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DOE OSTI2023

The crystal orientation of THF clathrates in nano-confinement by in situ polarized Raman spectroscopy

Gas hydrates form at high pressure and low temperatures in marine sediments and permafrost regions of the earth. Despite forming in nanoporous structures, gas hydrates have been extensively studied only in bulk. Understanding nucleation and growth of gas hydrates in nonporous confinement can help create ways for storage and utilization as a future energy source. Herein, we introduce a new method for studying crystal orientation/tilt during tetrahydrofuran (THF) hydrate crystallization under the influence of nano-confinement using polarized Raman spectroscopy. Uniform cylindrical nanometer size pores of anodic aluminum oxide (AAO) are used as a model nano-confinement, and hydrate experiments are performed in a glass microsystem for control of the flash hydrate nucleation kinetics and analysis via in situ polarized Raman spectroscopy. The average THF hydrate crystal tilt of 56 ± 1° and 30.5 ± 0.5° were observed for the 20 nm and 40 nm diameter pores, respectively. Crystal tilt observed in 20 and 40-nanometer-size pores was proportional to the pore diameter, resulting in lower tilt relative to the axis of the confinement at larger diameter pores. Finally, the results indicate that the hydrates nucleation and growth mechanism can depend on the nanoconfinement size. A 1.6 ± 0.01 °C to 1.8 ± 0.01 °C depression in melting point compared to the bulk is predicted using the Gibbs–Thomson equation as a direct effect of nucleation in confinement on the hydrate properties.

25 ENERGY STORAGE↗

DOE OSTI2026

Cyclic moisture reactivation of calcium sorbents for long duration thermochemical energy storage

The transition to a flexible and reliable energy infrastructure, using electro-thermal energy generation technologies such as geothermal, concentrated solar power, and nuclear, usually demands simultaneous advancement of thermal energy storage (TES) to support on-demand electricity generation and industrial applications while mitigating the inherent intermittency of renewable energy sources and power outages from direct energy generation. Among TES technologies, thermochemical energy storage (TCES) based on calcium looping emerges as a compelling high-power energy storage candidate due to its high reaction enthalpy, compatibility with elevated operating temperatures, and abundance of low-cost materials. However, the long-term durability of calcium-based sorbents for TCES is hindered by surface sintering and particle aggregation, leading to performance degradation over repeated thermal cycles. This study explores a moisture hydration-based strategy to regenerate a degraded calcium sorbent and mitigate performance degradation for long duration TCES. The addition of moisture transforms calcium oxide into calcium hydroxide and produces intercalation water layers, associated with a regenerated surface area and reduced calcium oxide crystallite size. Both these effects are beneficial in restoring the sorbents' reactivity for carbonization. Additionally, an optimized hydration-assisted reactivation protocol balances the recovered energy storage capacity with heating penalty required for moisture removal from hydrated samples, resulting in an enhanced energy storage capacity up to 176% compared to benchmark sorbents that undergo cycling without reactivation after 60 cycles. In conclusion, these results highlight the potential of hydration-assisted reactivation to enhance the long-term performance of TCES, providing an effective pathway to advancing electro-thermal storage technologies.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Expedition UT-GOM2-2 Site H

