Hydrogen Fluoride Research Articles

Efficient extraction of hydrogen fluoride using hollow fiber membrane contactors with the aid of active‐learning

AbstractThis study presents a sustainable approach to extracting hydrogen fluoride (HF) from wastewater using hollow fiber membrane contactors. HF, a widely used yet hazardous chemical, requires efficient separation techniques due to its environmental and health concerns. Our research compared two operational modes, vacuum mode and liquid–liquid extraction mode, revealing the latter as more efficient for HF separation. Notably, this study introduces a novel aspect by employing a data‐driven decision‐making method, Bayesian optimization (BO) for process optimization of the liquid–liquid extraction mode, aiming to maximize HF removal efficiency at low experimental costs. Subsequent validation through a 96‐h experimental run confirms the suitability of the optimized conditions for industrial applications. This study not only demonstrates an efficient HF separation process using hollow fiber membrane contactors but also establishes a new standard for complex industrial process optimization.

Effect of Silyl Ether Bulk on Excited-State Intramolecular Proton Transfer-Based Sensing of Extant Hydrogen Fluoride for G-Series Nerve Agent Detection.

Luminescence-based sensing provides a method for the rapid detection of nerve agents. Previous approaches have generally focused on sensing materials containing a nucleophilic group that can react with the electrophilic phosphorus atom found in nerve agents. Herein we report an alternative approach for the detection of phosphonofluoridate-based G-series nerve agents that utilizes the fact they contain hydrogen fluoride. We have developed silylated sensing materials based on an excited-state intramolecular proton transfer (ESIPT) reporter compound, 2-[benzo[d]thiazol-2-yl]phenol. Thin films of differently silylated 2-[benzo[d]thiazol-2-yl]phenol were found to react with the hydrogen fluoride found in di-iso-propyl fluorophosphate (DFP), a simulant of sarin (G-series nerve agent), and turn on the ESIPT emission of the reporter compound. The use of the ESIPT emission reduced the impact of background fluorescence and improved the sensitivity of the detection. The effectiveness of the approach was dependent on the stability of the silyl protecting group used, with the least sterically hindered (trimethylsilyl) found to be too unstable to the ambient environment while the most sterically hindered, e.g., tri-iso-propylsilyl and tert-butyldiphenylsilyl were found to be insufficiently reactive to be useful in a real detection scenario. The sensing material composed of the tert-butyl dimethylsilyl protected 2-[benzo[d]thiazol-2-yl]phenol was found to have the best balance between stability under ambient conditions, and reactivity and selectivity to hydrogen fluoride. In a 3s exposure, it could detect hydrogen fluoride down to a concentration of around 23 ppm in DFP with 99% purity.

Photoionization of hydrogen halides using the R-matrix method

Abstract In this study, we use the UK Molecular R-matrix (UKRMol) codes in the close-coupling approximation to examine the photoionization of hydrogen halides (hydrogen fluoride, hydrogen chloride, and hydrogen bromide). This article reports the total and partial photoionization cross sections for the X2Π, A2Σ+, and B2Σ+ ionic states of these halides. The calculated cross sections are compared with the available literature, which does not accurately represent the effective cross sections near the threshold region, which is dominated by the Rydberg series autoionization resonances converging to the A2Σ+ ionic state. There seems to have been minimal effort to investigate the Rydberg-bound states of these halides. Meanwhile, the R-matrix approaches have traditionally excelled at characterizing such studies. This indicates the effectiveness of this method for molecular photoionization as well as for understanding the resonant contribution to the photoionization cross sections. The detailed cross sections calculated comprise the complex autoionizing resonance structures capable of significantly contributing to the computations of total photoionization rates, which are necessary to maintain a steady state of ionization in astrophysical plasmas. Comparisons with the experimental measurements and the theoretical data generally show reasonable agreement across the reported energy range.

