Alloying of steel and graphite by hydrogen in nuclear reactor

NASA Astrophysics Data System (ADS)

Krasikov, E.

2017-02-01

In traditional power engineering hydrogen may be one of the first primary source of equipment damage. This problem has high actuality for both nuclear and thermonuclear power engineering. Study of radiation-hydrogen embrittlement of the steel raises the question concerning the unknown source of hydrogen in reactors. Later unexpectedly high hydrogen concentrations were detected in irradiated graphite. It is necessary to look for this source of hydrogen especially because hydrogen flakes were detected in reactor vessels of Belgian NPPs. As a possible initial hypothesis about the enigmatical source of hydrogen one can propose protons generation during beta-decay of free neutrons поскольку inasmuch as protons detected by researches at nuclear reactors as witness of beta-decay of free neutrons.

Hydrogen and lipid production from starch wastewater by co-culture of anaerobic sludge and oleaginous microalgae with simultaneous COD, nitrogen and phosphorus removal.

PubMed

Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Ren, Nanqi

2015-11-15

Anaerobic sludge (AS) and microalgae were co-cultured to enhance the energy conversion and nutrients removal from starch wastewater. Mixed ratio, starch concentration and initial pH played critical roles on the hydrogen and lipid production of the co-culture system. The maximum hydrogen production of 1508.3 mL L(-1) and total lipid concentration of 0.36 g L(-1) were obtained under the optimized mixed ratio (algae:AS) of 30:1, starch concentration of 6 g L(-1) and initial pH of 8. The main soluble metabolites in dark fermentation were acetate and butyrate, most of which can be consumed in co-cultivation. When sweet potato starch wastewater was used as the substrate, the highest COD, TN and TP removal and energy conversion efficiencies reached 80.5%, 88.7%, 80.1% and 34.2%, which were 176%, 178%, 200% and 119% higher than that of the control group (dark fermentation), respectively. This research provided a novel approach and achieved efficient simultaneous energy recovery and nutrients removal from starch wastewater by the co-culture system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photolysis of low concentration H2S under UV/VUV irradiation emitted from microwave discharge electrodeless lamps.

PubMed

Xia, Lan-Yan; Gu, Ding-Hong; Tan, Jing; Dong, Wen-Bo; Hou, Hui-Qi

2008-04-01

The photolysis of simulating low concentration of hydrogen sulfide malodorous gas was studied under UV irradiation emitted by self-made microwave discharge electrodeless lamps (i.e. microwave UV electrodeless mercury lamp (185/253.7 nm) and iodine lamp (178.3/180.1/183/184.4/187.6/206.2 nm)). Experiments results showed that the removal efficiency (eta H2S) of hydrogen sulfide was decreased with increasing initial H2S concentration and increased slightly with gas residence time; H2S removal efficiency was decreased dramatically with enlarged pipe diameter. Under the experimental conditions with pipe diameter of 36 mm, gas flow rate of 0.42 standard l s(-1), eta H2S was 52% with initial H2S concentration of 19.5 mg m(-3) by microwave mercury lamp, the absolute removal amount (ARA) was 4.30 microg s(-1), and energy yield (EY) was 77.3 mg kW h(-1); eta H2S was 56% with initial H2S concentration of 18.9 mg m(-3) by microwave iodine lamp, the ARA was 4.48 microg s(-1), and the EY was 80.5mg kW h(-1). The main photolysis product was confirmed to be SO4(2-) with IC.

40 CFR 63.7520 - What stack tests and procedures must I use?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Institutional Boilers and Process Heaters Testing, Fuel Analyses, and Initial Compliance Requirements § 63.7520... representative operating load conditions while burning the type of fuel or mixture of fuels that has the highest... measured hydrogen chloride concentrations, and the measured mercury concentrations that result from the...

Enhancement of Biohydrogen Production via pH Variation using Molasses as Feedstock in an Attached Growth System

NASA Astrophysics Data System (ADS)

Che Zuhar, C. N. S.; Lutpi, N. A.; Idris, N.; Wong, Y. S.; Tengku Izhar, T. N.

2018-03-01

In this study, mesophilic biohydrogen production by a mixed culture, obtained from a continuous anaerobic reactor treating molasses effluent from sugarcane bagasse, was improved by using granular activated carbon (GAC) as the carrier material. A series of batch fermentation were performed at 37°C by feeding the anaerobic sludge bacteria with molasses to determine the effect of initial pH in the range of 5.5 to 7.5, and the effect of repeated batch cultivation on biohydrogen production. The enrichment of granular activated carbon (GAC) immobilised cells from the repeated batch cultivation were used as immobilised seed culture to obtain the optimal initial pH. The cumulative hydrogen production results from the optimal pH were fitted into modified Gompertz equation in order to obtained the batch profile of biohydrogen production. The optimal hydrogen production was obtained at an initial pH of 5.5 with the maximum hydrogen production (Hm) was found to be 84.14 ml, and maximum hydrogen production rate (Rm) was 3.63 mL/h with hydrogen concentration of 759 ppm. The results showed that the granular activated carbon was successfully enhanced the biohydrogen production by stabilizing the pH and therefore could be used as a carrier material for fermentative hydrogen production using industrial effluent.