Pressure and conventional cores were collected at Site H of the Walker Ridge Protracted Area Block 313 in the Terrebonne Basin, deepwater Gulf of America (Gulf of Mexico) during the University of Texas (UT) Deepwater Hydrate Coring Expedition (UT-GOM2-2). Pressure and conventional cores were collected continuously to a depth of 155.1 meters below the seafloor (mbsf). At deeper depths, cores were taken periodically from hydrate-bearing sands and their bounding muds to a total depth of 861.3 mbsf. 162.6 m of conventional core and 54.8 m of pressure core were recovered. Twelve temperature measurements were made between 27.1 and 144.5 mbsf to determine the geothermal gradient. At the seafloor, more than 4 m of sandy silt of unknown origin was encountered. Beneath this sand, to a depth of about 200 mbsf, the section was composed of interbedded mud and biogenic carbonate ooze. The ooze correlated to low density and high porosity intervals observed in the previously acquired logging while drilling (LWD) data and as measured. These ooze intervals also correspond to lighter sediment color, increased Ca content based on X-ray florescence (XRF) core scanning, and increased calcareous nannofossil abundance. Calcareous nannofossil biostratigraphy constrains the entire record to the Pleistocene (< 0.91 million years), with a pronounced increase in sedimentation rate with depth. Below 200 mbsf, the section was predominantly composed of mud with two thicker, hydrate-bearing coarse-grained intervals, which are commonly known as the Blue and Orange sands. The dissolved gas concentration was quantified from pressure cores. In the shallow section, dissolved methane concentration increased below the sulfate-methane transition zone (SMTZ) and reaches saturation (the limit of solubility for methane) at 147 mbsf. Gas expansion was very common in conventional and depressurized pressure (conventionalized) cores below the SMTZ. At deeper depths, the methane concentration within muds bounding the Blue and Orange reservoirs was generally found to be less than saturation. The dissolved and hydrate gas composition is consistent with a microbial source, containing greater than 99.99% methane and only trace concentrations of ethane, propane, and butane. The methane to ethane ratio (C1 /C2 ) and the methane to ethane plus propane (C1 /(C2 +C3 )) decrease with depth down to at least 678 mbsf, mainly driven by the increase in ethane with depth. It is unclear if this trend continues through the Orange sand interval. The δ13C isotopic signature of methane ranges between -69.9 and -78.5 ‰ relative to the Vienna Pee Dee Belemnite (VPDB) standard. Pressure core recovery in sandy intervals was poor. However, pressure core logs of the Orange sand show intervals of low density and high velocity, which are indicative of high hydrate saturation. One pressure core was degassed and the average hydrate saturation in the core was determined to be 24%. One core from within the Orange sand was composed of interbedded graded sandy silt and mud. The sandy silts from this core are composed of mainly quartz and feldspar with some lithics. Most of the recovered pressure core samples are maintained at near in-situ pressure and temperature (within the hydrate stability field) at the University of Texas Pressure Core Center awaiting analysis. In the shallow section, samples will be used to determine the flux of organic carbon through the basin system, find the rate at which that carbon was consumed, and understand the microbial population responsible for these processes. In the deeper section, samples from in and around the hydrate reservoirs will be used to determine the petrophysical properties of the reservoir and bounding seals in these systems.

03 NATURAL GAS↗

DOE OSTI2021

Confinement effects on the solvation structure of solvated alkaline metal cations in a single-digit 1T-MoS 2 nanochannel: A first-principles study

Confinement plays an important role in determining ion transport in porous materials, which, in turn, may influence the performance of many energy storage and desalination devices. In this work, we combined density functional theory (DFT) with an implicit solvation model and ab initio molecular dynamics (AIMD) to investigate the effects of nanoconfinement on several solvated alkaline metal cations in a single-digit 1T-MoS 2 nanochannel. Our DFT calculations with a solvation model indicated that cations with stronger hydration energy introduce a higher number of co-intercalated water molecules into the channel, consistent with early experimental observation obtained for MXene (2D transition metal carbide) channels. The predicted optimal water numbers for the cations were then used for AIMD simulations that explicitly include the effects of the solvent. When compared with the cations in bulk solution, our simulations showed that the hydration structure and coordination number (CN) of the solvated cations confined in the MoS 2 channel can be significantly altered. Further, we found that larger cations with weaker hydration energy (K + , Rb + , and Cs + ) exhibited a distinctive CN decrease under confinement, while smaller cations (Li + and Na + ) retained a similar hydration shell as in the bulk solution. More specifically, the hydration shell of large cations (K + , Rb + , and Cs + ) in MoS 2 showed similar features of the coordination angle to the bulk, which suggests the partially broken hydration shell with no geometry change under confinement. Our simulations provided insights into the change of the hydration structure of alkaline metal cations under confinement, which may have important implications on their transport in the 1T-MoS 2 channel.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Standard Characterization Techniques for Inorganic Phase Change Materials