Safety and behavior of implantable electronic devices during cremation

BackgroundThe current standard of practice for cremating patients with cardiac implantable electronic devices (CIEDs) is surgical explantation before cremation to mitigate the risk of device explosion. This surgery may conflict with patient or family beliefs, whereas cremation of CIEDs may create occupational hazards. ObjectiveThis study sought to establish an ex vivo model for screening CIED behavior during cremation. MethodsSeven CIEDs underwent testing including projectile/sound testing, impact testing, and gas analysis. In the projectile test, devices were heated until thermal failure (explosion) and filmed with a high-speed camera and microphone. For impact testing, brick structures were built to assess damage after explosion. Gas chromatography–mass spectrometry identified released gases. Findings were compared with occupational health standards, where available. ResultsThe implantable loop recorder and leadless pacemaker produced minimal kinetic energy and impact risk with thermal failure. The remaining devices demonstrated explosive disintegration at thermal temperatures <500°C. The pacemakers and implantable cardiac defibrillators produced sound levels >120 dB and resulted in damage to brick structures. Small quantities of benzene and hydrogen fluoride were produced but at quantities within acceptable occupational exposure limits in a cremation chamber. ConclusionAll tested CIEDs experienced explosion at temperatures below crematorium standards. The smallest devices produced minimal risk of damage or injury, suggesting that they may safely remain in situ during cremation, whereas the larger devices produced more kinetic energy, testing chamber damage, and louder explosions, suggesting potential risk with cremation. Cadaveric testing in full-sized cremation chambers is required to determine real-world risk.

Abundances of trace constituents in Jupiter’s atmosphere inferred from Herschel/PACS observations

Context. On October 31, 2009, the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory observed far-infrared spectra of Jupiter in the wavelength range between 50 and 220 µm as part of the program “Water and Related Chemistry in the Solar System”. The spectra have an effective spectral resolution between 900 and 3500, depending on the wavelength and grating order. Aims. We investigate the disk-averaged chemical composition of Jupiter’s atmosphere as a function of height using these observations. Methods. We used the Planetary Spectrum Generator and the least-squares fitting technique to infer the abundances of trace constituents. Results. The PACS data include numerous spectral lines attributable to ammonia (NH3), methane (CH4), phosphine (PH3), water (H2O), and deuterated hydrogen (HD) in the Jovian atmosphere and probe the chemical composition from p ~ 275 mbar to p ~ 900 mbar. From the observations, we infer an ammonia abundance profile that decreases from a mole fraction of (1.7 ± 0.8) × 10−4 at p ~ 900 mbar to (1.7 ± 0.9) × 10−8 at p ~ 275 mbar, following a fractional scale height of about 0.114. For phosphine, we find a mole fraction of (7.2 ± 1.2) × 10−7 at pressures higher than (550 ± 100) mbar and a decrease of its abundance at lower pressures following a fractional scale height of (0.09 ± 0.02). Our analysis delivers a methane mole fraction of (1.49 ± 0.09) × 10−3. Analyzing the HD R(0) line at 112.1 µm yields a new measurement of Jupiter’s D/H ratio, D/H = (1.5 ± 0.6) × 10−5. Finally, the PACS data allow us to put the most stringent 3σ upper limits yet on the mole fractions of hydrogen halides in the Jovian troposphere. These new upper limits are &lt;1.1 × 10−11 for hydrogen fluoride (HF), &lt;6.0 × 10−11 for hydrogen chloride (HCl), &lt;2.3 × 10−10 for hydrogen bromide (HBr) and &lt;1.2 × 10−9 for hydrogen iodide (HI) and support the proposed condensation of hydrogen halides into ammonium halide salts in the Jovian troposphere.

Chemical etching of CAD-CAM glass-ceramic-based materials using fluoride solutions for bonding pretreatment.

The surface treatment of glass-ceramic-based materials, namely, lithium disilicate glass (IPS e.max CAD), feldspar porcelain (VITABLOCS Mark II), and a polymer-infiltrated ceramic network (VITA ENAMIC), using aqueous fluoride solutions and their influence on luting agent bonding were investigated. Six experimental aqueous fluoride solutions were applied to these materials, and their effects were assessed by surface topological analysis. The obtained results were compared using non-parametric statistical analyses. Ammonium hydrogen fluoride (AHF) etchant demonstrated the greatest etching effect. Subsequent experiments focused on evaluating different concentrations of the AHF etchant for the bonding pretreatment of glass-ceramic-based materials with a luting agent (PANAVIA V5). AHF, particularly at concentrations above 5 wt%, effectively roughened the surfaces of the materials and improved the bonding performance. Notably, AHF at a concentration of 30 wt% exhibited a more pronounced effect on both etching and bonding capabilities compared to hydrofluoric acid.

