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Results for “SULFURIC ACID”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Vertical distribution of water in the atmosphere of Venus - A simple thermochemical explanation

Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediate vicinity of the surface) or to serious conflicts in the profiles (different IR bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (1) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (2) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor in this wavelength region. A mean total water abundance of 50 + or - 20 parts/million and a near-surface free water vapor abundance of 10 + or - 4 parts/million are derived.

Lewis, John S.↗
DOE OSTI2022

Low permeability polybenzimidazole (PBI) gel membranes for redox flow batteries

Disclosed are redox flow battery membranes, redox flow batteries incorporating the membranes, and methods of forming the membranes. The membranes include a densified polybenzimidazole gel membrane that is capable of incorporating a high liquid content without loss of structure that is formed according to a process that includes in situ hydrolysis of a polyphosphoric acid solvent followed by densification of the gel membrane. The densified membranes are then imbibed with a redox flow battery supporting electrolyte such as sulfuric acid and can operate at very high ionic conductivities of about 50 mS/cm or greater and with low permeability of redox couple ions, e.g. vanadium ions, of about 10−7 cm2/s or less. Redox flow batteries incorporating the membranes can operate at current densities of about 50 mA/cm2 or greater.

Benicewicz, Brian C.↗
NASA NTRS1982

The Venus environment; Proceedings of the International Conference, Palo Alto, CA, November 1-6, 1981

Attention is given to noble gases in planetary atmospheres, the photochemistry of the stratosphere of Venus, the chemistry of metastable species in the Venusian ionosphere, the Venus ionosphere at grazing incidence of solar radiation, disappearing ionospheres on the nightside of Venus, and the observed composition of the ionosphere of Venus. Other investigations considered are concerned with the predicted electrical conductivity between 0 and 80 km in the Venusian atmosphere, sulfuric acid vapor and other cloud-related gases in the Venus atmosphere, the composition and vertical structure of the lower cloud deck on Venus, amorphous sulfur as the ultraviolet absorber on Venus, and polarization studies of the Venus UV contrasts. A description is provided of topics related to temporal variability of ultraviolet cloud features in the Venus stratosphere, zonal mean circulation at the cloud level on Venus, the influence of thermospheric winds on exospheric hydrogen on Venus, and an analysis of Venus gravity data.

Source record↗
NASA NTRS1985

Photochemical modelling of Venus clouds using Pioneer Venus data

In order to understand the evolution of water on Venus, we must know the hydrogen escape flux as a function of the tropospheric water abundance. We have studied the connection between total stratospheric hydrogen and exobase hydrogen available to non-thermal escape processes and examined the details of the photochemical trap for water at the Venus cloud tops. Our immediate goal is to calculate the stratospheric water abundance as a function of the tropospheric water abundance. Photochemical production of H2SO4 acts as a sink for both water and sulfur and is capable of keeping stratospheric abundances low if a proper balance exists between the tropospheric abundances. If production of H2SO4 were the only sink for H2O and SO2, the excess in tropospheric abundance of one over the other would reach the stratosphere, and the functional dependence of stratospheric H2O on tropospheric H2O would be linear near the present state. On Venus, however, sulfuric acid condenses at cloud top temperatures and the resulting aerosols can absorb additional water of hydration. This complicates the water budget, increasing the efficiency of sulfur as a sink for water. We have investigated the balance between tropospheric H2O and SO2 and how delicate the balance is. Our major conclusions from this work are the following: (1) H2O and SO2 are mutually limiting if proper tropospheric balance is maintained; (2) changes in tropospheric abundances on the order of 5 ppm are significant; and (3) changes in mixing rates near the cloud tops can cause dramatic changes in SO2 without causing dramatic changes in H2O.

