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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Molecular dynamics simulation studies of 1,3-dimethyl imidazolium nitrate ionic liquid with water

The fundamental understanding of intermolecular interactions of ionic liquids (ILs) with water is essential in predicting IL–water thermodynamic properties. In this study, intermolecular or noncovalent interactions were studied for 1,3-dimethyl imidazolium [DMIM]+ cation and nitrate [NO 3 ] – anion with water, employing quantum mechanics and molecular dynamics simulations. Molecular dynamics simulations were performed using a revised multipolar polarizable force field. The effect of water on ionic liquids was evaluated in terms of thermodynamic and dynamic properties. Thermodynamic properties included liquid densities ρ, excess molar volumes ΔV E , and liquid structures g(r)⁠. Dynamic properties included self-diffusion coefficients D of mixture constituents as a function of water concentration. The density of ionic liquid–water mixtures monotonically decrease with increasing concentration of water. A negative excess volume was obtained for low and high water concentrations, demonstrating strong intermolecular interactions of water with ionic liquid components. Liquid structures of ionic liquid–water mixtures revealed a tendency for anions to interact with cations at shorter intermolecular distances when the water concentration is increased. Diffusion rates were found to increase for all mixture components with increase in the fraction of water. A significant change in the diffusion rate was found at ~0.3 weight fraction of water. However, the water self-diffusion coefficient was dominant at all concentrations. Furthermore, the ratio of water/anion and anion/cation self-diffusion coefficients was found to decrease linearly with increasing concentration of water molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A self-consistent electrostatic electrified shallow water model for charged liquid surface dynamics

The dynamics of an electrified liquid surface are investigated using a shallow water model that is self-consistently coupled with an electrostatic solver. To account for the spatiotemporal variation of a curved liquid surface, the electric field on curved surfaces is calculated by solving a two-dimensional electrostatic equation using the weighted least squares (WLSQ) interpolation method. First, the WLSQ implementation is verified with analytical theory obtained from a Laplace solution assuming a half-cylinder liquid surface profile. Then, the coupled electrified shallow water model is used to study the instability of liquid surface perturbation as a function of the potential drop between an electrode and conducting liquid, surface tension, and gravity. We present a linear dispersion theory of liquid surface instability for long-wavelength perturbations, including the effects of liquid viscosity. Furthermore, the effects of multiple sinusoidal surface perturbations on the electrified liquid surface instability are investigated.

Capillary waves↗
DOE OSTI2024

Secondary electron emission measurements from imidazolium-based ionic liquids

The electron-induced secondary electron emission (SEE) yields of imidazolium-based ionic liquids are presented for primary electron beam energies between 30 and 1000 eV. These results are important for understanding plasma synthesis of nanoparticles in plasma discharges with an ionic liquid electrode. Due to their low vapor pressure and high conductivity, ionic liquids can produce metal nanoparticles in low-pressure plasmas through reduction of dissolved metal salts. In this work, the low vapor pressure of ionic liquids is exploited to directly measure SEE yields by bombarding the liquid with electrons and measuring the resulting currents. The ionic liquids studied are [BMIM][Ac], [EMIM][Ac], and [BMIM][BF 4 ]. The SEE yields vary significantly over the energy range, with maximum yields of around 2 at 200 eV for [BMIM][Ac] and [EMIM][Ac], and 1.8 at 250 eV for [BMIM][BF 4 ]. Molecular orbital calculations indicate that the acetate anion is the likely electron donor for [BMIM][Ac] and [EMIM][Ac], while in [BMIM][BF 4 ], the electrons likely originate from the [BMIM] + cation. The differences in SEE yields are attributed to varying ionization potentials and molecular structures of the ionic liquids. These findings are essential for accurate modeling of plasma discharges and understanding SEE mechanisms in ionic liquids.

ionic liquids↗
DOE OSTI2025

Surface deformation coupled with self-organized pattern on a liquid anode of 1 atm DC glow discharge

