Content Of H2O Research Articles

Low‐P melting of metapelitic rocks and the role of H2O: Insights from phase equilibria modelling

AbstractWater‐fluxed melting has long been thought to have a minor influence on the thermal and chemical structure of the crust. We report here on amphibolite facies metasedimentary rocks from the 490–450 Ma Famatinian Orogen, in northwest Argentina, that have undergone water‐fluxed incongruent biotite melting at relatively low temperature, which have produced and lost a significant volume of melt. The protoliths consist of the turbiditic Puncoviscana Formation (Neoproterozoic to Early Cambrian). The field area exhibits a condensed metamorphic field gradient, from greenschist to amphibolite facies suprasolidus conditions, recording a low pressure almost isobaric path, reaching peak conditions estimated at 700°C at 4 kbar. Thermodynamic modelling in the MnNCKFMASHTO system is applied to investigate melting at such low pressure as a function of water content. Calculations using a typical turbidite composition show how small amounts of added free H2O may increase significantly the melt fraction with little or no change in either the melt or residual phase compositions. They indicate negligible difference in normative An–Ab–Or proportions and ferromagnesian contents between melts derived by dehydration and water‐fluxed melts. The same is true for the content of H2O dissolved in melts, which remains constant and the melt produced is granitic whether or not aqueous fluids are present. Thus, neither the residue nor the melt composition are indicators of the presence of aqueous fluids during anatexis. Recognizing the impact of small additions of H2O to an anatectic terrane may therefore be difficult. The most significant change related to water‐fluxing is the relative proportions of minerals and melt fraction, rather than the actual mineral assemblage. The modal proportion of feldspar decreased while those of cordierite and biotite increased in the residual assemblages, as <5 mol.% of free H2O was added. The impact of this addition is to more than double the proportion of water‐undersaturated melt to 25–30 mol.%. We have also developed a simple way to estimate how much melt a residual rock has lost, if the compositional trends of the protoliths are known. In summary, we find that even though the addition of small amounts of free H2O impacts significantly on rock fertility, there is little obvious record in the field. The combined application of careful petrological investigation and thermodynamic modelling is the key to identify the influence of aqueous fluids, and exploit systems that became open not only to fluid influx but also to the extraction of melt.

The effect of CO2 on the solubility of aqueous chloride fluid in dacite, phonolite, and rhyolite melts

The solubility of H2O–CO2–Cl-containing fluids of various concentrations (0, 3, 10, and 23 wt % of HCl and from 0 to ~8–15 wt % of CO2) in dacite, phonolite, and rhyolite melts at 1000°C and 200 MPa was studied in experiments. It was shown that the Cl concentration in the melt increased substantially from rhyolite to phonolite and dacite (up to 0.25, 0.85, and 1.2 wt %, respectively). The introduction of CO2 into the system resulted in an increase in the Cl content in the melt composition by 20–25%. One may suppose that Cl reactivity in a fluid increases in the presence of CO2 to cause growth of the Cl content in the melt. The introduction of CO2 into the system considerably affects the content of H2O in aluminosilicate melts as well. Thus, the addition of CO2 decreases the H2O content in the melt by ~0.5–1.0 wt %. The decrease in the H2O content in an aluminosilicate melt is probably caused by fluid dilution with CO2 resulting in a decrease in the H2O mole fraction and fugacity in the fluid.

