Search

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.

Biofuels can contribute to reducing greenhouse gas emissions and bridging the gap between production and consumption. Ethanol is a renewable source of energy. It can reduce oil dependence and also can be appropriately used in gasoline as a blend. The high cost of dry ethanol has turned the researcher's attention to the more economic hydrous ethanol. However many works were focused on its impact on the engine performance and the exhaust emissions; few works were interested in the phase stability of those blends. This work aims to study the impact of blending cyclohexanol (CH) into hydrous ethanol-gasoline blends as a stabilizing agent. Four dual-alcohol (E5-3CH, E10-3CH, E15-3CH, and E20-3CH) blends were investigated besides their single hydrous ethanol (E0, E5, E10, E15, and E20) blends. The tests involved; water tolerance, distillation curve, and vapor pressure. Vapor lock protection potential, the area under the distillation curve (AUDC), and the area due to azeotrope formation (ADAF) were calculated. The obtained results show that cyclohexanol significantly increases the water tolerance of hydrous ethanol-gasoline blends. The blends of E5 and E10 which were separated at 30 °C converted into miscible and clear samples when they were blended with 3 vol% of cyclohexanol. These samples can also tolerate additional water. For E20, the addition of 3 vol% of cyclohexanol increased the water tolerance by about six times. Also, it was found that cyclohexanol does not have any negative effect on the volatility properties of the fuel blends. It was found that blending CH into the hydrous ethanol blends causes a significant increase in the AUDC and consequently, the area due to azeotrope formation (ADAF) decrease.

The volatilities of the components of the saturated vapors of molten UCl4–NaCl–KCl mixtures containing 2.0, 5.0, 12.2, 25.1, 32.9, and 49.7 mol % UCl4 are measured by a transpiration technique in the temperature range 880–1200 K. The chemical composition of the saturated vapors is determined. The vapor phase is most likely to contain the binary NaUCl5 and KUCl5 compounds, which make a significant contribution to the total vapor pressure over the molten mixtures. The molten mixtures are found to exhibit negative deviations from ideal behavior.

Introduction (problem statement and relevance). Hydrocarbon emissions from vaporizationtank fuel contribute significantly to the total emissions of hazardous substances from vehicles equipped with spark ignition engines. To meet the established standards for limiting hydrocarbon emissions caused by evaporation, all modern vehicles use fuel vapor recovery systems, the optimal parameters of which require the availability and application of mathematical models and methods for their determination.The purpose of the research was to develop a model of vapor generation processes in the car fuel tank and a methodology for determining the main quantitative parameters of the vapor-air mixture.Methodology and research methods. The analysis of the processes of vapor generation in the fuel tank was carried out. It was shown that the mass of hydrocarbons generated in the steam space was directly proportional to its volume and did not depend on the amount of fuel in the tank.Scientific novelty and results. New analytical dependences of the vaporization amount on the saturated vapor pressure, barometric pressure, initial fuel temperature and fuel heating during parking have been obtained.Practical significance. A formula was obtained to estimate the temperature of gasoline boiling starting in the tank, depending on the altitude above sea level and the volatility of gasoline, determined by the pressure of saturated vapors. Using the new equations, the vaporization analysis in real situations (parking, idling, refueling, explosive concentration of vapors) was carried out.

Bio-based ionogels with versatile properties are highly desired for practical applications. Herein, we designed a novel self-healing, anti-freezing, and self-adhesive ionogel with excellent sensor capability. The ionogel was obtained by cross-linking amino groups (chitosan) and aldehyde groups (dextran oxide) to form Schiff-base bonds in the ionic liquids (EMIMOAc) with TA. Ionogels inherited the superior electrical conductivity of ionic liquids (IG2, 1.1 mS cm−1). Due to the dynamic reaction of Schiff-base bonds, the obtained IG2 possessed self-healing properties (self-healing efficiency = 89%). The presence of TA also provided the ionogel with excellent self-adhesive properties (IG2/TA, adhesive strength to hogskin = 8.05 kPa). Owing to the low freezing point and low vapor pressure of ionic liquids, ionogels were endowed with anti-freeze properties and resistance to solvent volatility. Moreover, the ionogel can act as a strain sensor, and exhibited excellent sensitivity and sensing performance. Our work provided a green and effective method in preparation of the high performance ionogel sensor, which could accommodate future practical industrial applications.

The influence of bioethanol content and parameters of the cavitation field on the quality indicators of motor gasolines: volatility and octane number is studied. Studying the effect of bioethanol and cavitation treatment of bioethanol-gasoline mixture will make it possible to produce automotive fuels for different climatic zones, or winter (summer) versions of gasolines. The use of bioethanol and cavitation treatment of a bioethanol-gasoline mixture affect the fractional composition of motor gasoline and its volatility. The optimal content of the biocomponent, at which there is an increase in the volatility of gasoline, is established Also the results of the octane number change are presented depending on the intensity of cavitation treatment for gas condensate with the addition of bioethanol. The influence of bioethanol content on the increase in octane number during cavitation treatment is determined. It is found that the introduction of bioethanol into the composition of gasoline leads to an improvement in its volatility. In this case, cavitation treatment makes it possible to obtain a mixture resistant to delamination. The addition of bioethanol leads to an adequate increase in light fractions during mechanical mixing and to a change in the fractional composition of the bioethanol-gasoline mixture during cavitation treatment. The addition of bioethanol in amounts up to 10% leads to a decrease in the saturated vapor pressure during cavitation treatment of bioethanol-gasoline mixtures, and an increase in the bioethanol content up to 20% leads to an increase in the saturated vapor pressure, which is explained by a change in the chemical composition of fuel components in comparison with the mechanical method of preparing mixtures. By cavitation treatment it is possible to change the fractional composition, the pressure of saturated vapors and the volatility of bioethanol-gasoline mixtures, making cavitation a promising energy-saving process for the production of gasoline for various climatic conditions

In this study, four isomerate-enriched gasolines were formulated from the local refinery streams of Cairo Petroleum Refinery Co., Egypt. Each of these isomerate-enriched hydrocarbon gasolines were mixed with 10 vol% of anhydrous ethanol. Distillation data were collected for the eight formulated fuels using the standard ASTM-D86 distillation method. From these data, eight distillation profiles were constructed and subsequently eight distillation profiles equations, were developed. From these equations, areas under distillation curves for the hydrocarbon gasolines (AUDC)G and those for ethanol blended ones (AUDC)G-10E were estimated using calculus definite integration method. Accordingly, area due to azeotrope formation (ADAF) for each ethanol-blended fuel was calculated (AUDCG-AUDCG-10E). Also, vapor pressure, T(v/l) = 20, T50 and deriveability index (DI) of the fuel samples were studied. The results confirm that the volatility of all fuel formulations considerably increases with addition of 10 vol% ethanol while it slightly increases with the slight increase in the isomerate content.