Mcelroy, Michael B.↗
NASA NTRS1997

Anthropogenic Sulfate, Clouds, and Climate Forcing

This research work is a joint effort between research groups at the Battelle Pacific Northwest Laboratory, Virginia Tech University, Georgia Institute of Technology, Brookhaven National Laboratory, and Texas A&M University. It has been jointly sponsored by the National Aeronautics and Space Administration, the U.S. Department of Energy, and the U.S. Environmental Protection Agency. In this research, a detailed tropospheric aerosol-chemistry model that predicts oxidant concentrations as well as concentrations of sulfur dioxide and sulfate aerosols has been coupled to a general circulation model that distinguishes between cloud water mass and cloud droplet number. The coupled model system has been first validated and then used to estimate the radiative impact of anthropogenic sulfur emissions. Both the direct radiative impact of the aerosols and their indirect impact through their influence on cloud droplet number are represented by distinguishing between sulfuric acid vapor and fresh and aged sulfate aerosols, and by parameterizing cloud droplet nucleation in terms of vertical velocity and the number concentration of aged sulfur aerosols. Natural sulfate aerosols, dust, and carbonaceous and nitrate aerosols and their influence on the radiative impact of anthropogenic sulfate aerosols, through competition as cloud condensation nuclei, will also be simulated. Parallel simulations with and without anthropogenic sulfur emissions are performed for a global domain. The objectives of the research are: To couple a state-of-the-art tropospheric aerosol-chemistry model with a global climate model. To use field and satellite measurements to evaluate the treatment of tropospheric chemistry and aerosol physics in the coupled model. To use the coupled model to simulate the radiative (and ultimately climatic) impacts of anthropogenic sulfur emissions.

Ghan, Steven J.↗
NASA NTRS2007

Aqueous Alteration on Mars

Aqueous alteration is the change in composition of a rock, produced in response to interactions with H2O-bearing ices, liquids, and vapors by chemical weathering. A variety of mineralogical and geochemical indicators for aqueous alteration on Mars have been identified by a combination of surface and orbital robotic missions, telescopic observations, characterization of Martian meteorites, and laboratory and terrestrial analog studies. Mineralogical indicators for aqueous alteration include goethite (lander), jarosite (lander), kieserite (orbiter), gypsum (orbiter) and other Fe-, Mg-, and Ca-sulfates (landers), halides (meteorites, lander), phyllosilicates (orbiter, meteorites), hematite and nanophase iron oxides (telescopic, orbiter, lander), and Fe-, Mg-, and Ca-carbonates (meteorites). Geochemical indicators (landers only) for aqueous alteration include Mg-, Ca-, and Fe-sulfates, halides, and secondary aluminosilicates such as smectite. Based upon these indicators, several styles of aqueous alteration have been suggested on Mars. Acid-sulfate weathering (e.g., formation of jarosite, gypsum, hematite, and goethite), may occur during (1) the oxidative weathering of ultramafic igneous rocks containing sulfides, (2) sulfuric acid weathering of basaltic materials, and (3) acid fog (i.e., vapors rich in H2SO4) weathering of basaltic or basaltic-derived materials. Near-neutral or alkaline alteration occurs when solutions with pH near or above 7 move through basaltic materials and form phases such as phyllosilicates and carbonates. Very low water:rock ratios appear to have been prominent at most of the sites visited by landed missions because there is very little alteration (leaching) of the original basaltic composition (i.e., the alteration is isochemical or in a closed hydrologic system). Most of the aqueous alteration appears to have occurred early in the history of the planet (3 to 4.5 billion years ago); however, minor aqueous alteration may be occurring at the surface even today (e.g., in thin films of water or by acid fog).

Ming, Douglas W.↗
NASA NTRSDate not supplied

Cloud Habitability From Earth To Venus: Science & Technology Considerations

Early Venus and early Earth are believed to have shared many aspects associated with the emergence of an Earth-like biochemistry: surface geochemistry, rock/water interfacing, and geothermal activity. There is significant interest in whether such life – based on water and carbon – could have persisted to the present day in Venus’s sulfuric acid cloud and haze layers, where some liquid water remains. Investigations of this possibility have been connected to understanding observations such as disequilibria in atmospheric sulfur chemistry, strong atmospheric UV absorption, and the controversial recent claim of phosphine detection.

