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Results for “Inorganic acids and bases”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Methods of recovering lignin and other products from biomass

Methods of recovering lignin products and other products from biomass. The method comprises adding a chemical agent to a stored biomass comprising lignin to form a chemically-treated biomass. The chemical agent comprises an acid, a base, an inorganic salt, or a combination of the inorganic salt and one of the acid or the base. The chemically-treated biomass is stored under anaerobic conditions. Lignin products, such as high molecular weight lignin, medium molecular weight lignin, or low molecular weight lignin, are recovered from the chemically-treated biomass. Additional methods of recovering lignin products and other products from biomass are disclosed.

09 BIOMASS FUELS↗
NASA NTRS1994

Waste gas storage

Method for storing a waste gas mixture comprised of nitrogen, oxygen, carbon dioxide, and inert gases, the gas mixture containing corrosive contaminants including inorganic acids and bases and organic solvents, and derived from space station operations. The gas mixture is stored under pressure in a vessel formed of a filament wound composite overwrap on a metal liner, the metal liner being pre-stressed in compression by the overwrap, thereby avoiding any tensile stress in the liner, and preventing stress corrosion cracking of the liner during gas mixture storage.

Vickers, Brian D.↗
NASA NTRS1994

Gas stream purifier

A gas stream purifier has been developed that is capable of removing corrosive acid, base, solvent, organic, inorganic, and water vapors as well as particulates from an inert mixed gas stream using only solid scrubbing agents. This small, lightweight purifier has demonstrated the ability to remove contaminants from an inert gas stream with a greater than 99 percent removal efficiency. The Gas Stream Purifier has outstanding market and sales potential in manufacturing, laboratory and science industries, medical, automotive, or any commercial industry where pollution, contamination, or gas stream purification is a concern. The purifier was developed under NASA contract NAS9-18200 Schedule A for use in the international Space Station. A patent application for the Gas Stream Purifier is currently on file with the United States Patent and Trademark Office.

Adam, Steven J.↗
DOE OSTI2026

Quantifying Temperature Dependence of Pu(IV) Absorbance Spectra for Advanced Online Monitoring of Nuclear Processes

This article presents a systematic study of Pu(IV) absorbance spectral features as a function of temperature to develop an understanding of this parameter’s effect on chemometric models that can be used as online monitoring tools to support nuclear processing. The descriptive and predictive models that provide real-time feedback of these processes are usually constructed with data collected in conditions typical of a laboratory environment, which can differ drastically from a processing environment. To assess the impact of temperature on Pu(IV) absorbance spectra, 11 samples of Pu(IV) were synthesized with varying HNO 3 concentrations ranging from 0.6 to 9.5 M and heated between 15 and 45 °C. Ultraviolet (UV)–visible (vis)–near-infrared (NIR) absorption spectra collected at different HNO 3 concentrations and temperatures revealed that features associated with Pu(IV) are sensitive to temperature at all HNO 3 concentrations and that changes in features depend on HNO 3 concentration. The contributions of temperature and HNO 3 concentration to variation in Pu(IV) spectral features were evaluated using the principal component analysis of spectra that were baseline-corrected with an asymmetric least-squares method. Furthermore, predictive modeling for HNO 3 concentration with partial least-squares regression of UV–vis–NIR spectra highlighted the importance of accounting for temperature in the calibration set to optimize model performance. This methodology constitutes a new, systematic approach to account for the effect of temperature on the absorption spectra of metal ions and is useful for process monitoring applications in many industries.

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

Kinetics and Mechanism of Ce(IV) Phase Transfer by the Neutral Extractants Tributyl Phosphate and N,N -Di(2-ethylhexyl)isobutyramide

Tributyl phosphate and N,N-di(2-ethylhexyl)isobutyramide (DEHiBA) are uranium-selective extractants that could be used to recover low-enriched uranium from commercial used nuclear fuel. The economic viability of liquid-liquid extraction processes for chemical separations depends on both thermodynamic and kinetic considerations. Here we used microfluidic droplet extraction to measure interfacial phase transfer rate constants for the extraction and stripping of Ce(IV), a non-radioactive actinide surrogate. The Damkohler numbers for each system were calculated and the phase transfer processes were determined to be diffusion-limited under all conditions, contrary to prior studies using constant interface stirred cells and single drop methods. A well-extracted 2:1 DEHiBA/Ce(IV) complex in the organic phase was determined from batch distribution studies, suggesting a different extraction mechanism for Ce(IV) compared with poorly extracted Pu(IV). Finally, phase disengagement rates were found to be rapid in both systems, in agreement with other studies.

