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DOE OSTI2026

Sustainable extraction of rare earth elements from coal fly ash leachates using a recyclable ionic liquid

The growing demand for rare earth elements (REEs) has prompted interest in their recovery from alternative sources such as coal fly ash (CFA). This study explores the ionic liquid (IL) betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf 2 N], for selective extraction of REEs from leachates of a Class C CFA. While previous studies have demonstrated the effectiveness of using [Hbet][Tf 2 N] to extract REEs from different types of CFA in direct ash-IL systems, this study investigates four CFA leachates prepared using HCl, HNO 3 , H 2 SO 4 , and citrate. Extraction experiments were conducted across varying pH levels and with additives such as ascorbic acid and betaine. Among the systems tested, [Hbet][Tf 2 N] achieved REE recoveries of 51% and 47% from the HCl and citrate leachates, respectively, comparable to 49% REE recovery in ash-IL extraction. Co-extraction of bulk elements was significantly reduced in the leachate-IL systems. Optimal REE extraction occurred near pH 11, and addition of ascorbic acid effectively suppressed iron co-extraction without compromising REE recovery. Recycling experiments demonstrated that [Hbet][Tf₂N] retains its performance over five cycles with manageable losses. These results reveal the promise of [Hbet][Tf 2 N] for effectively recovering REEs from leachates of solid wastes, highlighting its applicability as a sustainable strategy for other aqueous REE feedstocks.

chemistry↗

DOE OSTI2020

Economic Extraction and Recovery of REEs and Production of Clean Value-Added Products from Low-Rank Coal Fly Ash

The University of North Dakota (UND) Energy & Environmental Research Center (EERC) teamed with Pacific Northwest National Laboratory (PNNL) , the North Dakota Industrial Commission Lignite Research Program, and commercial partners Basin Electric Power Cooperative, Great River Energy, and Southern Company to execute a Cooperative Agreement funded by the U.S. Department of Energy’s (DOE’s) National Energy Technology Laboratory (NETL) focused on identifying unique pathways and pretreatments to extract rare-earth elements (REEs) from low-rank coal (LRC) ash in a more economical and environmentally benign manner than current methods. The EERC drew upon the unique and deep knowledge of the team regarding LRC geochemistry, ash transformation mechanisms during combustion, and fly ash chemistry in the approach to understand the portioning of REEs in LRC ash. A comprehensive characterization effort was undertaken to fully establish the form, associations, and partitioning of the REEs and other elements/minerals of interest in fly ash, as well as the ash chemistry, mineralogy, and morphology. Using this information, the team tested methods of REE extraction to take advantage of the unique and advantageous properties of LRC ash. Multiple complementary approaches were evaluated that combined both novel and proven methods to develop an extractive process for REEs and other high-value metals from LRC ash that provide technological and economic progress on the current state of the art. Methodologies were also evaluated for the potential to synergistically remove toxic metals while extracting other high-value metals from the ash, generating a clean, safe ash material as a value-added product. This would eliminate waste and offer significant additional revenue potential. Based on laboratory-scale testing, an initial high-level technical and economic analysis to estimate operating expenses and product revenues to guide future phases of technology development was implemented. By focusing on minimizing process steps and consumptive use of extraction solutions, a tunable, economically viable process for REE extraction from LRC ash was developed. The tunable process has the ability to be adjusted to adapt to the differing ash chemical and physical properties that are characteristic of LRC ash. This is key to deployment as a commercial process. In demonstrating the process, the EERC was able to illustrate mixed REE concentration greater than the goal of 2 wt%. High-level economic analysis of the process with LRC ash of moderate REE levels demonstrated the potential of the process, but recovery of just the REEs was insufficient to cover operational costs. With the additional extraction of other high-value metals found in LRC ash, the process economics approach would break even, and it is anticipated that with process optimization, the developed process could potentially be economically sound. The same economic analysis performed utilizing LRC ash with high levels of REEs showed the recovery of the REEs alone would make the process economically viable even without further optimization.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2020

Economic Extraction, Recovery and Upgrading of Rare Earth Elements from Coal-Based Resources