Salt hydrates are promising candidates for phase change materials (PCMs) because of their low cost and high energy storage capacity. However, practical applications of salt hydrate based PCMs are limited due to their poor thermal cycling performance caused by phase separation and supercooling. Various techniques, including differential scanning calorimetry (DSC) and transient plane source (TPS) have been used to characterize salt hydrate based PCMs but may not provide full understanding of the degradation mechanism. In this manuscript, salt hydrate and graphite composites are prepared. Temperature history (T-History) method and X-ray diffraction (XRD) are utilized for measuring melting temperature, energy storage, and latent heat degradation of the PCM composites. Highlighting the importance of each technique and how each technique plays an important role in analyzing salt hydrates performance accurately. Temperature history, and X-ray diffraction are also used in conjunction to precisely predict the cause of degradation in salt hydrate PCMs with thermal cycling, as in most literatures the cause of degradation in salt hydrate are attributed to phase segregation, supercooling, and change in stichometry water concentration without any scientific validation.

Kumar, Navin↗

DOE OSTI2024

Development of Low-Cost, High-Performance, Easy-To-Apply, Non-Flammable, Inorganic Phase Change Material (PCM) Technology (Project Final Report)

This report describes a 45-months long research program focused on the development of novel, easy-to-apply, non-flammable, and high-performance inorganic phase change materials (PCMs) for building and industrial applications. The University of Massachusetts Lowell (UML) formed a world-class team consisting of researchers form InsolCorp (only N. American manufacturer of inorganic PCM systems for building applications), and a group of industrial advisors, to develop a universal/multipurpose, simple-to-manufacture and cost-effective PCM technology. The project team expects that the results of this work will spur in the future the adoption of thermal storage materials – a key building energy saving technology as identified by DOE BTO – for a variety of building envelope applications. The main goal of this project was to demonstrate a suite of low-cost, multipurpose, and durable inorganic PCM formulations with phase transition temperatures encompassing typical building applications (between +5 o C and +55 o C). The first objective was to design, fabricate, and experimentally validate a performance of inexpensive, durable, highly efficient, non-flammable, and easy to manufacture PCMs. To allow a variety of building applications, the project team focused on formulations that exhibit repeatable phase transitions between +5 o C and +55 o C. To follow the DOE BTO cost efficiency target without compromising thermal performance, our work was based on inorganic compounds (mostly salt hydrates) and their blends, which represent a fraction of the cost of most of organic PCMs with about twice as high density as well as significantly higher thermal conductivity and phase change enthalpy. The second objective was to develop easy-to-manufacture and -install packaging/encapsulation designs that are 1) a superior barrier to current state-of-the-art macro-packaging, which significantly reduces the risk of loss of hydration water and PCM leak, and 2) optimal in enhancing the heat exchange rates with the surroundings and within the PCM core to ensure complete charging/discharging of the entire PCM within the product. Finally, the project’s intend was to scale-up the fabrication process to demonstrate installation on system-scale applications, and to validate the performance under field conditions. This work aimed at developing low-cost, high-energy storage, and reliable latent heat storage technology for building applications. This development was realized by formulating and integrating the following two technology components: 1) inorganic salt hydrate based PCMs that have high latent enthalpies and are low-cost and durable, and 2) PCM encapsulation (packaging) technology that maximizes PCM concentration and enhances heat transport characteristics in the product and with the external environment/materials. High thermal storage capacity, low cost and fire resistance are key to the building market entry for PCM technology. Therefore, the project’s focus was on salt-hydrate-based formulations which satisfy all these criteria. Packaging and/or encapsulation of PCM is a key processing step. The project team recognized that a low-cost and simple-to-manufacture salt hydrate-based PCM technology holds the best chance to be successful in the building construction market, a market which is traditionally extremely sensitive to cost and where commodity thermal insulations are the benchmark for envelope-related energy saving measures. That is why, in this project, the main intention was to minimize the production cost and maximize the product energy storage density without sacrificing the PCM performance. It was achieved through: 1. Minimizing the non-PCM components (plastics, additives, packaging/encapsulation materials, etc.) because they are significantly more expensive than salt hydrates, 2. Using highly thermally conductive and lightweight PCM carrier (packaging material) to facilitate more complete phase cycling, and 3. Optimizing the thickness and minimizing air spaces in product design (such as in pouched PCM). For this purpose, our approach was to enable an easy system design, including selection of the PCM operating temperatures, optimizing the necessary heat storage capacity (by stacking together several layers of PCM products), and if needed, a synchronized usage of PCM products of different temperatures. A specially designed, robust, highly thermally conducting and highly impermeable packaging (to retain salt hydrate water during phase transition cycles) was designed and tested to increase the overall system thermal performance and durability. All PCM products developed during this project were tested in both lab scale and in full scale field conditions. It is expected that, after further developments and commercialization, the developed PCM technologies may be also applied in space conditioning, energy storage technologies, and heat transfer applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS2021

