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NASA NTRS2014

Collisional Effects on Magnesium-rich Minerals found in Comets and Asteroids

While generally touted to be the least-altered bodies remaining from the age of the solar system's formation, comets and asteroids have undergone evolutionary processing throughout the 4.5-billion-year lifetime of the solar system. They have suffered the effects of collisions by impactors ranging in size from micrometeoroids to other comets and asteroids. As such, we must ask ourselves: can we detect these evolutionary effects remotely through telescopic observations? With this in mind, a suite of experiments were conducted, impacting magnesium-rich minerals as analogues to those that have been detected in the spectra of both asteroid surfaces and in the dust of cometary comae, including forsterite (Mg2SiO4, olivine), orthoenstatite (Mg2SiO3, pyroxene), diopside (MgCaSi2O6, monoclinic pyroxene), and magnesite (MgCO3, carbonate). These minerals were impacted at velocities ranging from 2.0 km/s to 2.8 km/s using the vertical gun in the Experimental Impact Laboratory (EIL) at NASA Johnson Space Center. These speeds mimic typical velocities of impacts occurring in the Kuiper belt [1]. Two classes of projectile were used: spherical alumina ceramic, whose density mimics that of rock, and cylinders made from the same material that they impacted (e.g., forsterite impactors for forsterite targets, etc.). The peak shock pressure varies significantly, depending on the target and impactor materials and the velocity; thus, shock effects differed in targets impacted at the same velocity but with compositionally different projectiles. The results indicate both: (a) how varying the impactor-density might change the outcome from a scientific viewpoint, as well as (b) possible contamination effects of the ceramic projectile in the resultant spectra of the target minerals from an experimental perspective. Temperature effects were also investigated by impacting samples at both 25 deg. and -25 deg. to: (a) probe whether the varying temperatures experienced by small bodies plays a role in the resultant spectra, and (b) constrain necessary experimental parameters. Analysis of Fourier Transform Infrared (FTIR) spectra obtained from the experimentally shocked materials shows clear indications of spectral shifts in wavelength, as well as a change in relative peak strengths of the spectral signatures at one wavelength compared with another, in all minerals except magnesite. Samples of the forsterite and orthoenstatite that displayed the spectral changes were examined with a transmission electron microscope, which revealed evidence of planar dislocations. The density of the dislocations in the experimentally shocked minerals mimicked the dislocation densities measured in both forsterite and enstatite grains recovered from Comet Wild 2 by the Stardust mission [2, 3, 4]. Further discussion on analyses of peak shock pressure and temperature-dependent effects can be found in Jensen et al., this meeting

Lederer, S.↗

NASA NTRS2024

Hydrogen Isotopic Composition of Hydrous Minerals in Particles From Bennu

On September 24, 2023, NASA’s OSIRIS-REx mission delivered to Earth ~121 g of pristine carbonaceous regolith from asteroid Bennu. A first series of mineralogical observations and chemical/isotopic analyses of Bennu aggregate samples (fine to coarse particles up to a few mm) revealed that this material resembles the most chemically primitive chondrites and the samples returned by the JAXA’s Hayabusa2 mission from the carbonaceous asteroid Ryugu. Laboratory studies have confirmed the story gleaned from the spacecraft encounter that Bennu’s rock fragments underwent extensive aqueous alteration and are predominantly composed of hydrated minerals (serpentine, smectite) and other secondary minerals (e.g., magnetite, carbonates). The secondary phases were likely formed under the presence of liquid water on Bennu’s parent asteroid. The isotopic compositions of hydrous minerals and secondary phases can increase our understanding of the source and distribution of water and volatile elements in the protoplanetary disk [e.g., 5-8]. However, direct estimates of the hydrogen isotopic ratios (D/H) in hydrous minerals cannot be obtained easily in primitive rocks due to the difficulty in estimating the organic matter (OM) contribution to the whole H budget. In order to obtain hints on the initial constituents of Bennu’s parent asteroid and to test if Bennu's parent asteroid have formed beyond the snow line (hypothesis 4 of [9]), we measured the D/H and C/H ratios in chondritic matrices by secondary ion mass spectrometry (SIMS) and obtain information on the D/H ratio of water retained in the hydrated minerals. The method also gives clues on the hydrogen isotope variability among different Bennu rock fragments made available for measurement.

