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Thermogravimetry, differential scanning calorimetry, and flow methods were used to investigate thermal properties of a series of cobalt(II) β-iminoketonates [R2C(NR1)CHC(O)R2]. The consecutive order of their volatility was determined. The complexes do not decompose up to melting and do not undergo phase transitions. For the complex (R1 = Н, R2 = Me) the temperature dependence of sublimation ln (p/p0) = 32.02 ‒ 16822/T(K) at 402.6‒433.7 K was measured and the values of ΔsublH°Т* = 140±4 kJ/mol and ΔsublS°Т* = 266±10 J/(K·mol) were calculated.

Polonium is formed in relatively large quantities in lead-bismuth eutectic (LBE) cooled nuclear systems. Because of its radiotoxicity and volatility, a good understanding of the chemical equilibria governing polonium release from LBE is required. In this work, a set of thermochemical data is derived for the chemical species involved in the equilibrium between a solution of polonium in LBE and its vapor in inert conditions. The data were obtained by matching thermochemical models with experimental vapor pressure measurements and ab initio results. The dilute-limit activity coefficient of dissolved polonium in LBE is estimated, as well as the solubility of solid lead polonide in LBE. The results indicate that polonium evaporates from LBE according to the experimentally determined Henry’s law, up to dissolved polonium concentrations well above that expected in LBE cooled nuclear systems.

With regard to the radioactive waste vitrification technology, literature data on the behavior of technetium and its release into the gas phase are reviewed. In various types of spent nuclear fuel (SNF), the content of technetium varies from 16 to 1350 g per 1 ton of SNF. In nitric acid solutions, technetium exists mainly in the form of pertechnetate anions TcO4– and, when heated, is released into the gas phase in the form of Тс2О7 and НТсО4. The volatility of technetium during vitrification varies from fractions of a percent to 70%. Two directions of technological solutions for capturing technetium from the gas phase are described: low-temperature methods using liquid-type apparatus and high-temperature methods with capturing onto zeolite and aluminosilicate filters.

The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on‐line gas phase chromatography technique, in the temperature range 350–600 °C. Under the exactly same chemical conditions, comparative studies with the lighter homologues of Group 5 in the Periodic Table clearly indicate the volatility sequence being NbOCl3 > TaOCl3 ≥ DbOCl3. From the obtained experimental results, thermochemical data for DbOCl3 were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides., Dubnium obeys Mendeleev's periodicity. Fifty years after the discovery of this element, its chemical behavior was experimentally revisited. From the gas chromatographic investigation of the volatile oxychloride compound, a trend of decreasing volatility along Group 5 elements was deduced, in agreement with the expectations by the laws established in the Periodic Table.

Treatment of 3 equiv of the potassium salts derived from the β-amino ketones 1-(dimethylamino)-3,3-dimethylbutan-2-one (L1H), 3,3-dimethyl-1-(pyrrolidin-1-yl)butan-2-one (L2H), and 3,3-dimethyl-1-(...

Organoselenium compounds with perspective application as Se precursors for atomic layer deposition have been reviewed. The originally limited portfolio of available Se precursors such as H2Se and diethyl(di)selenide has recently been extended by bis trialkylsilyl)selenides, bis(trialkylstannyl)selenides, cyclic selenides, and tetrakis(N,N-dimethyldithiocarbamate)-selenium. Their structural aspects, property tuning, fundamental properties, and preparations are discussed. It turned out that symmetric four- and six-membered cyclic silyl selenides possess well-balanced reactivity/stability, facile and cost-effective synthesis starting from inexpensive and readily available chlorosilanes, improved resistance toward air and moisture, easy handling, sufficient volatility, thermal resistance, and complete gas-to-solid phase exchange reaction with MoCl5, affording MoSe2 nanostructures. These properties make them the most promising Se precursor developed for atomic layer deposition so far. Jsou představeny organoselenové sloučeniny s perspektivními aplikacemi jako selenové prekurzory pro depozice atomárních vrstev. Nabídka dostupných Se prekurzorů byla rozšířena o bis(trialkylsilyl)selenidy, bis(trialkylstannyl)seleniys, cyklické selenidy a tetrakis(N,N-dimethyldithiokarbamate)-selenium. Jsou diskutovány strukturní aspekty, základní vlastnosti, způsoby přípravy a ladění vlastností sloučenin.

Global warming is one of the arch challenges of this era mainly caused by the increasing concentration of carbon dioxide in the atmosphere. Methanation process utilizes carbon dioxide and hydrogen to produce methane gas as an energy-rich fuel. To supply the hydrogen for the methanation process, LOHC could be used as a medium for long-range hydrogen transportation. However, the heat of reaction is needed to recover hydrogen from the LOHC medium. In this study, a new method to utilize the heat from the methanation process for dehydrogenation and optimum conditions are calculated for various LOHC materials. The new process designed uses an Air-Brayton cycle to generate the required high pressure as well as compensate for the LOHC dehydrogenation thermal energy requirement using a proportionate amount of methane produced. Also, the performance of various LOHC materials is compared in the proposed process. The simulation is performed via Aspen Plus® simulator. Dibenzyltoluene is found to be the best selection among the selected LOHC materials for use in this process with a system efficiency of 46.7% with a 100% medium recovery. Pyrrole group LOHC exhibits lower dehydrogenation temperature and energy requirement however are prone to bond scission and generally toxic. Toluene has high volatility resulting in its maximum recovery limited to 96.2% at an elevated pressure of 7 bar decreasing to 84.5% at 1 bar and 30 °C with a system efficiency of 49.08% and a low CVA of 36.74%, while NEC has 63.78% CVA with 55.64% efficiency and DBT has 54.12% CVA with 47.99% efficiency.

A novel, high yield (91 ± 5%) photochemical vapor generation (PVG) method is reported for Os, achieved via photo-reduction reactions in a 1% CH₃COOH medium containing 50 mg L⁻¹ Fe³/²⁺. A sample flow rate of 2 mL min⁻¹ delivered to a flow-through photoreactor provided a 21 s irradiation time prior to passage of the volatile product to an inductively coupled plasma mass spectrometer for detection at m/z 192. A method detection limit of 0.16 pg mL⁻¹ was achieved, a 10-fold enhancement over that obtained using parallel photo-oxidation synthesis of OsO₄ from a 5% HNO₃ medium. Precision of replicate measurement was 4% (RSD) at 10 ng mL⁻¹. Although the identity of the product has not yet been ascertained by GC-MS, based on the chemistry of Os and the reaction conditions, as well as its difference in volatility from OsO₄, a carbonyl or alkyl-substituted carbonyl is suspected e.g., Osᵥᵥ(CO)ₓ(CH₃)ᵧHz.