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

A Rapid Microfluidic Neptunium Extraction Using a Supported Liquid Membrane Module

Extraction of neptunium from acidic matrices is important for its quantification, but its complex redox chemistry can cause variable yields. This study develops a microfluidic redox extraction for rapidly separating neptunium from submilliliter samples, achieving up to 90% process yield in less than 10 min for samples as small as 100 μL, with over 97% steady-state yield achieved after 20 min. It uses a supported liquid membrane module loaded with 30 vol % tributyl phosphate in n-dodecane, which performs forward- and back-extractions in a single, continuous step. Neptunium is first oxidized to +6 for extraction and then reduced during stripping. Bromate was selected as an oxidant over permanganate for its greater compatibility with the organic phase, achieving complete oxidation in under 30 s. Ascorbic acid and hydrogen peroxide were both effective reductants. Finally, the system’s high yield and rapid kinetics make it promising for future separations from complex mixtures.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Adsorption and Chromatographic Behavior of Dispersed Sodium Bismuthate Systems for the Separation of Americium from Curium

The selective partitioning of americium (Am) and curium (Cm) is integral for nuclear science areas such as the nuclear fuel cycle, stockpile stewardship, and isotope production but remains a long-standing radioanalytical challenge due to nearly identical chemical properties. Differences in redox chemistry can be exploited since Am can be oxidized to the hexavalent oxidation state. Sodium bismuthate (NaBiO 3 ) exhibits favorable oxidation and ion exchange characteristics conducive to a rapid and efficient Am/Cm chromatographic separation. Contact of nitric acid with NaBiO 3 was shown to significantly decrease the nitric acid concentration and solution volume. The adsorption, kinetic, and chromatographic behavior of Am and Cm in systems that disperse NaBiO3 in filter aids was evaluated. Further, dispersion of NaBiO 3 increased separation factors to over 100, with rapid kinetics achieved within 1 min of contact and sustained for at least 2 h. The adsorption capacity was more than doubled from 0.066 mequiv g –1 for solid NaBiO 3 alone to 0.149(6) and 0.156(9) meq g –1 when dispersed in Celite 545 and silica gel, respectively. Complete separation was achieved in all systems with ~100% recovery in the respective eluted fractions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Experimental and Multiscale Modeling Insights for Radiation-Driven Neptunium Redox Processes at Elevated Temperatures

Studies of the radiation-driven reactions of actinide elements at elevated temperatures are extremely limited, but important given that radiation heating of used nuclear fuel can affect the radiolytically promoted actinide redox processes occurring in hydroprocessing environments. Under these conditions, the high concentration of nitric acid present makes the reaction of actinides, such as neptunium, with nitric acid radiolysis products significant. Therefore, here we present derivation of the rate coefficients for the reaction of pentavalent neptunium with the nitrate radical at elevated temperature, resulting in Eyring and Arrhenius parameters for this important reaction. Here, we also revisit our previously published multiscale model predictions for radiation-induced neptunium redox chemistry and present an iteration which successfully operates over a wider range of nitric acid concentrations, 0.1–6.0 M.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Electrochemical Behavior of Cerium at an Indium Tin-Doped Oxide Electrode in Acidic Media

The redox behavior and speciation of cerium at mesoporous thin films composed of nanoparticles of indium tin-doped oxide (nITO) electrodes were characterized in pH 4.8, 0.1 M acetate buffer and both 0.1 and 1 M HNO 3 using electrochemical techniques and X-ray photoelectron spectroscopy. Anodic deposition of ceria species from Ce(III) to the nITO electrode was achieved under all solvent conditions via spontaneous condensation of electrochemically generated ceric hydroxide species. In 1 M nitric acid, the rate of CeO 2 dissolution is on the same order as CeO 2 deposition, resulting in negligible amounts of CeO 2 electrodeposited at the nITO surface. The cathodic stripping of CeO 2 from the nITO substrate deposited in 0.1 M nitric acid or pH 4.8 acetate buffer follows a 2-step process where Ce(IV)-oxide is initially reduced to an unstable Ce(III)-oxide species that rapidly undergoes acid catalyzed dissolution to yield soluble Ce(III) (aq) . These findings provide a foundation for the pH and anodic potential controlled deposition of CeO 2 thin films to ITO substrates, which can aid in the development of materials composed of ceria. As a result, they can also be used to infer likely analogous actinide redox behavior and speciation at these electrodes.