Role of Hydrogen and Structure on CMSX-2

NASA Technical Reports Server (NTRS)

Baker, C. L.; Chene, J.; Kromp, W.; Pinczolitis, H.; Bernstein, S. M.; Williams, J. C.

1985-01-01

The goal was to characterize and understand the detailed effect of hydrogen on the tensile and fatigue behavior of single crystals of CMSX-2. Specimens were solutionized, air cooled, and then aged in one of two ways. The resultant macro and microstructure included a pronounced dendritic structure with numerous low angle boundaries in the interdendritic region and on the average a high level of porosity with a large variation in size and distribution. Hydrogen permeability and diffusivity in this material was found to be very low at room temperature. Hydrogen concentration studies on thin samples yielded values significantly higher than found for similar charging conditions in nickel and stainless steels. The tensile mechanical properties were found to depend on hydrogen concentration. SEM observations of the brittle subsurface zone revealed a strong correlation between crack initiation sites and voids just beneath the surface. The hollow and solid samples were compared to better understand the influence of increased charged volume on the fatigue behavior.

Assessment of Remote Sensing Technologies for Location of Hydrogen and Helium Leaks

NASA Technical Reports Server (NTRS)

Sellar, R. Glenn; Wang, Danli

2000-01-01

The objective of this initial phase of this research effort is to: 1) Evaluate remote sensing technologies for location of leaks of gaseous molecular hydrogen (H2) and gaseous helium (He) in air, for space transportation applications; and 2) Develop a diffusion model that predicts concentration of H2 or He gas as a function of leak rate and distance from the leak.

Chronic toxicity of hydrogen peroxide to Daphnia magna in a continuous exposure, flow-through test system

USGS Publications Warehouse

Meinertz, J.R.; Greseth, Shari L.; Gaikowski, M.P.; Schmidt, L.J.

2008-01-01

A flow-through, continuous exposure test system was developed to expose Daphnia magna to an unstable compound. 35% Perox-Aid?? is a specially formulated hydrogen peroxide (a highly oxidative chemical) product approved for use in U.S. aquaculture and therefore has the potential to be released from aquaculture facilities and pose a risk to aquatic invertebrates. The study objective was to assess the effects of 35% Perox-Aid?? on an aquatic invertebrate by evaluating the survival, growth, production, and gender ratio of progeny from a representative aquatic invertebrate continuously exposed to 35% Perox-Aid??. The study design consisted of 6 treatment groups (10 test chambers each) with target hydrogen peroxide concentrations of 0.0, 0.32, 0.63, 1.25, 2.5, and 5.0??mg L- 1. The study was initiated with < 24-h-old Daphnia (1 daphnid per chamber) that were exposed to hydrogen peroxide for 21??days. Hydrogen peroxide concentrations ??? 1.25??mg L- 1 had no significant effect on Daphnia time to death compared to controls and no significant effect on the time to first brood production and the number of broods produced. Concentrations ??? 0.63??mg L- 1 had no significant effect on the total number of young produced. Concentrations ??? 0.32??mg L- 1 had a negative effect on Daphnia growth. Hydrogen peroxide had no significant effect on the gender ratio of young produced. All second generation Daphnia were female. A continuous discharge of hydrogen peroxide into aquatic ecosystems is not likely to affect cladocerans if the concentration is maintained at ??? 0.63??mg L- 1 for less than 21??days.

Production of hydrogen, ethanol and volatile fatty acids from the seaweed carbohydrate mannitol.

PubMed

Xia, Ao; Jacob, Amita; Herrmann, Christiane; Tabassum, Muhammad Rizwan; Murphy, Jerry D

2015-10-01

Fermentative hydrogen from seaweed is a potential biofuel of the future. Mannitol, which is a typical carbohydrate component of seaweed, was used as a substrate for hydrogen fermentation. The theoretical specific hydrogen yield (SHY) of mannitol was calculated as 5 mol H2/mol mannitol (615.4 mL H2/g mannitol) for acetic acid pathway, 3 mol H2/mol mannitol (369.2 mL H2/g mannitol) for butyric acid pathway and 1 mol H2/mol mannitol (123.1 mL H2/g mannitol) for lactic acid and ethanol pathways. An optimal SHY of 1.82 mol H2/mol mannitol (224.2 mL H2/g mannitol) was obtained by heat pre-treated anaerobic digestion sludge under an initial pH of 8.0, NH4Cl concentration of 25 mM, NaCl concentration of 50mM and mannitol concentration of 10 g/L. The overall energy conversion efficiency achieved was 96.1%. The energy was contained in the end products, hydrogen (17.2%), butyric acid (38.3%) and ethanol (34.2%). Copyright © 2015 Elsevier Ltd. All rights reserved.

Reversible depression in the T{sub c} of thin Nb films due to enhanced hydrogen adsorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jisrawi, N.M.; Ruckman, M.W.; Thurston, T.R.

