LiCl Salt Research Articles

Feasibility tests of nickel as a containment material of molten Li2O-LiCl salt containing Li metal at 650 °C during electrolytic reduction

In this study, we investigated the feasibility of nickel (Ni) as a material to contain molten Li2O-LiCl salt containing lithium (Li) metal at 650 °C as an electrolyte during the electrolytic reduction process of pyroprocessing (also known as oxide reduction, OR). First, the behaviors of Ni in four different LiCl salts (0.1 wt% Li-LiCl, 1 and 8 wt% Li2O-LiCl, and 8 wt% Li2O-0.1 wt% Li-LiCl) in an argon atmosphere were examined through immersion tests. Then, Ni was used as a vessel material for five consecutive OR runs of simulated oxide fuel using 1.0 wt% Li2O-LiCl salt. The tested Ni was analyzed by microbalance, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Concentrations of Ni in the salt were measured using inductively coupled plasma atomic emission spectroscopy. No corrosion product of Ni, except Cr2Ni3, was observed on the Ni used for both the salt-immersion tests and the OR runs because the Ni was not exposed to oxygen gas. However, leaching of Ni in the OR salt containing excessive Li metal was observed. Therefore, Ni can be used as the salt containment material in the OR process when excessive Li metal and oxygen gas in the salt are maintained at low levels.

Reoxidation of uranium in electrolytically reduced simulated oxide fuel during residual salt distillation

We report that residual salt removal by high-temperature distillation causes partial reoxidation of uranium metal to uranium oxide in electrolytically reduced simulated oxide fuel. Specifically, the content of uranium metal in the above product decreases with increasing distillation temperatures, which can be attributed to reoxidation by Li2O contained in residual salt (LiCl). Additionally, we estimate the fractions of Li2O reacted with uranium metal under these conditions, showing that they decrease with decreasing temperature, and calculate some thermodynamic parameters of the above reoxidation.

Complete reduction of high-density UO2 to metallic U in molten Li2O–LiCl

The large size and high density of spent fuel pellets make it difficult to use the pellets directly in electrolytic reduction (also called as oxide reduction, OR) for pyroprocessing owing to the slow diffusion of molten Li2O–LiCl salt electrolyte into the pellets. In this study, we investigated complete OR of high-density UO2 to metallic U without any remaining UO2. Only partial reductions near the surface of high-density UO2 pellets were observed under operation conditions employing fast electrolysis rate that allowed previously complete reduction of low-density UO2 pellets. Complete reduction of high-density UO2 pellets was observed at fast electrolysis rate when the pellet size was reduced. The complete reduction of high-density UO2 pellets without size reduction was achieved at slow electrolysis rate, which allowed sufficient chemical reduction of UO2 with the lithium metal generated by the cathode reaction.

Stable Performance of Aluminum‐Metal Battery by Incorporating Lithium‐Ion Chemistry

AbstractBased on the recent discovery of the ionic liquid involving the AlCl4−‐Al2Cl7− redox couple as an electrolyte, aluminum (Al) rechargeable batteries have received revamped interest. However, the corrosive nature of the chloride ion and Al2Cl7− makes it challenging to find suitable current collectors and cathode materials. Here, we screen various metals and carbon materials as current collectors, and indeed find that none of the metals commonly used for battery current collectors is stable against corrosion from the electrolyte. Only pyrolytic graphite is stable, but exhibits undesired AlCl4− intercalation at 1.7 V vs. Al/Al3+. The addition of lithium chloride (LiCl) salt to the electrolyte not only eliminates AlCl4− intercalation through Li−AlCl4− coordination, but also extends the stable voltage window to 2.3 V vs. Al/Al3+. Moreover, the incorporation of Li ions allows us to engage the established LiFePO4 olivine cathode in Li‐ion batteries. This Al−Li hybrid cell exhibits an operation voltage of 1.3 V with robust cyclability (83.4 % retention after 400 cycles) and minimal self‐discharge. This series of results suggest that proper employment of Li‐ion chemistry can improve the electrochemical performance and safety of Al rechargeable batteries.