Cloud↗
NASA NTRS1976

Stratospheric aerosols and climatic change

Generated primarily by volcanic explosions, a layer of submicron silicate particles and particles made of concentrated sulfuric acids solution is present in the stratosphere. Flights through the stratosphere may be a future source of stratospheric aerosols, since the effluent from supersonic transports contains sulfurous gases (which will be converted to H2SO4) while the exhaust from Space Shuttles contains tiny aluminum oxide particles. Global heat balance calculations have shown that the stratospheric aerosols have made important contributions to some climatic changes. In the present paper, accurate radiative transfer calculations of the globally-averaged surface temperature (T) are carried out to estimate the sensitivity of the climate to changes in the number of stratospheric aerosols. The results obtained for a specified model atmosphere, including a vertical profile of the aerosols, indicate that the climate is unlikely to be affected by supersonic transports and Space Shuttles, during the next decades.

Baldwin, B.↗
DOE OSTI2022

Stability and Activity of Cobalt Antimonate for Oxygen Reduction in Strong Acid

Guided by computational Pourbaix screening and high-throughput experiments aimed at the development of precious-metal-free fuel cells, we investigate rutile CoSb 2 O 6 as an electrocatalyst for oxygen reduction in 1 M sulfuric acid. Following 4 h of catalyst conditioning at 0.7 V vs RHE, operation at this potential for 20 h yielded an average current density of –0.17 mA cm –2 with corrosion at a rate of 0.04 nm hour –1 that is stoichiometric with catalyst composition. Surface Pourbaix analysis of the (111) surface identified partial H coverage under operating conditions. The Sb active site has an HO* binding free energy of 0.49 eV, which is near the peak of the kinetic 4e – ORR volcano for transition-metal oxides in acidic conditions. Furthermore, the experimental demonstration of operational stability and computational identification of a reaction pathway with favorable energetics place rutile CoSb 2 O 6 among the most promising precious-metal-free electrocatalysts for oxygen reduction in acidic media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1990

Sulfur mass loading of the atmosphere from volcanic eruptions: Calibration of the ice core record on basis of sulfate aerosol deposition in polar regions from the 1982 El Chichon eruption

Major volcanic eruptions disperse large quantities of sulfur compound throughout the Earth's atmosphere. The sulfuric acid aerosols resulting from such eruptions are scavenged by snow within the polar regions and appear in polar ice cores as elevated acidity layers. Glacio-chemical studies of ice cores can, thus, provide a record of past volcanism, as well as the means for understanding the fate of volcanic sulfur in the atmosphere. The primary objectives of this project are to study the chemistry and physical properties of volcanic fallout in a Greenland Ice Core in order to evaluate the impact of the volcanic gases on the atmospheric chemistry and the total atmospheric mass of volcanic aerosols emitted by major volcanic eruptions. We propose to compare the ice core record to other atmospheric records performed during the last 10 years to investigate transport and deposition of volcanic materials.

Sigurdsson, Haraldur↗
NASA NTRSDate not supplied

Evaluation of the Maximum Soluble Water Recovery from Pretreated Urine Brines in Low Earth Orbit

The Urine Processor Assembly (UPA) on the International Space Station recovers water from pretreated urine by thin-film, vacuum compression distillation (VCD). A number of iterative improvements to the distiller assembly (DA) have enabled increases in on-orbit water recovery and improved distillate water quality at on-orbit recoveries up to 87% by volume relative to the volume of pretreated urine. The phosphoric acid-based pretreatment formulation has enabled these higher recoveries on-orbit since May of 2016. Application of simple empirical chemistry models have allowed water recovery of sulfuric-acid pretreated urine from the Russian Orbiting segment to be distilled with phosphoric acid pretreated urine from the U.S. Orbiting Segment. Returned liquid brine from brine filters in the UPA brine loop have enabled empirical measurement of gypsum solubility as a function of recovery, conductivity, or mass density in the real brines of ISS. Calculations of maximum soluble recovery, MSR, are based on preventing the precipitation of gypsum, which is the first mineral to precipitate for both types of pretreated urine. A statistical urine model of urine composition provides an estimate of worst-case urine from a crew of three during one year of operations on ISS. The MSR is defined based on the worst-case concentrations of urinary calcium and urinary sulfate that are pretreated, pooled, and distilled. The potential to increase water recoveries above 87% without gypsum precipitation are evaluated. The potential benefits and costs of the addition of a conductivity sensor or a Coriolis mass flow meter to the brine loop are evaluated.