The effect of large hydrogen concentrations ({approx}30{percent} atomic), on the superconducting transition temperature T{sub c} of Nb films is discussed. The hydrogen is incorporated in solutionlike phases which occur at these concentrations because the ({alpha} to {beta}) hydride transition in these films is suppressed. X-ray-diffraction data show an asymmetric expansion of the [110] Nb interplanar spacing. This can be as high as a 6{endash}8thinsp{percent} expansion perpendicular to the plane of the film for the addition of {approximately}70{percent} hydrogen, with only a 1{endash}2thinsp{percent} change in the plane of the film. T{sub c} is depressed to a value near 50{percent} of thatmore » of the undoped film with about 30{percent} atomic hydrogen, and returns to its initial value when the hydrogen is removed. A discussion is given of how both disorder and changes in the electronic structure can affect T{sub c}. {copyright} {ital 1998} {ital The American Physical Society}« less

Determination Hypoiodous Acid (HIO) By Peroxidase System Using Peroxidase Enzyme

NASA Astrophysics Data System (ADS)

Al-Baarri, A. N.; Legowo, A. M.; Widayat; Abduh, S. B. M.; Hadipernata, M.; Wisnubroto; Ardianti, D. K.; Susanto, M. N.; Yusuf, M.; Demasta, E. K.

2018-02-01

It has been understood that peroxidase enzyme including peroxidase serves as catalyzer to enzymatic reaction among hydrogen peroxide and halides, therefore this research was done for generating hypoiodous acid (HIO) from peroxidase system using peroxidase enzyme. Hydrogen peroxide, potassium iodide, and peroxidase enzyme were used to produce HIO. Determination the amount of formed HIO was done using 2,2'-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid) or ABTS as substrate through the colorimetric measurement of hydrogen peroxide residue during reaction process using at 412 nm. The result indicated that residual hydrogen peroxide showed the minimum concentration after 60 minutes reaction time. Because the reaction started at the beginning time of mixing, hydrogen peroxide was unable to be eliminated totally to produce HIO. The reaction of peroxidase system was able to determine the beginning of mixing process but the reaction process could not eliminate the initial concentration of hydrogen peroxide indicating the maximum amount of production of HIO could be determined. In conclusion, the less of H2O2, higher HIO obtained and peroxidase enzymes can accelerate the formation of HIO.

Study on Flake Formation Behavior and Its Influence Factors in Cr5 Steel

PubMed Central

Chen, Huitao; Zhao, Wu; Yan, Liang

2018-01-01

A flake is a crack that is induced by trapped hydrogen within steel. To study its formation mechanism, previous studies mostly focused on the formation process and magnitude of hydrogen pressure in hydrogen traps such as cavities and cracks. However, according to recent studies, the hydrogen leads to the decline of the mechanical properties of steel, which is known as hydrogen embrittlement, is another reason for flake formation. In addition, the phenomenon of stress induced hydrogen uphill diffusion should not be neglected. All of the three behaviors are at work simultaneously. In order to further explore the formation mechanism of flakes in steel, the process of flake initiation and growth were studied with the following three coupling factors: trap hydrogen pressure, hydrogen embrittlement, and stress induced hydrogen re-distribution. The analysis model was established using the finite element method, and a crack whose radius is 0.5 mm was set in its center. The cohesive method and Bilinear Traction Separate Law (BTSL) were used to address the coupling effect. The results show that trap hydrogen pressure is the main driving force for flake formation. After the high hydrogen pressure was generated around the trap, a stress field formed. In addition, the trap is the center of stress concentration. Then, hydrogen is concentrated in a distribution around this trap, and most of the steel mechanical properties are reduced. The trap size is a key factor for defining the critical hydrogen content for flake formation and propagation. However, when the trap size exceeds the specified value, the critical hydrogen content does not change any more. As for the crack whose radius is 0.5 mm, the critical hydrogen content of Cr5VMo steel is 2.2 ppm, which is much closer to the maximum safe hydrogen concentration of 2.0 ppm used in China. The work presented in this article increases our understanding of flake formation and propagation mechanisms in steel. PMID:29702610

Effects of hydrogen partial pressure on autotrophic growth and product formation of Acetobacterium woodii.

PubMed

Kantzow, Christina; Weuster-Botz, Dirk

2016-08-01

Low aqueous solubility of the gases for autotrophic fermentations (e.g., hydrogen gas) results in low productivities in bioreactors. A frequently suggested approach to overcome mass transfer limitation is to increase the solubility of the limiting gas in the reaction medium by increasing the partial pressure in the gas phase. An increased inlet hydrogen partial pressure of up to 2.1 bar (total pressure of 3.5 bar) was applied for the autotrophic conversion of hydrogen and carbon dioxide with Acetobacterium woodii in a batch-operated stirred-tank bioreactor with continuous gas supply. Compared to the autotrophic batch process with an inlet hydrogen partial pressure of 0.4 bar (total pressure of 1.0 bar) the final acetate concentration after 3.1 days was reduced to 50 % (29.2 g L(-1) compared to 59.3 g L(-1)), but the final formate concentration was increased by a factor of 18 (7.3 g L(-1) compared to 0.4 g L(-1)). Applying recombinant A. woodii strains overexpressing either genes for enzymes in the methyl branch of the Wood-Ljungdahl pathway or the genes phosphotransacetylase and acetate kinase at an inlet hydrogen partial pressure of 1.4 bar reduced the final formate concentration by up to 40 % and increased the final dry cell mass and acetate concentrations compared to the wild type strain. Solely the overexpression of the two genes for ATP regeneration at the end of the Wood-Ljungdahl pathway resulted in an initial switch off of formate production at increased hydrogen partial pressure until the maximum of the hydrogen uptake rate was reached.