ANALYSIS OF THE PROCESS OF WATER VAPOR CONDENSATION WITHIN GAS ATMOSPHERES AND COMBUSTION PRODUCTS

Water vapor is the most important working medium by the processes of energy generation and conversion. The H2O content in gases and gas mixtures serves as a standard of their desiccation by technological processes. The presence of vapor in the air-oxidizer provides a reduction of harmful substances formation by combustion. The values characterizing the saturation state: the dew point tdew and the wet bulb thermometer twb temperature are used to evaluate an approximation degree of the wet gas system (any air, gas mixtures or combustion products) to the condensation state. The values of these parameters have been determined for moist air in dependence on the basic temperature and the relative humidity of an air. The lower are the temperature values tdew, twb, the wider is the region of H2O existence in the vapor phase. The EUROSTAT’s gas fuels list includes the natural gas (NG), blast furnace gas (BFG), coke oven gas (COG). Calculations of dew point values of the combustion products for the gas fuels: NG, COG, BFG has been carried out in dependence on the characteristics of the combustion air: the oxidizer excess factor l, the temperature ta and the relative humidity ja. The dew point tdew values have been found under standard conditions for the combustion products of the listed gas fuels, presented by stoichiometric (l = 1.0) mixtures with dry air: pure methane, NG, COG, BFG. The tdew values make — respectively 59.3; 58.5; 11.1; 61.5. In the case of saturated air as an oxidizer at temperature of 25 °C, the dew point for the combustion products of the listed fuels makes the folloving values: 62.0; 61.5; 25.6; 64.0 °C respectively. The fractions of H2O in the vapor and liquid phases of natural gas combustion products are determined as a function of temperature by condition that the 100 % content of H2O in from of vapor state (without water) corresponds to the saturation temperature (or dew point).This temperature has value of about 60°C for combustion products under stoichiometric air/gas ratio. Bibl. 31, Fig. 10, Tab. 3.

Variations in gas components and total pressure in stem and root disc wood of conifer species

The content of CO2 and H2O in vacuum-extracted tree-ring wood of stem and root discs of certain conifer species was measured. Annual distributions of these gas components were found to exhibit cyclic behavior. Moreover, distinct cyclicity was also revealed in interannual variations of the total pressure of the vacuum-extracted tree-ring gas samples. It may be safely assumed that diffusion of stem CO2 into the atmosphere will show the same periodic variability. Two hypotheses about the origin of the cyclicity in the treering CO2 distributions are examined.

Application of the Synthesized Activated Carbon-4A Zeolite Composite from Elutrilithe in Wastewater Treatment.

The quartz abundant elutrilithe with several other elements from Pan zhihua, was taken as the main material to synthesize activated carbon-4A zeolite composite by hydrothermal crystallization after alkali fusion at 750 °C for 1 h under a flowing N2 atmosphere. Then the effect of alkali content and molar ratio of H2O versus Na2O on product was investigated, respectively. Finally, the activated carbon-4A zeolite composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry-differential scanning calorimetry (TG-DSC). The results showed that the crystallization product was activated carbon-4A zeolite composite with complete crystal form and the average particle size was about 1 μm. Moreover, the composite materials had well adsorption capacities to water, hexane and metal ions such as Cu2+, Ni2+, Zn2+ and Pb2+ analyzing by inductively coupled plasma atomic emission spectrometry (ICP).

Non-isothermal kinetic study of bituminous coal and lignite conversion in air and in argon/air mixtures

The exact characteristics of the pyrolysis and combustion kinetics for Siberian bituminous coals and lignites were studied for better understanding of the fuel conversion processes. The bituminous coal samples of Kuznetskiy deposit and lignite samples of Kansko-Achinsk deposit were investigated in argon and in argon/air gas mixtures. The pyrolysis and oxidation experiments were executed at four heating rates (5, 10, 20 and 30°C/min) under TG/DSC analyses coupled with mass-spectrometry. The activation energy for bituminous coal and lignite samples was decreased with conversion degree during oxidation. The combustion products of highest oxidation degree (CO2 and H2O) were dominated in gases released in oxidizing atmosphere. Contrariwise, activation energy was increased during pyrolysis with high content of CO, CO2, H2O, CH4, and H2 in released gases.The two isoconversional models were applied to determine the activation energy dependence on fuel samples conversion: Starink model and Ozawa iterative procedure. The mean arithmetic values of the resulted activation energy were 60kJ/mole and 400kJ/mole for oxidation and pyrolysis processes, respectively. These values are in good agreement with the results, presented previously for the other coals. The Starink model showed higher accuracy and lower activation energy values. The heating rate by non-isothermal oxidation and pyrolysis had the significant influence on the reaction rate because of evolution processes of the reactive surface and pore structure of the coal samples.

