environment based on the molecular dynamics of model systems confined in one dimension to mimic the AEM channels. In order to describe the proton hopping mechanism, the forces are obtained from the electronic structure computed at the density-functional tight-binding level. We find that the hydroxide diffusion depends on the channel size, modulation of the electrostatic interactions by the solvation shell, and its rearrangement ability. Hydroxide diffusion proceeds via both the vehicular and structural diffusion mechanisms with the latter playing a larger role at low diffusion coefficients. The highest diffusion coefficient is observed under moderate water densities (around half the density of liquid water) when there are enough water molecules to form the solvation shell, reducing the electrostatic interaction between ions, yet there is enough space for the water rearrangements during the proton hopping. Furthermore, the effects of cobaltocenium separation, orientation, chemical modifications, and the role of nuclear quantum effects are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Vapor-Fed Cathode Microbial Electrolysis Cells with Closely Spaced Electrodes Enables Greatly Improved Performance

Hydrogen can be electrochemically produced in microbial electrolysis cells (MECs) by current generated from bacterial anodes with a small added voltage. MECs typically use a liquid catholyte containing a buffer or salts. However, anions in these catholytes result in charge being balanced predominantly by ions other than hydroxide or protons, leading to anode acidification. To enhance only hydroxide ion transport to the anode, we developed a novel vapor-fed MEC configuration lacking a catholyte with closely spaced electrodes and an anion exchange membrane to limit the acidification. This MEC design produced a record-high sustained current density of 43.1 ± 0.6 A/m 2 and a H 2 production rate of 72 ± 2 LH 2 /L-d (cell voltage of 0.79 ± 0.00 V). There was minimal impact on MEC performance of increased acetate concentrations, solution conductivity, or anolyte buffer capacity at applied voltages up to 1.1 V, as shown by a nearly constant internal resistance of only 6.8 ± 0.3 mΩ m 2 . At applied external voltages >1.1 V, the buffer capacity impacted performance, with current densities increasing from 28.5 ± 0.6 A/m 2 (20 mM phosphate buffer solution (PBS)) to 51 ± 1 A/m 2 (100 mM PBS). Furthermore, these results show that a vapor-fed MEC can produce higher and more stable performance than liquid-fed cathodes by enhancing transport of hydroxide ions to the anode.

anion exchange membrane↗
DOE OSTI2025

Boosting the Oxygen Evolution Reaction by Tuning the Interfacial Iron Adsorption on Layered Double Hydroxide

Understanding the interaction between ions in the electrolyte and electrode materials plays an important role in optimizing the water electrolysis performance for hydrogen production. Herein, the synergistic effect of iron (Fe) in the electrolyte and interlayer anions within the layered structure on the oxygen evolution reaction (OER) has been investigated by combining material synthesis with controlled structure, multiple characterization techniques, and first-principles calculations. Nickel aluminum layered double hydroxides (NiAl-LDHs) with different interlayer anions (CO 3 2– , Cl – , and Br – ) show similar oxygen evolution activity in the absence of Fe species in the electrolyte. The addition of Fe into the electrolyte results in improved performance for all of the NiAl-LDHs, following the rank LDH-Br > LDH-Cl > LDH-CO 3 , under all of the conditions with varied concentration of Fe. X-ray absorption spectroscopy and identical location electron microscopy analyses show that the LDH structure remains unchanged after the OER activity test, while in situ stationary probe rotating disk electrode inductively coupled plasma mass spectrometry (SPRDE-ICP-MS) measurements show partial dissolution of the intercalating halide ions during cycling, with less dissolution for Br-intercalated materials. Insights from theoretical calculations demonstrate the thermodynamic preference of Br – to remain intercalated in the presence of Fe, while the stronger adsorption of Fe(OH) 3 species on the LDH-Br sample promotes the OER activity. In conclusion, these results provide mechanistic insights into the rational design of active layered materials with an enhanced OER performance for efficient water electrolysis.