An assessment of the government liquid hydrogen requirements for the 1995-2005 time frame including addendum, liquid hydrogen production and commercial demand in the United States

NASA Technical Reports Server (NTRS)

Bain, Addison

1990-01-01

Liquid hydrogen will continue to be an integral element in virtually every major space program, and it has also become a significant merchant product for certain commercial markets. Liquid hydrogen is not a universally available commodity, and the number of supply sources historically have been limited to regions having concentrated consumption patterns. With the increased space program activity it becomes necessary to assess all future programs on a collective and unified basis. An initial attempt to identify projected requirements on a long range basis is presented.

Estimating changes in urban ozone concentrations due to life cycle emissions from hydrogen transportation systems

NASA Astrophysics Data System (ADS)

Wang, Guihua; Ogden, Joan M.; Chang, Daniel P. Y.

Hydrogen has been proposed as a low polluting alternative transportation fuel that could help improve urban air quality. This paper examines the potential impact of introducing a hydrogen-based transportation system on urban ambient ozone concentrations. This paper considers two scenarios, where significant numbers of new hydrogen vehicles are added to a constant number of gasoline vehicles. In our scenarios hydrogen fuel cell vehicles (HFCVs) are introduced in Sacramento, California at market penetrations of 9% and 20%. From a life cycle analysis (LCA) perspective, considering all the emissions involved in producing, transporting, and using hydrogen, this research compares three hypothetical natural gas to hydrogen pathways: (1) on-site hydrogen production; (2) central hydrogen production with pipeline delivery; and (3) central hydrogen production with liquid hydrogen truck delivery. Using a regression model, this research shows that the daily maximum temperature correlates well with atmospheric ozone formation. However, increases in initial VOC and NO x concentrations do not necessarily increase the peak ozone concentration, and may even cause it to decrease. It is found that ozone formation is generally limited by NO x in the summer and is mostly limited by VOC in the fall in Sacramento. Of the three hydrogen pathways, the truck delivery pathway contributes the most to ozone precursor emissions. Ozone precursor emissions from the truck pathway at 9% market penetration can cause additional 3-h average VOC (or NO x) concentrations up to approximately 0.05% (or 1%) of current pollution levels, and at 20% market penetration up to approximately 0.1% (or 2%) of current pollution levels. However, all of the hydrogen pathways would result in very small (either negative or positive) changes in ozone air quality. In some cases they will result in worse ozone air quality (mostly in July, August, and September), and in some cases they will result in better ozone air quality (mostly in October). The truck pathway tends to cause a much wider fluctuation in degradation or improvement of ozone air quality: percentage changes in peak ozone concentrations are approximately -0.01% to 0.04% for the assumed 9% market penetration, and approximately -0.03% to 0.1% for the 20% market penetration. Moreover, the 20% on-site pathway occasionally results in a decrease of about -0.1% of baseline ozone pollution. Compared to the current ambient pollution level, all three hydrogen pathways are unlikely to cause a serious ozone problem for market penetration levels of HFCVs in the 9-20% range.

Species measurements in a hypersonic, hydrogen-air, combustion wake

NASA Technical Reports Server (NTRS)

Skinner, K. A.; Stalker, R. J.

1995-01-01

A continuously sampling, time-of-flight mass spectrometer has been used to measure relative species concentrations in a two-dimensional, hydrogen-air combustion wake at mainstream Mach numbers exceeding 5. The experiments, which were conducted in a free piston shock tunnel, yielded distributions of hydrogen, oxygen, nitrogen, water and nitric oxide at stagnation enthalpies ranging from 5.6 MJ kg(exp -1) to 1.2 MJ kg(exp -1) and at a distance of approximately 100 times the thickness of the initial hydrogen jet. The amount of hydrogen that was mixed in stoichiometric proportions was approximately independent of the stagnation enthalpy, in spite of the fact that the proportion of hydrogen in the wake increased with stagnation enthalpy. Roughly 50 percent of the mixed hydrogen underwent combustion at the highest enthalpy. The proportion of hydrogen reacting to water could be approximately predicted using reaction rates based on mainstream temperatures.

Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

NASA Technical Reports Server (NTRS)

Marek, C. John; Molnar, Melissa

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

Effects of External Hydrogen on Hydrogen Transportation and Distribution Around the Fatigue Crack Tip in Type 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Chen, Xingyang; Zhou, Chengshuang; Cai, Xiao; Zheng, Jinyang; Zhang, Lin

2017-10-01

The effects of external hydrogen on hydrogen transportation and distribution around the fatigue crack tip in type 304 stainless steel were investigated by using hydrogen microprint technique (HMT) and thermal desorption spectrometry. HMT results show that some silver particles induced by hydrogen release are located near the fatigue crack and more silver particles are concentrated around the crack tip, which indicates that hydrogen accumulates in the vicinity of the crack tip during the crack growth in hydrogen gas environment. Along with the crack propagation, strain-induced α' martensite forms around the crack tip and promotes hydrogen invasion into the matrix, which will cause the crack initiation and propagation at the austenite/ α' martensite interface. In addition, the hydrogen content in the vicinity of the crack tip is higher than that at the crack edge far away from the crack tip, which is related to the stress state and strain-induced α' martensite.