The overall objective of this project is to produce a rare earth elements product with greater than 8% rare earth elements from coal-based resources using an economically viable and environmentally benign processing methodology. The objective of the coal processing work will be to acquire appropriate coal feed and produce a viable clean coal product, a concentrated REE feed stream, and a pyrite stream (where available) that can be used to enhance leaching. The objective of the bio-oxidation portion of the project is to utilize bacteria to oxidize sulfide minerals and ferrous ions to ferric ions to accelerate leaching and remove the sulfides to prevent future acid mine drainage and related liabilities. The objective of the solution conditioning work is to remove iron and control leaching solution conditions to facilitate extraction of REEs without significant thorium extraction. The objective of the column leaching work is to engineer/model and simulate heap leaching to demonstrate low-cost extraction of REEs from coal-based resources. The objective of the solvent extraction work is to selectively extract and recover through controlled stripping of REEs that are solubilized through leaching. The objective of the precipitation portion of the project is to recover the REEs from the solvent extraction stripping solutions and dry them to achieve the final product of rare earth elements that is > 8 % REEs. The objective of the technical, economic, and environmental analysis is to determine the overall viability of the processing approach that is demonstrated in this project. This project encompasses a range of technologies that are currently in industrial practice that are applied and engineered to produce rare earth element product from coal feed sources. The potential sources include large coal feed resources in active coal mines in addition to coal waste. This technology involves the utilization of advanced coal processing technology that can be used to deliver clean coal for the market as well as rare-earth-element-bearing non-coal rock that is of the correct size for heap leaching applications in addition to providing concentrated sulfide minerals (for mid to high sulfur coals) for cleaner coal and for enhanced bio-oxidation to accelerate leaching of REEs from the non-coal rock. The removal of the sulfide minerals cleans the coal, accelerates subsequent REEs extraction, and it removes the future potential for most acid-rock drainage. (For low sulfur coals some pyrite may be purchased if needed.) The processing method also utilizes bio-oxidation to enhance ferric ion production to enhance leaching, while also consuming the sulfide mineral and its associated environmental liability. The project includes a technical, economic, and environmental analysis to facilitate an appropriate assessment of commercial viability for this processing technology.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2020

Conceptual design for a blanket tritium extraction test stand

Tritium breeding is fundamentally required for a sustainable fusion fuel cycle, yet the technological readiness of blanket technology lags far behind other fusion systems. Breeder concepts are divided into solid and liquid media, where solid breeders typically rely on a sweep gas, such as helium, to carry away tritium from lithium containing ceramic materials, and liquid breeders produce tritium from lithium containing eutectics (e.g., PbLi) or molten salts (FLiBe). In each case, tritium must be harvested from the breeding medium. A promising method for tritium extraction is through a vacuum permeator, in which a concentration gradient from the tritium- containing fluid promotes diffusion through a membrane with high hydrogen permeability to the vacuum. This technology has been demonstrated for hydrogen gas systems using Pd and PdAg permeators, but relatively little work has been done to test tritium extraction from PbLi. A Tritium Extraction eXperimental (TEX) loop is being designed to test tritium extraction in a vacuum permeator configuration. The system design is such that it will allow the testing of tritium extraction from both helium and PbLi. A phased approach is being taken that will allow testing of small specimens for fundamental permeation measurements, to multi-meter component testing at near-prototypic conditions. A molten PbLi loop is challenging due to the toxic and explosive nature of Pb and Li, respectively, radiological concerns by introducing tritium, and high temperatures involved in such a system. In addition, PbLi corrosion is a significant issue at high temperatures (>400C). The TEX system will not employ a neutron source for volumetric production of tritium. Herein we present the design and methods used for 1) pumping PbLi, 2) introducing deuterium or tritium into the PbLi, 3) quantifying the amount of deuterium in the loop, 4) extracting deuterium and tritium, and 5) quantifying the total amount of extracted deuterium or tritium from the permeator. In addition, the safety design for operating such a system will be discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

Fabrication of Biofunctionalized PVA/PEI Nanofibers for Rare Earth Element Extraction from Coal Mine Tailings

The need for rare earth elements (REEs) for new technology is becoming increasingly stiff with demand at a record high. Biological ligands like lanmodulin and lanthanide binding tags (LBT) have gained noticeable attention for their selective extraction of valuable lanthanide metals in aqueous solution. Building on previous work using microbeads as the extraction media, we propose that nanofibers can improve extraction capabilities. Nanofibers could provide more efficient flow and higher extraction yields due to their high surface area to volume ratio. Relying on thiolmaleimide click chemistry as the biological ligand immobilization route, electrospinning as the nanofiber manufacturing method, and numerous characterization techniques, we produced electrospinning polymer solutions and nanofibers with a maximum neodymium adsorbent capacity of 12.1 μmol/g of extraction media immobilized with LBT. Although the prior work produced an extraction media with an equivalent capacity of ~40 μmol/g, the electrospinning process is much more economical and scalable. This work paves the way for an industrially relevant, environmentally-friendly REE extraction material. Further work is required to produce higher quality nanofibers, to investigate common ion interference with REE adsorbance, and to scale production up to a relevant scale.