Highly concentrated electrolytes exhibit advantages in enhanced stability, low solvent volatility, and superior battery safety. It is therefore important to design salts that push the limit of solu...

The development of sensitive fluorescence sensors and efficient preparation of samples is a challenge in the detection of pesticides in complex samples. In this study, multicolor nitrogen dots (M-Ndots) were synthesised via microwave irradiation at 140 °C for 10 min with 5-amino-1H-tetrazole and p-phenylenediamine as precursors, which have a high fluorescence quantum yield of up to 31%. Furthermore, the M-Ndots were employed as fluorescence sensors for pesticide detection by being combined with a gas membrane separation device, to eliminate the interference from the complex sample matrix. In this process, the M-Ndots were used for sensing thiram and chlorpyrifos through their affinities to Cu2+ and Fe3+, respectively. Because thiram could decompose into volatile CS2, its derivate was sensed using the fluorescence of M-Ndots via a complexation reaction with Cu2+. Chlorpyrifos, due to its volatility, can reduce the Fe3+ ion by inhibiting the activity of acetylcholinesterase, which produces H2O2 to oxidise Fe2+. In a real application, the time consumption for 96 samples was less than 30 min in one run of the gas membrane separation device. The recoveries for thiram and chlorpyrifos ranged from 90.0% to 115.0%, and the analytical results were validated using LC-MS/MS methods, with relative errors ranging from −7.4% to 10.1%.

As a step toward licensing a lead–bismuth eutectic (LBE) based reactor design, the adsorption behavior of iodine evaporated from LBE on fused silica was examined. Using inert and reducing carrier gases, depositions with an adsorption enthalpy of − 95 to − 113 kJ mol−1 were observed. These depositions are compatible with a single species, tentatively identified as bismuth monoiodide, BiI. When introducing oxidizing conditions, multiple iodine species with higher volatility form, with adsorption enthalpies ranging from − 67 to − 86 kJ mol−1. Based on an empirical correlation one of these species was identified as monatomic iodine. This work provides fundamental understanding of the LBE/iodine gaseous chemistry and related adsorption deposition behavior.

Mercury in flue gas has been identified to be one of the most harmful environmental pollutants to humans and other organisms as a result of its bioaccumulation, volatility, persistence, high toxici...

Unlike the deep understanding of highly oxygenated organic molecules (HOMs) driving continental new particle formation (NPF), little is known about the organic compounds involved in coastal and open-ocean NPF. On the coastline of China we observed intense coastal NPF events initiated by iodine nucleation, but particle growth to cloud condensation nuclei (CCN) sizes was dominated by organic compounds. This article reveals a new group of C18,30HhOoNn and C20,24,28,33HhOo compounds with specific double-bond equivalents and oxygen atom numbers in new sub 20 nm coastal iodine particles by using ultrahigh-resolution Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR-MS). We proposed these compounds are oxygenated or nitrated products of long-chain unsaturated fatty acids, fatty alcohols, nonprotein amino acids or amino alcohols emitted mutually with iodine from coastal biota or biologically active sea surface. Group contribution method estimated that the addition of –ONO2, –OH and –C=O groups to the precursors reduced their volatility by 2–7 orders of magnitude and thus made their products condensable onto new iodine particles in the coastal atmosphere. Nontarget MS analysis also provided a list of 440 formulas of iodinated organic compounds in size-resolved aerosol samples during the iodine NPF days, which facilitates the understanding of unknown aerosol chemistry of iodine.

The photochemical transformation processes occurring at the sea surface lead to the formation of low volatility organic compounds that contribute to new particle formation in the marine boundary la...

Zhundong coalfield is a super-large coal reserve, with high-alkali feature exacerbating ash deposition. Oxy-fuel combustion technology could propel the clean utilization of Zhundong high-alkali coal. While the ash deposition behavior of high-alkali coal under oxy-fuel condition has yet to be sufficiently investigated. The present study compared the differences of ash deposits between oxy-fuel and air combustion, and also examined the effects of oxygen content on ash deposition mechanism, employing a drop-tube furnace equipped with a specially designed sampling probe and some analysis methods, such as X—ray diffraction equipment, simultaneous thermal analyzer, etc. Experimental results indicated that ash deposition was weaker, with fewer contents of sodium chloride, calcium sulphate and less agglomeration ash in oxy-fuel atmosphere compared to the air case with same oxygen content. The content of the ash particle distributed in the range of 0–40 μm was up to 60% under oxy-fuel condition. The first weight loss of ash deposits, around 850 °C, was put down to the decomposition of carbonate and the second one, about 1150 °C, was ascribed to the decomposition of the sulphate minerals in the thermal process. Ash deposition worsened with more large particles (>120 μm), as the oxygen content rose. Sodium chloride content reached 9.7% with 50% oxygen content. The present study not only focuses on the morphology and chemical components, but also probes into the thermal volatility of ash deposits, which benefits the further understanding of the ash deposition mechanism and utilization of Zhundong high-alkali coal during oxy-fuel combustion.

Producing hydrogen by water electrolysis with solar and wind energy will be one of the main methods of hydrogen production. The inherent intermittency and volatility are, however, the biggest obsta...

To investigate the short- and long-term accumulated emissions from a nuclear facility, charcoal air filter cartridges were exposed at a reactor site for seven days. The short-lived 131I adsorbed in these filters was measured by gamma counting immediately after the samples were retrieved. The very long-lived 129I was analyzed later by AMS. For this purpose, two methodologies were developed: an extraction method and direct analysis, i.e., inserting an aliquot of the filter carbon directly into the target piece. The former method used a system designed to avoid sample loss resulting from the high I2 species volatility. Iodine-125 was used as a tracer to monitor the efficiency of this extraction process. The direct method was based on our experience with charcoal in the analysis of 14C in Cs sputter ion sources. In this direct analysis, charcoal samples were first spiked with a known quantity of stable iodine (127I), in an excess over the quantity naturally present in the filter, and then pressed into targets. In this way, 129I concentrations from all the charcoal samples were quickly determined. In both methods, it was found that the atom concentration of 129I in these samples exceeded that of the 131I by 2–3 orders of magnitude. These studies demonstrate the effectiveness of the charcoal capture method as a diagnostic tool for monitoring the emissions from nuclear facilities. This approach may be extended for the detection of other long-lived radioactive isotopes, which would further expand the scope of such monitoring studies.