Intricate, self-organized plasma structures observed above the surface of a liquid anode of atmospheric DC glow discharge were found to give rise to coherent, organized surface deformation and mechanical wave formation at the plasma–liquid interface. This new phenomenon indicates that the liquid is closely coupled to the plasma by the anode sheath’s electrohydrodynamic (EHD) force. A scientific question then arises: Do surface perturbations, coupled with the nonuniform surface charge distribution, enhance the electric field and induce self-organization? Using the reflective background-oriented schlieren technique, the liquid surface profile under the plasma pattern was measured for the first time. The results show that surface distortions are driven by the repulsive Coulomb force of nonuniform net-negative surface charge acted by the anode sheath field. The impacts of various operating parameters on the patterns and surface waves were examined, revealing the significance of gas heating and liquid charge relaxation time in the pattern formation mechanism. Time-resolved dynamics of a pulsed DC discharge indicated that the surface deformation only appeared after the establishment of plasma patterns. Statistically, the surface wave under the plasma has high wave numbers (8000–16000 m −1 ) and small amplitudes ($<$ 10 µm), generally found in the capillary wave regime. Yet the motion of surface deformations is in tandem with the plasma pattern and exhibits a nondispersive nature of constant phase velocity (0.1–0.4 m s −1 ), suggesting the dominant role of EHD force over the surface tension in the observed surface wave. These results indicate that the deformed liquid surface is driven by the EHD force of the plasma sheath. Although they share a similar geometry, the deformation and wave dynamics of the liquid surface do not stimulate a plasma pattern. Importantly, the complex EHD coupling in the plasma–liquid system raises awareness and new challenges for plasma control engineering, and the quantitative characteristics of the nondispersive surface wave are informative for advancing relevant theory and modeling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Ionic Liquids for Direct Air Capture of CO 2 using Electric‐Field‐Mediated Moisture Gradient Process (Final Technical Report)

The final report provides executive summary, a list of publications, and information on training graduate students and postdoctoral researchers. We carried out computational and experimental research on understanding molecular-level mechanism of how CO 2 is absorbed in a solution containing ethylene glycol as the solvent and KOH as the salt in the presence of ionic liquids and under the influence of electric field. In doing so, we developed an automated high-throughput method which allowed us to measure the solubility of CO 2 in a large number of ionic liquids, considerably speeding up the CO 2 solubility measurement. We also demonstrated how varying the concentration of ionic liquids in ethylene glycol can result in a maximum in ionic conductivity. Reaction of CO 2 and subsequent release results in a 50% reduction when the process is operated at an ionic liquid-ethylene glycol concentration yielding maximum ionic conductivity amongst all the ionic liquid-ethylene glycol combinations studied as a part of this research. We utilized machine learning models to identify unique ionic liquid-solvent combinations with ionic conductivity much higher than that measured for ionic liquid-ethylene glycol combinations. We demonstrated that the rate of CO 2 reaction with KOH in ethylene glycol can be optimized with the type of ionic liquid and its concentration. Overall, the research led to publication of 10 peer-reviewed research articles and several presentations at national conferences. We are also in the process of developing additional manuscripts based on the research carried out as a part of this project. Two graduate students and two postdoctoral researchers were supported on the funding.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRSDate not supplied

Improvements in Ionic Liquid Technology for Carbon Dioxide Removal Applications

Carbon dioxide removal from cabin air continues to be of vital importance for future space missions. Current and proposed approaches have employed solid sorbents, hollow fiber membrane separators, and direct liquid sorbent contactors. Recent developments in ionic liquids have potential to improve performance in all three of these technologies. Efficient encapsulation of ionic liquids by polymeric shell can enable their use in a solid sorbent-like configuration without significant integration intervention to the current space technology. Poly(ionic liquid)-ionic liquid membranes have the potential to cross over the Robeson selectivity-permeability upper bound, and thereby outperform traditional membranes used in hollow fibers. Advances in ionic liquid chemistry enables performance improvements in liquid sorbent contactors owing to the tunable gravimetric CO2 capacity, reaction enthalpy and liquid viscosity. This paper will describe recent work in each of these areas.