High-pressure behavior of HEU-type zeolites: X-ray diffraction study of clinoptilolite-Na

Clinoptilolite-Na, Na2.55Ca1.67K0.37(H2O)21.5[Al6.21Si29.79O72], with the space group C2/m, a = 17.6229(4), b = 17.9957(3), c = 7.39625(15) Å, β = 116.353(3)°, V = 2101.85(7) Å3, and Z = 1 has been studied by single-crystal X-ray diffraction method in normal conditions as well as under compression in penetrating (water-containing) and non-penetrating (paraffin) media. When compressing in water medium, clinoptilolite is subjected to the additional hydration at the starting stage unlike the structurally similar heulandite with persistent increasing the content of H2O over the wide pressure range. This occurs owing to the additional population of partially vacant positions. With further increasing the pressure, H2O molecules are redistributed in the extraframework subsystem saving the total number. Both literature and our data on compression of zeolites of the isomorphous heulandite-clinoptilolite series in non-penetrating media evidence that the compressibility along the coordinate directions noticeably differs from sample to sample including differences in the direction of the largest compression. This is evidently associated with variations in the zeolite composition.

KARAKTERISASI TANAH LEMPUNG GAMBUT KALIMANTAN SELATAN SEBAGAI BAHAN BAKU PEMBUATAN MEMBRANE SUPPORT

Inorganic materials (such as silica and alumina) is a material that is very important and the most desirable in the field of membrane technology. This is due to the physical characteristics and permeation properties owned by the two materials is much better when compared to other polymerbased material. Alumina, for example, this material mostly can be found in clay, and the price is much cheaper as well as easy to find if compared to silica material. The use of peat clay as raw material to produce alumina as membranes support from natural materials would save production costs. This material is also easy to find in South Kalimantan especially around the wetland areas. The aim of this study is to characterize the peat clay as raw material to fabricate membranes module (membranes support). The method is by drying the clay material in uniform particle size (monosize). The raw material powder is then mixed with the organic additives. This organic content provide the hydrophilicity and prorosity agent. Furthermore, it then was calcined and characterized to determine the functional group of the material weather it is more hydrophilicity and porosity. The result shows that the addition of H2O and starch content of functional groups affect the content of the Si-O-Si and Si-O-Al groups on clay material. The content of Si-O-Si and Si-O-Al decreases if content of H2O and starch is higher. It is shown that the streching the Si-OH groups that are more hydrophilic transform into Si-O-Si and Si-O-Al groups that are more hydrophobic. Therefore, the calcined material will be more hydrophobic and more porous.

LES-CMC simulations of a turbulent hydrogen jet in oxy-combustion regimes

The paper presents the results of numerical simulations of a combustion process for a pure hydrogen jet in the atmosphere of oxygen and water vapor. The research was performed using Large Eddy Simulations (LES) combined with Conditional Moment Closure (CMC) model and included the analysis of auto- and forced (spark) ignition, flame development and flame propagation. In the configuration analyzed in the study, the fuel jet issues into a hot co-flowing oxidizer stream (O2/H2O). We considered two different co-flow temperatures, 1030 K and 1045 K, and various oxidizer compositions with H2O mass fraction over the range of Y H2O=0.1−0.9 and with YO2=1−YH2O. The analyses were carried out with assuming constant 30% excess of the mass flow rate of oxygen relative to the hydrogen. It was found that: (i) the auto-ignition process occurs only for a low content of H2O in the co-flow (YH2O≤0.5), (ii) and is additionally determined by its temperature; (iii) depending on O2/H2O proportion the flames stabilizes as attached or lifted. By alteration of YH2O in the oxidizer, the maximum flame temperature and the lift-off height (LH) can be changed in the range of 1500K→3000K and LH=0→11 jet diameters, respectively.

