Intensity of the self-broadened fundamental band of hydrogen chloride
Hydrogen chloride self broadened fundamental vibration rotation band intensity variation with pressure investigated by absorption spectroscopy analysis
Burnett, S. C.↗
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Three dimensional simulation of hydrogen chloride and hydrogen fluoride during the Airborne Arctic Stratospheric Expedition
Simulations of the evolution of stratospheric distributions of hydrogen chloride (HCl) and hydrogen fluoride (HF) have been carried out for the period of the Airborne Arctic Stratospheric Expedition (AASE) with a three-dimensional chemistry-transport model. Simulations were performed assuming only homogeneous gas phase chemistry for HF and both homogeneous gas phase and heterogeneous chemistry for HCl. Results show heterogeneous loss of HCl is needed to provide agreement with infrared column measurements. Estimates of the impact of heterogeneous loss on the global HCl distribution are obtained from the model. Reductions of HCl due to heterogeneous loss are calculated to be localized to regions of high vorticity, even after more than a month of integration.
Kaye, Jack A.↗
Ground cloud hydrogen chloride measurements from three Titan launches at the Kennedy Space Center during 1978 and 1979
Total hydrogen chloride and gaseous hydrogen chloride concentrations were measured in the exhaust cloud produced at three Titan 3 launches at the Kennedy Space Center in March 1978, December 1978, and November 1979 to determine the degree of hydrogen chloride partitioning in a solid rocket exhaust cloud between gaseous hydrogen chloride and hydrochloric acid aerosol as a function of ambient relative humidity. Moderately low relative humidity conditions were present during a daytime launch on Mar 25, 1978, and high relative humidity conditions were present during a nighttime launch on December 13, 1978. Gaseous hydrogen chloride concentrations and meteorological data, as a function of time after launch, are presented. Hydrogen chloride is present in both the gaseous and aerosol phase in the exhaust cloud. Total HCl concentrations ranged from 18 parts per million by volume (ppm) several minutes after launch down to 1 ppm after the cloud stabilization period, depending on the meteorological conditions. Gaseous HCl concentrations ranged from 2 to 3 ppm several minutes after launch to less than 1 ppm after cloud stabilization. These measured concentrations indicated significant HCl aerosol formation.
Seabacher, D. I.↗
Evaluation of a hydrogen chloride detector for environmental monitoring
The paper describes a hydrogen chloride detector designed to monitor concentrations of hydrogen chloride gas in the ambient environment. The detector was developed for NASA for use in launch vehicle effluent monitoring. The detector operates on chemiluminescence principles with a lower detection limit of less than 5 x 10 to the -3rd ppm (by volume). The hydrogen chloride in the air sample reacts with a bromide-bromate coating in the inlet tube of the instrument producing bromine. Bromine is then quantitated by chemiluminescent oxidation of luminol. The visible light generated in the chemiluminescent reaction is proportional to the hydrogen chloride concentration of the sampled airstream. The detector is most suited to laboratory or field studies where hydrogen chloride is the dominant pollutant, as compared to the interfering species. Interferences include strong acids, acid-forming gases, and halogen gases. Of the interferences investigated the most serious in these groups are hydrochloric and sulfuric acid, sulfur dioxide, and chlorine, respectively. The detector has been in use since 1974 and has been found to be highly portable, rugged, and stable under extreme environmental conditions.
Gregory, G. L.↗
Adsorption of hydrogen chloride on microcrystalline silica
The interaction of hydrogen chloride with quartz was studied to determine the extent to which silica can irreversibly remove hydrogen chloride from the atmosphere. Adsorption isotherms were measured at 30 C for hydrogen chloride on silica outgassed between 100 C and 400 C. Readsorption isotherms were also measured. The silica surface was characterized further by infrared spectroscopy, electron spectroscopy for chemical analysis, scanning electron microscopy, and immersional calorimetry. Ground debris samples obtained from the Kennedy Space Center, were likewise examined.
Kang, Y.↗
Passive, Direct-Read Monitoring System for Selective Detection and Quantification of Hydrogen Chloride
Monitoring the exposure of an employee to hydrogen chloride or hydrochloric acid in the presence of other acids has been a challenge to the industrial hygiene community. The capability of a device to differentiate the levels of acid vapors would allow for more accurate determinations of exposure and therefore improved occupational health. In this work, a selective direct-read colorimetric badge system was validated for Short Term Exposure Limit (STEL) monitoring of hydrogen chloride. The passive colorimetric badge system consists of a direct reading badge and a color scale. The badge has a coated indicator layer with a diffusive resistance in the shape of an exclamation mark. An exclamation mark will appear if hydrogen chloride is present in the atmosphere at concentrations at or above 2.0 ppm. By using the color scale, the intensity of the color formed on the badge can be further quantified up to 25 ppm. The system was validated according to a protocol based on the NIOSH Protocol for the Evaluation of Passive Monitors. The badge was exposed to relative humidities ranging from 11% to 92%, temperatures ranging from 7 C to 400 C and air velocities ranging from 5 cm/sec to 170 cm/sec. All experiments were conducted in a laboratory vapor generation system. Hydrofluoric acid, nitric acid, sulfuric acid, chlorine, hydrogen sulfide and organic acids showed no effect on the performance of the hydrogen chloride monitoring system. The passive badge and color scale system exceeded the accuracy requirements as defined by NIOSH. At ambient conditions, the mean coefficient of variation was 10.86 and the mean bias was 1.3%. This data was presented previously at the American Industrial Hygiene Conference and Exposition in Toronto, Canada in June 1999.