Cerium↗
DOE OSTI2026

CMPO-Functionalized Silica Sorbents for pH-Tunable Separation and Enrichment of Rare-Earth Elements from Environmental Matrices

Rare-earth elements (REEs) are crucial in many applications, yet mutual separation is challenging due to their similar chemical behavior. Octylphenyl- N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) is an organophosphorus ligand originally developed for extracting actinides and lanthanides from spent nuclear fuel. Here, we report a pH-tunable CMPOfunctionalized silica sorbent for selective REE separation from complex aqueous matrices. A CMPO-associated silica gel sorbent was synthesized and characterized by Brunauer−Emmett−Teller (BET) surface area, scanning electron microscopy, and X-ray photoelectron spectroscopy to confirm the surface functionalization and binding behavior. Sorbent performance was evaluated by using a synthetic 46- element solution and a real phosphate rock fertilizer leachate. Notably, REEs were successfully eluted with ultrapure water, demonstrating reversible desorption controlled by pH adjustment. Packed-bed column studies increased the REE mass fraction from 3.6% to 64% (20-fold enrichment), with up to 30-fold enrichment of neodymium. The adsorption process follows the Langmuir isotherm behavior and follows pseudo-second-order kinetics. The uptake capacity of 1 μmol of REEs per 4.2 μmol of CMPO supports the formation of a predominantly 4:1 ligand:rare earth element(III) pseudocomplex. These results demonstrate CMPO-functionalized silica as a selective, water-elutable, and low-chemical-input platform for sustainable REE recovery from environmental and industrial sources.

chelating ligands↗
DOE OSTI2025

Enabling Solar Water Oxidation by BiVO 4 in Strongly Acidic Solutions

The oxygen evolution reaction (OER) is paired with various electrochemical and photoelectrochemical reduction reactions used for fuel and chemical production. As there is a strong interest in performing many of these reduction reactions in strongly acidic solutions to increase the reaction rate, efficiency, or selectivity, there is also a great interest in enabling efficient and stable OER in strongly acidic solutions. In this study, we report stable photoelectrochemical OER (POER) of a BiVO 4 photoanode in 0.1 M HNO 3 (pH 1). This was achieved by using Nb 2 O 5 as a protection layer. While Nb 2 O 5 was rarely used as a protection layer for photoelectrodes in the past, we show its excellent capability to suppress both the chemical and photoelectrochemical dissolution of BiVO 4 at pH 1. After stabilizing BiVO 4 with a Nb 2 O 5 protection layer, we added Co 2+ ions to the electrolyte as an OER catalyst to enhance the POER. We found that Co (aq) 2+ can serve as a homogeneous OER catalyst without being deposited as a CoO x solid catalyst on Nb 2 O 5 . When we performed the POER using unprotected BiVO 4 with Co (aq) 2+ under the same condition, although POER was enhanced, the enhancement could not be sustained due to the chemical dissolution of BiVO 4 . After the POER, we found that a Co 3+ -containing OER catalyst was deposited on the bare BiVO 4 surface. This result suggested that the use of Co 2+ ions as a homogeneous catalyst was possible due to the inertness of the Nb 2 O 5 surface toward the adsorption or deposition of Co ions. This study enabling stable POER of BiVO 4 in 0.1 M HNO 3 using the combination of a Nb 2 O 5 protection layer and Co (aq) 2+ as a homogeneous OER catalyst provides promising possibilities for acidic POER and OER.