In this work, we study the effect of fluorosubstitution on the crystal structure of phthalocyanines of copper, cobalt, and vanadyl and analyze the correlations between the structure and volatility ...

Cobalt content in Li-ion battery cathodes has become a top concern due to its price volatility and limited source availability. Low-cobalt, Ni-rich active materials are promising candidates for next-generation cathodes due to their high capacities, and water-based processing of these materials can further reduce both cost and environmental impact. We systematically evaluated the water compatibility of four different LiNixMn1-x-yCoyO2 (NMC) powders with increasing nickel contents. Comprehensive characterization verified there is no major change to their bulk structures, and only slight surface modifications related to the removal of contaminant species. For the first time, we demonstrate that LiNi0.8Mn0.1Co0.1O2 (NMC 811) cathodes can be formulated in water and cycled 1000 times in full pouch cells with excellent capacity retention (~70% compared to ~76% for NMP-processed cells). When implemented in future battery production lines, aqueous processing of Ni-rich NMC will simultaneously enable cost reductions and higher cell energy densities.

Iodine radioisotopes, one of the major fission products in the nuclear industry, will cause widespread pollution due to their volatility when their inadvertent environmental release occurs. In this paper, a strategy for the efficient capture and real-time detection of iodine by amine-functionalized fluorescent conjugated mesoporous polymers (CMPs) is developed. CMPs are built up through a rigid skeleton and different flexible binding sites for iodine by the Sonogashira–Hagihara coupling reaction. Among them, CMP with N,N-diethylpropylamine (CMPN) shows outstanding capture ability for iodine vapor and dissolved iodine and also exhibits excellent stability against β- or γ-ray irradiation. Moreover, owing to the fluorescence quenching amplification of the conjugation skeleton, a CMPN-coated test paper enables highly sensitive detection of iodine even at 4 °C with a low vapor pressure of 16.8 Pa. To the best of our knowledge, CMPN with flexible and rigid binding sites gives the highest uptake values for iodine among all CMP-based materials reported to date, and it is the first functional material exhibiting the simultaneous adsorption and field detection of iodine vapor.

This study examines the impact of the addition of bio-ethanol/bio-ETBE on the main volatility properties of gasoline. Although several studies have been published on the addition of ethanol or ETBE to gasoline, the simultaneous addition of these oxygenates has not been studied by taking the maximum oxygen content of 3.7% m/m into account. The EN 228:2012-A1:2017 standard specifies the requirements for marketed unleaded gasoline. This standard is able to determine, among other things, a gasoline type with a maximum oxygen content of 3.7% m/m and sets the maximum limits for ethanol content at 10% v/v and 22% v/v for ethers with a minimum five carbon atoms, such as ΕΤΒΕ. Five refinery fractions were mixed in various proportions and were used as base fuels. A total of 30 samples were prepared by blending the base fuels with bio-ethanol/bio-ETBE. In each of these base fuels, bio-ethanol was added in concentrations up to 10% v/v. Subsequently, bio-ETBE was added to each of these fuels in concentrations up to 20.8% v/v for use as a stabilizer. All of the samples were examined using the EN ISO 13016-1 and EN ISO 3405 test methods while considering the volatility requirements set by EN 228. The results showed that the addition of bio-ETBE has a beneficial effect on the volatility characteristics of the samples, as it reduces the vapor pressure of the final blend and sets all fuels in compliance with the required specification limits set by the EN 228 standard.

Rapid capture of 129 I with high volatility and toxicity in the environment has attracted much attention. Herein we reported a firstly synthesized nonporous material: pyridine N-oxides (NTPO and ATPO) as iodine adsorbent. Both of NTPO and ATPO exhibit remarkable performance on the adsorption of iodine in aqueous solution, vapor state and organic solvents. Upon the capture of iodine, pyridine N-oxides were transformed to binary cocrystals combined with the pyridine N-oxides and iodine which is driven by halogen bond between iodine and oxygen atoms. Moreover, pyridine N-oxides shows high chemical, thermal and moisture stability.

Aerosols from surface emission can be transported upwards through convective mixing in the planetary boundary layer (PBL), which subsequently interact with clouds, serving as important sources to nucleate droplets or ice particles. However, the evolution of aerosol composition during this vertical transport has yet to be explicitly understood. In this study, simultaneous measurements of detailed aerosol compositions were conducted at two sites, namely urban Beijing (50 m above sea level – a.s.l.) and Haituo mountain (1344 m a.s.l.) during wintertime, representing the anthropogenically polluted surface environment and the top of the PBL, respectively. The pollutants from surface emissions were observed to reach the mountain site on daily basis through daytime PBL convective mixing. From the surface to the top of PBL, we found efficient transport or formation of lower-volatility species (black carbon, sulfate, and low-volatile organic aerosol, OA); however, a notable reduction in semivolatile substances, such as the fractions of nitrate and semivolatile OA reduced by 74 % and 76 %, respectively, during the upward transport. This implies that the mass loss of these semivolatile species was driven by the evaporation process, which repartitioned the condensed semivolatile substances to the gas phase when aerosols were transported and exposed to a cleaner environment. In combination with the oxidation processes, these led to an enhanced oxidation state of OA at the top of the PBL compared to surface environment, with an increase of oxygen to carbon atomic ratio by 0.2. Such a reduction in aerosol volatility during vertical transport may be important in modifying its viscosity, nucleation activity, and atmospheric lifetime.

210Po, a highly toxic element with strong volatility, is one of the main source terms of a Gen-IV lead-cooled fast reactor (LFR). Therefore, the radioactive safety caused by 210Po has become an important topic in LFR-related research. In order to simulate the behavior of 210Po in an LFR, this work developed a multi-physics model of an LFR from the perspective of radioactive transport. Considering the effects of nuclide decay, cover gas leakage, containment ventilation, and Po aerosol deposition, a comprehensive simulation was carried out to evaluate the sensitivity of those effects on the 210Po distribution in detail. Preliminary results indicate that during normal operation, most of the 210Po in the LBE exist in the form of PbPo, and around 10–9 of 210Po could evaporate from the LBE into the cover gas, and then further leak into the containment. In addition, even if the leakage rate of 210Po in the cover gas into the containment is maintained at 5‰ per day, due to the deposition of Po aerosol, the 210Po contamination on the inner surface of the containment is still below the radioactivity concentration limits.

