Search

The solubilities of the rare earth chlorides REECl3, where REE = (La, Nd, Er), were measured in HCl bearing water vapor from 350 to 425 °C with water partial pressures ranging from 8 to 170 bar. Solubility data were fit to the Pitzer-Pabalan quasi-chemical model in order to extract thermodynamic parameters for the formation of the gaseous REE-chloride-water clusters REECl3(H2O)n. The data show that the solubility of the REE chlorides are orders of magnitude higher than salts such as NaCl or CuCl at low water fugacities, despite their sublimation energies being substantially higher. This enhanced solubility is likely due to the high enthalpy associated with binding a single water molecule to form the species REECl3(H2O), with derived enthalpies ranging from −378 to −465 kJ/mol. Addition of further water molecules to form higher order clusters (n > 1) involves enthalpy changes of ~−20 kJ/mol, and are in effect thermodynamically suppressed over the temperature range 350–425 °C. Despite the enhanced solubility of small REECl3 water clusters, simulations of boiling processes demonstrate that the REE show highly conservative behavior, partitioning strongly into the dense aqueous phase. Not surprisingly, the presence of phosphates in the system makes this effect even more pronounced, completely immobilizing the REE. This would reduce transport in both the vapor and aqueous phase to negligible levels. However, we suggest that vapor phase transport of the REE may play a significant role in systems having a relatively low partial pressure of water (below the saturation point), where the relatively high stability of the first hydrated REE chloride clusters (REECl3(H2O) and REECl3(H2O)2) will give a preference for gas transport of the REE relative to other elements. This can likely happen in systems involving a gas/melt exchange in fumarolic exhalations, where water vapor discharges at relatively low (close to atmospheric) pressures.

Polycatechol and polyguaiacol are light-absorbing and water-insoluble compounds that are produced from biomass burning emissions. The aerosol can act as seeds for cloud droplet formation.

In this work, we present a tandem ion mobility spectrometer (IMS) utilizing a highly efficient ion manipulator allowing to store, manipulate, and analyze ions under high electric field strengths and controlled ion-neutral reactions at ambient conditions. The arrangement of tandem drift regions and an ion manipulator in a single drift tube allows a sequence of mobility selection of precursor ions, followed by storage and analysis, mobility separation, and detection of the resulting product ions. In this article, we present a journey exploring the capabilities of the present instrument by a study of eight different primary alcohols characterized at reduced electric field strengths E/N of up to 120 Td with a water vapor concentration ranging from 40 to 540 ppb. Under these conditions, protonated alcohol monomers up to a carbon number of nine could be dissociated, resulting in 18 different fragmented product ions in total. The fragmentation patterns revealed regularities, which can be used for assignment to the chemical class and improved classification of unknown substances. Furthermore, both the time spent in high electrical field strengths and the reaction time with water vapor can be tuned precisely, allowing the fragment distribution to be influenced. Thus, further information regarding the relations of the product ions can be gathered in a standalone drift tube IMS for the first time.

Calcium-aluminum-rich inclusions (CAIs) are known as the oldest high-temperature mineral assemblages of the Solar Sys-tem. The CAIs record thermal events that occurred during the earliest epochs of the Solar System formation in the form of heterogeneous oxygen isotopic distributions between and within their constituent minerals. Here, we explored the kinetics of oxygen isotope exchange during partial melting events of CAIs by conducting oxygen isotope exchange experiments between type B CAI-like silicate melt and 18O-enriched water vapor (PH2O = 5 x 10-2 Pa) at 1420 degrees C. We found that the oxygen iso-tope exchange between CAI melt and water vapor proceeds at competing rates with surface isotope exchange and self -diffusion of oxygen in the melt under the experimental conditions. The 18O concentration profiles were well fitted with the three-dimensional spherical diffusion model with a time-dependent surface concentration. We determined the self-diffusion coefficient of oxygen to be-1.62 x 10-11 m2 s-1, and the oxygen isotope exchange efficiency on the melt surface was found to be-0.28 in colliding water molecules. These kinetic parameters suggest that oxygen isotope exchange rate between cm -sized CAI melt droplets and water vapor is dominantly controlled by the supply of water molecules to the melt surface at PH2O < 10-2 Pa and by self-diffusion of oxygen in the melt at PH2O >-1 Pa at temperatures above the melilite liquidus (1420-1540 degrees C). To form type B CAIs containing 16O-poor melilite by oxygen isotope exchange between CAI melt and disk water vapor, the CAIs should have been heated for at least a few days at PH2O > 10-2 Pa above temperatures of the melilite liquidus in the protosolar disk. The larger timescale of oxygen isotopic equilibrium between CAI melt and H2O compared to that between H2O and CO in the gas phase suggests that the bulk oxygen isotopic compositions of ambient gas at-1400 degrees C in the type B CAI-forming region is preserved in the oxygen isotopic compositions of type B CAI melilite. Based on the observed oxygen isotopic composition, we suggest that a typical type B1 CAI (TS34) from Allende was cooled at a rate of-0.1-0.5 K h-1 during fassaite crystallization. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

A thermal desalination system with a flash drum, a spray-nozzle system, and a condenser under vacuum is designed. Theoretical yield of water vapor in the vacuum flash drum has been evaluated based on conservation equations of mass and energy in the range from 0.35 % to 8.37% at temperature of saline feed water from 40 °C to 60 °C, salinity from 0.035 to 0.04 kg/kg, feed flow rate of 40000 kg/day, and supersaturation from 2 °C to 50 °C. A thermal-fluid model has been adopted to simulate the dynamics of saline water droplets for flash evaporation under vacuum. At a moderate droplet velocity, the model predicts time scales for evaporation from 0.5 s to 1 s with yield of flashing vapor from 69.24 % to 84.59 % at droplet radius from 100 μm to 150 μm. The yield increases with the increase in supersaturation and feed temperature, whereas it increases appreciably with the decrease in droplet size. The design is based on the evaporation time scale and the theoretical yield. Both droplet dynamics for flash evaporation and theoretical yield have been validated with results from the literature.