We report on the vapor pressures at ambient temperatures of seven attractants of Bactrocera, Dacus, and Zeugodacus fruit flies—raspberry ketone, cuelure, raspberry ketone trifluoroacetate, methyl e...

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 ...

Prior studies have shown that neglecting the vapor wall loss could lead to the underestimation of the secondary organic aerosol (SOA) yields in smog chamber experiments. The majority of the previous studies investigated vapor wall loss of a wide range of semi-volatile organic vapors at room temperatures using extensive chemical analysis. This study poses a question: Can vapor wall deposition in a smog chamber be observed only using physical measurements of aerosol properties? This study assesses the significance of vapor wall loss using only the size evolution of pure organic compound particles. To our knowledge, this technique is used for the first time in assessing the vapor wall loss of chemical species in chamber experiments. Dark experiments were conducted by injecting pure levoglucosan particles into an outdoor smog chamber at multiple ambient temperatures, ranging from –10°C to +15°C. Peak diameter analysis revealed levoglucosan particles shrunk by ~37% at 15°C and ~20% at 10°C experiments, whereas no shrinkage was observed at temperatures below 0°C suggesting significant vapor wall loss of levoglucosan at warmer temperatures (> 10°C). Two-Moment Aerosol Sectional (TOMAS) and additional simple kinetic model simulations suggest that the effects of temperature on vapor wall loss can primarily be explained by the change in saturation vapor pressure of the organic compound and that the lack of apparent vapor wall loss of levoglucosan below 0°C was due to kinetics, i.e., slow evaporation relative to the chamber experiment timescales. The same approach can be applied to other organic species to expand the range of volatility relevant to chamber experiments.

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.

A modified community multiscale air quality model, which can simulate the regional distributions of 2,3-dihydroxy-4-oxopentanoic acid (DHOPA), a marker species for monoaromatic secondary organic aerosol (SOA), was applied to assess the applicability of using the DHOPA to aromatic SOA mass ratio (fSOA) from smog chamber experiments to estimate aromatic SOA during a three-week wintertime air quality campaign in urban Shanghai. The modeled daily DHOPA concentrations based on the chamber-derived mass yields agree well with the organic marker field measurements (R = 0.79; MFB = 0.152; and MFE = 0.440). Two-thirds of the DHOPA are from the oxidation of ARO1 (lumped less-reactive aromatic species; mostly toluene), with the rest from ARO2 (lumped more-reactive aromatic species; mostly xylenes). Modeled DHOPA is mainly in the particle phase under ambient organic aerosol (OA) loading but could exhibit significant gas-particle partitioning when a higher estimation of the DHOPA vapor pressure is used. The modeled fSOA shows a strong dependence on the OA loading when only semivolatile aromatic SOA components are included in the fSOA calculations. However, this OA dependence becomes weaker when non-volatile oligomers and dicarbonyl SOA products are considered. A constant fSOA value of ∼0.002 is determined when all aromatic SOA components are included, which is a factor of 2 smaller than the commonly applied chamber-based fSOA value of 0.004 for toluene. This model-derived fSOA value does not show much spatial variation and is not sensitive to alternative estimates of DHOPA vapor pressures and SOA yields, and thus provides an appropriate scaling factor to assess aromatic SOA from DHOPA measurements. This result helps refine the quantification of SOA attributable to monoaromatic hydrocarbons in urban environments and thereby facilitates the evaluation of control measures targeting these specific precursors.

Four hydrocarbon-base gasolines (BG) were formulated from the local refinery streams; isomerate, reformate, and light naphtha. The formulations were enriched in reformate. Each of these BG formulations was blended with 10 vol% of anhydrous ethanol. From ASTM-D86 distillation data, eight distillation curves were constructed and the trend line equations of these distillation curves were developed. Also, the area under each distillation curve (AUDC) was calculated through calculus definite integration technique. Subsequently, the area due to azeotrope formation (ADAF) for each BG-ethanol blend was estimated. In this paper, the influence of increasing reformate proportions on the created positive azeotrope, was studied. Also the influence of increasing reformate proportions on vapor pressure, Temperature for the vapor-liquid ratio of 20, T50 and octane number was studied. The results show that the R2 values of the distillation curve equations prove the reliability of the fits. Also, increasing reformate proportion in the fuel blend improves the octane number while increasing reformate proportion decreases the volatility of the fuel formulation. Keywords: Gasoline-ethanol blend, Reformate, Area under distillation curve, Vapor pressure, T50, Research octane number

Biofuels can contribute to reducing greenhouse gas emissions from the transportation sector. Ethanol is the main additive for gasoline in the United States, and gasoline containing 10 vol% ethanol is the most commonly used transportation fuel. However, the vapor pressure of these blends is significantly higher than gasoline, which contributes to evaporative emissions. One way to circumvent this and other issues is to use a dual-alcohol approach, mixing lower (methanol or ethanol) and higher alcohols with gasoline to obtain a blend with a vapor pressure close to that of the base gasoline. The goal of this study was to evaluate the fuel potential of dual alcohol blends experimentally and theoretically. Ten dual-alcohol blends were tested at blending ratios from 10 to 80 vol%, with methanol and ethanol used as the lower alcohols and iso-butanol and 3-methyl-3-pentanol as the higher alcohols. The corresponding single alcohol-gasoline blends were also evaluated. For each blend, Reid vapor pressure, vapor lock protection potential, distillation curve, lower heating value, kinematic viscosity, and water tolerance at three temperatures were measured. A model of droplet evaporation was also applied to provide insights into the azeotropic volatility behavior and mixing/sooting potential of the blends. The results of this study show that it is advantageous to use dual-alcohol blends containing up to 40 vol% because they have the characteristics necessary for good performance in existing spark-ignition engines, particularly in terms of volatility, kinematic viscosity, and water tolerance. This study is the first to characterize matched vapor pressure, dual-alcohol blends over a wide blending range as drop-in fuels for conventional spark ignition engines. Furthermore, this was the first investigation of the fuel potential of iso-butanol in dual-alcohol blends and of 3-methyl-3-pentanol in single- and dual-alcohol blends.