L Piani↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO2 Mineralization of Industrial Waste Brines

Calcium carbonate production via CO2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO2 in a stable form of fine precipitated calcium carbonate, a high-value product with unit price in the range of $230-$280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinders CO2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) CO2 generation sources (e.g. power plants) which often renders efficient integration of feedstocks impractical. To simultaneously address these challenges, a new process is developed to integrate CO2 mineralization-based carbonate production into the zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serves as the Ca-source. An H+/Na+ ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants as is. The CO2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams with low energy input, this process offers significant technical advantages in energy and CO2 footprint over the current paradigm of precipitated calcium carbonate production. Overall, the new process provides a unique route to integrate CO2 emissions control and wastewater treatment for coal power plants, while producing high-value product to offset the economic burden associated with waste management.

Simonetti, Dante↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO2 Mineralization of Industrial Waste Brines

Simonetti, Dante↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO 2 Mineralization of Industrial Waste Brines

Calcium carbonate production via CO 2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO 2 in a stable form of fine precipitated calcium carbonate, a high-value product with unit price in the range of $230-$280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinders CO 2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) CO 2 generation sources (e.g. power plants) which often renders efficient integration of feedstocks impractical. To simultaneously address these challenges, a new process is developed to integrate CO 2 mineralization-based carbonate production into the zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serves as the Ca-source. An H + /Na + ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants as is. The CO 2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams with low energy input, this process offers significant technical advantages in energy and CO 2 footprint over the current paradigm of precipitated calcium carbonate production. Overall, the new process provides a unique route to integrate CO 2 emissions control and wastewater treatment for coal power plants, while producing high-value product to offset the economic burden associated with waste management

Simonetti, Dante↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO 2 Mineralization of Industrial Waste Brines

Calcium carbonate production via CO 2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO 2 in a stable form of fine precipitated calcium carbonate, a high-value product with unit price in the range of $230-$280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinders CO 2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) CO 2 generation sources (e.g. power plants) which often renders efficient integration of feedstocks impractical. To simultaneously address these challenges, a new process is developed to integrate CO 2 mineralization-based carbonate production into the zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serves as the Ca-source. An H + /Na + ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants as is. The CO 2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams with low energy input, this process offers significant technical advantages in energy and CO 2 footprint over the current paradigm of precipitated calcium carbonate production. Overall, the new process provides a unique route to integrate CO 2 emissions control and wastewater treatment for coal power plants, while producing high-value product to offset the economic burden associated with waste management.

Simonetti, Dante↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO 2 Mineralization of Industrial Waste Brines

Calcium carbonate production via CO 2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO 2 in a stable form of fine precipitated calcium carbonate, a high-value product with unit price in the range of $230-$280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinders CO 2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) CO 2 generation sources (e.g. power plants) which often renders efficient integration of feedstocks impractical. To simultaneously address these challenges, a new process is developed to integrate CO 2 mineralization-based carbonate production into the zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serves as the Ca-source. An H + /Na + ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants as is. The CO 2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams with low energy input, this process offers significant technical advantages in energy and CO 2 footprint over the current paradigm of precipitated calcium carbonate production. Overall, the new process provides a unique route to integrate CO 2 emissions control and wastewater treatment for coal power plants, while producing high-value product to offset the economic burden associated with waste management.

Simonetti, Dante↗

DOE OSTI2019

Fine Calcium Carbonate Production by CO 2 Mineralization of Industrial Waste Brines

Calcium carbonate production via CO 2 mineralization offers an attractive route for carbon capture and utilization. The process sequesters CO 2 in a stable form of fine precipitated calcium carbonate, a high-value product with unit price in the range of $230-&dollar;280/t and a global market projected to reach 99 M tons in 2020. However, two critical barriers hinders CO 2 mineralization—(i) the need for costly processes such as electrolysis or addition of alkali hydroxides to maintain alkalinity during mineralization, and (ii) the geographic location mismatch between Ca-rich solutions (or brines) CO 2 generation sources (e.g. power plants) which often renders efficient integration of feedstocks impractical. To simultaneously address these challenges, a new process is developed to integrate CO 2 mineralization-based carbonate production into the zero liquid discharge water (ZLD) treatment systems at coal-fired power plants. In this process, Ca-rich streams, such as produced water from oil and gas extraction or carbon storage operations, serves as the Ca-source. An H + /Na + ion-exchange cycle is designed to provision alkalinity during mineralization and regenerate the ion-exchange reagent in solutions with high salinity. Ca-depleted streams are then treated within a centralized ZLD system. The process beneficially utilizes reject streams that are available at substantial quantities in the vicinity of coal power plants within several U.S regions. In addition, the process utilizes post-desulfurization flue gas from coal-fired power plants as is. The CO 2 conversion reactions are performed in alkaline streams at ambient pressure, thereby minimizing the energy burden. By beneficiation of industrial waste streams with low energy input, this process offers significant technical advantages in energy and CO 2 footprint over the current paradigm of precipitated calcium carbonate production. Overall, the new process provides a unique route to integrate CO 2 emissions control and wastewater treatment for coal power plants, while producing high-value product to offset the economic burden associated with waste management.