Hydrogen Abundance and Distribution on (101955) Bennu

Asteroids were likely a major source of volatiles and water to early Earth. Quantifying the hydration of asteroids is necessary to constrain models of the formation and evolution of the Solar System and the origin of Life on Earth. The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission showed that near-Earth asteroid (101955) Bennu contains widespread, abundant hydrated phyllosilicates, indicated by a ubiquitous absorption at ~ 2.7 μm. The objective of this work is to quantify the hydration—that is, the hydrogen content—of phyllosilicates on Bennu's surface and investigate how this hydration varies spatially. We analyse spectral parameters (normalized optical path length, NOPL; effective single-scattering albedo, ESPAT; and Gaussian modeling) computed from the hydrated phyllosilicate absorption band of spatially resolved visible–near-infrared spectra acquired by OVIRS (the OSIRIS-REx Visible and InfraRed Spectrometer). We also computed the same spectral parameters using laboratory-measured spectra of meteorites including CMs, CIs, and the ungrouped C2 Tagish Lake. We estimate the mean hydrogen content of water and hydroxyl groups in hydrated phyllosilicates on Bennu's surface to be 0.71 ± 0.16 wt%. This value is consistent with the hydration range of some aqueously altered meteorites (CMs, C2 Tagish Lake), but not the most aqueously altered group (CIs). The sample collection site of the OSIRIS-REx mission has slightly higher hydrogen content than average. Spatial variations in hydrogen content on Bennu's surface are linked to geomorphology, and may have been partially inherited from its parent body.