The ESO SupJup Survey II. The 12C/13C isotope ratios of three young brown dwarfs with CRIRES+

Young brown dwarfs exhibit atmospheric characteristics similar to those of super-Jupiters, providing a unique opportunity to study planetary atmospheres. Atmospheric retrievals of high-resolution spectra reveal detailed properties of these objects, with elemental and isotopic ratios offering insights into their formation history. The ESO SupJup Survey, utilising CRIRES$^+$ on the Very Large Telescope, aims to assess the role of as a formation tracer. We present observations of three young brown dwarfs: 2MASS J12003792-7845082, TWA 28, and 2MASS J08561384-1342242. Our goal is to constrain their chemical compositions, thermal profiles, surface gravities, spin rotations, and Cratio. We conducted atmospheric retrievals of CRIRES$^+$ K-band spectra, coupling the radiative transfer code petitRADTRANS with the Bayesian inference algorithm MultiNest The retrievals provide a detailed characterisation of the atmospheres of the three objects. We report the volume mixing ratios of the main molecular and atomic species: HF, Na, Ca, and Ti, including the novel detection of hydrogen fluoride (HF) in the atmosphere of a brown dwarf. We determine values of $ and $79^ $ in the atmospheres of TWA 28 and J0856, respectively, with strong significance ($&gt;3 We also report tentative evidence ($ of in J1200, at $. Additionally, we detect at moderate significance in J0856 (3.3sigma ) and TWA 28 (2.1sigma ). The retrieved thermal profiles are consistent with hot atmospheres ($2300-2600$ K) with low surface gravities and slow spins, as expected for young objects. The measured carbon isotope ratios are consistent among the three objects and show no significant deviation from that of the local interstellar medium, suggesting a fragmentation-based formation mechanism similar to star formation. The tentative detection of in two objects of our sample highlights the potential of high-resolution spectroscopy to probe additional isotope ratios, such as O in the atmospheres of brown dwarfs and super-Jupiters.

Accelerating Density Matrix Embedding with Stochastic Density Fitting Theory: An Application to Hydrogen Bonded Clusters.

In this work, we demonstrate how using semistochastic density fitting (ss-DF) can accelerate self-consistent density matrix embedding theory (DMET) calculations by reducing the number of auxiliary orbitals in the three-indexed DF integrals. This reduction results in significant time savings when building the Hartree-Fock (HF) Coulomb and Exchange Matrices and in transforming integrals from the atomic orbital (AO) basis to the embedding orbital (EO) basis. We apply ss-DF to a range of hydrogen-bonded clusters to showcase its effectiveness. First, we examine how the amount of deterministic space impacts the quality of the calculation in a (H2O)10 cluster. Next, we test the computational efficiency of ss-DF compared to deterministic DF (d-DF) in water clusters containing 6-30 water molecules using a triple-ζ basis set. Finally, we perform numerical structural optimizations on water and hydrogen fluoride clusters, revealing that DMET can recover weak interactions using a back-transformed energy formula. This work demonstrates the potential of using stochastic resolution of identity in quantum embedding theories and highlights its capability to recover weak interactions effectively.

The Effect of Surface Treatments on the Retentive Strengths of Crowns Fabricated From Polymethylmethacrylate (PMMA) Reinforced With Graphene Nanoparticles After Thermocycling: An In Vitro Study.

The study aimsto assess the effect of surface treatments by chemical agents on the retentive strengths of crowns fabricated from polymethylmethacrylate (PMMA)reinforced with graphene nanoparticles adhesively bonded to abutments after thermocycling. In vitro comparative study. This study is composed of four groups - one control, one treated with 99% pure etchant acetone solution, one treated with 15 wt% potassium hydrogen fluoride solution, and the last group treated with a combination of both solutions. The results showed that the mean load in Group A is 228.46±3.16, Group B is 252.57±7.14, Group C is 184.51±6.61, and Group D is 211.03±2.54. The mean score is highest for Group B followed by Group A and Group D, and it is least for Group C. One-way analysis of variance (ANOVA) detected highly significant differences (p<0.01) among the four groups. It can be concluded that acetone is the best chemical etchant solution forcrowns fabricated from G-CAMdiscs (Graphenano Dental, Graphenano Nanotechnologies, Spain).