Simonetti, Dante↗

DOE OSTI2019

Implementation of Ion Exchange Processes on Industrial Waste Streams for CO 2 Mineralization

Economic development and population growth will lead to an increase in global energy consumption. Large coal-fired power plants (>500 MW) account for almost half of the total CO 2 emissions from fossil fuel combustion, and nearly 26% of the global fossil fuel and industry CO 2 emissions. Long-term management of the more than 36 Gt of CO 2 that is emitted globally per year is urgently needed. CO 2 mineralization is an attractive method of sequestering CO 2 because it captures CO 2 as an insoluble carbonate mineral, mimicking the natural process of rock weathering. Here, we present a pathway for accelerated CO 2 mineralization enabled by divalent cations sourced from liquid streams. In this work, we investigate a mineralization route that converts flue gas CO 2 to precipitated calcium carbonate (PCC) using waste aqueous streams as the calcium source. The proposed mineralization route integrates CO 2 utilization and waste liquid management at coal power plants. Maintaining alkalinity during carbonation is the primary challenge in this process. Instead of relying on the consumption of costly and unsustainable sources of alkalinity (e.g., sodium hydroxide), we used regenerable solids to increase the pH of water by ion exchange. The increase in alkalinity creates a more thermodynamically favorable environment for calcite precipitation. The capacities for ion exchange of various commercially available zeolites and ion exchange resins in CO 2 -saturated water were studied through batch equilibrium and column ion-exchange experiments. During ion exchange, H + in the water exchanges with Na + , Ca 2+ or K + in the zeolite or resin. Batch equilibrium isotherms for H + –Na + exchange were collected by first adding varying amounts of the ion exchange solid (0 – 1.0 kg per kg of water) to CO 2 -saturated water (pCO 2 = 1 atm, pH 4) to determine the maximum H + –Na + exchange achievable. Ion-exchange column studies were performed to determine breakthrough capacity of the system. In both systems, an increase in pH coupled with an increase in Na concentration was observed, demonstrating the feasibility of forward ion exchange. Zeolitic materials increased the alkalinity of the solution from pH 4 to around 10, whereas ion exchange resins containing weakly acidic functional groups (e.g., carboxylic acid) exhibited higher affinity for H + , increasing pH to 11.3 and surpassing the pH shift induced by the zeolitic materials. The extent of calcite precipitation was evaluated by mixing the alkaline CO 3 2- -rich water obtained after passing through the ion-exchange column and a CaCl 2 solution. Calcite yields are as expected from chemical thermodynamics. Calcium carbonate yields found experimentally were about 26 and 8 mmol per kg water for the weakly acidic ion exchange resin and zeolitic materials, respectively. The results from these studies indicate that ion exchange processes can be used as an alternative to the addition of stoichiometric inorganic bases (e.g., sodium hydroxide) to induce alkalinity for the consequent precipitation of CaCO 3 . Instead, weakly acidic ion exchange resins commonly used for water hardness removal were alternatively used to induce pH swings in the aqueous solutions. The high calcium carbonate yields obtained for the materials examined demonstrate the potential application of this process. In addition, the successful operation of the calcium carbonate production process at standard temperature and pressure conditions support its potential for industrial implementation.

Simonetti, Dante↗

DOE OSTI2021

Wellbore Leakage Mitigation Using Advanced Mineral Precipitation Strategies (Final Scientific/Technical Report)

This research project, entitled Wellbore Leakage Mitigation using Advanced Mineral Precipitation Strategies, was directed toward advancing mineral precipitation technologies to seal wellbore leaks and other potential carbon dioxide (CO 2 ) leakage pathways, including compromised wellbore cement and fracture networks of varying geometries throughout the wellbore and surrounding formation. The advanced mineral sealing techniques were evaluated in the laboratory and the field to expand the range of temperature, pressure, and chemical conditions where mineral precipitation could be used. Rates of enzymatically or thermally induced calcium carbonate precipitation (EICP, TICP) were determined as well as rates of enzyme inactivation at elevated temperatures (>60 °C). Immobilization was shown to enhance the thermal stability of urease enzyme and provide protection from inhibition in low pH conditions. Mineral seals promoted by EICP and TICP were used to seal fractured composite (cement/sandstone) and shale cores in high pressure reactors operated at temperatures greater than 55 °C and 130 °C, respectively. A computational model was updated to model processes of EICP and TICP. The work resulted in a successful field test, which showed that EICP in the presence of low pH fluids (CO 2 -impacted brine) could promote permeability reduction and seal a channel in the near-wellbore environment.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Calcium carbonate minerals as scavengers of metals and radionuclides: Their role in natural attenuation and remediation