Understanding the volatility and mixing state of atmospheric aerosols is important for elucidating the formation of fine particles and to help determining their effect on environment and climate. In this study, the volatility of the fine particles is characterized by the size-dependent volatility shrink factor (VSF) for summer and winter in the urban area of Beijing using measurements of a volatility tandem differential mobility analyzer (VTDMA). We show the volatility of aerosols is always with one high-volatile and one less- or non-volatile mode both in the summer and winter. On average, the particles are more volatile in the summer (with mean VSF of 0.3) than in the winter (with mean VSF of 0.6). The outstanding high-volatile mode around noontime illustrates the role of nucleation in producing more volatile particles in the summer. We further retrieve the mixing state of the ambient fine particles from the size-resolved VSF and find that the non-black carbon (BC) particles that formed from nucleation processes accounted for 52–69 % of the total number concentration in the summer. While, particles containing a refractory core that is thought to be BC-containing particles dominate and contribute 67–77 % toward the total number concentration in the winter. The diurnal cycles of the retrieved aerosol mixing state for the summer further supports the conclusion that nucleation process is the main contributors to non-BC particles. In addition, the extent of aging of BC particles was characterized as the ratio of the BC diameter before and after heating at 300 °C (Dp/Dc), showing that the average ratio of ~2.2 in the winter is higher than the average of ~1.5 in the summer, which indicates that BC aging is more efficient in wintertime, with resulting differences in light absorption enhancement between cold and warm seasons.

Potassium volatility and activity in a novel K–Ca–Si–O glass catalyst was investigated over extended periods of soot oxidation. Soot was continuously deposited and oxidized by maintaining a glass catalyst-coated filter at temperatures above the oxidation balance point to provide a soot mass equivalent to 100 000 miles of engine operation. Testing revealed the 52-SiO2, 35-K2O, and 13-CaO wt % glass catalysts show a significant improvement in soot oxidation performance over a Pt catalyst. The glass catalyst retains soot oxidation catalytic activity even after testing equivalent to 100 000 miles of use. Migration of potassium in the catalyzed filter from the inlet to the outlet channels was observed. Although potassium was detected on an uncoated downstream core after 50 h of testing, showing that some volatilization of K occurs, the catalyst retains remarkable activity. Surface analysis characterization shows K enrichment of the catalytic glass surface relative to the bulk, which supports the proposed mecha...

A rapid method for the determination of polonium-210 in urban matrices has been developed that can be used following a radiological event. Samples such as concrete, soil and granite are fused with sodium hydroxide to minimize polonium volatility during sample digestion and to achieve complete sample dissolution. Complete dissolution of samples is important to ensure method ruggedness. Polonium is concentrated and separated from the sample matrix using an iron hydroxide precipitation and extraction chromatography and subsequently measured by alpha spectrometry following microprecipitation with bismuth phosphate. The chromatographic separation removes alpha emitting interferences and matrix constituents which can adversely impact the measurement via alpha spectrometry.

Three hetero-ligand volatile iridium (I) complexes with β-diketonate derivatives [Ir(cod)(L)] (cod = 1,5-cyclooctadiene, L = CH3C(O)CHC(X)CH3, X = O (acac) 1, N–H (i-acac) 2, N–CH3 (Mei-acac) 3) have been synthesized, purified and characterized in order to investigate the influence of (O,O) and (O,N) coordination sites in chelate ligand on the thermochemical properties of this type compounds. β-Ketoiminate complexes (L = i-acac, Mei-acac) were prepared for the first time. Thermal behavior of iridium complexes in condensed phase has been studied by differential scanning calorimetry and thermodynamic parameters of melting processes (Δmelt.Hm.p., Δmelt.S°m.p.) have been determined for the first time. The temperature dependencies of saturated vapor pressures over the solid complexes have been measured by flow (transpiration) method (temperature intervals (363–423) K, (383–431) K and (383–420) K for compounds 1, 2 and 3, respectively). Using these data, the thermodynamic parameters of sublimation processes (ΔsubHT, ΔsubS°T) have been calculated. It has been found that although the ligand modification has a minor effect on the vaporization characteristics of this type complexes, the volatility unexpectedly decreases in the following sequence: L = acac > i-acac > Mei-acac. However, the vapor pressure values in the above-mentioned temperature interval are sufficient to all complexes studied be used as effective volatile precursors to obtain iridium-containing coatings by chemical vapor-phase deposition methods.

The formation of NbOCl3 and TaOCl3 and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values (ΔHads) at zero surface coverage of –ΔHads(NbOCl3) = 102 ± 4 kJ/mol and –ΔHads(TaOCl3) = 128 ± 5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb and Ta complexes with a Monte-Carlo simulation method based on an adsorption–desorption kinetic model. By applying an empirical correlation, the experimental ΔHads values were successively related to the macroscopic standard sublimation enthalpy, ΔH°subl, as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between ΔHads and ΔH°subl for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted ΔH°subl(DbOCl3), a ΔHads(DbOCl3) value of 135 ± 2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl3 under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.

In this work, an analytical method was proposed for the simultaneous determination of mercury and selenium in fish samples using Atomic Fluorescence Spectrometry (AFS). Multivariate designs were performed to evaluate the variables and optimize the best condition of chemical vapor generation (CVG) and simultaneous determination of mercury and selenium by AFS. Fish samples were prepared via acid digestion in digester block with cold finger reflux system, which ensured that the elements were not lost by volatility. The proposed analytical method was validated, and excellent figures of merit have been achieved, such as detection limits of 0.33 and 9.18 ng g−1 for mercury and selenium, respectively. The method was applied for simultaneous determination of mercury and selenium in canned sardines. Mercury concentrations ranged from 0.057 to 0.203 μg g−1 and selenium concentration from 1.76 to 2.21 μg g−1, providing a mean molar ratio (Se:Hg) equivalent to 36.