Dynamics of the content of H2O, Na, K, Ca and Mg in the eggs of bream, Abramis brama L. in natural conditions and under stress

Objective: To study the dynamics of H2O, Na, K, Ca and Mg content in the oocytes of bream, Abramis brama observed in prespawning period on breeding ground and in reply to catching, transportation and subsequent remaining of spawners in a cage. Methods: For research on the dynamics of H2O and cations content in the oocytes of bream females, Abramis brama in the course of eggs transition from maturity Stage IV to Stage V, fishes were caught from breeding ground in the coastal zone of the Volga Reach of the Rybinsk reservoir at the Vereteya Station. For studying the influence of stress, the bream (76 individuals) were caught from breeding ground by hauling the seine during 15 min. Capture, sorting and transportation for 3 h to the ponds were the stress factors. Samples of oocytes from 6-8 fishes were taken immediately after capturing, then two more were taken during transportation. Later fishes were removed from the cage in certain time intervals. Concentration of Na and K in the dissolved samples of oocytes was measured by the spectrometer (Flapho-4, Carl Zeiss, Iena, Germany) and content of Ca and Mg was measured by atomic-absorption spectrometer-1 (the same producer). Results: In natural conditions before spawning in the course of maturation of oocytes from maturity Stage IV to V, H2O content in the ovicells of bream has increased by 3.3% and concentration of Na, K, Ca and Mg has decreased by 24.9%, 38.1%, 56.2% and 65.7%, accordingly. Stress caused by capturing, transportation and the subsequent remaining of bream spawners in a cage did not change parameters of water-salt exchange of the oocytes. Conclusions: In natural conditions before spawning, the maturation of oocytes of bream from maturity Stage IV to V take place. Stress caused by capturing, transportation and the subsequent remaining of bream spawners in a cage prevents the transition of eggs from maturity Stage IV to V. It is suggested that in order to develop optimal technique stimulating oocytes maturation and the process of ovulation in industrial conditions, study of these reactions of spawners of one or another species in natural environment is preferentially conducted. Conditions of incubation and combination of hormonal preparations selected on the basis of these

Effect of the Acidity of HZSM-5 Zeolite and the Binder in the DME Transformation to Olefins

The effect of the catalyst properties, particularly matrix acidity and its properties, has been studied in the transformation of dimethyl ether (DME) to light olefins. The catalysts used were prepared by agglomerating HZSM-5 zeolite with a different SiO2/Al2O3 ratio (30, 80, and 280) with bentonite or boehmite as a binder and α-Al2O3 as inert filler. The experiments have been carried out in a fixed bed reactor, under the following reaction conditions: 350 and 400 °C; space-time, 0.4 gzeolite h molC–1; time on stream, 4 h. The lower content of H2O in the reaction medium compared to that of the methanol transformation explains the advancement on the reaction scheme (with the transformation of olefins in other hydrocarbons) and more rapid deactivation by coke, which advises the use of catalysts with lower acidity and shaping the catalyst particles with a porous structure that attenuates the blocking of acid sites. The acidic properties of the zeolite have a significant impact on the DME conversion, yield and...

Characterization and performance in preferential oxidation of CO of CuO–CeO2 catalysts synthesized using polymethyl metacrylate (PMMA) as template

CuO–CeO2 catalysts have been synthesized using polymethyl metacrylate (PMMA) microspheres as template and copper and cerium acetates as precursors, leading to a homogeneous porous framework of nanocrystalline materials with uniform pore size distribution and well dispersed copper species between 1 and 9 wt.%. The catalysts have been characterized by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), High-resolution Transmission Electron Microscopy (HRTEM), Raman spectroscopy, adsorption-desorption of N2 at −196 °C, thermoprogrammed reduction with H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS). CuO–CeO2 catalysts have been evaluated in the CO-PROX reaction, reaching high conversion values (>95%) at 115 °C for all samples. Moreover, these catalysts have been tested under high content of CO2 and H2O in the feed, simulating a CO-PROX unit, obtaining conversion efficiency values higher than 90% at 115 °C, which indicates a high tolerance of the catalysts in both CO2 and H2O gases.