Modelling of discrete TDS-spectrum of hydrogen desorption

NASA Astrophysics Data System (ADS)

Rodchenkova, Natalia I.; Zaika, Yury V.

2015-12-01

High concentration of hydrogen in metal leads to hydrogen embrittlement. One of the methods to evaluate the hydrogen content is the method of thermal desorption spectroscopy (TDS). As the sample is heated under vacuumization, atomic hydrogen diffuses inside the bulk and is desorbed from the surface in the molecular form. The extraction curve (measured by a mass-spectrometric analyzer) is recorded. In experiments with monotonous external heating it is observed that background hydrogen fluxes from the extractor walls and fluxes from the sample cannot be reliably distinguished. Thus, the extraction curve is doubtful. Therefore, in this case experimenters use discrete TDS-spectrum: the sample is removed from the analytical part of the device for the specified time interval, and external temperature is then increased stepwise. The paper is devoted to the mathematical modelling and simulation of experimental studies. In the corresponding boundary-value problem with nonlinear dynamic boundary conditions physical- chemical processes in the bulk and on the surface are taken into account: heating of the sample, diffusion in the bulk, hydrogen capture by defects, penetration from the bulk to the surface and desorption. The model aimed to analyze the dynamics of hydrogen concentrations without preliminary artificial sample saturation. Numerical modelling allows to choose the point on the extraction curve that corresponds to the initial quantity of the surface hydrogen, to estimate the values of the activation energies of diffusion, desorption, parameters of reversible capture and hydride phase decomposition.

Liquid-phase hydrogenation of citral over Pt/SiO{sub 2} catalysts. 2. Hydrogenation of reaction intermediate compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, U.K.; Sysak, M.N.; Vannice, M.A.

2000-04-01

Liquid-phase hydrogenation of the four principal reaction intermediates formed during citral hydrogenation, i.e., nerol, geraniol, citronellal, and citronellol, was studied at 298 and 373 K under 20 atm H{sub 2} at concentrations of 0.5 to 1.0 M in hexane. A decrease in the initial reaction rate as temperature increased from 298 to 373 K was exhibited during the hydrogenation of all four compounds, just as reported earlier for citral; however, the decrease in rate at 373 K was only one-half for citronellal whereas it was orders of magnitude greater for nerol and geraniol. Furthermore, simultaneous hydrogenation of citronellal and geraniolmore » at 298 K resulted in a continuous decrease in the rate of citronellal disappearance in contrast to the nearly constant rate of disappearance observed during hydrogenation of citronellal alone. Competitive hydrogenation of citral with either geraniol or citronellal showed that geraniol hydrogenation to citronellol is kinetically insignificant during citral hydrogenation at 373 K. The initial activity for hydrogenation of the intermediates at 298 K follows the following trend: geraniol > nerol < citronellol < E-citral, citronellal > Z-citral. Based on the relative hydrogenation rates of the intermediate alone versus its hydrogenation in the presence of other reactants, the relative size of the adsorption equilibrium constants for the various organic compounds appears to be as follows: citral > citronellal > geraniol, nerol > citronellol > 3,7-dimethyloctanol. This study indicates that activation of the C{double_bond}O bond should be performed at higher reaction temperatures to maximize selectivity to the unsaturated alcohols.« less

Photochemical Degradation of Organic Pollutants in Wastewaters

NASA Astrophysics Data System (ADS)

Balbayeva, Gaukhar; Yerkinova, Azat; Inglezakis, Vassilis J.; Poulopoulos, Stavros G.

2018-01-01

In the present work, the photochemical treatment of a synthetic wastewater in a batch recycle photochemical reactor using ultraviolet irradiation (254 nm, 6 W), hydrogen peroxide and ferric ions was studied. Reactor volume was 250 mL with 55.8 mL of irradiated volume in the annular photoreactor. The synthetic wastewater was composed mainly of organic carbon. The effect of initial total carbon (136-1080 mg L-1), initial H2O2 amount (1332-5328 mg L-1), pH, and Fe(III) presence (2-40 ppm), on total carbon (TC) removal was studied. Each experiment lasted 120 min, and the process was attended via pH and TC concentration. Direct photolysis in the absence of any oxidant had practically no effect on TC removal. Regarding the effect of initial TC concentration in the wastewater keeping the same initial hydrogen peroxide concentration (2664 mg L-1), it was observed that for 136-271 mg L-1 TC, around 60% TC removal was achieved, while when initial TC was increased at 528 mg L-1, the TC removal observed decreased to 50%. For a further increase in TC at 1080 mg L-1, TC removal dropped to 14%. Initial pH adjustment of the wastewater resulted in slight variations of the TC removals achieved. Finally, adding Fe(III) in the process was beneficial in terms of TC removal obtained. Particularly, the addition of 40 ppm Fe(III) in the presence of 2664 mg L-1 H2O2 and initial TC equal to 528 mg L-1 increased the TC removal from 50% to 72%.