Calcium carbonates (CaCO3) are ubiquitous naturally occurring minerals in subsurface sediments. Calcium carbonate coatings are common in many terrestrial environments and are known to coat a variety of reactive mineral surfaces in soils and sediments, altering their reactivity and chemical behavior. For these reasons, contaminant interactions with CaCO3 minerals are relevant to contaminant fate and transport. Significant advancements have been made recently toward identifying relevant contaminant (e.g., U, I, and Cr) attenuation mechanisms, which may also serve as a basis for in situ remediation strategies. Hence, the objective of this review paper is to 1) describe the state-of-knowledge of calcium carbonate minerals as universal scavengers of metals and radionuclides; 2) provide a state of the science of how calcium carbonate interactions affect contaminant fate and transport in the subsurface environmental systems; and 2) provide insights on the use of calcium carbonate natural attenuation mechanisms and their application to the remediation of complex sites. Knowledge gaps are also identified that, when closed, can advance the use of carbonate minerals for in situ remedy applications.

Qafoku, Nikolla↗

DOE OSTI2024

Search for Heavy Neutral Leptons at the MINER$\nu$A detector

Heavy Neutral Leptons (HNL) are particles hypothesised to provide a mass generation mechanism for the active (observed) neutrino species, which are known to have nonzero mass from the definitive observation of neutrino oscillations. HNL are eigenstates of mass of the order $\mathcal{O}(0.1 − 1\,\,\mathrm{GeV}/c^{2})$, which mix into the active flavour eigenstates through the extended leptonic mixing matrix. Apart from neutrino mass, they could provide a natural dark matter candidate and a mechanism for matter-antimatter asymmetry in the early Universe, giving rise to today’s matter-dominated cosmos. Searches for HNL typically attempt to either confirm the existence of HNL through an excess in data that is most compatible with an HNL hypothesis, or by setting limits on the HNL parameter space $\left(M_{N4}, \left|U_{\alpha 4}\right|^{2}\right)$ in the case of statistically insignificant excess. Such searches are intensifying as part of a global research programme at both colliders and accelerator / atmospheric neutrino experiments. One such setting is the MINER$\nu$A experiment, located in the NuMI beamline at Fermilab. MINER$\nu$A has collected a large amount of data over seven years of operation to measure the cross-sections of neutrino-nucleus interactions necessary to drive systematic uncertainties down, in order for neutrino oscillation experiments to achieve sensitivity to CP violation in the neutrino sector. With the high-energy, high-intensity NuMI beam, and with good timing, position, and angular resolution leading to sensitivity to HNL decays, MINER$\nu$A is fertile ground for an HNL search, which is performed in this thesis. Specifically, a novel, experiment-agnostic and general simulation of HNL production and decay is presented and deployed; this simulation has been incorporated in the ubiquitous GENIE neutrino event generator for use with neutrino experiments in the future. The event selection and background characterisation is discussed in detail, including the primary background coming from charged-current coherent and diffractive pion production from neutrino-nucleus interactions, and constraints on the background using control regions from MINER$\nu$A data are derived. Finally, by means of a fake-data study given a background of $\mathcal{O}(500)$ events, the discovery potential and limit-setting capacity of MINER$\nu$A is demonstrated, and ways to improve this capacity are expounded upon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Resolving dynamic mineral-organic interactions in the rhizosphere by combining in-situ microsensors with plant-soil reactive transport modeling