The Fate of Fluorine Post Per- and Polyfluoroalkyl Substances Destruction during the Thermal Treatment of Biosolids: A Thermodynamic Study

Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated synthetic chemicals that are highly recalcitrant, toxic, and bio-accumulative and have been detected in biosolids worldwide, posing potential risks to humans and the environment. Recent studies suggest that the organic C-F bond in PFAS can be destructed and potentially mineralised into inorganic fluorides during thermal treatment. This study focuses on thermodynamic equilibrium investigations and the fate of fluorine compounds post-PFAS destruction during biosolid thermal treatment. The results indicate that gas-phase fluorine compounds are mainly hydrogen fluoride (HF) and alkali fluorides, whereas solid-phase fluorine compounds include alkaline earth fluorides and their spinels. High moisture and oxygen content in the volatiles increased the concentration of HF in the gas phase. However, adding minerals reduced the emission of HF in the gas phase significantly and enhanced the capture of fluorine as CaF2 spinel in the solid phase. This study also investigates the effect of feedstock composition on the fate of fluorine. High ash content and low volatile matter in the feedstock reduced HF gas emissions and increased fluorine capture in the solid product. The findings of this work are useful in designing thermal systems with optimised operating conditions for minimising the release of fluorinated species during the thermal treatment of PFAS-containing biosolids.

Na[GeF5]·2HF: the first quarternary phase in the H-Na-Ge-F system.

The structure of cis- or trans-bridged [GeF5]- anionic chains have been investigated [Mallouk et al. (1984). Inorg. Chem. 23, 3160-3166] showing the first crystal structures of μ-F-bridged pentafluorogermanates. Herein, we report the second crystal structure of trans-pentafluorogermanate anions present in the crystal structure of sodium trans-pentafluorogermanate(IV) bis(hydrogen fluoride), Na[GeF5]·2HF. The crystal structure [orthorhombic Pca21, a= 12.3786 (3), b= 7.2189 (2), c= 11.4969 (3) Å and Z= 8] is built up from infinite chains of trans-linked [GeF6]2- octahedra, extending along the b axis and spanning a network of pentagonal bipyramidal distorted Na-centred polyhedra. These [NaF7] polyhedra are linked in a trans-edge fashion via hydrogen fluoride molecules, in analogy to already known sodium hydrogen fluorides and potassium hydrogen fluorides.

SYNTHESIS AND CHARACTERISTICS OF ZnS NANOWIRES

The creation of a nanoporous silicon dioxide layer in the a-SiO2/Si-n structure was accomplished by irradiation with xenon ions at a cyclotron and then chemical etching with an aqueous solution of hydrogen fluoride with the addition of palladium. The truncated cone-shaped nanopores had diameters ranging from 486 to 509 nm. Then ZnS nanowires synthesized by electrochemical deposition (ECD) method, depending on the voltage at the electrodes of the electrolytic cell and as a result zinc sulfide nanowires with cubic structure and spatial symmetry group F-43m (216) were obtained. The sample is characterized by (111), (200), (220), (331) (311) planes, respectively, which is in good agreement with the cubic phase of ZnS. The charge-voltage characteristics (CVC) of ZnS showed that an n-type conductivity semiconductor was formed. Measurements of the photoluminescence (PL) spectra of ZnS were recorded on a CM 2203 spectrofluorimeter. The PL spectra were recorded in the range of 250 nm to 450 nm at room temperature. The PL spectra of the precipitated precipitates reveals emission in a wide UV-visible spectral range. It can be seen that the luminescence spectra have quite complex components and can be divided into five Gaussian curves. As can be seen the FL spectrum of the deposited ZnS consists of bands at 3.15 eV, 3.3 eV, 3.4 eV, 3.55 eV and 3.73 eV. Also analyzing the spectra energy dispersive analysis showed that the ZnS nanoproofs consist of Zn – 42.5% and S – 57.5%.