A study of separation and solidification of group II nuclides in waste salt delivered from the pyrochemical process of used nuclear fuel

If group II nuclides, which contain high heat-generative elements, in waste salt are fabricated into a waste form rich in group II nuclides, the waste form can be used in radionuclide thermoelectric generator applications. For this reason, the separation of group II nuclides in salt (LiCl, LiCl-KCl) was conducted, after which a waste form rich in them was fabricated. In this study, group II nuclide chlorides in salt were effectively separated into a carbonate or oxychloride form, and the separated nuclides were successfully fabricated into a homogenous and stable glass waste form with high contents (45–50 wt%) of these nuclides.

Phase diagram of the quaternary system LiCl+MgCl2+KCl+H2O at 323.15 K

ABSTRAT Solubility isotherms as well as the corresponding solid phases of the quaternary system LiCl+MgCl 2 +KCl+H 2 O and the eutectic points for the ternary systems LiCl+MgCl 2 +H 2 O, LiCl+KCl+H 2 O and MgCl 2 +KCl+H 2 O at 323.15 K have been elaborately determined by an isothermal equilibrium method. Five crystallization fields including two double salts (LiCl·MgCl 2 ·7H 2 O(s) and KCl·MgCl 2 ·6H 2 O(s)), two hydrate salts (MgCl 2 ·6H 2 O(s) and LiCl·H 2 O(s)) and one single salt (KCl(s)) were detected in the quaternary system. The reliability of the experimental results were verified both by testing the phase diagram rule and comparing with the literature data. It was found that all of the results were accordance with the phase diagram rule, and moreover, the excellent agreement between the experimental data and the literature data was also obtained, which indicate that the solubility data obtained in this work are reliable. Based on the quaternary phase diagram, the example was provided for industrial application. The measured phase diagram reported in this work are the essential tool to guide industrial process of extracting Li from the salt lake brine containing MgCl 2 and LiCl using KCl reagent.

Quantitative Analysis of Oxygen Gas Exhausted from Anode through In Situ Measurement during Electrolytic Reduction

Quantitative analysis by in situ measurement of oxygen gas evolved from an anode was employed to monitor the progress of electrolytic reduction of simulated oxide fuel in a molten Li2O–LiCl salt. The electrolytic reduction of 0.6 kg of simulated oxide fuel was performed in 5 kg of 1.5 wt.% Li2O–LiCl molten salt at 650°C. Porous cylindrical pellets of simulated oxide fuel were used as the cathode by loading a stainless steel wire mesh cathode basket. A platinum plate was employed as the anode. The oxygen gas evolved from the anode was exhausted to the instrumentation for in situ measurement during electrolytic reduction. The instrumentation consisted of a mass flow controller, pump, wet gas meter, and oxygen gas sensor. The oxygen gas was successfully measured using the instrumentation in real time. The measured volume of the oxygen gas was comparable to the theoretically calculated volume generated by the charge applied to the simulated oxide fuel.

Separation of Electrolytic Reduction Product from Stainless Steel Wire Mesh Cathode Basket via Salt Draining and Reuse of the Cathode Basket

We demonstrated that the metallic product obtained after electrolytic reduction (also called oxide reduction (OR)) can be simply separated from a stainless steel wire mesh cathode basket only by using a salt drain. First, the OR run of a simulated oxide fuel (0.6 kg/batch) was conducted in a molten Li2O–LiCl salt electrolyte at 650°C. The simulated oxide fuel of the porous cylindrical pellets was used as a cathode by loading a stainless steel wire mesh cathode basket. Platinum was employed as an anode. After the electrolysis, the residual salt of the cathode basket containing the reduction product was drained by placing it at gas phase above the molten salt using a holder. Then, at a room temperature, the complete separation of the reduction product from the cathode basket was achieved by inverting it without damaging or deforming the basket. Finally, the emptied cathode basket obtained after the separation was reused for the second OR run by loading a fresh simulated oxide fuel. We also succeeded in the separation of the metallic product from the reused cathode basket for the second OR run.