A. Praet↗

DOE OSTI2021

Towards ternary binders involving limestone additions — A review

The review summarises literature to examine the transition from portland limestone cement system to composite ternary binder systems involving limestone. Interest in limestone addition as an ideal component in multicomponent binder systems has surged as evident from the large volume of literature published in the recent past. A ternary blended system, with co-substitution of limestone, has the potential to complement the reaction of the supplementary cementitious materials (SCMs). The direct addition of limestone powder helps to attain higher substitution levels of portland cement clinker, improve early age properties, and supplement SCM's reactivity. However, the dilution of hydrates could hamper the long-term benefits. In this review, the interaction of fine limestone is classified and elaborated under two broad umbrellas: physical and chemical interactions. The physical interactions can manifest in three ways, namely, filler action, shearing action and improved packing, which alters reaction rate and extent at early ages. The chemical interactions also modify the reaction kinetics and phase assemblage due to nucleation of C-S-H on calcite surfaces, preservation of the ettringite phase and formation of carboaluminates. Two different forms of carboaluminate hydrates — hemicarboaluminate and mono-carboaluminate can be present in the hydrate matrix depending on the balance between carbonate ions and aluminates in the pore solution. Several factors such as replacement level, particle size, choice of SCM, its reactivity and reactive aluminates content, sulphate levels, curing temperature, and duration of curing can control the carboaluminate formation, reaction degree of SCMs and chemical interaction from limestone additions. A combination of physical and chemical effects makes fine limestone a potential material for co-substitution with aluminosilicate based SCMs, mainly fly ash, slag, and calcined clay. In this review, the factors affecting limestone-SCM composites are summarised based on a detailed literature survey. The effects of SCM-limestone cement composites on hydration kinetics, reaction chemistry, the reactivity of SCMs, the stability of hydrated phases, and contribution to the physical structure development and macroscopic properties by evaluating hydration and mechanical properties are discussed. The importance of AFm (Al{sub 2}O{sub 3}–Fe{sub 2}O{sub 3}-mono) phases in various deterioration mechanisms in concrete and their influence on performance characteristics in different exposure environment is critically appraised.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Improving Proton Conductivity by Navigating Proton Trapping in High Scandium-Doped Barium Zirconate Electrolytes

Proton-conducting oxides are used in intermediate-temperature (300 °C < T < 700 °C) applications of fuel cells, electrolyzers, membrane reactors, hydrogen pumps, and sensors. The proton conductivity of doped ABO 3 perovskites is partly dependent on the proton concentration and hence on the level of material hydration. However, how the material hydration ability is affected by differences in doping is not fully understood. Here, we show the prospect of proton trapping and detrapping that influences material hydration and dehydration. The proton-trapping influence is significant for Sc-doped BaZrO 3 compared to Y-doped BaZrO 3 . Here, our work offers a perspective to understand how defect interaction/associations influence the hydration ability of proton-conducting oxides. Furthermore, positron annihilation lifetime spectroscopy was revealed to be a valuable technique for studying the proton-trapping phenomena and the defect chemistry of dense proton conductors. Density functional theory calculations also showed that a high hydration level in Sc-doped BaZrO 3 boosts proton migration. In contrast, the effect of boosting the proton migration due to increased hydration is limited for Y-doped BaZrO 3 . This effect, in turn, might explain the trend of conductivity with dopant concentration in doped BaZrO 3 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Ion and Water Dynamics in the Transition from Dry to Wet Conditions in Salt-Doped PEG

The influence of the water content on ion and water transport mechanisms in polymer membranes under low to moderate hydration conditions remains poorly understood. In this study, we combine ion and water diffusivity (PFG-NMR) measurements with atomistic molecular dynamics simulations to better understand transport processes in hydrated salt-doped poly(ethylene glycol). Above the water percolation threshold, the experimental and simulated diffusivities are in good agreement with the free volume transport models. At low hydration levels, unlike dry systems, ion diffusion cannot be described by polymer segmental dynamics alone. We rationalize such observations by the interplay between ion–water and ion–polymer solvation of cations and between ion–water and cation–anion interactions for anions. Further, we demonstrate that a two-state model combining ion–water solvation and free volume transport can describe water dynamics across the entire hydration range of interest. Here, our findings provide a more encompassing analysis of ion and water transport in hydrated polyelectrolytes, specifically in the low hydration regime.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Evaluation of a Robust, In-Situ Surface Treatment for Pipeline Solids Deposition Mitigation in Flowing Systems