Nitrogen oxides ( NO x ≡ NO + NO 2 ) are centrally involved in the photochemical processes taking place in the Earth's atmosphere. Measurements of NO2 , particularly in remote areas where concentrations are of the order of parts per trillion by volume (pptv), are still a challenge and subject to extensive research. In this study, we present NO2 measurements via photolysis–chemiluminescence during the research aircraft campaign CAFE Africa (Chemistry of the Atmosphere – Field Experiment in Africa) 2018 around Cabo Verde and the results of laboratory experiments to characterize the photolytic converter used. We find the NO2 reservoir species MPN (methyl peroxy nitrate) to produce the only relevant thermal interference in the converter under the operating conditions during CAFE Africa. We identify a memory effect within the conventional photolytic converter (type 1) associated with high NO concentrations and rapidly changing water vapor concentrations, accompanying changes in altitude during aircraft measurements, which is due to the porous structure of the converter material. As a result, NO2 artifacts, which are amplified by low conversion efficiencies, and a varying instrumental background adversely affect the NO2 measurements. We test and characterize an alternative photolytic converter (type 2) made from quartz glass, which improves the reliability of NO2 measurements in laboratory and field studies.

High-resolution Fourier transform infrared (FTIR) solar observations are particularly relevant for climate studies, as they allow atmospheric gaseous composition and multiple climate processes to be monitored in detail. In this context, the present paper provides an overview of 20 years of FTIR measurements taken in the framework of the NDACC (Network for the Detection of Atmospheric Composition Change) from 1999 to 2018 at the subtropical Izaña Observatory (IZO, Spain). Firstly, long-term instrumental performance is comprehensively assessed, corroborating the temporal stability and reliable instrumental characterization of the two FTIR spectrometers installed at IZO since 1999. Then, the time series of all trace gases contributing to NDACC at IZO are presented (i.e. C2H6, CH4, ClONO2, CO, HCl, HCN, H2CO, HF, HNO3, N2O, NO2, NO, O3, carbonyl sulfide (OCS), and water vapour isotopologues H216O, H218O, and HD16O), reviewing the major accomplishments drawn from these observations. In order to examine the quality and long-term consistency of the IZO FTIR observations, a comparison of those NDACC products for which other high-quality measurement techniques are available at IZO has been performed (i.e. CH4, CO, H2O, NO2, N2O, and O3). This quality assessment was carried out on different timescales to examine what temporal signals are captured by the FTIR records, and to what extent. After 20 years of operation, the IZO NDACC FTIR observations have been found to be very consistent and reliable over time, demonstrating great potential for climate research. Long-term NDACC FTIR data sets, such as IZO, are indispensable tools for the investigation of atmospheric composition trends, multi-year phenomena, and complex climate feedback processes, as well as for the validation of past and present space-based missions and chemistry climate models.

Atmospheric pressure cold plasma generated using a radio frequency hollow cathode (RFHC) device recently showed its potent virucidal characteristics. For this purpose, the atmospheric pressure cold plasma of Ar was generated with a specially designed electrode using RF (13.56 MHz) power. In order to establish a correlation between the generated plasma species and its virucidal activity, systematic optical emission spectroscopy (OES) investigations were conducted on the plasma. OES studies revealed that the generated plasma using this device shows the emission of important species in the ultraviolet (UV) region and reactive oxygen species (ROS) in the optimized operation condition, required for virucidal action. Furthermore, investigations revealed that similar active species can be generated by placing a commercial nebulizer in front of plasma. Investigations conducted on the aerosol capturing efficiency of N-95 mask revealed that cold plasma treatment leaves functional aspects of this medical personal protection equipment (PPE) unchanged. The results indicate that such an RF-HC device in combination with a nebulizer for introducing water mist in plasma can effectively destroy bacteriophage of Aeromonas bacteria at low operating power (70–90 W).

Temperature affects humidity. The interaction of temperature and humidity also directly affects the health and well-being of humans. The relative humidity (RH) of the air is an indication of how much water vapor is in the air at a particular temperature compared with how much water vapor the air could actually hold at that temperature. Air at 100 % relative humidity holds the maximum amount of water possible at that particular temperature and is said to be saturated. Therefore, air at 50% relative humidity, regardless of temperature, is holding half of its total possible water capacity. In essence, cold air cannot hold as much water vapor as warm air. In a closed environment such as a display case, there will be a fixed amount of water vapor, referred to as the absolute humidity. If the temperature inside the case falls then the relative humidity will rise. If the temperature rises the relative humidity will fall. Such changes in relative humidity could be caused by many factors including direct sunlight, spotlights and air-conditioning failures. Research carried out by experimental studies that we can get the humidity ratio and specific enthalpy in a kind of rooms either using The Psychrometric Chart and The formula. The specific humidity or humidity ratio of an air sample is the ratio of the weight of water vapor contained in the sample compared to the weight of the dry air in the same sample. Enthalpy is the amount of heat (energy) in the air per unit mass. Enthalpy is the total amount of energy present in the air, both from air and water vapor contained therein. And, Specific enthalpy of moist air is defined as the total enthalpy of the dry air and the water vapor mixture - per unit mass of dry air. Keywords: Temperature; Relative Humidity; Humidity Ratio; Specific Enthalpy.