The role of ion-water interactions in determining the Soret coefficient of LiCl aqueous solutions.

The application of a thermal gradient to an aqueous electrolyte solution induces the Soret effect, and the salt migrates towards hot (thermophilic) or cold regions (thermophobic). Experimental studies of LiCl reported changes in the sign of the Soret coefficient as well as a minimum in this coefficient at specific salt concentrations and temperatures. At the minimum the thermodiffusive response of the solution is enhanced significantly. We have performed non-equilibrium molecular dynamics simulations of LiCl solutions to quantify the dependence of the sign change and minimum of the Soret coefficient with salt concentration and temperature. We find that the ion mass plays a secondary role in determining the magnitude of the Soret coefficient, while the diameter of the cation has a significant impact on the coefficient and on the observation of the minimum. Our simulations show that the ordering of water around Li+ plays a key role in determining the Soret coefficient of LiCl salts.

Reoxidation of uranium metal immersed in a Li2O-LiCl molten salt after electrolytic reduction of uranium oxide

We present our findings that uranium (U) metal prepared by using the electrolytic reduction process for U oxide (UO2) in a Li2O–LiCl salt can be reoxidized into UO2 through the reaction between the U metal and Li2O in LiCl. Two salt types were used for immersion of the U metal: one was the salt used for electrolytic reduction, and the other was applied to the unused LiCl salts with various concentrations of Li2O and Li metal. Our results revealed that the degree of reoxidation increases with the increasing Li2O concentration in LiCl and that the presence of the Li metal in LiCl suppresses the reoxidation of the U metal.

Molten Salt Electrolytically Produced Carbon/Tin Nanomaterial as the Anode in a Lithium Ion Battery

A carbon/tin nanomaterial, consisting of predominantly Sn-filled carbon nanotubes and nanoparticles, is prepared by molten salt electrochemistry, using electrodes of graphite and an electrolyte of LiCl salt containing a small admixture of SnCl2. The C/Sn hybrid material generated is incorporated into the active anode material of a lithium ion battery and tested with regard to storage capacity and cycling behavior. The results demonstrate that the C/Sn material has favorable properties, in terms of energy density and in particular long-term stability, that exceed those of the individual components alone. The initial irreversible capacity of the material is somewhat larger than that of conventional battery graphite which is due to its unique nanostructure. Overall the results would indicate the suitability of this material for use in the anodes of lithium ion batteries with high rate capability.

Separation of CsCl and SrCl2 from a ternary CsCl-SrCl2-LiCl via a zone refining process for waste salt minimization of pyroprocessing

The purification of LiCl salt mixture has traditionally been carried out by a melt crystallization process. To improve the throughput of zone refining, three heaters were installed in the zone refiner. The zone refining method was used to grow pure LiCl salt ingots from LiCl-CsCl-SrCl2 salt mixture. The main investigated parameters were the heater speed and the number of passes. A change in the LiCl crystal grain size was observed according to the horizontal direction. From each zone refined salt ingot, samples were collected horizontally. To analyze the concentrations of Sr and Cs, an inductively coupled plasma optical emission spectrometer and inductively coupled plasma mass spectrometer were used, respectively. The experimental results show that Sr and Cs concentrations at the initial region of the ingot were low and reached their peak at the final freezing region of the salt ingot. Concentration results of zone refined salt were compared with theoretical results yielded by the proposed model to validate its predictions. The keff of Sr and Cs were 0.13 and 0.11, respectively. The decontamination factors of Sr and Cs were 450 and 1650, respectively.