Abstract The formation/precipitation and deposition of pipeline solids, such as gas hydrates, asphaltenes, and waxes have long plagued production fields. Given the vast differences in chemistries of these solids, any current prevention or mitigation strategy, particularly for cases where multiple issues are a concern, is likely to involve an extensive assortment of undefined chemical additives that are both costly and add complexity to the system. Surface treatments (coatings), on the other hand, present a relatively new viable option for management strategies. A chemically and physically robust surface treatment with the ability to address deposition issues for multiple pipeline solids could not only decrease the operating expenditures for a field through material cost savings and obviation of downstream separation, but could also simplify produced fluids by eliminating additional chemicals from the mixture. The purpose of this study is to explore the feasibility of a particular surface treatment as part of a solids management strategy. This work utilizes an omniphobic surface treatment to probe its effects on gas hydrate, asphaltene, and wax deposition. Specifically, high pressure rocking cells are employed to study gas hydrate nucleation and deposition. A bench-scale flowloop filled with crude oil and heptane is used to quantify the deposition of crude oil and asphaltenes after a set time period. Lastly, a mechanical shear device measures the adhesion force of wax deposits on untreated/treated surfaces. The gas hydrate rocking cell tests demonstrate an increase in induction time and occasional elimination of hydrate nucleation with the surface treatment. Moreover, the same apparatus indicates that the critical shear to avoid hydrate deposition may be lowered in the presence of the surface treatment compared to untreated pristine carbon steel coupons. A custom-built asphaltene flowloop then establishes that this surface treatment is effective in dramatically reducing the deposition of the aliphatic components of a crude oil, with a moderate reduction in the asphaltene fraction. Finally, mechanical adhesion force measurements for solidified paraffin wax display trends in agreement with the asphaltene results. The surface treatment on both pristine and corroded surfaces is able to reduce the adhesion of wax deposits to values below a pristine, untreated surface.

03 NATURAL GAS↗

DOE OSTI2024

Natural carbonation of portland cement with synthetic zeolite Y as a supplementary cementitious material

Risks associated with carbonation are a key limitation to greater replacement levels of ordinary portland cement (OPC) by supplementary cementitious materials (SCMs). The addition of pozzolanic SCMs in OPC alters the hydrate assemblage by forming phases like calcium-(alumina)-silicate-hydrate (C-(A)-S-H). The objective of the present study was to elucidate how such changes in hydrate assemblage influence the chemical mechanisms of carbonation in a realistic OPC system. Here, in this paper, we show that synthetic zeolite Y (faujasite) is a highly reactive pozzolan in OPC that reduces the calcium content of hydration products via prompt consumption of calcium hydroxide from the evolving phase assemblage prior to CO 2 exposure. Suppression of portlandite at moderate to high zeolite Y content led to a more damaging mechanism of carbonation by disrupting the formation of a passivating carbonate layer. Without this layer, carbonation depth and CO 2 uptake are increased. Binders containing 12–18% zeolite Y by volume consumed all the calcium hydroxide from OPC during hydration and reduced the Ca/(Si+Al) ratio of the amorphous products to near 0.67. In these cases, higher carbonation depths were observed after exposure to ambient air with decalcification of C-(A)-S-H as the main source of CO 2 buffering. Binders with either 0% or 4% zeolite Y contained calcium hydroxide in the hydrated microstructure, had higher Ca/(Si+Al) ratios, and formed a calcite-rich passivation layer that halted deep carbonation. Although the carbonated layer in the samples with 12% and 18% zeolite Y contained 70% and 76% less calcite than the OPC respectively, their higher carbonation depths resulted in total CO 2 uptakes that were 12x greater than the OPC sample. Passivation layer formation in samples with calcium hydroxide explains this finding and was further supported by thermodynamic modeling. High Si/Al zeolite additives to OPC should be balanced with the calcium content for optimal carbonation resistance.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Reaction Layer Formation on MgO in the Presence of Humidity