Ionic Liquid,Carbon Dioxide,Air Revitalization↗
DOE OSTI2022

CO2 Sorption in Ionic Liquid Crystals

Ionic liquid crystals (ILCs) have an affinity for certain polarizable gases such as CO2, due to their similarity to ionic liquids. We investigated three ILCs in the [1-alkyl-3-methylimidazolium+] family: n=12,14 with [BF4-] and [PF6-]: liquid crystalline analogues to ionic liquids with moderate (e.g., 1-2 mol%) CO2 solubility at atmospheric conditions: [1-butyl-3-methylimidazolium+] with [BF4-] and [PF6-]. While ionic liquids show high CO2 solubility, regenerating the CO2 is a high-energy process. Liquid crystals show low CO2 solubility but have a much lower regeneration energy requirement. Will ionic liquid crystals uptake CO2? What are the energy requirements of regenerating CO2? Conclusions: 1. C12mim BF4- shows the highest sorption at 0.12 wt% CO2 in the isotropic phase vs. C14mim BF4- with 0.097 wt% in the smectic phase. We hypothesize that the increase in chain length affects the free volume of the smectic vs. isotropic phase of C14mim BF4-, increasing the latter. 2. The change in anion from BF4- to PF6- decreased the sorption to an insignificant level more analogous to a physical adsorption onto the material in all phases. We hypothesize that the change in anion to the larger, less charge dense PF6- decreased the attractive forces between CO2 and the anion. 3. 0.12 wt% of CO2 in C12mim BF4- is small but significant. This in combination with the room temperature release of CO2 after only requiring refrigeration temperatures to occlude the CO2, making ionic liquid crystals promising materials for future.

carbon dioxide sorption↗
DOE OSTI2019

French Innovative Thermal Treatment Processes for The Management Radioactive Organic Liquid Waste - 19017

The nuclear industry as well as hospitals or some research laboratories produce Radioactive Organic Liquid Waste (ROLW) such as scintillation cocktails for medical imaging, labeled molecules for medical research or liquids from former activities. In order to be compatible with disposal facilities requirements, this waste must be inerted and stabilized in solid matrix. The route generally used is incineration in the Centraco facilities at the Marcoule site (Gard, France), ashes produced being cemented downstream. However, liquids whose chemical or radiological characteristics are not compatible with the incinerator operating rules (high level of {sup 14}C or halogen content, corrosive gas production etc.) cannot follow this path. The purpose of the MILOR project is then to propose alternative paths to treat all kinds of ROLW. Initiated in September 2017, this project has the technical objective of developing, over a four-year period, two pilot-scale mineralization processes. Two variants of complementary plasma technologies are evaluated: aerial plasma with the 'IDOHL' process and submerged plasma with the 'ELIPSE' process. Compared with other methods, thermal plasmas have unique characteristics such as rapid decomposition with high throughput, fast startup and shutdown, and high-energy delivery. The process called IDOHL consists of a process involving an induction plasma in which the liquids are directly introduced. It has been designed for organic liquids without mineral load and for treatment rates less than 0.5 l/h. This type of plasma allows the destruction of liquid organohalogens without any prior evaporation or treatment. Specific gas treatment systems have been developed to direct the gas produced to a dry or wet gas treatment system. One aim of the project is to subsequently install the process in a radioactive zone at Saclay DRF. The second called ELIPSE consists of a breakthrough process involving a submerged plasma at the heart of which organic liquids are also introduced. Current research has demonstrated that such a technique may enable the instantaneous and complete destruction of liquids with a wide variety of constituents, such as chlorine, fluorine, or phosphorus. The submersion solution offers many advantages: quenching and cleaning of combustion gases; filtering of the particles they contain; and cooling maintained for the entire process, which guarantees excellent corrosion control. An advantage of this type of design is that the gas treatment system can be reduced to a demister-condenser followed by a simple safety filter, thereby offering the additional advantage of an extremely compact treatment system. This design also allows the ELIPSE process to become by this way an embeddable process if required. The MILOR project, financed by the French State through investment program is a tripartite project bringing together Andra, in charge of radioactive waste management, the CEA in charge of leading scientific and technological researches to propose effective ways of treatment and the company A3i whose role is to ensure the subsequent industrial development. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Low Melting Temperature Gallium–Indium Liquid Metal Anode for Solid-State Li-Ion Batteries