Theoretical investigations of the reaction mechanism and kinetic for the reaction between mercury and hydrogen fluoride

Theoretical investigations of the reaction mechanism and kinetic for the reaction between mercury and hydrogen fluoride

Снижение экологической нагрузки на регион за счет рационального способа утилизации фторангидрита

The article considers the chemical industry technologies contaminating the environment with sulfate-calcium waste in three regions of the former Soviet Union, i.e., the Tomsk region (SHK LLC, Seversk), the Perm territory (Galopolimer JSC, Perm), and East Kazakhstan region (UMZ JSC, Ust-Kamenogorsk). The differences and similarities of technological processes of anhydrous calcium sulfate production in the above-mentioned regions have been considered. Some properties of sulfate calcium (acid fluoride) that until recently was the main environmental contaminator used in the technology of hydrogen fluoride production have been specified. The objective of the study is to provide generalized positive results obtained by the authors of the article in the field of optimization of sulfuric decomposition of fluorspar not changing the production conditions and the quality of the main product — hydrogen fluoride. As a result of the process, the solid waste of hydrogen fluoride production is transformed into a target product, i.e., a technogenic anhydrite binder that can be an alternative to Portland cement and gypsum binders in the construction industry. Therefore, acid fluoride waste is removed from the hydrogen fluoride technology, and the environmental contamination with sulfate-calcium waste is prevented. In addition, a new trend in the construction industry is set, which is the industry production of anhydrite materials and products. The list of pilot-industrial and semi-industrial tests of the production of various anhydrite products has been provided (as an image listing the fields of use of acid fluoride in the industry of construction materials). In conclusion, the amount of environmental damage caused by the acid fluoride waste has been specified. In the Ob basin of the West Siberian region, it was 270 million rubles for 2023.

Characterization of process-related interfacial dielectric loss in aluminum-on-silicon by resonator microwave measurements, materials analysis, and imaging

We systematically investigate the influence of the fabrication process on dielectric loss in aluminum-on-silicon superconducting coplanar waveguide resonators with internal quality factors (Qi) of about one million at the single-photon level. These devices are essential components in superconducting quantum processors; they also serve as proxies for understanding the energy loss of superconducting qubits. By systematically varying several fabrication steps, we identify the relative importance of reducing loss at the substrate–metal and substrate–air interfaces. We find that it is essential to clean the silicon substrate in hydrogen fluoride (HF) prior to aluminum deposition. A post-fabrication removal of the oxides on the surface of the silicon substrate and the aluminum film by immersion in HF further improves the Qi. We observe a small, but noticeable, adverse effect on the loss by omitting either standard cleaning (SC1), pre-deposition heating of the substrate to 300 °C, or in situ post-deposition oxidation of the film’s top surface. We find no improvement due to excessive pumping meant to reach a background pressure below 6 × 10−8 mbar. We correlate the measured loss with microscopic properties of the substrate–metal interface through characterization with x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, transmission electron microscopy, energy-dispersive x-ray spectroscopy, and atomic force microscopy.

The Q-cascade Theory with Material Losses and Gains

Material losses and gains are generally unavoidable in isotope separation cascades because of air leakage into the cascade and chemical reactions of the materials in contact with the process gas. Both losses and gains are incorporated into the well-known Q-cascade theory and can be considered differently for each component. The theory is applied, as an example, to investigating the separation of natural uranium to produce low-enriched uranium of 5% 235U, in which UF6 incurs material losses, generating the light impurity hydrogen fluoride (HF). Two approaches are discussed, one using a carrier gas and another purging the light impurity to prevent the light impurity from exceeding the upper limit in the cascade product end for safe cascade operation. The results show that using carrier gas increases the relative total flow of the cascade, whereas purging the light impurity requires the development of a purging technology. The investigation presents a complicated but real practical scenario, where the components of different physical and chemical properties (some with and without material losses, and some with gains) all appear in the process gas, and demonstrates the applicability of the theory in the study of separation cascades.