Preparative isolation of aquatic humic substances

USGS Publications Warehouse

Thurman, E.M.; Malcolm, R.L.

1981-01-01

A useful procedure has been developed which utilizes adsorption chromatography followed by size-exclusion chromatography, hydrogen saturation by ion exchange, and lypholization to obtain low-ash aqueous humic substances. The preparative concentration of aquatic humic substances is done by multiple reconcentration procedures even though initial concentrations of aqueous humus may be less than 25 ??g/L. The procedure yields concentration factors of 25 000 times for both humic and fulvic acid in water.

Simulation of Water Gas Shift Zeolite Membrane Reactor

NASA Astrophysics Data System (ADS)

Makertiharta, I. G. B. N.; Rizki, Z.; Zunita, Megawati; Dharmawijaya, P. T.

2017-07-01

The search of alternative energy sources keeps growing from time to time. Various alternatives have been introduced to reduce the use of fossil fuel, including hydrogen. Many pathways can be used to produce hydrogen. Among all of those, the Water Gas Shift (WGS) reaction is the most common pathway to produce high purity hydrogen. The WGS technique faces a downstream processing challenge due to the removal hydrogen from the product stream itself since it contains a mixture of hydrogen, carbon dioxide and also the excess reactants. An integrated process using zeolite membrane reactor has been introduced to improve the performance of the process by selectively separate the hydrogen whilst boosting the conversion. Furthermore, the zeolite membrane reactor can be further improved via optimizing the process condition. This paper discusses the simulation of Zeolite Membrane Water Gas Shift Reactor (ZMWGSR) with variation of process condition to achieve an optimum performance. The simulation can be simulated into two consecutive mechanisms, the reaction prior to the permeation of gases through the zeolite membrane. This paper is focused on the optimization of the process parameters (e.g. temperature, initial concentration) and also membrane properties (e.g. pore size) to achieve an optimum product specification (concentration, purity).

Hydrogen peroxide concentration by pervaporation of a ternary liquid solution in microfluidics.

PubMed

Ziemecka, Iwona; Haut, Benoît; Scheid, Benoit

2015-01-21

Pervaporation in a microfluidic device is performed on liquid ternary solutions of hydrogen peroxide-water-methanol in order to concentrate hydrogen peroxide (H2O2) by removing methanol. The quantitative analysis of the pervaporation of solutions with different initial compositions is performed, varying the operating temperature of the microfluidic device. Experimental results together with a mathematical model of the separation process are used to understand the effect of the operating conditions on the microfluidic device efficiency. The parameters influencing significantly the performance of pervaporation in the microfluidic device are determined and the limitations of the process are discussed. For the analysed system, the operating temperature of the chip has to be below the temperature at which H2O2 decomposes. Therefore, the choice of an adequate reduced operating pressure is required, depending on the expected separation efficiency.

Biosurfactant-enhanced hydrogen production from organic fraction of municipal solid waste using co-culture of E. coli and Enterobacter aerogenes.

PubMed

Sharma, Preeti; Melkania, Uma

2017-11-01

The effect of biosurfactants (surfactin and saponin) on the hydrogen production from organic fraction of municipal solid waste (OFMSW) was investigated using co-culture of facultative anaerobes Enterobacter aerogenes and E. coli. The biosurfactants were applied in the concentration ranges of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 5.0% each. Cumulative hydrogen production (P), maximum hydrogen production rate (Rmax) and lag phases (λ) were analyzed using modified Gompertz model. Results revealed that both the biosurfactants were effective in hydrogen production enhancement. The maximum cumulative hydrogen production of 743.5±14.4ml and 675.6±12.1ml and volumetric hydrogen production of 2.12L H2 /L substrate and 1.93L H2 /L substrate was recorded at 3.5% surfactin and 3.0% saponin respectively. Corresponding highest hydrogen yields were 79.2mlH 2 /gCarbo initial and 72.0mlH 2 /gCarbo initial respectively. Lag phase decreased from 12.5±2.0h at control to a minimum of 9.0±2.8h and 9.5±2.1h at 3.5% surfactin and 3.0% saponin respectively. Volatile fatty acid generation was increased with biosurfactants addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced leachate recirculation and stabilization in a pilot landfill bioreactor in Taiwan.