Solid-state Li-ion batteries are attracting attention for their enhanced safety features, higher energy density, and broader operational temperature range compared to systems based on liquid electrolytes. However, current solid-state Li-ion batteries face performance challenges, such as suboptimal cycling and poor rate capabilities, often due to inadequate interfacial contact between the solid electrolyte and electrodes. To address this issue, we incorporated a gallium–indium (Ga–In) liquid metal as the anode in a solid-state Li-ion battery setup, employing Li 6 PS 5 Cl as the solid electrolyte. Operating at room temperature, this configuration achieved an initial capacity of 389 mAh g –1 and maintained 88% of this capacity after 30 cycles at a 0.05 C rate. It also demonstrated a capacity retention of 66% after 500 cycles at a 0.5 C rate. In comparison to solid anode materials, such as tin, the Ga–In liquid metal exhibited superior cycling stability and rate capacity, which is due to the self-healing and fluid properties of the alloy that ensure stable interfacial contact with solid electrolytes. In situ X-ray diffraction (XRD) and ex situ scanning electron microscope (SEM) analyses revealed that indium does not directly participate in the lithiation/delithiation process. Instead, it helps maintain the alloy’s low melting point, facilitating its return to a liquid state after delithiation. In a comparative analysis of stack pressure during cycling in cells utilizing Ga–In liquid metal and tin, the Ga–In liquid metal cell demonstrated an ability to buffer pressure increases associated with deformation. In conclusion, these findings suggest a promising approach for enhancing solid-state batteries by integrating liquid metal anodes, which improve interfacial contact and stability.

Alloys↗
DOE OSTI2016

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid–liquid and liquid–vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecular signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable to use for in situ liquid SIMS to study solid–liquid and liquid–vacuum interfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Understanding Relationships between Free Volume and Oxygen Absorption in Ionic Liquids

In this report understanding the factors that govern gas absorption in ionic liquids is critical to the development of high-capacity solvents for catalysis, electrochemistry, and gas separations. Here, we report experimental probes of liquid structure that provide insights into how free volume impacts the O 2 absorption properties of ionic liquids. Specifically, we establish that isothermal compressibility - measured rapidly and accurately through small-angle X-ray scattering - reports on the size distribution of transient voids within a representative series of ionic liquids and is correlated with O 2 absorption capacity. Additionally, O 2 absorption capacities are correlated with thermal expansion coefficients, reflecting the beneficial effect of weak intermolecular interactions in ionic liquids on free volume and gas absorption capacity. Molecular dynamics simulations show that the void size distribution - in particular, the probability of forming larger voids within an ionic liquid - has a greater impact on O 2 absorption than the total free volume. These results establish relationships between the ionic liquid structure and gas absorption properties that offer design strategies for ionic liquids with high gas solubilities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Gold Nanocrystal Etching as a Means of Probing the Dynamic Chemical Environment in Graphene Liquid Cell Electron Microscopy