Chapman, K. B.↗
Modeling the Uptake of Hydrogen Chloride onto Interior Spacecraft Materials
Hydrogen chloride (HCl) is a major combustion product from the pyrolysis of polyvinyl chloride (PVC) insulated electrical wires, a common spacecraft fire safety concern. Models at two different scales were developed to predict HCl uptake on anodized, chromate conversion coated (Iridite), and bare aluminum surfaces, as well as on Nomex fabric: a macroscopic one-step global surface reaction model where all the active sites are on the exterior surface, and a pore model where the interior active sites deeper into the oxide layer can also be accessed by HCl. Experiments were performed to calibrate kinetic and diffusion constants in the models. A cast acrylic test cell was used to measure the differences between the inlet and outlet concentration of HCl after inserting a sample rod of the test material. For the materials with a thin (< 200 µm) or no oxide layer, the macroscopic surface reaction model adequately predicts the experimental measurements. For the anodized aluminum with a thicker oxide layer, the pore model provided a better match to experimental results. The results will be discussed with respect to the spacecraft fire safety project (Saffire).
modeling↗
Feasibility demonstration for hydrogen chloride detection using a chemisorption technique and a quartz crystal microbalance
A method of measuring concentrations of hydrogen chloride between 1 part per billion and 10 parts per million at standard temperature and pressure is presented. The feasibility of a low-cost device incorporating a chemisorption technique coupled with a quartz crystal microbalance was demonstrated in the field at the Viking B launch using a Titan-Centaur vehicle from Kennedy Space Center on August 20, 1975. Hydrogen chloride is a product of solid rocket combustion. The concentration level of hydrogen chloride for this particular launch was measured as approximately 0.2 parts per million at 4 km from the launch site.
Jex, D. W.↗
Mechanism for forming hydrogen chloride and sodium sulfate from sulfur trioxide, water, and sodium chloride
A molecular orbital study of sodium sulfate and hydrogen chloride formation from sulfur trioxide, water, and sodium chloride shows no activation barrier, in agreement with recent experimental work of Kohl, Fielder, and Stearns. Two overall steps are found for the process. First, gas-phase water reacts with sulfur trioxide along a pathway involving a linear O-H-O transition state yielding closely associated hydroxyl and bisulfite which rearrange to become a hydrogen sulfate molecule. Then the hydrogen sulfate molecule transfers a hydrogen atom to a surface chloride in solid sodium chloride while an electron and a sodium cation simultaneously transfer to yield sodium bisulfate and gas-phase hydrogen chloride. This process repeats. Both of these steps represent well-known reactions for which mechanisms have not been previously determined.
Anderson, A. B.↗
Summary of airborne chlorine and hydrogen chloride gas measurements for August 20 and September 5, 1977 Voyager launches at Air Force Eastern Test Range, Florida
Airborne chlorine and hydrogen chloride measurements were made in the tropospheric ground cloud following the Voyager launches of August 20 and September 5, 1977. The maximum observed hydrogen chloride concentration for both launches was about 25 to 30 parts per million (ppm) occurring typically 2 to 6 minutes after launch. By completion of the sampling mission (1-1/2 hours for August, 4-1/2 hours for September), the maximum in-cloud concentration decayed to about 1 to 2 ppm. Maximum observed chlorine concentrations were about 40 to 55 parts per billion (ppb) about 2 to 8 minutes after launch; by about 15 minutes after launch, chlorine concentrations were less than 10 ppb (detection limit). In-cloud chlorine concentrations were well below 1 percent of hydrogen chloride concentrations. The appendix of the report discusses the chlorine instrument and the laboratory evaluation of the detector.
Gregory, G. L.↗
Solid propellant exhausted aluminum oxide and hydrogen chloride - Environmental considerations
Measurements of gaseous hydrogen chloride (HCl) and particulate aluminum oxide (Al2O3) were made during penetrations of five Space Shuttle exhaust clouds and one static ground test firing of a shuttle booster. Instrumented aircraft were used to penetrate exhaust clouds and to measure and/or collect samples of exhaust for subsequent analyses. The focus was on the primary solid rocket motor exhaust products, HCl and Al2O3, from the Space Shuttle's solid boosters. Time-dependent behavior of HCl was determined for the exhaust clouds. Composition, morphology, surface chemistry, and particle size distributions were determined for the exhausted Al2O3. Results determined for the exhaust cloud from the static test firing were complicated by having large amounts of entrained alkaline ground debris (soil) in the lofted cloud. The entrained debris may have contributed to neutralization of in-cloud HCl.