PubMed

Huang, Fu-Shih; Hung, Jui-Min; Lu, Chih-Jen

2012-08-01

This study focused on the treatment of municipal solid waste (MSW) by modification and recirculation of leachate from a simulated landfill bioreactor. Hydrogen peroxide was added to recirculated leachate to maintain a constant oxygen concentration as the leachate passed again through the simulated landfill bioreactor. The results showed that leachate recirculation increased the dissolved oxygen concentration in the test landfill bioreactor. Over a period of 405 days, the biochemical oxygen demand (BOD(5)) in the collected leachate reduced by 99.7%, whereas the chemical oxygen demand (COD) reduced by 96%. The BOD(5)/COD ratio at the initial stage of 0.9 improved to 0.09 under aerobic conditions (leachate recirculation with added hydrogen peroxide) compared with the anaerobic test cell 0.11 (leachate recirculation alone without hydrogen peroxide). The pH increased from 5.5 to 7.6, and the degradation rate of organic carbon was 93%. Leachate recirculation brings about the biodegradation of MSW comparatively faster than the conventional landfill operation. The addition of a constant concentration of hydrogen peroxide was found to further increase the biodegradation. This increased biodegradation rate ultimately enables an MSW landfill to reach a stable state sooner and free up the land for further reuse.

Degradation of sulfamethazine by gamma irradiation in the presence of hydrogen peroxide.

PubMed

Liu, Yuankun; Wang, Jianlong

2013-04-15

The gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated. The initial SMT concentration was 20mg/L and it was irradiated in the presence of extra H2O2 with initial concentration of 0, 10 and 30 mg/L. The results showed that gamma irradiation was effective for removing SMT in aqueous solution and its degradation conformed to the pseudo first-order kinetics under the applied conditions. When initial H2O2 concentration was in the range of 0-30 mg/L, higher concentration of H2O2 was more effective for the decomposition and mineralization of SMT. However, the removal of total organic carbon (TOC) was not as effective as that of SMT. Total nitrogen (TN) was not removed even at absorbed dose of 5 kGy, which was highest dose applied in this study. Major decomposition products of SMT, including degradation intermediates, organic acids and some inorganic ions were detected by high performance liquid chromatography (HPLC) and ion chromatography (IC). Sulfate (SO4(2-)), formic acid (HCOOH), acetic acid (CH3COOH), 4-aminophenol, 4-nitrophenol were identified in the irradiated solutions. Possible pathways for SMT decomposition by gamma irradiation in aqueous solution were proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Exploitation of dark fermented effluent of cheese whey by co-culture of Rhodobacter sphaeroides and Bacillus firmus for photo-hydrogen production.

PubMed

Pandey, A; Pandey, A

2017-07-31

In this study photo-hydrogen production from cheese whey dark fermentation (DF) effluent by the co-culture of Rhodobacter sphaeroides -NMBL-01 and Bacillus firmus - NMBL-03 has been reported. The effect of pH, initial chemical oxygen demand (COD) and the concentration effect of FeSO4.7H2O on photo-hydrogen production have been investigated. The end products of dark fermentation effluent of cheese whey were mainly comprised of soluble organic acids, i.e. butyric acid and lactic acid. The batch process was carried out under light intensity of 2.5 kLux at 32 ± 2oC without any addition of extra carbon and nitrogen source. The single parameter optimization studies revealed optimum pH 6.5, initial COD 4.71 g/L and supplementation of Fe2+ concentration 100 mg/L. The maximum cumulative hydrogen production and yield were found to be 469 ± 45.8 ml H2/L and 146.56 ± 14.31 ml H2/g COD reduced (67.9% reduction in COD) respectively. The mutual interactions among the process parameters were also investigated by three factorial Box-Behnken design of response surface methodology. The optimized experimental values were found concurrent with the calculated values obtained from the theoretical model.

Method of generating hydrogen-storing hydride complexes

DOEpatents

None, None

2013-05-14

A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

Hydrogen-storing hydride complexes

DOEpatents

Srinivasan, Sesha S [Tampa, FL; Niemann, Michael U [Venice, FL; Goswami, D Yogi [Tampa, FL; Stefanakos, Elias K [Tampa, FL

2012-04-10

A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

H partitioning between NAMs in garnet-bearing peridotite at subsolidus conditions

NASA Astrophysics Data System (ADS)

Demouchy, S. A.; Shcheka, S.; Denis, C. M. M.; Thoraval, C.

2017-12-01

Hydrogen distribution between nominally anhydrous minerals (NAMs) of a garnet-lherzolite under subsolidus conditions has been investigated. Separated NAMs from a garnet-peridotite from Patagonia (Chile) are annealed together (olivine, orthopyroxene, clinopyroxene and garnet) using a piston-cylinder at 3 GPa and 1100 °C using talc-Pyrex cell assembly for 10, 25 and 100 hours. The talc-pyrex assembly provides enough hydrogen in the system to re-equilibrate the hydrogen concentrations at high pressure. The three co-existing nominally anhydrous minerals (NAMs, i.e., olivine, orthopyroxene and clinopyroxene) were successfully analyzed using FTIR. The resulting hydrogen concentrations exceed significantly the initial hydrogen concentration by a factor of 13 for olivine and a factor of 3 for both pyroxenes. Once mineral-specific infrared calibrations are applied, the average concentrations in NAMs are 115±12 ppm wt H2O for olivine, 635±75 ppm wt H2O for orthopyroxene and 1214±137 ppm wt H2O for clinopyroxene, garnet grains are dry. Since local equilibrium seems achieved over time (for 100 hours), the calculated concentration ratios are interpreted as mineral-to-mineral hydrogen partition coefficients (i.e., Nernst `s law) for a garnet-peridotite assemblage. It yields, based on mineral-specific infrared calibrations, Dopx/ol=5±1, Dcpx/ol= 10±2, and Dcpx/opx=1.9±0.4. While Dcpx/opx is in agreement (within error) with previous results from experimental studies and concentration ratios observed in mantle-derived peridotites, the Dpx/ol from this study are significantly lower than the values reported from mantle-derived xenoliths and also at odd with several previous experimental studies where melt and/or hydrous minerals co-exists with NAMs. The results confirm the sensitivity of hydrogen incorporation in olivine regarding the amount of water-derived species (H) in the system and/or the amount of water in the co-existing silicate melt. The results are in agreement with an important but incomplete dehydration of mantle-derived olivine occurring at depth, during transport by the host magma or during slow lava flow cooling at the surface. The rapid concentration modification in mantle pyroxenes also points out that pyroxenes might not be a hydrogen recorder as reliable as previously thought.