In direct-injection engines, fuel components of different volatility can segregate in the transient evaporating spray. The resulting spatial mixture inhomogeneities may impact ignition and combustion. The technique presented here images the effect of preferential evaporation of a multi-component gasoline surrogate fuel in an optically-accessible direct-injection engine motored on nitrogen. It is based on laser-induced fluorescence (LIF) of two aromatic tracers with different volatilities, 1,4-difluorobenzene (representing light to medium components) and 1-methylnaphthalene (heavy component) added to a base-fuel of n-pentane, iso-octane, and n-undecane. LIF from the two tracers is spectrally separated and detected on two cameras, with channel crosstalk corrected in post-processing. Consistent with previous measurements in a high-pressure vessel, the light components are preferentially found downstream, towards the front of the evaporated fuel jet. Throughout large regions of the field of view, about 20% surplus of 1-methylnaphthalene is found, and throughout smaller ones about 40% of 1,4-difluorobenzene. To better assess the impact of the (unknown) local temperature on the measurement accuracy, two-color thermometry based on LIF of anisole (methoxybenzene) is performed in separate experiments. In the relevant range of crank-angles the local temperature is found to be 25 K lower in regions of high fuel concentration than in the rest of the charge, implying a systematic temperature-induced error in the fuel-tracer ratio of 0.11.

Niobium is one of the fission products contained in spent nuclear fuel. Since niobium pentafluoride (NbF5) has high volatility, it is considered that niobium volatilizes with uranium hexafluoride when applying the fluoride volatility method, which is a promising pyro-reprocessing method. In this study, fluorination behavior characteristics of niobium compounds, such as reaction temperature, volatility, and reaction path, were investigated by thermogravimetric and differential thermal analyses and X-ray diffraction analysis. The target compounds were niobium metal, the niobium oxides NbO, Nb2O3, NbO2 and Nb2O5, and niobium oxyfluoride (NbO2F). All the niobium compounds reacted exothermically and were volatilized completely by the reaction with F2. It was considered that niobium volatilized as NbF5. The fluorination reactions started respectively at 180, 200, 300, and 300 °C for niobium metal, NbO, NbO2 and Nb2O5. In the fluorination of niobium oxides, the intermediate product NbO2F was also fluorinated above 300 °C and volatilized completely. Nb2O3, which seemed to be a mixture of NbO and NbO2, reacted with F2 as described by the summation of the fluorination reactions of NbO and NbO2. The reaction mechanism for the fluorination of niobium compounds obtained in this study is applicable to evaluation of the niobium transfer phenomena in the reprocessing process of the fluoride volatility method.

The high toxicity and low volatility of PCDD/Fs prevent detailed study of their catalytic degradation removal characteristics. In this study, firstly, 1,2-dichlorobenzene (1,2-DCBz) was initially used as a model to investigate the catalytic characteristics of various vanadium-based catalysts prepared by different methods. Then, the optimized catalyst was used for catalytic degradation of real PCDD/Fs at low-temperatures based on a self-made stable source. The VOx/TiO2 catalysts synthesized by the mechanochemical method (VTi-MC2) had a higher 1,2-DCBz removal efficiency (> 85%) and stability (> 420 min) at low temperatures (oC) compared to VTi-SG (sol-gol method) and VTi-WI (wetness impregnation method). The physico-chemical properties of catalysts were studied using comprehensive characterization. It was found that the VTi-MC2 has better VOx species distribution and possesses the highest V5+ species and surface adsorbed oxygen content, which are the key factors contributed to the higher removal efficiency. Accordingly, the mechanochemical method can be used to control the physico-chemical properties of catalyst by adjusting the milling parameters. The optimum ball-milling time is 2 h and the suitable precursor is NH4VO3 for VOx/TiO2. Moreover, the removal efficiency of gas phase PCDD/Fs catalyzed by VTi-MC2 is 97% within a temperature range below 200 ℃, and the catalytic degradation of PCDD/Fs surges to 50%, which is higher than those reported research. In general, the mechanochemical strategy reported provides a means for seeking more efficient catalysts used for low-temperature degradation of various trace organic pollutants.

Hydrogen-fired gas turbines have the potential to play an important role in decarbonized energy sectors. However, a demand-oriented supply of CO2-neutral hydrogen for the operation of gas turbines is technically and economically challenging. These challenges mainly arise due to various interdependencies between the volatility of renewable power generation, available hydrogen production capacities, available hydrogen storage capacities and the operational demands to be met by gas turbines. The present study aims to quantify these interdependencies by conducting a detailed model-based analysis of an exemplary combined heat and power system featuring a hydrogen-fired industrial gas turbine with on-site hydrogen production via electrolysis and on-site hydrogen storage in pressure vessels. In order to identify the sought-after interdependencies, simulation runs featuring various combinations of available hydrogen production and storage capacities are analyzed. If only local power surpluses are utilized for the electrolysis, the obtained results reveal a strong non-linear impact of both the hydrogen production capacity and the storage capacity on the ability to provide hydrogen for the gas turbine. Furthermore, the results indicate that an exclusive utilization of local power surpluses leads to very limited periods of hydrogen-based gas turbine operation and low utilization rates of the available hydrogen production and storage capacities. If additional power for the operation of electrolyzers is supplied by the grid, increased utilization rates and prolonged periods of hydrogen-based gas turbine operation can be achieved. However, in order to realize an overall reduction of CO2 emissions, this mode of operation requires the supply of large quantities of renewable power by the grid. Furthermore, the results of an additional economic analysis reveal that both investigated operational modes are currently not economically viable within the considered economic framework.