Graphene liquid cell electron microscopy has the needed temporal and spatial resolution to enable the in situ observation of nanoscale dynamics in solution. Yet, the chemistry of the solution in the liquid cell during imaging is as yet poorly understood due to the generation of a complex mixture of radiolysis products by the electron beam. In this work, the etching trajectories of nanocrystals were used as a probe to determine the effect of the electron beam dose rate and preloaded etchant, FeCl 3 , on the chemistry of the liquid cell. Initially, illuminating the sample at a low electron beam dose rate generates hydrogen bubbles, providing a reservoir of sacrificial reductant. Increasing the electron beam dose rate leads to a constant etching rate that varies linearly with the electron beam dose rate. Comparing these conclusions with the oxidation potentials of the species in solution, the electron beam likely controls the total concentration of oxidative species in solution and FeCl 3 likely controls the relative ratio of oxidative species, independently determining the etching rate and chemical potential of the reaction, respectively. Correlating these liquid cell etching results with the ex situ oxidative etching of gold nanocrystals using FeCl 3 provides further insight into the liquid cell chemistry while corroborating the liquid cell dynamics with ex situ synthetic behavior. This understanding of the chemistry in the liquid cell will allow researchers to better control the liquid cell electron microscopy environment, enabling new nanoscale materials science experiments to be conducted systematically in a reproducible manner.

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

Plasma parameters and the reduction potential at a plasma-liquid interface

We report nonthermal plasmas in contact with liquids have been shown to generate a variety of reactive species capable of initiating reduction–oxidation (redox) reactions at the electrochemically active plasma–liquid interface. In conventional electrochemical cells, selective redox chemistry is achieved by controlling the reduction potential at the solid electrode–electrolyte interface by applying a bias via an external circuit. In the case of plasma–liquid systems, an analogous means of tuning the reduction potential near the interface has not clearly been identified. When treated as a floating surface, the liquid is expected to adopt a net negative charge to balance the flux of hot electrons and relatively cold positive ions. The reduction potential near the plasma–liquid interface is hypothesized to be proportional to the floating potential, which can be approximated using an analytical model provided the plasma parameters are known. Herein, we present a framework for correlating the electron density and electron temperature of a noble gas plasma jet to the reduction potential near the plasma–liquid interface. The plasma parameters were acquired for an argon atmospheric plasma jet in contact with an aqueous solution by means of laser Thomson scattering. The reduction potential was determined using identical reference electrodes to measure the potential difference between the plasma–liquid interface and bulk solution. Interestingly, the measured reduction potentials near the plasma–liquid interface were found to be in good agreement with the model-predicted values determined using the plasma parameters obtained from the Thomson scattering experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Experimental demonstration of hydraulic jump control in liquid metal channel flow using Lorentz force

Here in this paper, hydraulic jump control using electromagnetic force in a liquid metal flow is presented. The control methods used give insight into the hydraulic jump behavior in the presence of magnetic fields and electrical currents. Flowing liquid metals is a proposed solution to heat flux challenges posed in fusion reactors, specifically the tokamak. Unfortunately, thin, fast-flowing liquid metal divertor concepts for fusion reactors are susceptible to hydraulic jumps that drastically reduce the liquid metal flow speed, leading to potential problems such as excessive evaporation, unsteady power removal, and possible plasma disruption. Highly electrically conductive flows within the magnetic fields do not exhibit traditional hydraulic jump behavior. There is very little research investigating the use of externally injected electrical currents and magnetic fields to control liquid metal hydraulic jumps. By using externally injected electrical currents and a magnetic field, a Lorentz force (also referred to as j × B force) may be generated to control the liquid metal jump behavior. In this work, a free-surface liquid metal—GaInSn eutectic or “galinstan”$-$flow through an electrically insulating rectangular duct was investigated. It was shown that applying a Lorentz force has a repeatable and predictable impact on the hydraulic jump, which can be used for liquid metal control within next-generation fusion reactors.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Plasma dynamics, instabilities and OH generation in a pulsed atmospheric pressure plasma with liquid cathode: a diagnostic study