Enhanced electrochemical reduction of rare earth oxides in simulated oxide fuel via co-reduction of NiO in Li2O–LiCl salt

Rare earth oxides in spent oxide fuel from nuclear plants have poor reducibility in the electrochemical reduction process due to their high oxygen affinity and thermodynamic stability. Here, we demonstrate that the extent of their reduction can be enhanced via co-reduction of NiO in a Li2O–LiCl electrolyte for the electrochemical reduction of a simulated oxide fuel (simfuel). First, the electrochemical behaviors of Nd2O3, NiO, and Nd2O3–NiO were studied by cyclic voltammetry and voltage control electrolysis. Then, the electrochemical reduction of the simfuel containing UO2 and rare earth oxides (Nd2O3, La2O3, and CeO2) was conducted in molten LiCl salt with 1wt.% Li2O via the co-reduction of NiO. The extent of reduction of the rare earth oxides was found to be significantly improved.

Electrolytic reduction rate of porous UO2 pellets

The electrolytic reduction rate of porous UO2 pellets in a LiCl salt was investigated for various applied charges. The degree of reduction (α) value was evaluated from the ratios of cross-sectional areas of the reduced and oxide parts. An analysis of the experimental results revealed that the first-order reaction model is the best geometry function to describe the reduction reaction. An electrolytic reduction rate equation was proposed using the first-order model, although it was available in a limited region of (0≤α≤0.56). A power law based reaction rate equation was also suggested for the whole range of α, and the reaction time for a complete reduction, estimated using the power law equation, was confirmed through the experimental results. Changes in the Li-Li2O concentration around the reduced pellets for various applied charges were also measured, which increased up to 23 wt% with increasing α.

Formation of binary salts in the system LiCl–CsCl–H2O

In the ternary system LiCl–CsCl–H2O the binary salt LiCl·2CsCl·4H2O was formed. Its structure was proved by the X-ray structural analysis. The binary compound formed in the aqueous solution by the structurally-forced insertion mechanism.

Selective Recognition of H3.1K36 Dimethylation/H4K16 Acetylation Facilitates the Regulation of All-trans-retinoic Acid (ATRA)-responsive Genes by Putative Chromatin Reader ZMYND8

ZMYND8 (zinc finger MYND (Myeloid, Nervy and DEAF-1)-type containing 8), a newly identified component of the transcriptional coregulator network, was found to interact with the Nucleosome Remodeling and Deacetylase (NuRD) complex. Previous reports have shown that ZMYND8 is instrumental in recruiting the NuRD complex to damaged chromatin for repressing transcription and promoting double strand break repair by homologous recombination. However, the mode of transcription regulation by ZMYND8 has remained elusive. Here, we report that through its specific key residues present in its conserved chromatin-binding modules, ZMYND8 interacts with the selective epigenetic marks H3.1K36Me2/H4K16Ac. Furthermore, ZMYND8 shows a clear preference for canonical histone H3.1 over variant H3.3. Interestingly, ZMYND8 was found to be recruited to several developmental genes, including the all-trans-retinoic acid (ATRA)-responsive ones, through its modified histone-binding ability. Being itself inducible by ATRA, this zinc finger transcription factor is involved in modulating other ATRA-inducible genes. We found that ZMYND8 interacts with transcription initiation-competent RNA polymerase II phosphorylated at Ser-5 in a DNA template-dependent manner and can alter the global gene transcription. Overall, our study identifies that ZMYND8 has CHD4-independent functions in regulating gene expression through its modified histone-binding ability.

Translocation frequency of double-stranded DNA through a solid-state nanopore.

Solid-state nanopores are single-molecule sensors that measure changes in ionic current as charged polymers such as DNA pass through. Here, we present comprehensive experiments on the length, voltage, and salt dependence of the frequency of double-stranded DNA translocations through conical quartz nanopores with mean opening diameter 15 nm. We observe an entropic barrier-limited, length-dependent translocation frequency at 4M LiCl salt concentration and a drift-dominated, length-independent translocation frequency at 1M KCl salt concentration. These observations are described by a unifying convection-diffusion equation, which includes the contribution of an entropic barrier for polymer entry.