Amino acid salt (AAS) is a promising class of green material for CO2 capture due to its extremely low toxicity, negligible volatility and decent absorption capacity. However, the slow absorption kinetics and significant regeneration energy requirements hinder its widespread application. Here, for the first time, we present the encapsulation of AAS into solid polymer matrices to simply prepare a scalable material, namely liquid AAS hydrogel particles (LAHPs), for carbon capture. Owing to the enlarged contact area and more intense interaction between CO2 and the AAS, the absorption rate was significantly increased. Meanwhile, CO2 uptakes of LAHPs were improved, on average, by 40% compared to their stirred aqueous AAS solutions counterparts for a wide spectrum of AASs. Moreover, breakthrough experiments demonstrated that LAHPs had sufficient kinetics and capacity characteristics to be used across many fields such as post-combustion capture (15.0 vol% CO2), CO2 removal from enclosed systems (e.g., submarines at 0.5 to 1.0 vol% CO2) and direct air capture of CO2, with CO2 uptake values of 62.8, 53.1, and 42.4 mg g-1 absorbent, respectively. For regeneration, low-grade steam proved to be an effective heating source for LAHPs regeneration, which could significantly decrease overall energy costs if the waste industrial steam was readily available. We have also explored replacing water with a higher boiling point polar solvent (i.e. ethylene glycol). A 30 wt% solution of potassium sarcosinate in ethylene glycol can be infused into a cross-linked poly(N-hydroxyethyl acrylamide) hydrogel. Furthermore, with the use of a higher boiling point solvent (i.e. ethylene glycol), the sorbent can be regenerated with minimal loss of solvent at 60 °C in a vacuum for 60 minutes. CO2 uptake capacities of 36.5 mg g-1 absorbent (average of 11 sorption-regeneration cycles) and 18.7 mg g-1 absorbent with pure CO2 and air, respectively, were obtained. Although the CO2 uptake of LAHPs is not among the highest reported, the simplicity of this approach may provoke ideas on the design of AAS-based CO2 absorbents that are green, versatile, readily scalable and economically regenerable.

Frontiers in Chemistry 9, 753738 (2021). doi:10.3389/fchem.2021.753738, Published by Frontiers Media, Lausanne

The current portfolio of organoselenium compounds applicable as volatile precursors for atomic layer deposition can be denoted as very limited. Hence, we report herein facile and cost-effective preparation of two bis(trialkylstannyl)selenides as well as one selenole and three bis(trialkylsilyl)selenides. Their syntheses have been optimized to: (i) use readily available and inexpensive starting materials, (ii) involve operationally simple methodology (heating in a pressure vessel), (iii) use a minimum amount of additives and catalysts, and (iv) either exclude additional purification or involve only simple distillation. The chemical structure of prepared Se derivatives was confirmed by multinuclear NMR and GC/MS. Their fundamental thermal properties were investigated by differential scanning calorimetry (DSC) and TGA methods that revealed thermal stability within the range of 160&ndash, 300 &deg, C.

This paper demonstrates a carbene stabilized precursor [Cu(tBuNHC)(hmds)] with suitable volatility, reactivity and thermal stability, that enables the spatial plasma-enhanced atomic layer deposition (APP-ALD) of copper thin films at atmospheric pressure. The resulting conductive and pure copper layers were thoroughly analysed and a comparison of precursor and process with the previously reported silver analogue [Ag(tBuNHC)(hmds)] revealed interesting similarities and notable differences in precursor chemistry and growth characteristics. This first report of APP-ALD grown copper layers is an important starting point for high throughput, low-cost manufacturing of copper films for nano- and optoelectronic devices.

A cobalt-free tungsten carbide cermet (WC-FeNi) has been subjected to oxyacetylene flame tests to simulate extreme operating conditions such as a worst-case fusion reactor accident. In such an accident, air-ingress to the reactor may impinge on components operating at surface temperatures in excess of 1000 °C, leading to tungsten oxide formation and its subsequent hazardous volatilisation. Here, the most challenging accident stage has been simulated, where the initial air-ingress could lead to extremely rapid air-flow rates. These conditions were simulated using an oxidising oxyacetylene flame. The separation between flame nozzle and sample was varied to permit peak surface temperatures of ~950–1400 °C. When the peak temperature was below 1300 °C, the cermet gained mass due to the dominance of oxide scale formation. Above 1300 °C, the samples transitioned into a mass loss regime. The mass loss regime was dominated by liquid-phase ablation of the scale rather than its volatilisation, which was confirmed by performing a systematic thermogravimetric kinetic analysis. The result was unexpected as in other candidate shielding materials, e.g. metallic tungsten, volatilisation is considered the primary dispersion mechanism. The unusual behaviour of the cermet scale is explained by its relatively low melting point and by the lower volatility of its FeWO4 scale compared to tungsten's WO3 scale. The substantially lower volatility of the WC cermet scale compared to metallic W scales indicates it may have a superior accident tolerance.

Volatility and viscosity are important properties of organic aerosols (OA), affecting aerosol processes such as formation, evolution, and partitioning of OA. Volatility distributions of ambient OA particles have often been measured, while viscosity measurements are scarce. We have previously developed a method to estimate the glass transition temperature (Tg) of an organic compound containing carbon, hydrogen, and oxygen. Based on analysis of over 2400 organic compounds including oxygenated organic compounds, as well as nitrogen- and sulfur-containing organic compounds, we extend this method to include nitrogen- and sulfur-containing compounds based on elemental composition. In addition, parameterizations are developed to predict Tg as a function of volatility and the atomic oxygen-to-carbon ratio based on a negative correlation between Tg and volatility. This prediction method of Tg is applied to ambient observations of volatility distributions at 11 field sites. The predicted Tg values of OA under dry conditions vary mainly from 290 to 339 K and the predicted viscosities are consistent with the results of ambient particle-phase-state measurements in the southeastern US and the Amazonian rain forest. Reducing the uncertainties in measured volatility distributions would improve predictions of viscosity, especially at low relative humidity. We also predict the Tg of OA components identified via positive matrix factorization of aerosol mass spectrometer (AMS) data. The predicted viscosity of oxidized OA is consistent with previously reported viscosity of secondary organic aerosols (SOA) derived from α-pinene, toluene, isoprene epoxydiol (IEPOX), and diesel fuel. Comparison of the predicted viscosity based on the observed volatility distributions with the viscosity simulated by a chemical transport model implies that missing low volatility compounds in a global model can lead to underestimation of OA viscosity at some sites. The relation between volatility and viscosity can be applied in the molecular corridor or volatility basis set approaches to improve OA simulations in chemical transport models by consideration of effects of particle viscosity in OA formation and evolution.