Cofer, W. R., III↗
Interaction of hydrogen chloride and water with oxide surfaces. III - Titanium dioxide
The adsorption of hydrogen chloride and water vapors on five TiO2 powders in both the anatase and rutile crystalline forms was studied as a function of temperature, pressure, and outgas conditions. The adsorbents were characterized utilizing X-ray powder diffraction, scanning electron microscopy, surface area analysis, indicator method, microelectrophoresis, XPS, and infrared spectroscopy. It was found that both outgas temperature and adsorption temperature influenced the adsorption of water vapor on TiO2, while water vapor adsorption on TiO2 was completely reversible. It is argued that the number of hydroxyl groups present on the surface determines the adsorption capacity of water on the different titanium dioxides. It was found that heats of immersion in water were affected significantly by outgas temperature. Hydrogen chloride adsorption isotherms at 30 C measured on TiO2 after outgassing at 100-400 C showed that a part of the total HCl adsorbed was irreversibly adsorbed. The highest HCl adsorption capacity per unit area was exhibited by anatase, while pure rutile exhibited the lowest adsorption capacity.
Siriwardane, R. V.↗
Hydrogen chloride measurements in the Space Shuttle exhaust cloud - First launch, April 12, 1981
Partitioning of hydrogen chloride between the aerosol and gaseous phases in the first Space Shuttle exhaust cloud was experimentally investigated as the exhaust cloud was diluted with ambient air. Airborne measurements were obtained of gaseous hydrogen chloride (HCl), total HCl, relative humidity, and temperature to determine the conditions controlling HCl aerosol formation in the Shuttle exhaust cloud. Two segments of the cloud, each at a significantly different relative humidity, were monitored. Equilibrium predictions of HCl aerosol formation agreed with the measured HCl partitioning at the higher and lower relative humidity conditions, but do not agree at the aerosol formation threshold region. Measurements were taken in the Shuttle exhaust cloud from 8.6 min until 2 h and 8 min after launch. HCl concentrations ranged from 17.5 to 0.9 ppm and relative humidity from 86% to less than 10%.
Sebacher, D. I.↗
Hydrochloric acid aerosol formation by the interaction of hydrogen chloride with humid air
The conditions in which hydrochloric acid aerosol is predicted by the interaction of hydrogen chloride gas with the water vapor in humid air are analyzed. The liquid gas phase equilibrium for the HCL-H2O system is expressed in terms of relative humidity and hydrogen chloride concentration as parts per million, units commonly used in pollution studies. Presented are the concentration (wt %) of HC1 in the aerosol and the concentration of aerosol (ppm) predicted.
Rhein, R. A.↗
A study of the intensity of the self-broadened fundamental band of hydrogen chloride
Intensity study of self-broadened fundamental band of hydrogen chloride
Burnett, S. C.↗
Hydrochloric acid aerosol and gaseous hydrogen chloride partitioning in a cloud contaminated by solid rocket exhaust
Partitioning of hydrogen chloride between hydrochloric acid aerosol and gaseous HCl in the lower atmosphere was experimentally investigated in a solid rocket exhaust cloud diluted with humid ambient air. Airborne measurements were obtained of gaseous HCl, total HCl, relative humidity and temperature to evaluate the conditions under which aerosol formation occurs in the troposphere in the presence of hygroscopic HCl vapor. Equilibrium predictions of HCl aerosol formation accurately predict the measured HCl partitioning over a range of total HCl concentrations from 0.6 to 16 ppm.
Sebacher, D. I.↗
Antarctic stratospheric chemistry of chlorine nitrate, hydrogen chloride, and ice - Release of active chlorine
The reaction rate between atmospheric hydrogen chloride (HCl) and chlorine nitrate (ClONO2) is greatly enhanced in the presence of ice particles; HCl dissolves readily into ice, and the collisional reaction probability for ClONO2 on the surface of ice with HCl in the mole fraction range from about 0.003 to 0.010 is in the range from about 0.05 to 0.1 for temperatures near 200 K. Chlorine is released into the gas phase on a time scale of at most a few milliseconds, whereas nitric acid (HNO3), the other product, remains in the condensed phase. This reaction could play an important role in explaining the observed depletion of ozone over Antarctica; it releases photolytically active chlorine from its most abundant reservoir species, and it promotes the formation of HNO3 and thus removes nitrogen dioxide from the gas phase. Hence it establishes the necessary conditions for the efficient catalytic destruction of ozone by halogenated free radicals.
Molina, Mario J.↗
Adsorption of water on sodium chloride - The effect of prior exposure to hydrogen chloride, carbon dioxide and water vapor.
Water adsorption on cleaved sodium chloride crystals treated in advance with various chemicals, obtaining water isotherms
Lad, R. A.↗