Reduction Kinetics of Fine Iron Ore Powder in Mixtures of H2-N2 and H2-H2O-N2 of Fluidized Bed

Reduction kinetics of fine iron ore powder in different gas mixtures were investigated in high-temperature fluidized bed at a scale of kilograms. Influence of processing parameters, such as particle size, gas flow velocity, height of charge, temperature, compositions of gas mixture, and percentage of inert components, on reduction kinetics was experimentally determined under the condition of fluidization. The equations for calculating instantaneous and average oxidation rates were deduced. It was found that an increasing H2O percentage in the gas mixture could obviously decrease the reduction rate because the equilibrium partial pressure of H2 decreased with increasing content of H2O in the gas mixture and then the driving force of reduction reaction was reduced. When the H2 content was high, the apparent reaction rate was so rapid when the average size of iron ore fines was less than 1 mm that the reaction temperature can be as low as 750 °C; when the average size of iron ore fines was more than 1 mm, a high reaction temperature of 800 °C was required. In addition, it was also found that the content of H2O should be less than 10% for efficient reduction.

Study on the influence mechanism of trace H<sub>2</sub>O on SF<sub>6</sub> thermal decomposition characteristic components

To explore the influence mechanism of trace H2O on SF6 decomposition characteristics under partial thermal fault and establish the foundation of using SF6 thermal decomposition principle to diagnose the thermal fault of SF6 electrical equipment, a series of artificial thermal fault decomposition experiments with different H2O concentrations were conducted on the designed SF6 thermal decomposition experimental system. A trace water injector was used to control the content of trace H2O accurately and gas chromatograph, chromatography-mass spectrometry as well as Fourier transform infrared spectroscopy were used to measure decomposed components. Finally, the thermal decomposition characteristic under 340 ° was achieved. The analysis results indicate no matter how much H2O content is, SF6 can decomposes into many kinds of decomposition characteristics, such as CO2, SOF2, SO2, SOF4, SO2F2, H2S, HF. The concentrations of all these decomposition characteristics increase with the time extended, but change differently with the increase of H2O content, because H2O plays different role in the formation process of each decomposition characteristic components. The variation of H2O content not only affects the production of the decomposition characteristic components, but also makes SO2 and HF gradually evolved into the main characteristic components of SF6 thermal decomposition. In addition, the higher the H2O content is, the stronger the promoting effect on SO2 and HF is.

Effect of Ge content on the synthesis and structure of Ge-ITQ-13 zeolite

A series of ge-itq-13 zeolites with si/ge molar ratio from 10 to 40 were synthesized and characterized with xrd, ir, fe-sem, and si-29 mas nmr techniques. the results verified that almost of all the ge atoms in the synthesis gel was incorporated into the itq-13 framework. ge plays a structure-directing role in the crystallization process as a result of facilitating formation of double four-membered ring structural units. as a consequence, itq-13 zeolites can be synthesized with the synthesis gel having a high content of h2o in the presence of ge. si-29 mas nmr spectroscopy shows that the incorporated ge atoms are not randomly distributed in the ge-itq-13 framework but selectively occupy certain lattice sites.

Photochemical removal of NO and SO2 from flue gas using UV irradiation

ABSTRACTThe simultaneous oxidation and removal efficiencies of SO2 and NO from simulated coal‐fired flue gas by UV irradiation were investigated experimentally. The influencing factors, such as the reaction temperature, the content of O2, H2O, SO2, and NO, on the removal of SO2 and NO were studied. The results indicated that NO had positive effect on the removal of SO2. Compared with the NO‐free case, the removal efficiency of SO2 was improved from 8% to 55% in the presence of 250 ppm NO. When the NO concentration rose from 250 to 700 ppm, the SO2 removal efficiency further increased from 55% to 64%. The increasing of reaction temperature enhanced the removal efficiencies of SO2 and NO, which increased by 28% and 36%, respectively, with the reaction temperature rising from 270 to 350 °C. It was found that O2 was conducive to the photochemical oxidization due to the generation of free radicals. As the O2 content increased from 0% to 8%, the removal efficiencies of NO and SO2 reached 40% and 55%, respectively. The positive effect of H2O on the simultaneous removal of NO and SO2 was also observed. The optimal conditions (250 ppm NO, 100 ppm SO2, 8% O2, 5% H2O, and reaction temperature 350 °C) were determined, and the removal efficiencies of SO2 and NO were 55% and 40%, respectively. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.