The predictive models that describe the fate and transport of radioactive materials in the atmosphere following a nuclear incident (explosion or reactor accident) assume that uranium-bearing particulates would attain chemical equilibrium during vapor condensation. In this study, we show that kinetically driven processes in a system of rapidly decreasing temperature can result in substantial deviations from chemical equilibrium. This can cause uranium to condense out in oxidation states (e.g., UO3 vs UO2) that have different vapor pressures, significantly affecting uranium transport. To demonstrate this, we synthesized uranium oxide nanoparticles using a flow reactor under controlled conditions of temperature, pressure, and oxygen concentration. The atomized chemical reactants passing through an inductively coupled plasma cool from ∼5000 to 1000 K within milliseconds and form nanoparticles inside a flow reactor. The ex situ analysis of particulates by transmission electron microscopy revealed 2-10 nm crystallites of fcc-UO2 or α-UO3 depending on the amount of oxygen in the system. α-UO3 is the least thermodynamically preferred polymorph of UO3. The absence of stable uranium oxides with intermediate stoichiometries (e.g., U3O8) and sensitivity of the uranium oxidation states to local redox conditions highlight the importance of in situ measurements at high temperatures. Therefore, we developed a laser-based diagnostic to detect uranium oxide particles as they are formed inside the flow reactor. Our in situ measurements allowed us to quantify the changes in the number densities of the uranium oxide nanoparticles (e.g., UO3) as a function of oxygen gas concentration. Our results indicate that uranium can prefer to be in metastable crystal forms (i.e., α-UO3) that have higher vapor pressures than the refractory form (i.e., UO2) depending on the oxygen abundance in the surrounding environment. This demonstrates that the equilibrium processes may not dominate during rapid condensation processes, and thus kinetic models are required to fully describe uranium transport subsequent to nuclear incidents.

International audience; Keywords: Copper(I) cyclopentadienyl triethylphophine Copper Thin films Metal-organic chemical vapor deposition Coalescence Nucleation Morphology Image analysis A B S T R A C T The rough, even discontinuous morphology of vapor-deposited copper films inhibits their attractive electrical properties. In the present study, we investigate the influence of deposition time, deposition temperature, and the flow rate of the precursors on the morphology of Cu films deposited from metalorganic chemical vapor de-position. We show that it is necessary to purify the copper(I) cyclopentadienyl triethylphophine (CpCuPEt 3) precursor in order to improve its stability and volatility. We also determined its saturated vapor pressure law, logP sat (Pa) = 8.614-2272/T (K). The Arrhenius plot of the global deposition reaction of Cu films in the presence of hydrogen between 431 and 523 K shows a low apparent activation energy of 10 kJ/mol. Electron probe microanalysis, grazing incidence X-Ray diffraction, and image analysis of the micrographs obtained by top-down surface scanning electron microscopy reveal metallic films composed of Cu islands. Their size and packed density increase and, ultimately, the islands coalesce with increasing precursor flow rate and, to a lesser extent, with increasing deposition temperature.

The integration of new materials in the next generation of optoelectronic devices leads to several challenges. For instance, the etching of indium tin oxide (ITO, In2O3:Sn) faces the issue of the low volatility of In- and Sn-based etch products at room temperature. This is challenging for the etching process itself, but even more problematic when the inductively coupled plasma (ICP) reactor must be cleaned after etching: since the reactor walls are bombarded by low energy ions only, the removal of In- and Sn-based products redeposited on the walls can be very long and laborious. Therefore, we have investigated several plasma chemistries to find the most efficient reactor cleaning process suitable for ITO plasma etching. The results show that after ITO plasma etching the walls are indeed contaminated by indium. At the low temperature at which the reactor walls are regulated, BCl3/Cl2 cleaning plasma is ineffective to remove this deposit while HBr and CH4/Cl2 chemistries provide promising results.

Secondary organic aerosol (SOA) forms a major part of the tropospheric submicron aerosol. Still, the exact formation mechanisms of SOA have remained elusive. Recently, a newly discovered group of oxidation products of volatile organic compounds (VOCs), highly oxygenated organic molecules (HOMs), have been proposed to be responsible for a large fraction of SOA formation. To assess the potential of HOMs to form SOA and to even take part in new particle formation, knowledge of their exact volatilities is essential. However, due to their exotic, and partially unknown, structures, estimating their volatility is challenging. In this study, we performed a set of continuous flow chamber experiments, supported by box modelling, to study the volatilities of HOMs, along with some less oxygenated compounds, formed in the ozonolysis of α-pinene, an abundant VOC emitted by boreal forests. Along with gaseous precursors, we periodically injected inorganic seed aerosol into the chamber to vary the condensation sink (CS) of low-volatility vapours. We monitored the decrease of oxidation products in the gas phase in response to increasing CS, and were able to relate the responses to the volatilities of the compounds. We found that HOM monomers are mainly of low volatility, with a small fraction being semi-volatile. HOM dimers were all at least low volatility, but probably extremely low volatility; however, our method is not directly able to distinguish between the two. We were able to model the volatility of the oxidation products in terms of their carbon, hydrogen, oxygen and nitrogen numbers. We found that increasing levels of oxygenation correspond to lower volatilities, as expected, but that the decrease is less steep than would be expected based on many existing models for volatility, such as SIMPOL. The hydrogen number of a compound also predicted its volatility, independently of the carbon number, with higher hydrogen numbers corresponding to lower volatilities. This can be explained in terms of the functional groups making up a molecule: high hydrogen numbers are associated with, e.g. hydroxy groups, which lower volatility more than, e.g. carbonyls, which are associated with a lower hydrogen number. The method presented should be applicable to systems other than α-pinene ozonolysis, and with different organic loadings, in order to study different volatility ranges. Secondary organic aerosol (SOA) forms a major part of the tropospheric submicron aerosol. Still, the exact formation mechanisms of SOA have remained elusive. Recently, a newly discovered group of oxidation products of volatile organic compounds (VOCs), highly oxygenated organic molecules (HOMs), have been proposed to be responsible for a large fraction of SOA formation. To assess the potential of HOMs to form SOA and to even take part in new particle formation, knowledge of their exact volatilities is essential. However, due to their exotic, and partially unknown, structures, estimating their volatility is challenging. In this study, we performed a set of continuous flow chamber experiments, supported by box modelling, to study the volatilities of HOMs, along with some less oxygenated compounds, formed in the ozonolysis of alpha-pinene, an abundant VOC emitted by boreal forests. Along with gaseous precursors, we periodically injected inorganic seed aerosol into the chamber to vary the condensation sink (CS) of low-volatility vapours. We monitored the decrease of oxidation products in the gas phase in response to increasing CS, and were able to relate the responses to the volatilities of the compounds. We found that HOM monomers are mainly of low volatility, with a small fraction being semi-volatile. HOM dimers were all at least low volatility, but probably extremely low volatility; however, our method is not directly able to distinguish between the two. We were able to model the volatility of the oxidation products in terms of their carbon, hydrogen, oxygen and nitrogen numbers. We found that increasing levels of oxygenation correspond to lower volatilities, as expected, but that the decrease is less steep than would be expected based on many existing models for volatility, such as SIM-POL. The hydrogen number of a compound also predicted its volatility, independently of the carbon number, with higher hydrogen numbers corresponding to lower volatilities. This can be explained in terms of the functional groups making up a molecule: high hydrogen numbers are associated with, e.g. hydroxy groups, which lower volatility more than, e.g. carbonyls, which are associated with a lower hydrogen number. The method presented should be applicable to systems other than alpha-pinene ozonolysis, and with different organic loadings, in order to study different volatility ranges.