A pilot unit for a concentrated solar thermal reactor with solar tracking was constructed. A 70 cm diameter concentrator dish could provide temperatures around 800 degrees C at a fairly steady rate. In the search for a redox pair that can work at such temperatures, studies were conducted on the feasibility of the Pb/PbO cycle for the splitting of H2O for H-2 production. Thermodynamics accounting for the vapor pressures of Pb and PbO indicated favorable water splitting until approximately 900 degrees C, at atmospheric steam pressures. After 1000 degrees C, the vapor pressure of PbO becomes greater than that of Pb, as a result, thermodynamic favorability in the gas phase begins to be suppressed. The thermodynamic estimations were tested experimentally both in lab scale, and in bench scale molten bed reactors. The process went through similar maxima in the hydrogen production rates. The field tests in solar concentrator using a Pb coated mullite system did not reveal much due to evaporative loss of Pb and PbO under high solar flux. In this paper, it was demonstrated that the relatively high vapor pressure of Pb and PbO can be exploited for designing efficient water splitting cycles at temperatures

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.

A principal mode of corrosion in combustion or fuel cell environments is the formation of volatile hydroxides and oxyhydroxides from metal or oxide surfaces at high temperatures. It is important to determine the degree of volatility and accurate thermodynamic properties for these hydroxides. Significant gaseous metal hydroxides/oxyhydroxides are discussed, along with available experimental and theoretical methods of characterizing species and determining their thermodynamic properties.

Head-space gas chromatography mass spectrometry (HS-GC-MS) was used for the first time to measure the total vapor pressure of hydrophobic deep eutectic solvents (DESs). The new method was developed as a valid alternative for thermogravimetric analysis (TGA), as TGA did not allow obtaining reliable total vapor pressure data for the hydrophobic DESs studied in this work. The main advantage of HS-GC-MS is that the partial pressure of each DES constituent and the contribution of each DES constituent to the total vapor pressure of the mixture can be measured. The results give a clear indication of the interactions occurring between the DES constituents. Also, activity coefficients, enthalpies of evaporation, and activation energies for fluid displacement were obtained and correlated to the measured vapor pressure data. It was confirmed that the total vapor pressures of the hydrophobic DESs are very low in comparison to vapor pressures of commonly used volatile organic solvents like toluene. The total vapor pressures of the hydrophobic DESs were successfully predicted with perturbed-chain statistical associating fluid theory (PC-SAFT) when using PC-SAFT parameters for the individual DES constituents.

200 g ZnMoO4 single crystals, both pure and doped with WO3, were grown from appropriate powder mixtures of oxides via the low-temperature gradient Czochralski technique, and plates cut from them were characterized in detail. The crystal-chemical formulas of non-stoichiometric Zn1.010ZnyMo1−yO1.010+3−2y (y = 0.007) crystals, being substitutional solid solutions with ionic defects, such as ZnMo4−, VO2+, and Zni2′, were established based on determination of the compositions, densities and lattice unit cell parameters with very high accuracy. This characterization allowed for clarification of the role played by each stage of crystal growth, including solid-phase powder synthesis, high-temperature homogenization and crystallization, which proceeded sequentially in one reactor that was semi-open to the air. It was shown that MoO3 volatility is the primary source of issues. The first stage, resulting in a non-equilibrium grain-zoning product, was the key to creating MoO3 vapor pressure in the reactor and a melt composition enriched by the ZnO component. The conditions for the stable crystallization of nonstoichiometric crystals were determined. The experimentally observed shifts in the characteristic liquidus and solidus temperatures of non-stoichiometric ZnMoO4 crystals doped by WO3 were found to be of importance to minimize the negative effects of peritectic melting.

Background: We tested the cutaneous distribution of 50 chemicals in frozen human skin. The mass balance (MB) values for 48% of the chemicals were < 90%, possibly due to evaporation. Methods: We confirmed the reduction in MB was due to evaporation for two chemicals tested in skin penetration experiments using a carbon filter above the skin to trap airborne chemical. An in vitro assay was used to predict the reduction in MB due to evaporation by comparing the recovery of chemicals after 4 h of incubation at room temperature in open and closed vials. Results: Evaporative losses in vitro correlated well with measured MBs (i.e., < 90%) in skin penetration experiments (R2 = 0.81). There was a correlation of the MB with the vapour pressure (VP) which could be used to group chemicals according to their likelihood to evaporate during the course of a skin penetration study. There was also a correlation of MB with Henry’s law constants, melting and boiling points. Conclusion: Our data support the use of a quick and simple test for volatility to account for the loss of MB in skin penetration experiment due to volatility. The best parameter to indicate the potential of a chemical to evaporate is the VP.

We demonstrate a new memristive device (IL-Memristor), in which an ionic liquid (IL) serve as a material to control the volatility of the resistance. ILs are ultra-low vapor pressure liquids consisting of cations and anions at room temperature, and their introduction into solid-state processes can provide new avenues in electronic device fabrication. Because the device resistance change in IL-Memristor is governed by a Cu filament formation/rupture in IL, we considered that the Cu filament stability affects the data retention characteristics. Therefore, we controlled the data retention time by clarifying the corrosion mechanism and performing the IL material design based on the results. It was found out that the corrosion of Cu filaments in the IL was ruled by the comproportionation reaction, and that the data retention characteristics of the devices varied depending on the valence of Cu ions added to the IL. Actually, IL-Memristors involving Cu(II) and Cu(I) show volatile and non-volatile nature with respect to the programmed resistance value, respectively. Our results showed that data volatility can be controlled through the metal ion species added to the IL. The present work indicates that IL-memristor is suitable for unique applications such as artificial neuron with tunable fading characteristics that is applicable to phenomena with a wide range of timescale.