01 COAL, LIGNITE, AND PEAT↗

NASA NTRS1978

The influence of unsteady aerodynamics on extracted aircraft parameters

The effect of accounting for unsteady aerodynamics on the parameters extracted from flight data is examined. Longitudinal equations of motion have been modified, and a parameter-extraction program developed to include the effects of unsteady aerodynamics. The approach used was to generate pseudo data using the unsteady-aerodynamics model and to use that data in two parameter-extraction programs, one including and the other neglecting unsteady effects to see if the parameters were significantly different. Flight data for a light airplane also was used with the two extraction programs for the same purpose. Results showed that, for the cases considered, including unsteady aerodynamics in the parameter-extraction program did affect the extracted quantities, particularly the damping in pitch. In addition, the parameter variances were lower when unsteady aerodynamics were included in the extraction program than when the effects were neglected.

Queijo, M. J.↗

NASA NTRS1998

Carboxylic and Dicarboxylic Acids Extracted from Crushed Magnesium Oxide Single Crystals

Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THE) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and (sup 1)H-NMR (Nuclear Magnetic Resonance). The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS (Gas Chromatography - Mass Spectroscopy) analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P2(sub 1)/c with a(sub o) = 5.543 A, b(sub o) = 8.845 A, c(sub o) = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg/g MgO. The MgO crystals from which these organic acids were extracted grew from the 2360 C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H, and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)(sup n-). The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

Freund, Friedemann↗

NASA NTRS1986

[3H]Indole-3-acetyl-myo-inositol hydrolysis by extracts of Zea mays L. vegetative tissue

[3H]Indole-3-acetyl-myo-inositol was hydrolyzed by buffered extracts of acetone powders prepared from 4 day shoots of dark grown Zea mays L. seedlings. The hydrolytic activity was proportional to the amount of extract added and was linear for up to 6 hours at 37 degrees C. Boiled or alcohol denatured extracts were inactive. Analysis of reaction mixtures by high performance liquid chromatography demonstrated that not all isomers of indole-3-acetyl-myo-inositol were hydrolyzed at the same rate. Buffered extracts of acetone powders were prepared from coleoptiles and mesocotyls. The rates of hydrolysis observed with coleoptile extracts were greater than those observed with mesocotyl extracts. Active extracts also catalyzed the hydrolysis of esterase substrates such as alpha-naphthyl acetate and the methyl esters of indoleacetic acid and naphthyleneacetic acid. Attempts to purify the indole-3-acetyl-myo-inositol hydrolyzing activity by chromatographic procedures resulted in only slight purification with large losses of activity. Chromatography over hydroxylapatite allowed separation of two enzymically active fractions, one of which catalyzed the hydrolysis of both indole-3-acetyl-myo-inositol and esterase substrates. With the other enzymic hydrolysis of esterase substrates was readily demonstrated, but no hydrolysis of indole-3-acetyl-myo-inositol was ever detected.

NASA Program Space Biology↗

NASA NTRS1999

Carboxylic and dicarboxylic acids extracted from crushed magnesium oxide single crystals

Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THF) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and 1H-NMR. The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P21/c with ao = 5.543 A, bo = 8.845 A, co = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg g-1 MgO. The MgO crystals from which these organic acids were extracted grew from the 2860 degrees C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)n-. The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