Catalysts↗
NASA NTRS1981

Carbon scrubber

Inorganic carbon is removed from samples to be analyzed for "total organic carbon". In automated water analysis systems, semipermeable membrane separates two sample streams, one treated with acid, other with base. Carbonate and bicarbonated ions are converted to dissolved CO2 by acid; reverse process occurs in basic stream. Only CO2 is passed by membrane, from acid treated stream to base treated stream. Acidic stream emerges free of all inorganic carbon.

Frant, M. S.↗
DOE OSTI2023

Photochemically‐Driven CO 2 Release Using a Metastable‐State Photoacid for Energy Efficient Direct Air Capture

Abstract One of the grand challenges underlying current direct air capture (DAC) technologies relates to the intensive energy cost for sorbent regeneration and CO 2 release, making the massive scale (GtCO 2 /year) deployment required to have a positive impact on climate change economically unfeasible. This challenge underscores the critical need to develop new DAC processes with substantially reduced regeneration energies. Here, we report a photochemically‐driven approach for CO 2 release by exploiting the unique properties of an indazole metastable‐state photoacid (mPAH). Our measurements on simulated and amino acid‐based DAC systems revealed the potential of mPAH to be used for CO 2 release cycles by regulating pH changes and associated isomers driven by light. Upon irradiating with moderate intensity light, a ≈55 % and ≈68 % to ≈78 % conversion of total inorganic carbon to CO 2 was found for the simulated and amino acid‐based DAC systems, respectively. Our results confirm the feasibility of on‐demand CO 2 release under ambient conditions using light instead of heat, thereby providing an energy efficient pathway for the regeneration of DAC sorbents.

Premadasa, Uvinduni I.↗
DOE OSTI2023

Photochemically-Driven CO 2 Release Using a Metastable-State Photoacid for Energy Efficient Direct Air Capture

One of the grand challenges underlying current direct air capture (DAC) technologies relates to the intensive energy cost for sorbent regeneration and CO 2 release, making the massive scale (GtCO 2 /year) deployment required to have a positive impact on climate change economically unfeasible. This challenge underscores the critical need to develop new DAC processes with substantially reduced regeneration energies. Here, in this work, we report a photochemically-driven approach for CO 2 release by exploiting the unique properties of an indazole metastable-state photoacid (mPAH). Our measurements on simulated and amino acid-based DAC systems revealed the potential of mPAH to be used for CO 2 release cycles by regulating pH changes and associated isomers driven by light. Upon irradiating with moderate intensity light, a ≈55 % and ≈68 % to ≈78 % conversion of total inorganic carbon to CO 2 was found for the simulated and amino acid-based DAC systems, respectively. Our results confirm the feasibility of on-demand CO 2 release under ambient conditions using light instead of heat, thereby providing an energy efficient pathway for the regeneration of DAC sorbents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Influence of Inorganic Carbon Sources on Low-pH Succinic Acid Production by Issatchenkia orientalis : Process Insights and Kinetic Analysis

Bio-based succinic acid (SA) production has attracted significant interest; however, the relationship between fermentation conditions and SA biosynthesis remains insufficiently understood, particularly under low-pH operation. In this study, an engineered, acid-tolerant, nonmodel yeast, Issatchenkia orientalis , was employed to investigate the role of inorganic carbon supplementation in SA production from glucose. Because regulation of gas-phase CO 2 during fermentation is challenging due to low solubility and off-gas losses, liquid-phase inorganic carbon sources, carbonic acid (H 2 CO 3 ) and sodium carbonate (Na 2 CO 3 ), were evaluated as indirect CO 2 donors. Fermentations were conducted in a corn steep liquor-based medium under acidic conditions. Shake-flask experiments demonstrated that H 2 CO 3 supplementation increased SA production, achieving a maximum titer of 8.9 g/L and a yield of 0.46 g/g glucose. Kinetic analysis of bench-scale fermentations showed that the SA formation was well described by the Luedeking–Piret model, indicating mixed growth-associated product formation with a substantial nongrowth-associated contribution under carbonic acid supplementation. Guided by these kinetic insights, a two-stage fed-batch fermentation strategy was implemented, resulting in an SA titer of 30 g/L and a yield of 0.57 g/g glucose within 115 h. Overall, this work provides process-relevant insights into integrating inorganic carbon utilization with low-pH fermentation to inform more sustainable SA biomanufacturing.

fed-batch fermentation↗