Headspace gas chromatography mass spectrometry (HS-GC–MS) was used to determine the volatility of six selected hydrophobic deep eutectic solvents (DESs). The partial pressure of each DES constituent (decanoic acid, thymol, 1-tetradecanol, menthol or lidocaine) was measured from 313.15 to 373.15 K. The activity coefficients of the hydrogen bond acceptor (HBA) and the hydrogen bond donor (HBD) were determined to quantify the interactions between the DES constituents, thereby deepening the understanding of the thermodynamic nature of the DESs. In addition, the activity coefficients for both components in each DES were predicted with the UNIFAC group contribution method. Similar trends and reasonably close values were obtained for the measured and predicted activity coefficients. It has been found that the interactions between the DES constituents tend to become weaker with increasing temperature. Strong interactions occur between thymol and lidocaine, and thymol interacts moderately with menthol. A weak force exists between decanoic acid and menthol. The mixtures of menthol with 1-tetradecanol or lidocaine are not strictly DESs since for each DES constituent both the measured and predicted activity value is close to unity. A viscosity study was also carried out to quantify the interactions and similar results were found. The ideal mixing rule was proven to correctly describe the viscosity for the mixture of menthol with 1-tetradecanol or lidocaine. While compared to the ideal mixture viscosity, an increase in viscosity was observed for other studied DESs indicating stronger interactions. Finally, the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was shown to accurately describe the thermodynamic properties, where the PC-SAFT pure-component parameters for the DESs were obtained by fitting to pure DES density and total vapor pressure data.

Flame spray pyrolysis (FSP) is a robust, scalable method of synthesizing powders. Nonetheless, many materials cannot be synthesized by FSP because their properties degrade when exposed to the high temperatures typical of flame processes. Herein, a low-temperature flame spray pyrolysis (LT-FSP) process is proposed, and the method is applied to the synthesis of a lithium, manganese rich-NMC material (LMR-NMC): Li1.2Mn0.54Ni0.13Co0.13O2. LMR-NMC materials have been studied intensively in the past decades and are some of the more attractive cathode materials under study for electric vehicles. However, their performance degrades if synthesized under the high temperatures typical of FSP. The proposed LT-FSP process incorporates ethanol, added to an aqueous precursor, as the fuel. Ethanol's unique properties -including a high vapor pressure enhanced by its high activity coefficient in water- allow for stable combustion and low post-flame temperature. Using a swirl-stabilized burner, a stable flame for the mixture was achieved, and the subsequent reactor temperature was found to be significantly lower than what can be attained via traditional FSP. The effects of reactor temperature, controlled via altering ethanol concentration, on the physical properties and electrochemical performance of the synthesized materials were characterized. Li1.2Mn0.54Ni0.13Co0.13O2 synthesized with 25 wt% ethanol showed the best performance, delivering a discharge capacity of 203 mAhg−1 after 100 cycles under C/3, and an initial capacity of 201 and 169 mAhg−1 at C/2 and C/1, respectively. These results are comparable to those obtained for Li1.2Mn0.54Ni0.13Co0.13O2 produced via co-precipitation. The process was modelled via RANS CFD to demonstrate that the high volatility of ethanol in water yields stable combustion at the base of the flame and a uniform low-temperature zone afterwards, leading to ideal conditions for synthesis of temperature sensitive materials in a scalable process. LT-FSP was also found to lead to improved material uniformity when compared to another spray pyrolysis method.

The evaporation/thermaldecompositionbehaviour of twoionicliquids with phosphoniumcation (PhosphoniumIonicLiquids, PhosphoniumILs,), namelytetraoctylphosphonium bis(trifluoromethansulfonyl)imide ([P8888]NTf2) and tetraoctylphosphonium perfluorobutylphosphonate ([P8888]NFBS) wasstudied by thermogravimetryand by the effusion-basedtechniques Knudsen Effusion Mass Spectrometry (KEMS) and Knudsen Effusioni Mass Loss (KEML). KEMS spectra show that no appreciable release of decomposition products occurs up to the highest temperature reached in the experiments (225 °Cfor [P8888]NTf2 and 262 °C [P8888]NFBS). Evaporation by loss of intact ion pair was detected at temperatures as low as 174 and 188 °C for the two compounds, much lower than the onset temperatures evaluated by the TG traces (383 °Cfor[P8888]NTf2 and 407 °C [P8888]NFBS). In the explored temperature intervals (185 °C – 242 °C for [P8888]NTf2 and 180 °C – 230 °C for [P8888]NFBS) the vapor pressures measured by KEML are very similar for the two compounds, falling in the ranges 1.8 10−3–0.19 Pa and 1.1 10−3–0.096 Pa. By monitoring the vapor pressure as a function of temperature, the following values of the evaporation enthalpies were determined at the average experimental temperature (227 °C):158.1 ± 2.0 kJ/mol ([P8888]NTf2) and 161.2 ± 2.2 kJ/mol ([P8888]NFBS), which confirm the very similar volatility of the two compounds under equilibrium conditions.

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 vapor pressure of tungsten was measured by the Langmuir method in the temperature range 2600 to 3100 K using a vacuum microbalance. Four series of data gave concordant results and three of the four series gave second and third law heats of sublimation in excellent agreement. A vapor pressure equation representing the data is log P(atm) = -45385/T + 7.871, based on our mean third law heat and tabulated entropies at 2800 K. The mean third law heat of sublimation at 298.15 K is 205.52 ± 1.1 kcal mol-1 (859.90 ± 4.6 kJ mol-1) where the uncertainty is an overall estimated error. Rates of vaporization are about 1/2 those previously accepted for tungsten.

Significant evaporation of pure aerosols in a Volatility Tandem Differential Mobility Analyzer (V-TDMA) creates two Condensation Particle Counter (CPC) response peaks. Two hypotheses for the observed peaks have been proposed: the existence of two phases or the separation of the singly charged experimental size distribution from the remaining experimental size distributions with charges greater than 1 (charge separation). To explore this observation, we atomized pure levoglucosan aerosol and evaporated the aerosol until two peaks formed. We used an additional classifier and neutralizer to select particles from each of the two peaks and assessed the number of charges on the particles. The smaller diameter peak contained singly charged particles, and the larger diameter peak contained the remaining charges. The charge separation hypothesis alone accounts for the two-peak observations. We used a new V-TDMA model named TAO and show that charge separation should occur in other pure components as well. The TAO model was then used to display the impact of different DMA transfer functions, different inlet size distributions, and different oven residence time distributions (RTDs) on the CPC response. Large errors are possible when direct measurement of the RTD is not performed or when wide RTDs are used. We recommend use of narrow transfer functions with narrow RTDs to detect charge separation. When the singly charged CPC response is isolated (smaller diameter peak in the two peak response), accurate estimations of vapor pressure can be recovered, assuming accurate values for gas phase diffusivity, surface energy, particle density, etc. are used. Copyright �� 2020 American Association for Aerosol Research