Dean L Muirhead↗
NASA NTRS1977

Knowledge of the systems H2O-SO3-N2O3. Report 1: The system H2SO4-H2O-N2O3

The amount of N2O3 being absorbed in 50-100% H2SO4 at 19, 60, and 95 C is directly proportional to the acid concentration and inversely proportional to the temperature. NO+ formation according to the above-formulated equation occurs only at H2SO4 concentrations greater than 52%. Absorption in highly concentrated sulfuric acid results in the formation of crystalline NOHSO4.

Stopperka, K.↗
NASA NTRS1980

Photochemistry of SO2 in Venus' upper cloud layers

The photochemical and transport processes that occur in the Venusian atmosphere in and above the upper cloud region are characterized with attention to the correlation with the Pioneer Venus spectrometer results for the cloud top SO2 distribution. The model uses upward-flowing SO2 and H2O to replace the sulfur and hydrogen lost through the lower boundary by the settling of sulfuric acid aerosols. Oxygen for the oxidation of SO2 to SO3 prior to hydration to H2SO4 is supplied by the photolysis of CO2. A model with SO2 as the major sulfur-bearing gas is consistent with the Pioneer data.

Winick, J. R.↗
NASA NTRS1994

Radiative Forcing of the Stratosphere by SO(sub 2) Gas, Silicate Ash, and H(sub 2)SO(sub 4) Aerosols Shortly after the 1982 Eruptions of El Chichon

The 1982 eruptions of El Chichon Volcano injected large quantities of sulfur dioxide gas and silicate ash into the stratosphere. Several studies have shown that the long-lived sulfuric acid aerosols derived from these volcanic effluents produced measurable changes in the radiative heating rates and the global circulation. The radiative and dynamical perturbations associated with the short-lived, but more strongly absorbing sulfur dioxide and ash clouds have received much less attention. We therefore used an atmospheric radiative transfer model and observations collected by satellites, aircraft, and ground based observers to estimate the amplitudes of the stratospheric radiative heating rate perturbations produced by each of these components during the first few weeks after the El Chichon eruption. One week after the April 4, 1982 eruption, net radiative heating rate perturbations exceeding 20 Kelvin per day were found at altitudes near 26 km.

El Chichon↗
NASA NTRS1994

Composition and freezing of aqueous H2SO4/HNO3 solutions under polar stratospheric conditions

The results of laboratory investigations of the freezing behavior of aqueous acid solutions indicate that in the stratosphere H2SO/H2O aerosol droplets would not freeze at temperatures above the ice frost point in the absence of HNO3; however, in the presence of typical levels of HNO3 liquid sulfuric acid aerosols take up significant amounts of HNO3 and H2O vapors and freeze much more readily. This is a consequence of the very rapid change in composition of the liquid droplets as the temperature drops to within two to three degrees of the equilibrium temperature at which HNO3 and H2O vapors would co-condense to form a liquid solution. In the high latitude stratosphere this HNO3/H2O 'dew point' is typically around 192-194 K at 100 mbar.

Beyer, K. D.↗
NASA NTRS2015

Volcanic Aerosol Radiative Properties

Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

Stratosphere↗
DOE OSTI2024

Structural, Electrical, and Optical Properties of Single-Walled Carbon Nanotubes Synthesized through Floating Catalyst Chemical Vapor Deposition

Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm) of mixed gases (Ar and H 2 ). SWCNT thin films with different thicknesses can be prepared by controlling the collection time of the SWCNTs on membrane filters. Transmission electron microscopy (TEM) showed that the SWCNTs formed bundles and that they had an average diameter of 1.46 nm. The Raman spectra of the SWCNT films suggested that the synthesized SWCNTs were very well crystallized. Although the electrical properties of SWCNTs have been widely studied so far, the Hall effect of SWCNTs has not been fully studied to explore the electrical characteristics of SWCNT thin films. In this research, Hall effect measurements have been performed to investigate the important electrical characteristics of SWCNTs, such as their carrier mobility, carrier density, Hall coefficient, conductivity, and sheet resistance. The samples with transmittance between 95 and 43% showed a high carrier density of 10 21– 10 23 cm –3 . The SWCNTs were also treated using Brønsted acids (HCl, HNO 3 , H 2 SO 4 ) to enhance their electrical properties. After the acid treatments, the samples maintained their p-type nature. The carrier mobility and conductivity increased, and the sheet resistance decreased for all treated samples. The highest mobility of 1.5 cm 2 /Vs was obtained with the sulfuric acid treatment at 80 °C, while the highest conductivity (30,720 S/m) and lowest sheet resistance (43 ohm/square) were achieved with the nitric acid treatment at room temperature. Different functional groups were identified in our synthesized SWCNTs before and after the acid treatments using Fourier-Transform Infrared Spectroscopy (FTIR).

36 MATERIALS SCIENCE↗
NASA NTRS1995

Prototype development and test results of a continuous ambient air monitoring system for hydrazine at the 10 ppb level

A Hydrazine Vapor Area Monitor (HVAM) system is currently being field tested as a detector for the presence of hydrazine in ambient air. The MDA/Polymetron Hydrazine Analyzer has been incorporated within the HVAM system as the core detector. This analyzer is a three-electrode liquid analyzer typically used in boiler feed water applications. The HVAM system incorporates a dual-phase sample collection/transport method which simultaneously pulls ambient air samples containing hydrazine and a very dilute sulfuric acid solution (0.0001 M) down a length of 1/4 inch outside diameter (OD) tubing from a remote site to the analyzer. The hydrazine-laden dilute acid stream is separated from the air and the pH is adjusted by addition of a dilute caustic solution to a pH greater than 10.2 prior to analysis. Both the dilute acid and caustic used by the HVAM are continuously generated during system operation on an "as needed" basis by mixing a metered amount of concentrated acid/base with dilution water. All of the waste water generated by the analyzer is purified for reuse by Barnstead ion-exchange cartridges so that the entire system minimizes the generation of waste materials. The pumping of all liquid streams and mixing of the caustic solution and dilution water with the incoming sample are done by a single pump motor fitted with the appropriate mix of peristaltic pump heads. The signal to noise (S/N) ratio of the analyzer has been enhanced by adding a stirrer in the MDA liquid cell to provide mixing normally generated by the high liquid flow rate designed by the manufacturer. An onboard microprocessor continuously monitors liquid levels, sample vacuum, and liquid leak sensors, as well as handles communications and other system functions (such as shut down should system malfunctions or errors occur). The overall system response of the HVAM can be automatically checked at regular intervals by measuring the analyzer response to a metered amount of calibration standard injected into the dilute acid stream. The HVAM system provides two measurement ranges (threshold limit value (TLV): 10 to 1000 parts per billion (ppb)/LEAK: 100 ppb to 10 parts per million (ppm)). The LEAK range is created by dilution of the sulfuric acid/hydrazine liquid sample with pure water. This dual range capability permits the analyzer to quantify ambient air samples whose hydrazine concentrations range from 10 ppb to as high as 10 ppm. The laboratory and field prototypes have demonstrated total system response times on the order of 10 to 12 minutes for samples ranging from 10 to 900 ppb in the lLV mode and is greater than 2 minutes for samples ranging from 100 to 1300 ppb in the LEAK mode. Service intervals of over 3 months have been demonstrated for continuous 24 hour/day, 7 day/week usage. The HVAM is made up of a purged cabinet that contains power supplies, RS422 signal transmission capabilities, a UPS, an on-site warning system, and a Line Replaceable Unit (LRU). The LRU includes all of the liquid flow system, the analyzer, the control/data system microprocessor and assorted flow and liquid-level sensors. The LRU is mounted on a track slide system so it can be serviced inplace or totally removed and quickly exchanged with another calibrated unit, thus minimizing analyzer downtime. Once an LRU is removed from an analyzer enclosure, it can be brought to a laboratory facility for complete calibration and periodic maintenance.

Meneghelli, Barry↗