Associations between minerals and organic matter represent one of the most important carbon storage mechanisms in soils. Plant roots are major sources of soil carbon, and resolving the dynamics and dominance of microbial consumption versus mineral sorption of root-derived carbon is critical to understanding soil carbon storage. Here we integrate in-situ rhizosphere microsensor and plant physiological measurements with a 3-D plant-soil reactive transport model to explore the fate of dissolved organic carbon (DOC) in the rhizosphere, particularly its microbial consumption and interaction with Fe oxide minerals. Over several days, a microdialysis probe sampling pore water at the root-soil interface of growing Vicia faba roots in live soil, revealed clear diel patterns of DOC concentration. Daytime DOC spikes coincided with peaks in leaf-level photosynthesis rates and were accompanied by declining redox potential and dissolved oxygen as well as increasing pH in the rhizosphere. Incorporating microsensor data into our modeling framework showed that the measured rapid loss of DOC after each mid-day spike could not be explained by consumption via aerobic respiration, nor via anaerobic respiration dominated by Fe oxide reduction. Rather, in the model, a large fraction of rhizosphere DOC was rapidly immobilized each day by adsorption to Fe oxides. Further, modeled microbial Fe reduction (fueled by DOC) did not mobilize significant organic carbon from Fe oxides during the day. Instead, the model predicted equilibrium desorption of organic carbon from Fe oxides at night. This new mechanistic modeling framework, which couples aboveground plant physiological measurements with non-destructive high-resolution monitoring of rhizosphere processes, has great potential for exploring the dynamics and balance of the various microbial reactions and mineral interactions controlling carbon transformations and storage in soils.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Subsurface mafic and ultramafic rock mapping and analysis for carbon mineralization in the United States (SubMAP-CO 2 )

Achieving durable, gigaton-scale carbon dioxide (CO₂) removal will require the development of storage strategies that are both permanent and scalable. Among the available options, carbon mineralization in mafic and ultramafic rocks offers a uniquely robust pathway for long-term CO₂ sequestration, converting CO₂ into thermodynamically stable carbonate minerals. While surface exposures of these lithologies have been extensively studied, particularly in ophiolitic and volcanic settings, the potential for carbon mineralization in the subsurface remains comparatively underexplored at national scale. This gap limits the ability to assess storage capacity, accessibility, and deployment pathways for mineralization-based carbon management in the United States.

08 HYDROGEN↗

DOE OSTI2024

Differential Organic Carbon Mineralization Responses to Soil Moisture in Three Different Soil Orders Under Mixed Forested System: Supporting Data

This data contains data from 90-day long incubation study which aimed to look at the soil moisture-texture relationship on soil organic carbon (SOC) cycling. Soils were collected from three distinct soil textures from mixed forests in 2017: sandy (Georgia, 2017-05-01), loamy (Missouri, 2017-06-14) and clayey (Texas, December 2017) were incubated at different soil moisture levels (air-dried, 25% water holding capacity (WHC), 50% WHC, 100% WHC and 175% WHC) at room temperature for a period of 90 days. Files contain microbial respiration, active and slow SOC pools, and their respective mineralization rates, extractable organic carbon (C), and C-acquiring extracellular enzymes. Findings from these data were used in Singh et al. (2021). This study aimed to examine the interactive effect of soil moisture and texture on SOC mineralization. Soil samples of three distinct textures (sandy, loamy, and clayey) were collected from mixed forests of Georgia, Missouri, and Texas, respectively. Soil cores of 5 cm diameter were collected from numerous random locations at each site from 0-15 cm depth after scraping the litter layer and mixed thoroughly to obtain a composite sample per site. Three additional soil cores were collected to determine the WHC using pressure plate extractors. Soil samples were composited, and triplicate soil samples were incubated in mason jars for a period of 90 days at room temperature under different moisture regimes: air dried, 25% WHC, 50% WHC, at WHC and 100% saturation. Soil respiration was measured weekly, and destructive sampling was conducted at 1, 15, 60, and 90 days to determine extractable organic C, C acquiring enzyme activity, and active and slow SOC pools with their respective mineralization rates. The C acquiring enzyme activity was the total activity of α-glucosidase, β-glucosidase, cellobiohydrolase, and β-xylosidase enzymes. Gas samples for microbial respiration measurements were collected from headspace of incubation jars through the sampling ports on the lids and then analyzed using a Shimadzu Gas Chromatograph (GC-2014). Prior to sampling, the vials were evacuated. Blank correction was also done by collecting gas samples from empty incubation jars. Double pool exponential decay model was used in SigmaPlot to determine the active and slow SOC pools and their mineralization rates (Farrar et al., 2012; Jagadamma et al., 2014). The C-acquiring extracellular enzymes were measured using the microplate method by German et al., (2011). Microbial community structure was determined using the phospholipid fatty acid (PLFA) and neutral lipid fatty acid (NLFA) analyses (Buyer and Sasser, 2012). This dataset has seven data files provided in comma-separate (*.csv) format. Additional metadata are provided: seven data dictionaries and a file-level metadata file in comma separate (*.csv) format and a user guide in PDF (*.pdf) format.