Ionic liquids (ILs) can be recycled as extractants for their low vapor pressure and volatility. More and more applications are applied to the separation of industrial organic matter. The industrial production of ILs has gradually been realized, which also widens the way for the application of ILs. In this work, the liquid-liquid extraction of cyclohexane-acetone azeotropic mixture with different ILs {1-butyl-3-methylimidazolium bis(trifluormethylsulfonyl), 1-butyl-3-methylimidazolium trifluoromethansulfonate and 1-butyl-3-methylimidazolium dicyanamide} is studied. The extraction mechanism is discussed based on the molecular scale. The relationship between hydrogen bond donor and acceptor between ILs and acetone is analyzed by COSMO-SAC. The interaction between molecules is optimized and calculated by Materials Studio 7.0. The extraction ability of ILs is analyzed by radial distribution function, and the experimental results are verified. The liquid-liquid equilibrium test is carried out at 298.15 K. Distribution and selectivity are indices used to judge the extraction efficiency of ILs. The NRTL model and UNIQUAC model are adopted to correlate the liquid-liquid equilibrium data. The results show that all of the two models can well correlate the experimental. This work is supported by the National Natural Science Foundation of China (No. 21776145), National Natural Science Foundation of China (No. 21676152).

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.

A binary set of gasoline-ethanol (GE) blends from three types of gasoline’s research octane number (RON), i.e., RON 88, RON 90, and RON 92, were formulated. Herein, the volatility characteristics, i.e., vapor pressure and distillation behavior were measured. Also, physiochemical properties, i.e., density and RON for each blend and oxygenating compounds influence from ethanol, were discussed. The obtained result revealed that the vapor pressure of GE blends is highly affected by non-ideal vapor-liquid equilibrium mixture. The initial boiling point of GE blends would gradually increase as the higher ethanol’s concentration. However, the final boiling point of the GE blends never exceeds the final boiling point of the pristine gasoline, yet never less than the final boiling point of pristine ethanol. Furthermore, RON, oxygenate content, and density, showed a linear increment curve by increasing ethanol content on each gasoline type. Finally, the results showed that it might be advantageous to use ethanol to provide the added value of gasoline RON 88, RON 90, or RON 92 to form a new gasoline product by considering a confident RON and the limitations for high and low volatility.

We have used COSMO-RS (the conductor-like screening model for real solvents), as implemented in the COSMOtherm program, to compute the saturation vapor pressures at 298 K of two photo-oxidation products of isoprene: the dihydroxy dihydroperoxide C5H12O6, and the dihydroperoxy hydroxy aldehyde, C5H10O6. The predicted saturation vapor pressures were significantly higher (by up to a factor of 1000) than recent experimental results, very likely due to the overestimation of the effects of intramolecular hydrogen bonds, which tend to increase saturation vapor pressures by stabilizing molecules in the gas phase relative to the liquid. Modifying the hydrogen bond enthalpy parameter used by COSMOtherm can improve the agreement with experimental results – however the optimal parameter value is likely to be system-specific. Alternatively, vapor pressure predictions can be substantially improved (to within a factor of 5 of the experimental values for the two systems studied here) by selecting only conformers with a minimum number of intramolecular hydrogen bonds. The computed saturation vapor pressures were very sensitive to the details of the conformational sampling approach, with the default scheme implemented in the COSMOconf program proving insufficient for the task, for example by predicting significant differences between enantiomers, which should have identical physical properties. Even after exhaustive conformational sampling, COSMOtherm predicts significant differences in saturation vapor pressures between both structural isomers and diastereomers. For C5H12O6, predicted differences in psat between structural isomers are up to 2 orders of magnitude, and differences between stereoisomers are up to a factor of 20 – though these differences are very likely exaggerated by the overestimation of the effect of intramolecular H-bonds. For C5H10O6, the maximum predicted differences between the three studied structural isomers and their diastereomer pairs are around a factor of 8 and a factor of 2, respectively, when only conformers lacking intramolecular hydrogen bonds are included in the calculations. In future studies of saturation vapor pressures of polyfunctional atmospheric oxidation products using COSMOtherm, we recommend first performing thorough conformational sampling and subsequently selecting conformers with a minimal number of intramolecular H-bonds.

Amorphous solid water is probably the most abundant form of solid water in the universe. Its saturation vapor pressure and thermodynamic properties, however, are not well known. We have investigated the saturation vapor pressure over vapor-deposited amorphous ice at temperatures between 133 and 147 K using a novel experimental method. The new method determines the absolute vapor pressures and the sublimation rates by measuring the mass growth rates of ice-covered nanoparticles under supersaturated water vapor conditions. We find that the vapor pressure of amorphous solid water is up to a factor of 3 higher than that predicted by current parameterizations, which are based in part on calorimetric measurements. We demonstrate that the calorimetric measurements can be reconciled with our data by acknowledging the formation of nanocrystalline ice as an intermediate ice phase during the crystallization of amorphous ice. As a result, we propose a new value for the enthalpy of crystallization of amorphous solid water of Δ H = 2312 ± 227 J/mol, which is about 1000 J/mol higher than the current consensus. Our results shine a new light on the abundance of water ice clouds on Mars and mesospheric clouds on Earth and may alter our understanding of ice formation in the stratosphere.