Mineralization by MgO is an attractive potential strategy for direct air capture (DAC) of CO 2 due to its tendency to form carbonate phases upon exposure to water and CO 2 . Hydration of MgO during this process is typically assumed to not be rate limiting, even at ambient temperatures. However, surface passivation by hydrated phases likely reduces the CO 2 capture capacity. Here, we examine the initial hydration reactions that occur on MgO(100) surfaces to determine whether they could potentially impact CO 2 uptake. We first used atomic force microscopy (AFM) to explore changes in reaction layers in water (pH = 6 and 12) and MgO-saturated solution (pH = 11) and found the reaction layers on MgO are heterogeneous and nonuniform. To determine how relative humidity (R.H.) affects reactivity, we reacted samples at room temperature in nominally dry N 2 (~11–12% R.H.) for up to 12 h, in humid (>95% R.H.) N 2 for 5, 10, and 15 min, and in air at 33 and 75% R.H. for 8 days. X-ray reflectivity and electron microscopy analysis of the samples reveal that hydrated phases form rapidly upon exposure to humid air, but the growth of the hydrated reaction layer slows after its initial formation. Reaction layer thickness is strongly correlated with R.H., with denser reaction layers forming in 75% R.H. compared with 33% R.H. or nominally dry N 2 . The reaction layers are likely amorphous or poorly crystalline based on grazing incidence X-ray diffraction measurements. After exposure to 75% R.H. in air for 8 days, the reaction layer increases in density as compared to the sample reacted in humid N 2 for 5–15 min. Further, this may represent an initial step toward the crystallization of the reaction layer. Overall, high R.H. favors the formation of a hydrated, disordered layer on MgO. Based on our results, DAC in a location with a higher R.H. will be favorable, but growth may slow significantly from initial rates even on short timescales, presumably due to surface passivation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

SANS quantification of bound water in water-soluble polymers across multiple concentration regimes

Contrast-variation small-angle neutron scattering (CV-SANS) is a widely used technique for quantifying hydration water in soft matter systems, but it is predominantly applied in the dilute regime or for systems with a well-defined structure factor. Here, CV-SANS was used to quantify the number of hydration water molecules associating with three water-soluble polymers with different critical solution temperatures and types of water–solute interactions in dilute, semidilute, and concentrated solution through the exploration of novel methods of data fitting and analysis. Multiple SANS fitting workflows with varying levels of model assumptions were evaluated and compared to give insight into SANS model selection. These fitting pathways ranged from general, model-free algorithms to more standard form and structure factor fitting. In addition, Monte Carlo bootstrapping was evaluated as a method to estimate parameter uncertainty through simulation of technical replicates. The most robust fitting workflow for dilute solutions was found to be form factor fitting without CV-SANS ( i.e. polymer in 100% D 2 O). For semidilute and concentrated solutions, while the model-free approach can be mathematically defined for CV-SANS data, the addition of a structure factor imposes physical constraints on the optimization problem, suggesting that the optimal fitting pathway should include appropriate form and structure factor models. The measured hydration numbers were consistent with the number of tightly bound water molecules associated with each monomer unit, and the concentration dependence of the hydration number was largely governed by the chemistry-specific interactions between water and polymer. Polymers with weaker water–polymer interactions ( i.e. those with fewer hydration water molecules) were found to have more bound water at higher concentrations than those with stronger water–polymer interactions due to the increase in the number of forced water–polymer contacts in the concentrated system. This SANS-based method to count hydration water molecules can be applied to polymers in any concentration regime, which will lead to improved understanding of water–polymer interactions and their impact on materials design.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Cooperative Research and Development Agreement between National Energy Technology Laboratory and Korea Institute of Energy Research (KIER) [Abstract]

KIER and NETL will collaborate to study hydrate-based technologies to enhance desalination, gas separation, and hydrocarbon flow through pipelines and wellbores. With optimized selections of hydrate formers and reactors, gas hydrates can be effective and economic mechanisms of separation for solid-water and gas mixtures, and gas hydrate formation or dissociation can be significantly delayed or expedited with suitably selected additives. Comprehensive laboratory studies, including identifying novel hydrate formers or inhibitors to control temperature and pressure requirements and understanding their working mechanism or developing reactor systems for production of large quantities of hydrates, will be performed at both KIER and NETL either parallelly or serially.