An experimental platform was set up to test the heat and mass transfer performance inside the membrane energy accumulator (MEA). Hollow fiber MEAs (HFMEAs) and flat MEAs (FMEAs) were designed and tested. Compared with HFMEAs, FMEAs have higher mass transfer efficiency. The average mass transfer speed of the water vapor increased by 108.34% when the evaporation temperature increased from 4.5 °C to 12.3 °C for HFMEA. When the evaporation temperature increased from 7.88 °C to 19.51 °C, the change in mass fraction of lithium bromide (LiBr) in FMEA increased by 62.36%. Compared with a 60% solution, the average mass transfer rate of water vapor molecules in a 70% LiBr solution increased by 49.83% for FMEA. In addition, the water vapor absorbed by the 70% LiBr solution in 30 min increased by 18.63% compared to that of the 60% solution for FMEA. The effect of the initial solution temperature on the mass transfer rate is closely related to the mass fraction of LiBr. Both the mass transfer rate and crystallization melting process of the LiBr solution will accelerate by increasing the initial mass fraction and evaporation temperature.

The relevance of research is to ensure and improve the reliability of turbine generators (TG) with a hydrogen-water cooling system by monitoring the content of dissolved gases in the water of a hydrogen-water cooling system with monoethanolamine (MEA) – C2H7NO and water vapor in the cooling hydrogen of the turbine. In this work, the influence of ultrasonic vibrations on the decomposition of a mixture of water and turbine oil, organic acids (acetic acid - С2Н4О2, formic acid - СН2О2, oxalic acid - С2Н2О4) or monoethanolamine was determined. The distribution coefficients values were definedd for the following dissolved gases Н2, О2, N2, СО, СН4, С2Н2, С2Н4, С2Н6, С3Н6, С3Н8, which are of degradation products of water mix components when exposed to ultrasonic oscillation in the following system: «dissolved gas – mixture «water + monoethanolamine» – extractant argon (Ar)». The obtained values of the Кі distribution coefficients for dissolved gases in systems «dissolved gas – mixture «water + С2Н7NО» – extractant argon (Ar)» at a temperature of 293 K and a concentration of С2Н7NО at the level of 1 g/dm3 are close to similar values for dissolved gases in deionized water. The principle flow chart of multichannel gas chromatograph for detecting dissolved gases in water and steam of water in hydrogen was developed. Developed flow chart of 4-chennel gas chromatographer for defining dissolved gases in water includes the one gas chromatographer with conductivity detector, methanator, flame ionization detector, argon gas-bearing and supplementary gases of hydrogen and air. Актуальність дослідження полягає у забезпеченні та підвищені надійності експлуатації турбогенератора з системою воднево-водного охолодження. Метою дослідження є забезпечення надійності експлуатації турбогенератора з водневим охолодженням за рахунок контролю вмісту розчинених газів у воді системи воднево-водного охолодження із моноетаноламіновим (С2Н7NО) водно-хімічним режимом та пару води в охолоджуючому водні турбогенератора. Завданнями дослідження є визначення впливу ультразвукових коливань на деградацію суміші води із турбінною оливою, органічними кислотами ( оцтовою – С2Н4О2, мурашиною – СН2О2, щавлевою – С2Н2О4) або із моноетаноламіном; визначення значень коефіцієнтів розподілу для розчинених газів Н2, О2, N2, СО, СН4, С2Н2, С2Н4, С2Н6, С3Н6, С3Н8 у суміші «розчинений газ – суміш «вода +моноетаноламін» – екстрагент аргон (Ar)»; розробка принципової структурної схеми багатоканального газового хроматографу для визначення у воді розчинених газів та пару води у водні. При визначені впливу ультразвукових коливань на деградацію суміші води із нафтовою турбінною оливою, органічними кислотами або із моноетаноламіном, продуктами деградації є гази Н2, СО, СО2, СН4, С2Н2, С2Н4, С2Н6. При визначенні коефіцієнтів розподілу Кі для розчинених газів у суміші «розчинений газ – суміш «вода +моноетаноламін» – екстрагент Ar» значення Кі при концентрації моноетаноламіну 1 г/дм3 близькі для аналогічних значень у дистильованій воді. Розроблена принципова структурна схема 4-х канального газового хроматографу для визначення у воді розчинених газів та пару води у водні дозволяє визначати вміст розчинених газів у воді та пару води у водні із залученням одного газового хроматографу із детектором за теплопровідністю, метанатором, полум'яно-іонізаційним детектором, газом-носієм аргоном та допоміжними газами воднем і повітрям.

The oxidation behavior of alloy 625 and 120 foils was studied at 650, 700 and 800 $$^\circ$$ C in dry air and flowing air + 10% H $$_2$$ O up to 10,000 h (alloy 625) or 30,000 h (alloy 120). The effect of water vapor on Cr loss was investigated. Manganese and iron in the 120 foil induced faster Cr depletion in the foil and breakdown of the Cr $$_2$$ O $$_3$$ scale into Fe and Cr-rich oxide compared to the alloy 625 foil. In the latter case, the presence of Nb led to the formation of Nb and Cr-rich oxide after breakdown of the Cr $$_2$$ O $$_3$$ scale. Simultaneous Cr loss due to oxidation and volatilization of the Cr $$_2$$ O $$_3$$ oxide scale was predicted and compared to experimental Cr loss measurements for exposures up to 30,000 h.

This work focuses on the high temperature oxidation of AISI 316L produced by Selective Laser Melting (SLM) and by conventional metallurgy (wrought), used as reference. Oxidation tests were performed at 900 °C for up to 3000 h in laboratory air and up to 1000 h in wet air (air-10 vol.% H2O). X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectrometry were used for the characterization of the corrosion products. SLM specimens exhibit a better oxidation resistance in both atmospheres. SLM samples exhibit parabolic behavior $$(k_{p} = 1.7~.10^{{ - 13}} g^{2} .cm^{{ - 4}} .s^{{ - 1}} )$$ throughout 3000 h in air while wrought $$(k_{p} = 1.4~.10^{{ - 13}} g^{2} .cm^{{ - 4}} .s^{{ - 1}} )$$ samples undergo breakaway oxidation after 1000 h of exposure. These observations are emphasized in wet air, since wrought coupons present catastrophic oxidation after 100 h, while parabolic behavior $$(k_{p} = 7.0~.10^{{ - 14}} g^{2} .cm^{{ - 4}} .s^{{ - 1}} )$$ is observed all along the 1000 h exposure for SLM samples. The better behavior observed for SLM samples can be explained by the growth of a dense and continuous Cr2O3 protective layer.