58 GEOSCIENCES↗
DOE OSTI2020

Disulfonamide Ligands as f-Element Extractants from Alkaline High-Level Waste

Almost 100 million gallons of high level waste (HLW) has been generated from defense reprocessing programs to support nuclear weapons production. HLW is currently stored at the Hanford and Savannah River Sites (SRS) [1]. It contains radioactive components, such as {sup 137}Cs, {sup 99}Tc and {sup 90}Sr, as well as large amounts of non-radioactive species, including solvated cations and insoluble metal hydroxides. HLW has high concentration of soluble hydroxides ([OH{sup -}] = 2 M at SRS [2]), complexing inorganic anions ([NO{sub 3}{sup -}] ∼ 0.65 - 3.7 M at SRS [2]) and a high ionic strength. Even though the majority of actinide component in alkaline HLW is precipitated, studies of An(III) and Ln(III) complexation in highly alkaline solutions in the presence of high nitrate concentrations have showed that soluble nitrate complexes can be formed [3]. The current treatment of HLW at SRS currently consists of two processes: The Actinide Removal Process (ARP) and the Next-Generation Caustic-Side Solvent Extraction process (NG-CSSX). Strontium and actinides are removed by sorption on monosodium titanate through the Actinide Removal Process (ARP) commonly referred to as the alpha-strike step [4]. Then, cesium is selectively extracted from the alkaline media via the Caustic-Side Solvent Extraction (CSSX) process [5]. The CSSX solvent consists of a calix[4]arene-crown-6 extractant dissolved in an inert hydrocarbon matrix containing i) a solvent modifier (alkylphenoxy alcohol) which increases extractant solubility and prevents third phase formation, and ii) a suppressor (trioctylamine or guanidine) - that mitigates surfactant effects. The CSSX process removes {sup 137}Cs selectively and rapidly, yet the post- CSSX aqueous stream may still contain high amounts of An, thus requiring a second ARP treatment (referred to as 'alpha-finishing') for some tanks. Despite the success of the ARP process in removing Sr and An, it often represents the kinetic bottleneck of integrated processing, as it is slower than solvent extraction. Understanding the complexation of actinides by organic ligands that are compatible with the CSSX process could eventually lead to a combined caustic-side Cs/Sr/actinide extraction process with better economics due to a reduced amount of monosodium titanate and/or a shorter required contact time with titanate during ARP. This would ensure a low-activity waste (LAW) stream with no actinides without additional ARP processing post-CSSX. Disulfonamides were studied for extraction of Sm(III) from alkaline aqueous media of pH 10-14 into dichloromethane. Up to 82% of Sm(III) was extracted from solutions of pH 12.5 -13.5 and up to 84% from solutions of pH 10.5 - 11.5. These results show some resemblance with Am extraction results by calixarene ligands previously reported [10]. Kinetic studies demonstrated that even 5 min is enough to complete stripping, whereas extraction is time-limiting process and requires up to 20 h for efficient removal of Sm(III) from alkaline aqueous media. Determination of composition of complexes in solution after extraction by the equilibrium shift method showed a 1:1 Sm(III):dsa-2 complexation ratio for the extracted species.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Surface-Enhanced Raman Detection of the CO 2 Moisture Swing

The development of scalable, energy-efficient carbon dioxide (CO 2 ) capture technologies is critical for achieving net-zero emissions. Moisture swing (MS) sorbents offer a promising alternative to traditional thermal regeneration methods by enabling reversible CO 2 binding through humidity-driven ion hydrolysis. In this study, we investigate the anion speciation dynamics in two classes of MS materials─an anion-exchange resin with a bicarbonate anion and activated carbon impregnated with potassium bicarbonate salt─using both sorption measurements and in situ surface-enhanced Raman spectroscopy (SERS). Ni-coated Ag nanowires were employed as SERS substrates to enhance signal intensity and enable the real-time detection of carbonate (CO 3 2– ), bicarbonate (HCO 3 – ), and hydroxide (OH – ) species under controlled humidity conditions in both air and nitrogen atmospheres. The results reveal humidity-dependent interconversion between anionic species with significant spectral shifts confirming the reversible hydrolysis reactions that drive the MS mechanism. Under humid conditions, we observed the depletion of bicarbonate signals and a concurrent increase in carbonate species, consistent with moisture-induced desorption of CO 2 . With the activated carbon samples, we further observed the formation of hydroxide. These findings not only validate the mechanistic models of humidity-driven anion exchange in MS sorbents but also demonstrate the practical potential of SERS as an operando diagnostic tool for monitoring CO 2 capture media. The ability to resolve and semiquantitatively evaluate the reversible transformation of carbonate, bicarbonate, and hydroxide ions under realistic environmental conditions provides valuable insight for the rational design, performance optimization, and quality control of next-generation sorbent materials for direct air capture applications.

CO2 capture↗