Carbon acquiring enzyme activity↗

DOE OSTI2023

Engineering In Situ Catalytic Cleaning Membrane Via Prebiotic-Chemistry-Inspired Mineralization

Pressure-driven membrane separation promises a sustainable energy-water nexus but is hindered by ubiquitous fouling. Natural systems evolved from prebiotic chemistry offer a glimpse of creative solutions. Herein, a prebiotic-chemistry-inspired aminomalononitrile (AMN)/Mn 2+ -mediated mineralization method is reported for universally engineering a superhydrophilic hierarchical MnO 2 nanocoating to endow hydrophobic polymeric membranes with exceptional catalytic cleaning ability. Green hydrogen peroxide catalytically triggered in-situ cleaning of the mineralized membrane and enabled operando flux recovery to reach 99.8%. The mineralized membrane exhibited a 9-fold higher recovery compared to the unmineralized membrane, which is attributed to active catalytic antifouling coupled with passive hydration antifouling. Electron density differences derived from the precursor interaction during mediated mineralization unveiled an electron-rich bell-like structure with an inner electron-deficient Mn core. This work paves the way to construct multifunctional engineered materials for energy-efficient water treatment as well as for diverse promising applications in catalysis, solar steam generation, biomedicine, and beyond.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Data‐Driven Insights into Rare Earth Mineralization: Machine Learning Applications Using Functional Material Synthesis Data

Understanding rare‐earth element (REE) mineralization mechanisms is essential for developing efficient separation strategies. Although the geochemical pathways that generate REE deposits are qualitatively known, quantitative links between specific conditions and mineralization outcomes remain limited. Herein, the repurpose laboratory REE hydrothermal synthesis data—originally collected for functional‐materials fabrication—as a surrogate for studying mineralization with data‐driven methods. The compiled 1,200+ hydrothermal reaction records and trained three machine‐learning models—K‐nearest neighbors (KNN), random forest (RF), and extreme gradient boosting (XGB)—to predict product elements and phases from precursors, additives, reaction conditions, and engineered features. Validation shows XGB achieves the highest accuracy. Feature importance indicates thermodynamic properties of cations and anions dominate model decisions. Correlations reveal positive relationships among precursor concentration, reaction time, pH, and temperature, consistent with classical crystallization behavior. XGB‐based regressors are built to predict crystallization temperature and pH from precursor/product attributes. Performance is strongest when similar training examples exist, while accuracy declines for underrepresented reactions, notably REE carbonates and heavy‐REE systems. Overall, the study shows that functional‐materials datasets can illuminate REE mineralization and provide priors for exploration and processing. Expanding datasets with less‐studied chemistries and conditions will improve generality and support deposit discovery and more efficient REE recovery.

feature importance analysis↗

DOE OSTI2022

Effect of second Si–O vibrational overtones/combinations on quantifying water in silicate and silica minerals using infrared spectroscopy, and an experimental method for its removal

Infrared spectroscopy (IR) is the most widely used analytical tool to quantify trace water in silicate and silica minerals. A prerequisite for highly accurate IR measurements of trace water is a good understanding of the effect of the second Si–O vibrational overtones/combination bands (2nd Si–O VOCBs) on the water peaks. Silicate and silica minerals can be divided as isolated (Q 0 ), paired (Q 1 ), ring (Q 2 ), chain (Q 1 or Q 2 ), sheet (Q 3 ) and framework (Q 4 ) structures according to the polymerization of their SiO 4 tetrahedral units, and the 2nd Si–O VOCBs of these different structural types attain different vibrational features which are expected to affect the water peaks to different extents. Here, we selected olivine (Q 0 ) and α-quartz (Q 4 ) as two endmember-like structural examples, performed extensive IR measurements on both pristine and heat-treated thin sections prepared for these two minerals, and explored the vibrational features of the 2nd Si–O VOCBs. In this work, we have found that the 2nd Si–O VOCBs are well separated from the water peaks in olivine, but severely overlap with the water peaks in α-quartz, confirming the different roles that the 2nd Si–O VOCBs play in quantifying trace water in silicate and silica minerals with different structural polymerizations. To remove the influence of the 2nd Si–O VOCBs (or any other species rather than water), an experimental protocol has been successfully developed, as approved by some fundamental equations and verified by the data of α-quartz in the literature. This development should lead to significant accuracy improvement in quantifying trace amounts of water in Earth and planetary materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