Catalytic decomposition of HFC-134a over metal oxide and phosphate catalysts to VDF: Reaction pathways of CH4 addition

HFC-134a refrigerants are commonly used in air-conditioners and refrigerators. HFC-134a has a GWP 1,430 times higher than that of CO2 and contributes significantly to climate change. Therefore, research has been conducted to eliminate HFC-134a via catalytic decomposition. The catalytic decomposition of HFC-134a with the addition of CH4 over metal oxide (CaO, MgO, and Al2O3) and phosphate catalysts (Ca2P2O7, Mg2P2O7, and AlPO4) is described herein. The prepared catalysts were characterized by NH3-TPD, TGA, and BET analysis. Metal phosphate catalysts exhibited higher HF resistance than metal oxide catalysts. XRD, XRF, and SEM-EDS confirmed the superior resistance of metal phosphates to corrosive hydrogen fluoride (HF). VDF (C2H2F2) is a valuable feed product that can be polymerized into polyvinylidene fluoride (PVDF). In addition, the VDF yield increased with CH4 addition during the HFC-134a decomposition reaction. The CaP-calcium phosphate-catalysts exhibited an efficiency of more than 80 % and the highest VDF yield of 28.8 % after 10 h at 900 °C, 1 bar, and HFC-134a:CH4:N2 = 1:2:17 and RT = 1.0. The introduced CH4 feed acts as a CH3 donor during the decomposition of HFC-134a. Consequently, a comprehensive mechanism of VDF synthesis was proposed by comparing the presence of CH4 feed.

Study on fluorine vacancy defects in yttrium fluoride coating materials

Abstract Rare-earth fluoride coating materials have attracted wide attention as a substitute for ThF4 low-refractive index materials. However, the coating materials and coated films fail to achieve the desired results due to vacancy defects caused by their fluorine-loss decomposition characteristics. To explore the rare earth fluoride coating materials’ fluorine loss influence law, the melt crystallization method is used to simulate the yttrium fluoride (YF3) pre-melting process through the electronic paramagnetic resonance (EPR) obtained at different temperatures under the fluorine vacancy defects change rule. According to the number of unpaired spintrons, the number of spintrons in each vacancy is calculated. The results show that the fluorine vacancy defects increase with the increase of temperature, the formation of YF3 fluorine vacancy defects does not affect the change of crystal structure, and the addition of the additive ammonium hydrogen fluoride (NH4HF2) can reduce the oxygen content of YF3 and effectively inhibit the formation of fluorine vacancy. The effect is gradually obvious with the amount of additives added.

Rapid preparation of Mo2CTx MXene by hydrothermal etching in ammonium hydrogen fluoride solution

In this paper, we report a novel method to rapidly prepare two-dimensional Mo2CTx MXene in a low-concentration etching solution. By this method, highly pure Mo2CTx MXene was synthesized from Mo2Ga2C by hydrothermal etching at 180 ℃ in the solution of ammonium hydrogen fluoride (NH4HF2). The whole process requires only 2 h and the etching solution concentration is only 1 M. Compared with the acid solutions used in other methods, NH4HF2 used in this method is in solid state and its water solution is mild for handling. Compared with other methods, this method requires a lower concentration of etching solution and a much shorter etching time. The Mo2CTx MXene made this method have comparable microstructure and properties with those made by other methods. The initial discharge capacity as an anode of lithium-ion batteries (LIB) was 139.35 mAh g-1 at 0.1 A g-1. After 150th cycles, the final discharge capacity was 62.42 mAh g-1 at 0.1 A g-1. The electrochemical performance is slightly higher than the sample made by general HF etching. This is the first report to make Mo2CTx MXene from the etching of bifluoride salt. Due to the short etching time and low concentration of the etching solution, this method can rapidly make Mo2CTx MXene at in low cost, which provides a route to explore the large-scale production of Mo2CTx MXene.

Percolation transition and bimodal density distribution in hydrogen fluoride.

Hydrogen-bond networks in associating fluids can be extremely robust and characterize the topological properties of the liquid phase, as in the case of water, over its whole domain of stability and beyond. Here, we report on molecular dynamics simulations of hydrogen fluoride (HF), one of the strongest hydrogen-bonding molecules. HF has more limited connectivity than water but can still create long, dynamic chains, setting it apart from most other small molecular liquids. Our simulation results provide robust evidence of a second-order percolation transition of HF's hydrogen bond network occurring below the critical point. This behavior is remarkable as it underlines the presence of two different cohesive mechanisms in liquid HF, one at low temperatures characterized by a spanning network of long, entangled hydrogen-bonded polymers, as opposed to short oligomers bound by the dispersion interaction above the percolation threshold. This second-order phase transition underlines the presence of marked structural heterogeneity in the fluid, which we found in the form of two liquid populations with distinct local densities.