The influence of atmospheric water vapor on the kinetics of the thermal decomposition of perlite concrete, which is used in the construction of sodium-cooled fast reactor (SFR) plants, was investigated. Changes in the overall thermal behavior were systematically tracked using humidity-controlled thermogravimetry (TG) at various heating rates (β) and atmospheric water vapor pressures (p(H2O)). The multistep process, mainly composed of the thermally-induced removal of various types of water molecules in the cement matrix and the thermal decompositions of Ca(OH)2 and CaCO3, was successfully separated into component reaction steps using kinetic deconvolution analysis (KDA) based on a cumulative kinetic equation. During the thermal dehydration steps, three derivative TG peaks became more clearly distinguishable and shifted to higher temperatures with increasing p(H2O). A significant retardation effect of p(H2O) was observed for the thermal decomposition of Ca(OH)2. Conversely, a slight but detectable catalytic effect of p(H2O) was observed for the thermal decomposition of CaCO3. Through isoconversional analysis of the kinetic curves extracted using KDA, universal kinetic descriptions for the thermal decompositions of Ca(OH)2 and CaCO3 over different β and p(H2O) values were achieved by introducing accommodation functions considering the effect of p(H2O) into the fundamental kinetic equation. The achieved universal kinetic descriptions for the thermal decompositions of Ca(OH)2 and CaCO3 can be introduced into the cumulative kinetic equation for the overall thermal decomposition of perlite concrete as a means to improve the kinetic information used in SFR plant simulation systems for safety assessment.

A prototype device for biological activation of aqueous solutions is presented. The activation is carried out using non-equilibrium (electrolyte) plasma generated by high-frequency glow discharge in water vapor at atmospheric pressure. The structure and functional features of the device are described. The results of investigation tests are presented, including the ranges of the main electrochemical parameters of activated aqueous solutions. It is shown that the activation of aqueous solutions with glow discharge electrolyte plasma is a low-cost procedure that can be implemented under laboratory or field conditions using a small-size device.

The method of mathematical processing of IR transmission spectra, which consists in estimating the changes in the absorption fraction of certain groups during the activation, was used to reveal weak systematic changes in the functional composition of the activated carbon surface. Analysis of the spectra of activated carbon samples prepared from bamboo stems and birch wood using this method has shown that activation is accompanied by condensation of aromatic nuclei, which leads to the formation of polyaromatic structures. To estimate the size of aromatic fragments, we calculated the ratio of the integrated intensity of the stretching vibration band of aromatic clusters at 1560 cm–1 to the integrated intensity of the vibration band of C–H bond at 870 cm–1. It is shown that an increase in the degree of burnout of charcoal upon activation is accompanied by an increase in the size of polycyclic aromatic structures.

To improve the measurement accuracy of the dew point humidity sensor (sensor), starting from the problem of water vapor release and adsorption during the temperature change and based on tunable diode laser absorption spectroscopy (TDLAS), the experimental environment is designed and built with an embedded water content tester (tester), low temperature dew point generator (dew point generator), MBW humidity standard device (standard device), variable temperature freezer refrigerator (variable temperature box) and other equipment. The water vapor release effect of the sensor when the ambient temperature rises and the water vapor adsorption effect when the ambient temperature decreases are verified, and the degree of water vapor release and adsorption effects under different temperature changes, different water vapor concentrations, and different flow rates are quantitatively measured. The results show that the greater the temperature change is, the greater the release and adsorption of water vapor; the greater the concentration of water vapor is under the same temperature change, the greater the release and adsorption of water vapor; and the greater the gas flow is, the less obvious the release and adsorption of water vapor. The water vapor release and adsorption under different water vapor concentrations, different starting temperature points, and different temperature changes in the gas path are calculated. Subsequently, a reference table of sensor variable temperature compensation coefficients is given, which provides a new way to further improve the accuracy of sensor measurement.

Through 58-yr isotopic data (3H, 18O, and 2H) in monthly precipitation for Hong Kong, we discuss how main controls, especially monsoon activities, effect temporal variation of isotopes in precipitation. By comparing the local meteoric water lines, we find that the recycled water vapor and sub-evaporation cause the slope of LMWL lower whereas the recycled water vapor supersaturated non-equilibrium condensation makes it higher. Given the “reverse temperature effect” in Hong Kong, we caution the use of temperature effect for paleoclimate reconstruction in humid and monsoonal locations. Our findings provide evidences on how environmental and anthropogenic factors affect precipitation isotopes in monsoonal areas.

A study of the discharge plasma with a vortex flow of an argon + water vapor mixture with aluminum particles in a tube of a plasma vortex reactor (PVR) was carried out. The parameters of the discharge, plasma, and working flow in the PVR have been measured. Spectral methods were used to estimate the electron temperature, rotational and vibrational temperatures of excited molecular complexes, the temperature of metal clusters, and the electron density of plasma. A kinetic scheme is proposed for calculating the operating modes in a reactor using a water vapor discharge with aluminum particles. Numerical simulation of a vortex flow of pure water vapor with aluminum particles in the presence of a heating source is carried out.