Five polysiloxane macromolecular photoinitiators containing different anion structures with ionic liquid character ([Si-di2959Im][X] (X = Br−, Ph4B−, TsO−, NO3−, CF3COO−)) were designed and synthesized. The effect of different anion structures on photochemical behavior, phoinitiating mechanism, the water solubility, thermal property and volatility of the photoinitiators was systematically explored. [Si-di2959Im][X] have high extinction coefficient that reaches up to 40,210 M−1 cm−1, and similar photoinitiating activity and mechanism to 2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methylpropan-1-one (Irgacure 2959), while the photopolymerization induction periods of the TPGDA systems initiated by [Si-di2959Im][X] (X = Ph4B−, CF3COO- and NO3) are slightly shorter than that by Irgacure 2959. In addition, [Si-di2959Im][X] have not only good water solubility, but also desirable thermal property and low saturated vapor pressure. The order of water-solubility of [Si-di2959Im][X] is Ph4B−

Quantifying the gas/particle partitioning of organic compounds is of great significance to the understanding of atmospheric aerosol indirect effect. Accurate determination of the hygroscopicities and vapour pressures of semi-volatile organic compounds (SVOC) is of crucial importance in studying their partitioning behaviour into atmospheric aerosol, as the influences on SVOCs evaporation from participation of inorganic species remains unclear. In this study we first present thermodynamic quantitative simulation and tweezed single particle measurement of hygroscopicity and volatility of single aerosol droplets. With thermodynamics simulation of the hygroscopicity, SVOC time dependent evaporation and potential chloride depletion reaction in a single trapped droplet, we illustrate influences from different process towards the trapped droplet. In optical tweezers measurement, the trapped droplet in the aerosol optical tweezers acts as a microcavity, which stimulates the cavity enhanced Raman spectroscopy (CERS) signal. Size and composition of the particle are calculated from Mie fit to the positions of the "whispering gallery modes" in the CERS fingerprint. Hygroscopic behaviours and SVOC saturated vapour pressure can then be extracted from the correlation between the changing droplet radius and solute concentration (derived from experimentally determined real part of refractive index (RI)) with good accuracy and reliability.

Emission of semivolatile organic compounds (SVOCs) from source materials usually occurs very slowly in indoor environments due to their low volatility. When the SVOC emission process is controlled by external mass transfer, the gasphase concentration in equilibrium with the material (y(0)) is used as a key parameter to simplify the source models that are based on solid-phase diffusion. A material-air-material (M-A-M) configured microchamber method was developed to rapidly measure y(0) for a polyisocyanurate rigid foam material containing organophosphate flame retardants (OPRFs). The emission test was conducted in 44 mL microchambers for target OPFRs, including tris(2-chloroethyl) phosphate (CASRN: 115–96-8), tris(1-chloro-2-propyl) phosphate (CASRN: 13674–84-5), and tris(1,3-dichloro-2-propyl) phosphate (CASRN: 13674–87-8). In addition to the microchamber emission test, two other types of tests were conducted to determine y(0) for the same foam material: OPFR diffusive tube sampling tests from the OPFR source foam using stainless-steel thermal desorption tubes and sorption tests of OPFR on an OPFR-free foam in a 53 L small chamber. Comparison of parameters obtained from the three methods suggests that the discrepancy could be caused by a combination of theoretical, experimental, and computational differences. Based on the y(0) measurements, a linear relationship between the ratio of y(0) to saturated vapor pressure concentration and material-phase mass fractions has been found for phthalates and OPFRs.

Measurements of density, viscosity and vapor pressure for binary mixtures of exo-tetrahydrodicyclopentadiene (JP-10) with isopropyl ether are reported at temperatures of (293.15, 298.15, 303.15, 308.15, and 313.15) K over the entire composition range. The excess molar volumes, viscosity deviation and excess Gibbs energies of activation for the binary systems were calculated from the experimental values and fitted with the Redlich–Kister equation. Isopropyl ether was added to enhance the vapor pressure of JP-10. Experimental vapor pressure data were correlated by the Antoine equation. Several semi-empirical equations were used to correlate the viscosity data. The McAllister equation gives relatively satisfactory results for the correlation. The experimental and correlated data could be used in the development of models for mixtures of hydrocarbons with oxygenates.

A correlation for the evaporation of sessile drops over a very broad range of conditions was developed based on measured evaporation rate data obtained for drops of acetone, methanol, and six hydrocarbons ranging from hexane to isooctane, evaporating in air, helium, argon, and krypton, over a range of ambient pressures from 96 kPa to 615 kPa. The experiments were designed to produce a large variation in the rates of diffusion and buoyancy-induced (natural) convection of the vapor phase amongst the experimental conditions. The correlation, which fits the measurements with an RMS relative error of 5.2%, is a simple equation involving conventional parameters for diffusive and convective transport and is applicable to conditions for which vapor transport limits the rate of evaporation. Application of the correlation requires knowledge of eight basic properties: the ambient pressure and temperature, the equilibrium vapor pressure of the evaporating component, the diffusion coefficient for the evaporating component in the ambient gas, the viscosity of the ambient gas, the radius of the sessile drop, and the molecular weights of the evaporating component and the ambient gas. The correlation is much easier to implement than a computational model based on the coupled conservation equations of mass, energy, and momentum for the two phases, and it offers a single mathematical expression that provides valuable insight into how the roles of diffusive and convective transport change with physical and geometrical parameters. The correlation can be a valuable tool to aid in the analyses of applications involving sessile drop evaporation and to support the validation of complex computational models. The range of experimental conditions resulted in a large variation in the rates of diffusive and naturally convective transport of the vapor. Over the range of experimental conditions, the liquid volatility, as indicated by the equilibrium vapor pressure, was varied by a factor of 16.7, the mass diffusivity by a factor of 52.2, the density difference ratio (the impetus for natural convection) by a factor of 3557, and the drop radius by a factor of 22. In terms of the Rayleigh number, the experimental data covers a range from 5 to 361,000. Consequently, the correlation is applicable to a very broad range of conditions. To our knowledge these evaporation rate measurements of sessile drops in gases other than air and at pressures above one atmosphere are the first to be reported in the literature.

Flashing spray is of great importance in a variety of engineering fields, which occurs as the pressurized liquid is released into a low-pressure environment below its saturation pressure. The initial stage close to the nozzle exit is furthest from thermodynamic equilibrium and the information of droplets is difficult to obtain by experimental ways due to the high density of droplets. This paper conducts a systematically numerical study on the spray and thermal characteristics of R404A flashing spray with high volatility and low saturation temperature, based on the open source tool OpenFOAM-2.4.0. Key physics involved in the complex process, including droplet flash boiling, evaporation, droplet transport, breakup, heat transfer and interaction between droplet and gas phases are taken into consideration, through Reynolds Averaged Navier Stokes simulations (RANS) with Eulerian Lagrangian framework for the continuous phase and discrete phase respectively. The spray morphology and droplet diameter coincide reasonably with those in the experiment. It presents explosive atomization with large cone angle and quick expansion towards the radial direction near the nozzle exit. Droplet diameter and temperature undergoes a rapid reduction, while velocity accelerates in this region. A warm core with high droplet temperature exists in the spray central region, and droplet velocity is also larger than that at spray periphery. The ambient pressure significantly affects spray profile, penetration distance and velocity. The whole spray profile transforms to the expansion shape as the pressure increases above 0.5 MPa whereby it presents contractive one in low ambient pressure. Higher ambient pressure leads to lower droplet velocity but with longer penetration distance. These numerical results provide further insight into the mechanism of the flashing spray with volatile cryogens.