NASA Discipline Exobiology↗

NASA NTRS2009

Microfluidic Extraction of Biomarkers using Water as Solvent

A proposed device, denoted a miniature microfluidic biomarker extractor (mu-EX), would extract trace amounts of chemicals of interest from samples, such as soils and rocks. Traditionally, such extractions are performed on a large scale with hazardous organic solvents; each solvent capable of dissolving only those molecules lying within narrow ranges of specific chemical and physical characteristics that notably include volatility, electric charge, and polarity. In contrast, in the mu-EX, extractions could be performed by use of small amounts (typically between 0.1 and 100 L) of water as a universal solvent. As a rule of thumb, in order to enable solvation and extraction of molecules, it is necessary to use solvents that have polarity sufficiently close to the polarity of the target molecules. The mu-EX would make selection of specific organic solvents unnecessary, because mu-EX would exploit a unique property of liquid water: the possibility of tuning its polarity to match the polarity of organic solvents appropriate for extraction of molecules of interest. The change of the permittivity of water would be achieved by exploiting interactions between the translational states of water molecules and an imposed electromagnetic field in the frequency range of 300 to 600 GHz. On a molecular level, these interactions would result in disruption of the three-dimensional hydrogen-bonding network among liquid-water molecules and subsequent solvation and hydrolysis of target molecules. The mu-EX is expected to be an efficient means of hydrolyzing chemical bonds in complex macromolecules as well and, thus, enabling analysis of the building blocks of these complex chemical systems. The mu-EX device would include a microfluidic channel, part of which would lie within a waveguide coupled to an electronically tuned source of broad-band electromagnetic radiation in the frequency range from 300 to 600 GHz (see figure). The part of the microfluidic channel lying in the waveguide would constitute an interaction volume. The dimensions of the interaction volume would be chosen in accordance with the anticipated amount of solid sample material needed to ensure extraction of sufficient amount of target molecules for detection and analysis. By means that were not specified at the time of reporting the information for this article, the solid sample material would be placed in the interaction volume. Then the electromagnetic field would be imposed within the waveguide and water would be pumped through the interaction volume to effect the extraction.

Amashukeli, Xenia↗

NASA NTRS2013

Rigging Test Bed Development for Validation of Multi-Stage Decelerator Extractions

The Low Density Supersonic Decelerator project is developing new decelerator systems for Mars entry which would include testing with a Supersonic Flight Dynamics Test Vehicle. One of the decelerator systems being developed is a large supersonic ringsail parachute. Due to the configuration of the vehicle it is not possible to deploy the parachute with a mortar which would be the preferred method for a spacecraft in a supersonic flow. Alternatively, a multi-stage extraction process using a ballute as a pilot is being developed for the test vehicle. The Rigging Test Bed is a test venue being constructed to perform verification and validation of this extraction process. The test bed consists of a long pneumatic piston device capable of providing a constant force simulating the ballute drag force during the extraction events. The extraction tests will take place both inside a high-bay for frequent tests of individual extraction stages and outdoors using a mobile hydraulic crane for complete deployment tests from initial pack pull out to canopy extraction. These tests will measure line tensions and use photogrammetry to track motion of the elements involved. The resulting data will be used to verify packing and rigging as well, as validate models and identify potential failure modes in order to finalize the design of the extraction system.

Low Density Supersonic Decelerator (LDSD)↗

NASA NTRS2022

Natural Language Understanding and Extraction of Flight Constraints Recorded in Letters of Agreement

This paper presents an automated information extraction and inference technique using natural language processing for extracting flight operational procedures and constraints embedded in heritage air traffic management documents. The extracted flight constraints can be digitized and fit into existing airspace information exchange models such as the Aeronautical Information Exchange Model (AIXM). This approach offers a digitized solution to disseminate airspace operating conditions to diverse air users and stakeholders in the National Airspace System (NAS). Furthermore, the digitized flight procedures can provide operational flexibility for emerging advanced air mobility providers and reduce traffic controller workload while maintaining current safety standards. To demonstrate this process, 1,972 Letters of Agreement (LOAs) have been selected for processing, named entity extraction, constraint identification and extraction. This dataset is derived from a subset of documents related to Air Route Traffic Control Centers (ARTCC) operations. We experimented with various traditional information extraction techniques, state-of-the-art machine learning and deep learning models to perform named entity recognition and pattern recognition on our dataset. We present the results from our experiments and demonstrate 99.0% F-1 score for named entity recognition, and a 96.6% accuracy for our entire workflow up to named entity recognition. We also discuss constraint definitions using generic patterned templates and extensions to this work in applying entity linking to digitally extracting relevant constraints.