The kinetics of reactions between minerals and water vapor or two water phases simultaneously (liquid + vapor) is still understood inadequately poorly, and the absence of these data disable realistic and comprehensive quantitative description of the evolution of hydrothermal system after its fluid heterogenizes. To bridge this gap, we have conducted quenching experiments with quartz crystals and water at 300°C and Psat = 86 bar. In addition to usually applied analytical techniques (ICP-AES, SEM, XRD, and optical microscopy), we used 3d scanning of the crystals, measured their surface areas, and plotted the changes in the crystal sizes because of dissolution and deposition reactions. In the experimental runs with the crystal occurring in the vapor phase, the first ever data were acquired on the rate constant of quartz dissolution for saturated water vapor (Psat = 86 bar) at 300°C (2.7 nmol m–2 s–1). The constant turned out to be 630 times lower than that for pure water. Calculations indicate that equilibrium between quartz and water and vapor is established during comparable time spans, but quartz recrystallization in vapor due to the temperature gradient proceeds two orders of magnitude more slowly than in water. In the runs with the crystal occurring in both water and vapor, not only the stable quartz dissolved, but also metastable cristobalite-tridymite opal was formed. The opal was deposited on the autoclave walls and even on the quartz itself above the water surface, and the silica concentration in the water remained remarkably lower that the quartz solubility. The rate of opal formation (10–7.5 mol m–2 s–1) was 3.5 orders of magnitude higher than the quartz recrystallization rate (which is the only process possible in this system according to the traditional geochemical approach). This disagreement is explained within the framework of the distillation hypothesis, which is based on the preferential evaporation of the thin (

Combustion of pyridine in rich, stoichiometric, and lean mixtures of C5H5N/O2( $$\rho_\mathrm{ Py}=0.11$$ and 0.15 mol/dm3; $$\rho_\mathrm{ O_2}=0.71$$ –1.18 mol/dm3) diluted with argon or water vapor was investigated at uniform heating of the reactor to 823 K. Analysis of the time dependences of the temperature and pressure of the reaction mixtures revealed differences in the mechanisms of pyridine oxidation at temperature measurement with a Pt-Rh/Pt or nichrosil-nisil thermocouple introduced into the center of the reaction volume. The Pt-Rh/Pt thermocouple was found to intensify the combustion of pyridine in the near-surface region and initiate detonation of the reaction mixture. Increase in the density of the water vapor prevents detonation. Increase in the oxygen content in the reaction mixture leads to decrease in the ignition temperature of pyridine and growth of the degree of carbon burnout and of the fraction of nitrogen that had transformed into N2. With a nichrosil-nisil thermocouple, which has no catalytic properties, the surface oxidation of pyridine on the reactor wall was shown to dominate. Results of mass spectrometry analysis show that in the presence of water vapor, the oxidation of pyridine proceeds through the formation of NH3 as the main intermediate.

In this study, freestanding fully porous polyimide (FFPP) membranes were prepared in batches by the scraping technique and vapor-induced phase separation (VIPS) and used for thin film microextraction (FFPP-TFME). When water vapor was applied simultaneously during scraping, the resulting membrane surface was highly porous, in contrast to the dense and smooth surface obtained without vapor. The micro/nanocomposite pore structure was revealed by scanning electron microscopy and nitrogen adsorption–desorption. The diameters of the micropores, nanopores and fibrous polyimide (PI) nanofibers were 0.5–1.5 μm, ca. 30 nm and ca. 250 nm, respectively. The extraction performance of the FFPP-TFME method was evaluated with organochlorine pesticides (OCPs) as model analytes in water. The extracted OCPs were desorbed in acetone and then quantified by gas chromatography–mass spectrometry. The effects of extraction time, ionic strength, desorption solvent, desorption volume and desorption time were investigated. Under the optimized conditions, the limits of detection (LODs) for eight OCPs (4.4–83 ng L−1), linear ranges (0.05–50 μg L−1), correlation coefficients (0.997–0.999), intrabatch relative standard derivations (RSDs, 0.88–9.20%) and interbatch RSDs (6.35–13.5%) were obtained. The method was also successfully applied to the analysis of environmental water samples, and the relative recoveries of all real water samples were 73.6–116.4%. These results show that the FFPP-TFME method is a simple, efficient and environmentally friendly method for the pretreatment of trace organic pollutants in water samples.

Bastnasite is widespread in alkali granite, carbonatite and REE ore deposits. The U-Th-Pb ages of bastnasite can constrain the mineralization age. Currently, the lack of suitable in situ analysis reference material is the major obstacle of bastnasite U-Th-Pb geochronology. In this study, the matrix effects of U-Pb and Th-Pb age determination in bastnasite using glass NIST 610 as the external calibration reference were evaluated with the 193-nm excimer LA-ICP-MS analysis in normal and additional gases laser ablation modes. The obtained U-Th-Pb ages of bastnasite were approximately 7–11% lower than their reference values in the normal analytical mode (without additional gas). Fortunately, the determined systematic age biases in U-Th-Pb dating were significantly reduced (less than 1–2%) with the addition of water vapor within the ablation chamber. This reduction may be attributed to the observed significant suppression of 206Pb/238U and 208Pb/232Th downhole fractionation in both NIST 610 glass and bastnasite by introducing a small quantity of water vapor in the ablation chamber. In addition, the obtained 206Pb/238U and 208Pb/232Th ages of bastnasite K-9, LZ1384, and MAD809 showed great consistency with their corresponding recommended values. The obtained results show that accurate and precise U-Th-Pb ages of bastnasite can be simultaneously obtained by using glass NIST 610 as the primary calibration standard in 193-nm LA-ICP-MS with the water vapor-assisted method. This simple and effective water vapor-assisted non-matrix-matched laser ablation method helps to promote the geological application of bastnasite U-Th-Pb geochronology.