Two cobalt(II) guanidinate compounds of the general type [((R)2NC(iPrN)2)2Co] (R = Me, SiMe3) were synthesized and characterized by elemental analysis, 1H NMR, and single crystal X-ray diffraction. The compounds were easily synthesized using a conventional salt-elimination reaction of CoCl2 with the corresponding lithium salt of guanidinate ligands in a general procedure. The thermal properties of the compounds including their volatility, vapour pressure, and thermal stability were studied by thermogravimetric analysis (TGA). The results indicated that both compounds volatilized in a single step with residual mass remaining (13.2% and 10.5%). Moreover, the compounds that were potentially CVD precursors were investigated through deposition experiments conducted in a hot-wall CVD reactor. A film was successfully deposited through CVD, which indicated that the compounds were capable of being precursors for the CVD of cobalt-based films.

The novel aminopyridinato Mn(II) compound has been synthesized and characterized by elemental analysis and X-ray diffraction. It was easily obtained through a conventional salt-elimination reaction. Thermal properties, including stability, volatility, transport behavior and vapor pressure, were evaluated by thermogravimetric analysis (TGA) to confirm that it is suitable for the CVD procedure. Deposition was accomplished in a hot-wall CVD reactor, verifying its ability to act as a CVD precursor for the fabrication of manganese containing films.

The use of ionic liquids (ILs) as solvent in the liquid-liquid extraction of aromatic compounds is one of their most studied applications. Nevertheless, the recovery of the extracted hydrocarbons has been much less investigated, being a required task to complete the global separation process. Taking into account the negligible vapor pressure of the ILs, this step could be easily carried out by flash distillation, which requires the study of vapor-liquid equilibrium (VLE). In order to study this topic deeper, in this work a systematic analysis of the VLE and vapor-liquid-liquid equilibrium (VLLE) data for {aromatic hydrocarbon + IL} binary mixtures was carried out, from both an experimental and computational point of view. For that, new experimental VLE and VLLE data of 24 {toluene + IL} binary mixtures were measured at 323.15 K using a technique based on the static headspace gas chromatography (HS-GC), providing relevant information on the toluene retained in the liquid depending on the cation/anion structure of the IL in the mixture. Furthermore, the quantum chemical Conductor-like Screening Model for Real Solvents (COSMO-RS) method was applied to better understand the structure-property relationship determining the phase behavior of {aromatic hydrocarbon + IL} binary systems. First, the suitability of COSMO-RS to predict VLE and VLLE data of {toluene + IL} binary mixtures was evaluated by comparison to 225 experimental data at 323.15 K, including 24 different ILs over the whole composition range. Valuable conclusions were achieved respect to the molecular model of IL needed to adequately predict VLE and VLLE data of the {aromatic hydrocarbon + IL} binary mixtures. Once the computational approach was stated, COSMO-RS methodology was used to analyze the influence of the intermolecular interactions between the toluene and the IL component on the phase behavior of their mixtures. As a result, COSMO-RS was demonstrated as a useful tool for the rational design of ILs with optimized properties for the separation of aromatic + aliphatic hydrocarbon binary mixtures, considering both liquid-liquid extraction and solvent regeneration steps, The authors are grateful to Ministerio de Economía y Competitividad (MINECO) of Spain for financial support of Projects CTQ2014-52288-R and CTQ2014–53655-R and to Comunidad Autónoma de Madrid for the Project S2013/MAE-2800. Pablo Navarro thanks Fundação para a Ciência e a Tecnologia for awarding him a postdoctoral grant (Reference SFRH/BPD/117084/2016). Marcos Larriba also thanks MINECO for awarding him a Juan de la Cierva-Formación Contract (Reference FJCI-2015-25343).

When liquid fuel is injected under superheated conditions, it would experience rapid evaporation in the form of flash boiling. Bubbles constantly generated inside liquid can enhance the atomization and evaporation of fuel spray, and further changes spray macroscopic structure. Former studies have shown that the presence of high volatility fuel can significantly prompt the atomization of low volatility fuel. However, the effects of component proportion on the flash boiling atomization of multi-component fuel spray have not been fully understood yet. Moreover, the lack of an appropriate superheated index for multi-component fuel spray hinders the deeper physical insight into their flash boiling behavior. To bridge these gaps, three single-component alkanes (n-pentane, iso-octane, and n-decane) with noticeably various vapor pressures were blended in different mixtures to investigate the influence of component proportion on their flash boiling behavior. Their macroscopic spray cross-patterns were tested under various fuel temperature and ambient pressure using a high-speed planar laser Mie-scattering imaging system. The difference of their spray cross-patterns was analyzed. The results indicated that the component proportion of light-end component (with the highest vapor pressure) dominates the spray flash boiling behavior due to its high likelihood of evaporation. Based on these results, a new superheated index modified from the ratio of ambient pressure and bubble point pressure was proposed to predict their flash boiling behavior. This newly proposed superheated index was found to better elucidate the flash boiling behavior of test fuels.

This paper addresses the role of solvent volatility on diameter selection of bicomponent polymer nanofibers produced via gas jet fibers (GJF) process whereby an axisymmetric turbulent gas jet is used for liquid jet initiation, liquid jet stretching, and solvent evaporation. Several morphological forms, such as interpenetrating network (IPN), bi-lobal, and core-shell are obtained by spinning homogeneous solutions of two immiscible polymers in two mutually miscible solvents. The diameter selection of fibers of the same morphology, e. g., bi-lobal, is achieved by spinning polymer solutions of two sets of solvents of different volatility. The results show that fiber diameter is strongly dependent on the value of vapor pressure of the solvents while the morphology is strongly dependent on the vapor pressure difference of the two respective solvents. The diameter selection by GJF process is most prominent for IPN nanofibers, moderately prominent for core-shell fibers, and almost indifferent for bi-lobal nanofibers. The relative rates of solvent evaporation are useful in interpreting the experimental trend.