Abstract While plasma–liquid interactions have been an important focus in the plasma research community, the impact of the strong coupling between plasma and liquid on plasma properties and processes remains not fully understood. In this work, we report on the impact of the applied voltage, pulse width and liquid conductivity on the plasma morphology and the OH generation for a positive pulsed DC atmospheric pressure plasma jet with He–0.1% H 2 O mixture interacting with a liquid cathode. We adopted diagnostic techniques of fast imaging, 2D laser induced fluorescence of OH and Thomson scattering spectroscopy. We show that plasma instabilities and enhanced evaporation occur and have a significant impact on the OH generation. At elevated plasma energies, it is found that the plasma contracts due to a thermal instability through Ohmic heating and the contraction coincides with a depletion in the OH density in the core due to electron impact dissociation. For lower plasma energies, the instability is suppressed/delayed by the equivalent series resistor of the liquid electrode. An estimation of the energy flux from the plasma to the liquid shows that the energy flux of the ions released into the liquid by positive ion hydration is dominant, and significantly larger than the energy needed to evaporate sufficient amount of water to account for the measured H 2 O concentration increase near the plasma–liquid interface.

Physics↗
DOE OSTI2023

Influence of liquid conductance on the temporal evolution of self-organization patterns in atmospheric pressure DC glow discharges

Abstract Self-Organized Patterns (SOPs) at plasma-liquid interface in atmospheric pressure plasma discharges refer to the formation of intricate and puzzling structures due to the interplay of electrodynamic and hydrodynamic processes. Studies conducted to date have shown that this phenomenon results in the formation of distinctive patterns such as circular ring, star, gear, dots, spikes, etc., and primarily depends on working gas, electrolyte type, gap distance, current, conductivity, etc. However, an adequate understanding of how these patterns change from one type to another is still not available. This study aims to elucidate the influence of initial liquid conductance ( σ i ) on the temporal evolution of SOPs in liquid-anode discharges. The discharge was generated in a pin-to-liquid anode configuration at a constant helium (He) flow rate of 500 sccm and DC applied voltage of 6 kV at a gap distance of 12 mm. Through the gradual increment of σ i from 1.8 μ S to 4820 μ S, we observe that the trend in the evolution of SOPS takes place as solid discs, spikes, dots, rings, double rings, and stars. The continuous formation of reactive species onto the liquid anode in all conductive solutions results in a decrease in pH, an increase in bulk liquid temperature, and an increase in total dissolved solutes, and these have been confirmed through experimental measurements. Observations using optical emission spectroscopy show that the electrons at the plasma-liquid interface participate in the reduction of cations followed by their excitation & ionization due to which electron density as well as emissions from excited species (mainly hydroxyl radicals & excited nitrogen) decrease with time. Our investigation provides experimental evidence on the presence of cations at the plasma-liquid interface required for SOP formation.

Physics↗
DOE OSTI2013

Cadarache LOR (liquides organiques radioactifs) treatment by a solidification process using NOCHAR polymers