We scrutinized the barrier capability of SiOx, plasma Al2O3 (P-Al2O3)/SiOx, and SiNx/SiOx passivation layers (PLs) on the environmental stabilities of back-channel etched Al-doped InSnZnO (Al-ITZO) TFTs at 85 °C with a relative humidity of 85 % for 30 days. Turn-on voltage (VON) of SiNx/SiOx-passivated TFTs was dramatically shifted to the negative direction and became conductive. Compared to those of SiOx and P-Al2O3/SiOx films, more hydroxyl groups existed at the PL/active interface of SiNx/SiOx-passivated Al-ITZO films. Water vapor transmission rates showed that abnormal behavior was not attributed to barrier capability of PL against the water vapor. When all TFTs were kept at 85 °C for 30 days in an air-drying oven, only the VON of SiNx/SiOx-passivated TFTs shifted negative direction and finally became conductive. Secondary ion mass spectroscopy (SIMS) results revealed that this abnormal behavior originates from the formation of oxygen vacancy due to highly existed hydroxyl group at SiOx/Active interface at an elevated temperature.

The steam reforming and partial oxidation of methane to produce hydrogen under dielectric barrier discharge were conducted in the CH4-O2-N2-H2O reaction system; the effects of H2O/CH4 molar ratio, O2/N2 molar ratio, total gas flow, discharge voltage and discharge frequency on the hydrogen production were investigated and the reaction mechanism was analyzed on the basis of the in-situ diagnostic emission spectroscopy. The results indicate that the conversion of methane and the yield of hydrogenincrease with the increase of H2O/CH4 molar ratio, O2/N2 molar ratio, and discharge voltage, but decrease with the increase of the total gas flow rate and show a volcano-shape trend with the increase of discharge frequency (peaked at 9.8 kHz). Under the conditions with an H2O/CH4 molar ratio of 1.82, O2/N2 molar ratio of 2.1, total flow rate of 136 mL/min, discharge voltage of 18.6 kV and discharge frequency of 9.8 kHz, in particular, the conversion of methane and the yield of hydrogen reach 47.45% and 21.33%, respectively. During the reaction, methane and water vapor may dissociate by the action of high energy electrons to generate CHx·, H·, OH·, O· and other free radicals and hydrogen is then produced through the collision between the free radicals. H· may come from the electronic dissociation of CH4 as well as the dissociation of OH· formed primarily from the water vapor dissociation. The partial oxidation of methane is mainly manifested by the oxidation of CH2· with O·, where O· is produced by the electronic dissociation of O2 as well as the further dissociation of OH·

The effect of ambient humidity on the electrical conductivity of α-Ga2O3 and α-Ga2O3/ε-Ga2O3 is investigated. Polymorphic epitaxial Ga2O3 layers are deposited by the method of chloride vapor-phase epitaxy on sapphire substrates. The contacts are made of Pt and Pt/Ti. It is discovered that the I–V characteristics of the Pt/α-Ga2O3/Pt and Pt/Ti/α-Ga2O3/ε-Ga2O3/Ti/Pt structures have a high sensitivity to atmospheric humidity in the temperature range of 25–100°C. It is found that the effect of water vapor on the I–V characteristics is reversible, and the most significant current changes in the samples are observed at a relative humidity of RH ≥ 60%. As the temperature rises, the effect of atmospheric humidity on the I–V characteristics decreases and disappears at temperatures of T > 100°C. The experimental results obtained are explained within the framework of the Grotthuss mechanism.

The use of optical circular multipass absorption cells (CMPAC) in an open-path configuration enables the sampling free analysis of cylindrical gas flows with high temporal resolution and only minimal disturbances to the sample gas in the pipe. Combined with their robust unibody design, CMPACs are a good option for many applications in atmospheric research and industrial process monitoring. When deployed in an open-path configuration, the effects of inhomogeneities in the gas temperature and composition have to be evaluated to ensure that the resulting measurement error is acceptable for a given application. Such an evaluation needs to consider the deviations caused by spectroscopic effects, e.g., nonlinear effects of temperature variations on the intensity of the spectral line, as well as the interaction of the temperature and concentration field with the characteristic laser beam pattern of the CMPAC. In this work we demonstrate this novel combined evaluation approach for the CMPAC used as part of the tunable diode laser absorption spectroscopy (TDLAS) reference hygrometer in PTB’s dynH2O setup for the characterization of the dynamic response behavior of hygrometers. For this, we measured spatially resolved, 2D temperature and H2O concentration distributions, and combined them with spatially resolved simulated spectra to evaluate the inhomogeneity effects on the line area of the used H2O spectral line at 7299.43 cm−1. Our results indicate that for dynH2O, the deviations caused by the interaction between large concentration heterogeneities and the characteristic sampling of the beam pattern of the CMPAC are three orders of magnitude larger than deviations caused by small temperature heterogeneity induced spectroscopic effects. We also deduce that the assumption that the “path-integrated” H2O concentration derived with the open-path CMPAC setup represents an accurate H2O area average in the flow section covered by the CMPAC in fact shows significant differences of up to 16% and hence does not hold true when large H2O concentration gradients are present.

In this work, we prepared CuCe/Ti catalysts in a dielectric barrier discharge (DBD) reactor and proposed a new method for flue gas mercury oxidation using DBD coupling CuCe/Ti catalyst. Our experiments verified the oxidation efficiency of flue gas Hg0 (ηHg) and clarified the influence of O2 content, NO concentration, SO2 concentration, water vapor content, and discharge voltage on ηHg. The oxidation mechanism of Hg0 in the DBD-CuCe/Ti reactor was also illustrated. The Hg0 oxidation experiment on the simulated flue gas (70 μg/m3 Hg0 + 300 mg/m3 NO + 1000 mg/m3 SO2 + 6%O2) with a flow rate of 1 L/min showed that when the amount of catalyst was 1.25 g and the discharge voltage was 9.5 kV, a ηHg of 93% can be achieved, which indicates that the DBD coupling CuCe/Ti technology is suitable for Hg0 conversion and flue gas mercury removal.