03 NATURAL GAS↗

DOE OSTI2020

Cooperative Research and Development Agreement between National Energy Technology Laboratory and Raytheon Technologies Corporation [Abstract]

02 PETROLEUM↗

NASA NTRS2015

Aram Chaos: a Long Lived Subsurface Aqueous Environment with Strong Water Resources Potential for Human Missions on Mars

Aram Chaos, Mars is a crater 280 kilometers in diameter with elevations circa. minus 2 to minus 3 kilometers below datum that provides a compelling landing site for future human explorers as it features multiple scientific regions of interest (ROI) paired with a rich extensible Resource ROI that features poly-hydrated sulfates [1]. The geologic history of Aram Chaos suggests several past episodes of groundwater recharge and infilling by liquid water, ice, and other materials [1-3]. The creation of the fractured region with no known terrestrial equivalent may have been caused by melting of deep ice reservoirs that triggered the collapse of terrain followed by catastrophic water outflows over the region. Aram Chaos is of particular scientific interest because it is hypothesized that the chaotic terrain may be the source of water that contributed to the creation of nearby valleys such as Ares Vallis flowing toward Chryse Planitia. The liquid water was likely sourced as groundwater and therefore represents water derived from a protected subsurface environment making it a compelling astrobiological site [2]. The past history of water is also represented by high concentrations of hematite, Fe-oxyhydroxides, mono-hydrated and poly-hydrated sulfates [1, 2]. Poly-hydrated sulfates are likely to contain abundant water that evolves at temperatures below 500 degrees Centigrade thus conferring Aram Chaos a potentially high value for early in-situ resource utilization (ISRU) [4]. The geologic history also calls for future prospecting of deep ice deposits and possibly liquid water via deep drilling. The most recent stratigraphic units in the central part of Aram Chaos are not fractured, and are part of a dome-shaped formation that features bright, poorly-consolidated material that contains both hydrated sulfates and ferric oxides according to OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) data [5]. These surface material characteristics are preliminary indications of their potential use in civil engineering activities that involve regolith moving and hauling, while further study is needed to assess traverse-ability challenges. The widespread distribution of sulfates is also of interest as a resource for the use of sulfur as a binding compound in regolith-based concrete for constructions. The terrain depressions caused by the rock fracturing events may challenge surface mobility but also suggest the possibility of using such natural features for additional shielding from space radiation and as emplacement of nuclear surface power reactors for the same reason. The high concentration of hematite (up to 16 percent) in some of the smoother recent terrains of the central part of Aram Chaos [2] is a favorable attribute for metal extraction ISRU to create iron-based feedstock for in-situ fabrication of replacement parts or their repairs. Preliminary data on Aram Chaos indicate that it offers a combination of many critical criteria for human missions to the surface of Mars: equatorial region at low Mars Orbiter Laser Altimeter (MOLA), evidence of hydrated minerals over large areas and at high concentrations tied to historic evidence of liquid water over long periods.

Sibille, L.↗

DOE OSTI2024

Systems, methods, and compositions for purifying water

Systems for removing one or more contaminants from water are provided that can include a hydrate formation chamber assembly; a contaminated water diffusion assembly within the hydrate formation chamber assembly; a space between a wall of the hydrate formation chamber assembly and the diffusion assembly; and a guest compound conduit configured to provide a guest compound within the space and form a hydrate comprising water and the guest compound. Methods for removing one or more contaminants from water are provided that can include providing a contaminated water mixture and one or more guest compounds; forming a hydrate complex comprising water and the one or more guest compounds; and separating the water from the guest compounds to provide water with less contaminant. Mixtures are also provided that can include a liquid component comprising water and at least one contaminant, and a solid component comprising a hydrate complex. One embodiment of the system provides methods for production of excess electric power as a byproduct of the desalination process.

McGrail, Bernard P.↗