Hydrogen permeability and chemical stability of Ni–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ membrane in concentrated H2O and CO2

Ni–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (Ni–BZCYYb) membrane shows improved and stable performance in dry H2 and CO2 (Fang et al., ACS Appl. Mater. Interfaces 6 (2014) 725–730). However, the stream from steam methane reforming contains high contents of H2O, CO2, and CO, which poses crueler challenges to the chemical stability of Ni–BZCYYb membrane than dry H2 and CO2. In this work, we tested the Ni–BZCYYb membrane in wet H2 and CO2 which generated high content of H2O and CO due to reverse water gas shift (RWGS) reaction at high temperature. High content of H2O improves the proton conductivity of BZCYYb and hydrogen transport through the membrane. On the other hand, H2 content reduction and decomposition of BZCYYb promoted by high content of H2O lead to performance degradation. The steady-state hydrogen flux may increase or decrease depending on the balance among these effects. Besides, CO-induced Ni corrosion was found in both surface and bulk due to metal dusting. In general, Ni–BZCYYb membrane still displayed much better performance stability in wet H2 and CO2 than Ni–BaCe0.8Y0.2O3−δ and Ni–BaZr0.1Ce0.7Y0.2O3−δ composites, making it a candidate material system for further studies aimed at membrane processing of hydrocarbons.

Water content in minerals of mantle xenoliths from the Udachnaya pipe kimberlites (Yakutia)

Distribution of water among the main rock-forming nominally anhydrous minerals of mantle xenoliths of peridotitic and eclogitic parageneses from the Udachnaya kimberlite pipe, Yakutia, has been studied by IR spectroscopy. The spectra of all minerals exhibit vibrations attributed to hydroxyl structural defects. The content of H2O (ppm) in minerals of peridotites is as follows: 23–75 in olivine, 52–317 in orthopyroxene, 29–126 in clinopyroxene, and 0–95 in garnet. In eclogites, garnet contains up to 833ppm H2O, and clinopyroxene, up to 1898ppm (~0.19wt.%). The obtained data and the results of previous studies of minerals of mantle xenoliths show wide variations in H2O contents both within different kimberlite provinces and within the Udachnaya kimberlite pipe. Judging from the volume ratios of mineral phases in the studied xenoliths, the water content varies over narrow ranges of values, 38–126ppm. At the same time, the water content in the studied eclogite xenoliths is much higher and varies widely, 391–1112ppm.

Formation of Malachite Rusts on Bronze in Environments with Excess of CO2

The formation of rusts consisted mainly of malachite on bronze was simulated with a new process, by which the corrosion test of bronze samples was performed in controllable environ- ments with excess of CO2 contents, water vapor and chlorine ions. The chemical composition, mi- crostructure and phase constituents of the corrosion products were characterized by means of opti- cal microscopy, scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Raman microscopy. The results revealed that the characteristics of corrosion products were related with the content of CO2 and H2O in the environment. The growth mechanism of the rusts in these environments was discussed and the suggestions for preservation of the ancient bronzes were proposed.

Generation of reactive oxygen species in simulated flue gas under vacuum ultraviolet radiation

Reactive oxygen species, which are responsible for the removal of SO2 and NOx, generated under vacuum ultraviolet (VUV) radiation in simulated flue gas (N2/O2/CO2/H2O (v/v)=74%/8%/10%/8% without SO2 and NOx) were determined. Under typical experimental conditions, 26.5μmol ozone, 1.7μmol hydrogen peroxide, and 0.3μmol hydroxyl radical were detected. The effects of H2O and O2 contents, gas flow rate, and lamp power on the generation of reactive oxygen species were investigated. Results show that H2O and O2 contents as well as flow rate significantly affected O3 and H2O2 production. High content of H2O resulted in a decrease in O3 production but an increase in H2O2 production, whereas O2 content demonstrated the opposite effects owing to its varying absorption across sections. O3 and H2O2 production increased with increasing flow rate, while their concentrations changed slightly. High-power lamps had a negligible effect on O3 and H2O2 production, but O3 production decreased and H2O2 production increased under extremely low-power lamp radiation. In addition, the variations of the production of reactive oxygen species were also correlated with the oxidation processes of VUV-induced simultaneous desulfurization and denitrification.