A mid-infrared laser-based sensor is designed and demonstrated for trace detection of benzene at ambient conditions. The sensor is based on a distributed feedback inter-band cascade laser operating near $3.3~\mu \text{m}$ and off-axis cavity-enhanced absorption spectroscopy. A multidimensional linear regression algorithm was applied to enable benzene measurements in the presence of interfering species, such as ethylene, methane and water vapor. A minimum detection limit of 2 ppb was achieved for benzene at an integration time of 6 seconds; the detection limit reduces to 200 ppt in dry conditions. A cross-sensitivity analysis was performed to study the effect of interfering species on benzene measurements. The sensor can be used to detect tiny leaks of benzene in petrochemical facilities and to monitor air quality in residential and industrial areas. The sensor performance was demonstrated by measuring air samples collected from various locations such as a petrol station, parking garage and ambient air.

International audience; We present the design and operation of a specialized Atomic Layer Deposition (ALD) system, dedicated to stable isotopic tracing experiments of oxide film growth, using isotopically labelled water as the oxide reactant. A small chamber volume allows operation with only very small quantities of water vapor, minimising the consumption of the isotopically labelled water. The first results for growth of ZnO and TiO2 using Diethlyzinc (DEZ) and Tetrakis(dimethylamino)titanium (TDMAT) as the zinc and titanium precursors, and unlabelled water as reactant, are presented, to establish the growth conditions for stoichiometric ZnO and TiO2 on silicon. Absolute film compositions and thickness are determined by RBS and NRA as a function of vapor pulse duration, number of ALD cycles and substrate temperature. Physical thickness is determined by ellipsometry. The first results obtained for growth of ZnO using water highly enriched in 18O are also presented.

This work describes plasma destruction of SF6 in a zirconia (ZrO2) packed bed plasma reactor (PBR). Electric signals, equivalent parameters, emission spectra and degradation results have been utilized to evaluate the influence of ZrO2 size on PBR discharge characteristics and SF6 degradation. The results present that the size of ZrO2 has a significant impact on PBR discharge characteristics due to its influence on physical parameters. Moreover, bigger ZrO2 beads packing shows a better performance in SF6 degradation because of longer gas residence time. In addition, the key operating parameters including flowrate, SF6 concentration, oxygen concentration, and water vapor concentration were optimized by response surface methodology (RSM) with Box-Behnken design (BBD). The proposed optimization model shows satisfactory correlation between the predicted and actual results. For energy yield (EY), the mutual effect of flowrate, SF6 concentration and water vapor concentration was significant. For SO2F2 selectivity, the mutual effect of SF6 concentration and water vapor concentration was significant. The optimum SF6 abatement was predicted from RSM as 14.64 g/kWh and 14.42% for EY and SO2F2 selectivity at flowrate of 200 mL/min, SF6 concentration of 3%, oxygen concentration of 0.83% and water vapor concentration of 1.89%.

Thermodynamic analysis of chromium reduction from its oxide in gas phase Н2 – Н2О – СО – СО2 in contact with carbon was performed. Oxidation potential (pO2 ) was determined by two nomograms in the coordinates and taking into account condition normalizations xH2O + xH2 + xCO2+ xCO = 1. In calculations, possible parameters of reduction of chromium from Cr2O3 oxide were determined by ratio of dissociation elasticity of the oxide and oxidation potential of the gas phase. In the СО – СО2 – С system, chromium is reduced at temperature of 1505 K if xCO > 0.9995. At this temperature, Cr2O3 compound is reduced in water gas of the following composition xH2 = 0.0186, xH2O = 0.28·10–4, xCO = 0.9809, xCO2 = 4.86·10–4, for which the oxidation potential is equal to dissociation elasticity of oxide With an increase in hydrogen concentration from 0.0186 to 0.99, oxidation potential of water gas in contact with carbon decreases by four orders of magnitude to This should lead to a significant increase in reduction rate. In such a gaseous atmosphere, it is possible to reduce chromium at temperature of 1230 K. It is technologically simple to obtain reducing water gas and at the lowest cost, for example, by heating water vapor in contact with carbon. It is shown that at temperature of 1500 K water gas is obtained with traces of Н2О and СО2 compounds with parameters xH2 = 0.4999, xCO = 0.4996, Oxidizing potential of such a gas is less than that of chromium oxide, and this difference significantly increases with increasing temperature.

Oxidation-induced degradation of structural materials employed as exhaust valves within internal combustion engines (ICEs) will be a relevant life-limiting mechanism, in addition to creep and mechanical fatigue, due to ever-increasing severity of operating temperatures and pressures. Ni–Cr-based alloys, which form external chromia-based scales at the relevant operating temperatures are being considered as suitable candidate materials. Thermal cycling of these alloys in water vapor-containing atmospheres, such as those present during hydrocarbon fuel combustion within ICEs, can considerably influence their oxidation behavior. In this study, the role of typical alloying additions such as Mn, Si, Al and Ti on the cyclic oxidation behavior of model NiCr–X (X = Mn,Si,Al,Ti) alloys exposed in dry air and air + 10% $$\hbox {H}_{2}\hbox {O}$$ at $$800\, ^{\circ }\hbox {C}$$ and $$950\, ^{\circ }\hbox {C}$$ was investigated. Combined additions of Mn and Si reduced scaling rates compared to binary Ni–22Cr alloys. The presence of water vapor possibly suppressed formation of NiMnCr spinel and thereby the Cr depletion in the alloy. Combined Al and Ti additions mainly resulted in accelerated oxidation kinetics due to the Ti doping of chromia scales. More porous external scales were observed in water vapor leading to a much deeper depth of nitridation in the Ni–22Cr–Al–Ti alloys.