Natural Language Processing↗

NASA NTRSDate not supplied

Natural Language Understanding and Extraction of Flight Constraints Recorded in Letters of Agreement

Natural Language Processing↗

DOE OSTI2020

Benzenesulfonamide Derivatives as Complexants and Extractants for Addressing the Mercury Problem at the Savannah River Site

Mercury (Hg) is a major global pollutant arising from both natural and anthropogenic sources. Its widespread use in medicinal and industrial applications makes it a common chemical exposure and environmental pollutant. It can exist in several forms which include: Metallic mercury (Hg{sup 0}), mercurous (Hg{sub 2}{sup 2+}), mercuric salts (Hg{sup 2+}), and organic mercury (e.g. CH{sub 3}Hg{sup +}), with the latter being the most toxic of all the species. Due to mercury's high toxicity, new approaches towards its detection has received significant attention in the scientific community. Mercury exposure at the Savannah River Site (SRS) has been a recent concern especially with increasing amounts of organic mercury in the saltstone. It originates mainly from its use as an acidic dissolution catalyst of aluminum cladding from target fuels within the uranium and plutonium processing operations [1]. It is present to an amount of about 60 metric tons in the high-level waste (HLW) tanks. Organic Mercury species have been found in low activity waste (LAW) at the site that eventually ends up in the saltstone. Therefore, there is a need for: i) Converting organic mercury to other less toxic forms and ii) Complexation and removal of Hg prior of disposal of LAW in saltstone. Various methods have been developed for selective sensing of mercury in the presence of other toxic metals. These methods include using ligands that can form organo-soluble metal complexes with different optical and spectroscopic properties that can be used for toxic metal sensing. In 2005, our group pioneered an ion-exchange extraction method, in which o-phenylenediamine-derived disulfonamides were used to complex and selectively extract and sense Pb{sup 2+} from aqueous solutions into an organic phase [2,3]. Herein, a disulfonamide and a bis-dansylamide have been shown to extract, complex and sense Hg(II). Ligand 1: The crystal structure of the disulfonamide-Hg complex confirms the complexation of Hg(II) with the ligand. Complexation was corroborated by the {sup 1}H-NMR spectra obtained after contacting solutions of various concentrations of Hg{sup 2+} with 2 mM ligand in chloroform. Distinct resonances are observed at Hg/L ratio of 0.5 that are also observed for the isolated 1:2 complex. In the presence of excess mercury, new resonances, as well as the movement of Et{sub 3}N resonances indicate the formation of a different Hg-sulfonamide-triethylamine complex, presumably having 1:1 Hg:L stoichiometry. The electronic spectra of aqueous phases after extraction show that there was no free ligand absorption at 0.5 eq of Hg, indicating a complete complexation. Complexation was also confirmed by the UV-visible titrations with Hg{sup 2+} at constant ligand concentration. pH-dependent extraction carried out shows that extraction of Hg(II) by ligand 1 was over 90% for most alkaline pHs. Ligand 2: The crystal structure of the Ligand 2 complex formed with Hg(OAc){sub 2} shows a remarkable coordination pattern with 4:2 metal:ligand stoichiometry. The fluorescent bis-dansyl disulfonamide derivative was found to complex and sense HgCl{sub 2} and Hg(OAc){sub 2} by demonstrating fluorescence quenching upon Hg(II) addition in comparison with other metals (Zn(II), Cd(II), Pb(II)). No were observed for Cu(II), Ag(I) and Co(II). We have shown the complexation of Hg(II) by a disulfonamide and a bis-dansyl disulfonamide ligand using several spectroscopic methods. Ligand 1 was able to extract mercury into chloroform and form a complex in the presence of excess mercury by synergistic complexation with triethylamine acting as a co-ligand. X-ray and NMR both confirm a 1:2 HgL{sub 2} stoichiometry. Ligand 2 can be used for sensing of Hg(II) as fluorescence quenching was observed after addition of Hg(II)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Systematic and statistical uncertainties of the hilbert-transform based high-precision FID frequency extraction method

Pulsed nuclear magnetic resonance (NMR) is widely used in high-precision magnetic field measurements. The absolute value of the magnetic field is determined from the precession frequency of nuclear magnetic moments. The Hilbert transform is widely used to extract the phase function from the observed free induction decay (FID) signal and then its frequency. In this paper, a detailed implementation of a Hilbert-transform based FID frequency extraction method is described. How artifacts and noise level in the FID signal affect the extracted phase function are derived analytically. A method of mitigating the artifacts in the extracted phase function of an FID is discussed. Correlations between noises of the phase function samples are studied for different noise spectra. We discovered that the error covariance matrix for the extracted phase function is nearly singular and improper for constructing the $\chi^2$ used in the fitting routine. A down-sampling method for fixing the singular covariance matrix has been developed, so that the minimum $\chi^2$-fit yields properly the statistical uncertainty of the extracted frequency. Other practical methods of obtaining the statistical uncertainty are also discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2023