The increased use of fertilizers from phosphates in agriculture generates water pollution by heavy metals contained in these phosphates at levels higher than the standards. In our study, we used a cadmium nitrate Cd(NO3)2 solution to simulate artificially polluted water, whose decontamination efficiency will be evaluated by an electrocoagulation/flotation process. During this work, we aimed to optimize the electrocoagulation process according to the following factors: initial pH of the solution, density of the electrolysis current, cell time, and nature of the supporting electrolyte and its concentration. The criteria adopted during the optimization of the process are relatively different from those used in similar studies. Indeed, we have tried to achieve maximum efficiency and also seeking to minimize costs and facilitate implementation. We achieved a 98% Cd removal efficiency from the solution at pH = 7, J = 6.25 A/m2, t = 10 min, and [K2SO4] = 0.01 M. In addition, during the characterization of the flocs obtained as a supernatant, we first highlighted the presence of Cd in this gelatinous body and then the relatively easy volatility of Cd as well as that of aluminum oxide (Al2O3).

Sodium hydrosulfite (Na 2 S 2 O 4 ) is widely considered as the most common bleaching agent for bean sprouts. However, this chemical is harmful to human health, especially to the digestive system and metabolism. The present work aims to develop an efficient and ecologically-friendly method for the detection of sodium hydrosulfite using an electronic nose based on metal oxide semiconductor gas sensors. An array of different eight gas sensors was used to measure sodium hydrosulfite volatile as present in the bleached sprouts. The signals from gas sensors were collected and analyzed using the Principal Component Analysis (PCA) via a monitoring computer. From the PCA, the volatility data can be clearly distinguished into two groups: (i) bleached and (ii) non-bleached as divided by the PC1 axis. Moreover, PC1 is capable of generating a calibration curve for quantitative analysis. Our method is demonstrated to be an effective performance for detecting sodium hydrosulfite with the sensitivity as low as 0.01 g/L.

The growth of vanadium dioxide (VO2) thin films using tetrakis (ethyl-methyl) amino vanadium (TEMAV) and H2O by atomic layer deposition (ALD) has been investigated as a function of the exposure dose and residence time. A novel multiple pulse mode has been employed to mitigate the small deposition rate brought about by the low vapor pressure of TEMAV. Compared to the conventional ALD cycle with a single pulse of precursor, the use of multiple pulsing with very short pulse time allows lower consumption of precursor, but larger exposure dose and longer residence time on the growth surface, resulting in a higher growth rate for a low volatility precursor, while maintaining a good film uniformity across 4-in. wafers. The Raman analysis and the electrical resistivity modulation of the VO2 thin films show that the films synthesized by the multiple pulse mode is comparable to the films synthesized by the conventional single pulse mode.

Fuel pretreatment methods have attracted attention due global warming concerns. However, these methods impact the combustion and emission behaviors of pretreated fuels, and variations in fuel characteristics influence the formation of NO x during combustion. We investigated the impact of different pretreatment methods (torrefaction and ashless process) on combustion and NOx emission characteristics. Two biomass fuels, i.e., woody ( pitch pine sawdust ( PSD)) and herbaceous (Kenaf), and their pretreated fuels were subject to combustion analysis. The fundamental properties and structural pore characteristics as well as unburned carbon (UBC) and NO x emissions following combustion tests, with both raw and pretreated biomasses, were investigated. The results show torrefaction of both fuels improves the fuel ratio (FR), whereas the ashless process reduces the FR. For both fuels, torrefaction increased the fuel-N by approximately 30%–50%, whereas the ashless process decreased fuel-N. In fixed conditions, the combustion index (S) indicates the ashless process provides greater reactivity for both fuels. Upon torrefaction, S is higher for the PSD samples but lower for the Kenaf samples. In entrained conditions, the UBC for both samples decreased after the ashless process, but increased following torrefaction of Kenaf, which corresponds to the fuel ratios. The ashless process resulted in lower NOx emissions, whereas torrefaction resulted in a different tendency due to variations in N-compounds and fuel volatility for each fuel. These results indicate that the combustion and NOx emissions from different pretreatments are closely linked to characteristics of devolatilization and pore distribution in a fuel.

Rhenium (Re), a non-radioactive surrogate for technetium (Tc), was incorporated into the lattice of SnO2 by reductive co-precipitation process at room temperature, and Re volatility from Re(SnO2) under different atmospheres (in air and N2 and with glass frit) at elevated temperatures was carefully investigated. Re began to evaporate from Re(SnO2) both in air and N2 at 400 °C, while Re exhibited a faster volatilization in air than in N2, as all Re was gone at 1200 °C in air, but ∼40% of Re still remained at 1200 °C in N2. Additionally, Re did not volatilize from Re(SnO2)-containing glass frit until 800 °C and only ∼15% of Re volatilized at 1200 °C, suggesting the loss of Re decreased by ∼30 percentage points through incorporation of Re into SnO2 before vitrification The analysis of Re valence transition revealed that the reduced Re4+ was easily oxidized to volatile Re7+ in air, but in N2, Re4+ disproportionated to form Re7+ and the lower valence states of Re at temperatures from 600 °C to 1000 °C. In Re(SnO2)-containing glass frit, the formation of NaReO4 during vitrification inhibited Re7+ volatilization before 800 °C, while the presence of Re4+ in the glass melt enhanced Re retention at temperature above 800 °C.