This paper reports a new method for the determination of sludge water content by a multiple headspace extraction gas chromatographic (MHE-GC) method. It is based on measuring the GC signals for the water vapor in a sample vial from the first five headspace extractions, from which the water content in the sludge sample can be extrapolated according to the established calculation equation. The results show that the method has a good repeatability (the relative standard deviation is less than 1%) and accuracy. The maximum relative difference is less than 16% compared to the reference method. The present method is very simple and efficient, and suitable for rapid sample testing in related applications.

In this article, we introduce an analytical method for measuring the quantitative ratio of components in a mixture, using terahertz time-domain spectroscopy (THz-TDS) in the ambient atmosphere. A reconstructed terahertz time-domain signal was used to filter out oscillations caused by water vapor. The reconstructed signal was found to be very similar to a reference sample signal that was measured after purging with dry air or nitrogen. Since the amplitude of the reconstructed signal is not the same as the reference sample signal, the sample absorption coefficient cannot be calculated. In this article, the concentrations of monosaccharide mixtures were measured, based on their refractive index, using THz-TDS in the ambient atmosphere. The results confirmed the feasibility of the concentration analysis method, and we believe this method will benefit analytical chemistry or nondestructive characterization industries in real-world applications.

The results of one-dimensional calculations of the height profiles of nucleated sulfate aerosol particles for the northern mid-latitudes and tropics in winter are presented. Numerical calculations were performed using a three-dimensional model of the transport and transformation of multicomponent gas and aerosol substances in the atmosphere, incorporating photochemistry, nucleation involving neutral molecules and ions, as well as condensation/evaporation and coagulation. It is found that the resulting dynamics of the formation of aerosol particle nuclei is not a simple sum of ion and binary (water vapor/sulfuric acid) nucleation rates. This dynamics is determined by the ratio of critical radii of nucleated particles due to binary and ion nucleation of these substances (rcr_bin and rcr_ion) depending on temperature, relative humidity, and ionization rate. This should be taken into account in modeling the gas and aerosol composition of the atmosphere and comparing calculated and observed data.

It is now well documented that mercury is extremely toxic to both humans and the environment. A close-packed gold nanorod (Au-NR) monolayer was deposited on a titanium-based quartz crystal microbalance (QCM) and its performance for elemental mercury (Hg0) vapor sorption and detection was compared with that of a typical gold thin film (Au CTRL) based QCM device. The developed Au-NR based Hg0 sensor showed an up to ∼1.7 times higher response magnitude than its Au CTRL counterpart when exposed to Hg0 vapor concentrations of 0.21 to 3.26 mg m−3 at two different operating temperatures of 30 and 75 °C. The repeatability of the Au-NR sensor was calculated to be >90% when exposed to a series of sorption/desorption events with a Hg0 vapor concentration of 3.26 mg m−3. The calibration curves (i.e. response magnitudes vs. Hg0 concentrations) of the Au-NR sensor were found to follow the Langmuir extension isotherm, indicating the sensor's suitability to detect relatively low concentrations (ppb levels) of Hg0 vapor. Furthermore, the newly developed Au-NR sensor showed good selectivity (∼97%) toward Hg0 vapor when acetaldehyde co-existed in the gas mix. However, the selectivity of the sensor decreased to 66% and 67% when Hg0 vapor was detected in the presence of ammonia and water vapor, respectively. The selectivity data from the tested sensors were analysed to understand the selectivity performance of Au NRs toward Hg0 vapor in the presence of different gas species in order to implement improvements in developing the sensor for real world applications.

The presence of water vapour in the input gas stream influences the performance of air electrodes of solid oxide cells. In this work, the oxygen transport kinetics were determined by isotopic exchange depth profiling at 350 °C on polycrystalline La0.6Sr0.4Co0.2Fe0.8O3-δ samples in humidified oxygen, comparing the differences in tracer diffusion profile using either 18O2 or H218O as the labelling medium. The apparent surface exchange coefficients of oxygen were determined in each case and used together to estimate the oxygen surface exchange coefficients of molecular oxygen and water. It was found that, in humid conditions, the surface exchange coefficient of molecular oxygen is significantly decreased in comparison to a reference in dry conditions. In addition, the surface exchange coefficient of water is higher than that for molecular oxygen. This is in good agreement with the hypothesis that, water monopolises the active exchange sites at the material surface and thus oxygen from water exchanges faster than the one of molecular oxygen.

High-pressure gasification processes are important for conversion of solid materials into gaseous fuels and other chemicals. Laser absorption diagnostics are an important means to study these processes, but are challenging to implement due to the extreme temperatures and pressures present in the system. Here, we combine broadband high-resolution dual-comb spectroscopy with an advanced spectral absorption database and a new means for baseline-free absorption spectroscopy analysis to enable measurements of temperature and water vapor concentration in the core of an entrained flow gasifier operating at up to 1700 K and 15 bar. The dual-comb spectrometer measures the absorption of water vapor from 6800 to 7150 cm−1 with a point spacing of 0.0067 cm−1. The bandwidth is helpful for resolving the complex, congested absorption fingerprint of water vapor that is used to determine the species concentrations and temperature. We interpret the spectrum with absorption models based on a database measured under carefully controlled high-temperature conditions with the dual-comb spectrometer. The database includes the pressure broadening, shift, and temperature dependence of these parameters for water vapor in argon, which is the gasifier bath gas. Finally, fitting the absorption model to the data is enabled by modified free induction decay analysis, which is an approach for quantitatively obtaining species and temperature information without determining the baseline intensity of the spectrometer. The baseline-free approach is crucial to success in this environment, where there are no non-absorbing regions of the spectrum to anchor the normalization of the laser intensity as in traditional direct absorption spectroscopy. We demonstrate good agreement with temperatures measured on the reactor core via optical pyrometry, and show that water vapor concentrations in the reactor core did not reach the expected system set points during some experiments.