Effect of salt removal and heat-pressing treatments on mechanical properties of electrospun meta-aramid nanofibres

Compared with commercial meta-aramid fibres, the electrospun meta-aramid nanofibres (mANFs) show insufficient mechanical properties because the polymer chains are not possible to have a well-developed molecular orientation. The aligned mANFs with LiCl salt was prepared using electrospinning apparatus with drum-collector, and the nanofibres with enhanced mechanical properties were obtained by repetitive washing and fast heat-pressing treatment. The salt remaining between meta-aramid chains interrupted the arrangement of the chains, whereas salt-removed nanofibre showed arrangeability of polymer segments. The fast heat-pressing induced effective adhesion between nanofibres, and the mechanical properties of heat-pressed nanofibres increased dramatically along the nanofibre-aligned direction. These results indicate that removal of salt in nanofibres and a physical adhesion between adjacent nanofibre strands contribute to the enhancement of mechanical properties of mANFs.

Calculation of NaCl, KCl and LiCl Salts Activity Coefficients in Polyethylene Glycol (PEG4000)–Water System Using Modified PHSC Equation of State, Extended Debye–Hückel Model and Pitzer Model

AbstractFor biomolecules and cell particles purification and separation in biological engineering, besides the chromatography as mostly applied process, aqueous two-phase systems (ATPS) are of the most favorable separation processes that are worth to be investigated in thermodynamic theoretically. In recent years, thermodynamic calculation of ATPS properties has attracted much attention due to their great applications in chemical industries such as separation processes. These phase calculations of ATPS have inherent complexity due to the presence of ions and polymers in aqueous solution. In this work, for target ternary systems of polyethylene glycol (PEG4000)–salt–water, thermodynamic investigation for constituent systems with three salts (NaCl, KCl and LiCl) has been carried out as PEG is the most favorable polymer in ATPS. The modified perturbed hard sphere chain (PHSC) equation of state (EOS), extended Debye–Hückel and Pitzer models were employed for calculation of activity coefficients for the considered systems. Four additional statistical parameters were considered to ensure the consistency of correlations and introduced as objective functions in the particle swarm optimization algorithm. The results showed desirable agreement to the available experimental data, and the order of recommendation of studied models is PHSC EOS > extended Debye–Hückel > Pitzer. The concluding remark is that the all the employed models are reliable in such calculations and can be used for thermodynamic correlation/predictions; however, by using an ion-based parameter calculation method, the PHSC EOS reveals both reliability and universality of applications.

Light-Harvesting Properties and Morphology of Porphyrin Nanostructures Depend on Ionic Species Inducing Aggregation

Self-assembled, excitonically coupled aggregates of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) in aqueous solutions of HCl and of the alkali chloride salts LiCl, NaCl, KCl, and CsCl were studied by absorption and resonance light scattering (RLS) spectroscopy. Aggregates deposited from these solutions were imaged by transmission electron microscopy and atomic force microscopy. In NaCl and KCl, the J band in the absorption spectrum was broadened, while in CsCl it was narrowed, as compared to aggregates in HCl. In LiCl and NaCl, the relative excitonic coherence as determined from RLS was increased as compared to aggregates in HCl, while in KCl and CsCl it was reduced. The discrepancy between measures of coherence based on exchange narrowing in the absorption spectrum and those on RLS intensity points to morphology-dependent composite J band structures. Delocalization of excitons between nanotubular subunits of bundled aggregates appears to increase excitonic coherence. Loosening of intermonomer forces, observed as bending in the images, and possibly the inclusion of alkali and/or chloride ions within composite structures, appear to limit excitonic coherence by increasing disorder. The dependence of morphologies on counterion species can be explained, in part, by the cations’ differing kosmotropic versus chaotropic ion-pairing properties and effects on water structure. The results may inform methods to tune the spatial and spectral properties of excitons in these systems.