In France, two options can be considered to handle the Very Low Level Waste (VLLW) and the Low Level Waste (LLW). The first one is the incineration at CENTRACO facility and the second one is the disposal at ANDRA sites. The waste acceptance in these two channels is dependent upon the adequacy between the waste characteristics (physical chemistry and radiological) and the channel specifications. If the waste characteristics and the channel specifications (presence of significant quantities of halogens, complexing agents, organic components... or/and high activity limits) are incompatible, an alternative solution have to be identify. It consists of a waste pre-treatment process. For Cadarache LOR (Liquides Organiques Radioactifs) waste streams, two radioactive scintillation cocktails have to be treated. They are composed of a mix of organic liquids and water: for the first one, 19 % of organic compounds (xylene, mesitylene, diphenyloxazole, TBP...) and 86.9 % of water, and for the second one, 23 % of organic compounds (TBP...) and 77 % of water. They contain halogens (chlorine and fluorine), complexants agents (nitrate, sulphate, oxalate and formate) and have got αβγ spectra with mass activities equal to some 100 Bq/g. Therefore, tritium is also present. As a consequence, in order for storage acceptance at the ANDRA site, it is necessary to pre-treat the waste. An adequate solution seems to be a solidification process using NOCHAR polymers. Indeed, NOCHAR polymers correspond to an important variety of products applied to the treatment of radioactive aqueous and organic liquids (solvent, oil, solvent/oil mixing ...) and sludge through a mechanical and chemical solidification process. For Cadarache LOR, N910 and N960 respectively dedicated to the organic and aqueous liquids solidification are considered. With the N910, the organic waste solidification occurs in two steps. As the organic liquid travels moves through the polymer strands, the strands swell and immobilize the liquid. Then as the polymer-organic cure, over time, the polymer continues to collapse on the organic to create a permanent chemical bond. The N960 has the ability to absorb aqueous waste up to 100 times its own weight. It creates a strong mechanical bond which permanently traps the contamination imbedded in the aqueous liquids. Therefore, these two NOCHAR polymers seem to be able to constitute a suitable solidification matrix for a final acceptance in storage on ANDRA sites. In order to validate the solidification process using NOCHAR polymers as an acceptable solution for Cadarache LOR treatment, some solidification tests realised with N910 and N960, have been carried out for different Waste/Polymer ratios. To determine the best Waste/Polymer ratio and the optimal experimental parameters, exudation tests have been made. Indeed, the process prevents leaching and it results in the absence residual free organic or aqueous liquid which is forbidden in storage by ANDRA specifications. With these results, the obtained scientific data constitute a fundamental basis of an ANDRA agreement. As a conclusion, the aim of this study is to demonstrate that the pre-treatment by solidification using NOCHAR polymers can constitute a solution for Cadarache LOR handling and more generally, for various organic and mixed organic/aqueous waste which can not be directly acceptable at CENTRACO facility or at ANDRA storage sites. So then, this study is a solid background to demonstrate the feasibility of the waste pre-treatment by solidification with NOCHAR polymer and to encourage this process development. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Optimal spectral resolution for solids and liquids using FT and other infrared spectrometers: How much resolution do you really need?

In this study we investigate the possibility of using spectral resolutions for infrared measurements of solids and liquids that are not powers of two, e.g. are not at 1, 2, 4, 8, or 16 cm-1 resolution. In almost all reported literature of the last fifty years the resolution used to record for a Fourier transform infrared spectrum has been a power of two. This stems from the fact that 1) the Cooley-Tukey algorithm used to compute such a transform was constructed to use only powers of two and was also driven by 2) the fact that the computing horsepower required to compute the Fourier transform increases as N?log?_2 (N), where N is the number of points in the interferogram (spectrum). For typical spectra, however, the CPU time is no longer a consideration. Our study is based on both liquid and solid spectra, all of which were recorded at 2 cm-1 resolution. There were at total of 70 solids spectra representing 2,472 spectral peaks and 61 liquids spectra (1,765 spectral peaks), each peak being inspected for being singlet / multiplet in nature. Of the 1,765 liquid bands examined, only 27 had widths less than 5 cm-1. Of the 2,472 solid bands examined, only 39 peaks have widths less than 5 cm-1. For liquids, the mean peak width is 24.7 cm-1 but the median peak width is 13.7 cm-1, and, similarly, for solids, the mean peak width is 22.2 cm-1 but the median peak width is 11.2 cm-1. In both cases, solids and liquids, a skewed peak widths distribution was observed, the peak of the distribution representing narrower bands in the 7 to 9 cm-1 FWHM range but displaying a long tail to the very broad bands, with some displaying spectral widths of 100 cm-1 or more. Because one of the most important criteria for successful instrumental design in IR spectroscopy is the spectral resolution, the data were further analyzed showing that a value to resolve 95% of all bands is 5.7 cm-1 for liquids and 5.3 cm-1 for solids; such a resolution would capture the native linewidth (no instrumental broadening) of 95% of all the solids and liquid bands, respectively. Based on the present results we suggest that, when accounting only for intrinsic linewidths an optimized resolution of 6.0 cm-1 will capture 91% of all condensed-phase bands for IR detection of chemical, mineral, and biological materials.

Forland, Brenda M.↗