Enhanced, continuous, liquid-liquid extraction and in-situ separation of volatile fatty acids from fermentation broth

In 2018 alone, the US landfilled 35.3 million tons of food waste, about 24% of the total landfilled mass. In addition to the negative impacts landfills have demonstrated on the environment and human health, some states have begun to outlaw or dissuade the disposal of food waste and sewage sludge into landfills altogether. An urgent need has thus been created for the development of digestion processes like anaerobic digestion (AD) and arrested methanogenesis (AM) to convert food waste into valuable chemical products. Unfortunately, the buildup of volatile fatty acids (VFAs) during these processes eventually halts the reaction, and energy efficient methodologies for VFA removal are critical for the operation of fermenters. Additionally, VFAs themselves can serve as valuable chemical precursors, and recently AD processes have been modified to increase VFA production during fermentation. However, even with significant research over the past three decades, the separation of VFAs from the fermenter broth has remained expensive. Moreover, the separation of these VFAs from the fermenter broth may cost up to 50% of the entire process budget, hindering the widespread commercial adoption of AD and AM. Here we present a novel liquid-liquid extraction process termed CLEANS (Continuous Liquid-liquid Extraction And iN-situ Separation) as a highly efficient method for continuously separating VFAs from a real fermentation broth solely under gravity. Our optimized process (using an aqueous broth feed pH of 2.5, tri-noctylamine as an extractant, and a 10:1 ratio of aqueous broth to organic extractant), achieved a VFA distribution constant K D = 44.5 ± 7.9, a single-pass recovery = 81.3 ± 2.5%, and an extraction factor = 8.1 ± 0.3. These KD values are over an order of magnitude higher than what has been previously reported for comparable processes. A high aqueous-to-organic flowrate ratio, enabled for the first time by CLEANS, was found to be particularly crucial for achieving optimal extraction. Our separation process demonstrates excellent reproducibility and potential for scalability. The economic and environmental implications of this work are briefly discussed.

42 ENGINEERING↗

DOE OSTI2022

Extraction of 197 mHg with TIBPS in HNO 3 and HCl media

Here, the extraction of no carrier added mercury by tri-isobutyl phosphine sulfide (TIBPS) was characterized in HCl and HNO 3 media. The extraction of 197 mHg as a function of acid concentration was similar in both acids over a large acid concentration (0.001 M to conc.) with high extraction (D ~ 1000) at low concentrations and decreasing extraction for higher concentrations (≥ 4 M). The kinetics of extraction were rapid (~ 5 min.) in both acids. Speciation experiments indicated that the extraction mechanism is 1:2 ( 197 mHg:TIBPS) in HCl and 1:1 in HNO 3 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2024

Phosphonate functionalized magnetic mesoporous silica for rare earth element recovery from citrate assisted solid waste extracts

The growing high demand of rare earth elements (REEs) has prompted extensive research on REE recovery from waste streams. This study reports the synthesis and evaluation of phosphonate-functionalized magnetic mesoporous silica (MMS-PP) for REE recovery from the acidic extracts of solid wastes. MMS-PP was synthesized using surfactant template and post-synthesis methods, and tested using simulated and real extraction solutions from citrate-assisted REE extracts from municipal solid waste incineration (MSWI) ash. The organic-inorganic hybrid MMS-PP was evaluated for La recovery from 50 mM simulated citrate extract, with the adsorption capacity of 13.5 mg/g compared to ∼2.5 mg/g for non-functionalized MMS. The MMS-PP material exhibited fast adsorption within 10 min, good La selectivity against competing Na + and Ca 2+ , moderate selectivity against Al 3+ and Fe 3+ , high recyclability over multiple adsorption-desorption cycles, and equivalent efficiency for La, Ce, Nd, and Y recovery. Furthermore, the MMS-PP material also demonstrated 70–95% REE recovery from real citrate extracts of MSWI ash, and the spent MMS-PP material can be regenerated and reused for multiple cycles. Functionalized mesoporous materials in combination with organic-ligand assisted extraction can potentially provide a green, effective, and tunable solid-liquid separation platform for REE recovery from complex solid waste streams.

REE recovery↗