Semi-volatile organic compounds (SVOCs) are widely used in various indoor materials and their adverse health effects have been increasingly recognized. The gas-phase SVOC concentration in equilibrium with the source material ( y 0 ), as a characteristic parameter for SVOC sources, is mostly assumed to be constant in previous studies. However, decreases in y 0 with time have been observed in some studies. As a first step to reveal the mechanism behind the phenomenon, this study quantitatively investigated the variation of y 0 over time under two conditions: natural exposure to outdoor ambient (Case 1), and storage in a controlled ventilated chamber (Case 2). Three phthalates (Di-iso-butyl Phthalate (DiBP), Di-n-butyl Phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP)) emitted from polyvinyl chloride (PVC) floorings and one flame retardant (tris(2-chloroisopropyl) phosphate, TCPP) emitted from polyurethane foam (PUF) were targeted. Experimental results indicated that, for SVOCs with higher volatility, i.e., DiBP, DnBP, and TCPP, y 0 decreased 16%–49% after 60 days' exposure for Case 1; and 16%–36% for Case 2. For SVOCs with lower volatility, i.e., DEHP, no significant decrease in y 0 was observed after 60 days in both cases; while if prolonging the time to about 1.5 years, a decrease of 38% was observed. Discussion about potential reasons for the decrease of y 0 was presented. The results obtained here provide a further understanding about SVOC source characteristics and therefore help providing source strength for estimating indoor SVOC health exposure.

A germanium(II) aminopyridinato compound has been synthesized and characterized by 1H and 13C NMR spectroscopy, elemental analysis and X-ray diffraction. It was easily obtained in high yield through a salt-elimination reaction by mixing the corresponding lithium salt and the GeCl2-dioxane adduct. Thermal properties, including stability, volatility, transport behavior and vapor pressure, were evaluated by thermogravimetric analysis (TGA) to confirm that it is suitable for the CVD procedure. Deposition was accomplished in a hot-wall CVD reactor system, which verified its ability as a CVD precursor for the fabrication of germanium containing films.

Mass spectrometry (MS) with low temperature plasma (LTP) as an ionization source is one of the widely used ambient methods in analyzing various bio-chemical samples for their detection, identification, differentiation, etc. While the LTP-MS allows selective analysis of a sample with low-molecular weight without thermal damages, it has difficulties desorbing a target molecule from the sample surface with a low volatility. Hence, for the purpose of enhancing the desorption and ionization efficiencies of the LTP-MS when analyzing the fatty acids, two methods were compared: directly heating the sample surface and increasing the vapor pressure of the fatty acid itself by derivatization. In addition, the fatty acids in Drosophila were directly analyzed with the LTP-MS. As a result, it was found that the LTP-MS detection efficiency was enhanced with the derivatization as much as with the heating condition while there was little synergy in employing both of the heating and derivatization together.

Evaporation of sulfuric acid from particles can be important in the atmospheres of Earth and Venus. However, the equilibrium constant for the dissociation of H2SO4 to bisulfate ions, which is the one of the fundamental parameters controlling the evaporation of sulfur particles, is not well constrained. In this study we explore the volatility of sulfate particles at very low relative humidity. We measured the evaporation of sulfur particles versus temperature and relative humidity in the CLOUD chamber at CERN. We modelled the observed sulfur particle shrinkage with the ADCHAM model. Based on our model results, we conclude that the sulfur particle shrinkage is mainly governed by H2SO4 and potentially to some extent by SO3 evaporation. We found that the equilibrium constants for the dissociation of H2SO4 to HSO4−(KH2SO4) and the dehydration of H2SO4 to SO3 (xKSO3) are KH2SO4 = 2–4 × 109 mol kg−1 and xKSO3 ≥ 1.4 × 1010 at 288.8 ± 5 K.

The thermal behavior of volatile heterometallic CuPdL4 compound and parent β-diketonate complexes CuL2 and PdL2 (L = 2-methoxy-2,6,6-trimethylheptane-3,5-dionate; (CH3)3CCOCHCOC(CH3)2OCH3) were investigated by different methods. It is demonstrated that the combination of data on the gradient sublimation, TG–DTA, the mass transfer in a stream of inert gas and mass spectrometry can determine the composition of the gas phase. The volatility of the heterometallic complex was shown to follow the vapor-phase composition presented by binuclear [CuL2PdL2] molecules, and there was no decomposition into monometallic complexes within the studied temperature range (403–438 K). Temperature dependences of the saturated vapor pressure were obtained, and thermodynamic parameters of the sublimation process were computed for these three compounds for the first time. The thermal decomposition of the bimetallic complex vapor was found to start with the surface reaction of dissociation into monometallic complexes followed by their thermolysis with the formation of Cu/Pd alloy films.

Studies of high-water-content fuels (a.k.a., wet fuels) have demonstrated that, under proper conditions, stable combustion can be achieved at very high water concentrations. Stable spray flames of wet fuels have been attained with fuel/water mixtures having stoichiometric adiabatic flame temperatures as low as 251 °C. In this study, we investigate low-volatility wet fuels, using glycerol as the fuel and ethanol as a stabilization additive. This study expands on previous work by determining the minimum amount of ethanol that needs to be added to a glycerol/water mixture to produce a stable flame and by investigating the spray dynamics and structure for these fuels, to delineate the mechanism of ignition and to understand how ethanol alters the vaporization behavior, droplet breakup, and spray dynamics. Detailed 2-D velocity, Sauter mean diameter (SMD), 2-D flux, and number concentration measurements were performed with a Phase Doppler Particle Analyzer (PDPA) in sprays of three fuel/water mixtures: (a) 30% glycerol/70% water, (b) 30% glycerol/10% ethanol/60% water, and (c) the same mixture as (b) but in a combusting spray. All percentages are by weight. Results show that the addition of ethanol to the glycerol/water mixture turns the hollow-cone spray pattern into a narrow full-cone pattern, leading to recirculation of fine droplets in the region just downstream of the nozzle, which is essential to ignition. The high concentration of fine droplets, along with the high vapor pressure and high activity coefficient of ethanol, lead to extremely rapid vaporization of ethanol in the inner recirculation zone. The combustion of the ethanol raises the temperature in this region, while the swirling flow brings heat upstream towards the nozzle, further enhancing stability. These results explain why the addition of 10% ethanol can lead to robust flames of glycerol/water mixtures that might not be expected to yield stable combustion.