Oxidation and Destruction of Polyvinyl Alcohol under the Combined Action of Ozone-Oxygen Mixture and Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Zimin, Yu. S.; Kutlugil'dina, G. G.; Mustafin, A. G.

2018-03-01

The oxidative transformations of a polyvinyl alcohol in aqueous solutions are studied under the simultaneous action of the two oxidizing agents, an ozone-oxygen mixture and a hydrogen peroxide. Effective parameters a and b, which characterize the first and second channels of carboxyl group accumulation, respectively, grow linearly upon an increase in the initial concentration of H2O2. After the temperature dependence of a and b parameters (331-363 K) in a PVA + O3 + O2 + H2O2 + H2O reaction system is studied, the parameters of the activation of COOH group accumulation are found (where PVA is a polyvinyl alcohol). New data on the effect process conditions (length of oxidation, temperature, and hydrogen peroxide concentration) have on the degree of destructive transformations of polyvinyl alcohol in the investigated reaction system are obtained.

Degradation of 2,4,6-Trichlorophenol and hydrogen production simultaneously by TiO2 nanotubes/graphene composite

NASA Astrophysics Data System (ADS)

Slamet, Raudina

2017-11-01

Industrial waters in coal pyrolysis process, synthetic chemicals and oil and gas process contain phenol derivatives that are dangerous to the environment and needs to be removed, one of them is 2,4,6-Trichlorophenol. Degradation of 2,4,6-Trichlorophenol and hydrogen production simultaneously have been investigated using TiNT/Graphene composite at various graphene loading and initial concentration of 2,4,6-Trichlorophenol. Optimal graphene loading of 0.6 wt% was obtained in the simultaneous system with 89% elimination of 2,4,6-Trichlorophenol and 986 µmol of hydrogen production. Test results showed that addition of 2,4,6-Trichlorophenol would subsequently increased 2,4,6-Trichlorophenol conversion and enhanced hydrogen production linearly. 2.7 times greater hydrogen production was found in addition of 50 ppm 2,4,6-Trichlorophenol.

Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels.

PubMed

Papula, Suvi; Sarikka, Teemu; Anttila, Severi; Talonen, Juho; Virkkunen, Iikka; Hänninen, Hannu

2017-06-03

Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC) phases ferrite and α'-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α'-martensite increases the hydrogen-induced cracking susceptibility.

Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels

PubMed Central

Papula, Suvi; Sarikka, Teemu; Anttila, Severi; Talonen, Juho; Virkkunen, Iikka; Hänninen, Hannu

2017-01-01

Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC) phases ferrite and α’-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α’-martensite increases the hydrogen-induced cracking susceptibility. PMID:28772975

Bioelectrochemical ethanol production through mediated acetate reduction by mixed cultures.

PubMed

Steinbusch, Kirsten J J; Hamelers, Hubertus V M; Schaap, Joris D; Kampman, Christel; Buisman, Cees J N

2010-01-01

Biological acetate reduction with hydrogen is a potential method to convert wet biomass waste into ethanol. Since the ethanol concentration and reaction rates are low, this research studies the feasibility of using an electrode, in stead of hydrogen, as an electron donor for biological acetate reduction in conjunction of an electron mediator. Initially, the effect of three selected mediators on metabolic flows during acetate reduction with hydrogen was explored; subsequently, the best performing mediator was used in a bioelectrochemical system to stimulate acetate reduction at the cathode with mixed cultures at an applied cathode potential of -550 mV. In the batch test, methyl viologen (MV) was found to accelerate ethanol production 6-fold and increased ethanol concentration 2-fold to 13.5 +/- 0.7 mM compared to the control. Additionally, MV inhibited n-butyrate and methane formation, resulting in high ethanol production efficiency (74.6 +/- 6%). In the bioelectrochemical system, MV addition to an inoculated cathode led directly to ethanol production (1.82 mM). Hydrogen was coproduced at the cathode (0.0035 Nm(3) hydrogen m(-2) d(-1)), so it remained unclear whether acetate was reduced to ethanol by electrons supplied by the mediator or by hydrogen. As MV reacted irreversibly at the cathode, ethanol production stopped after 5 days.

Degradation of Acid Blue 25 in aqueous media using 1700kHz ultrasonic irradiation: ultrasound/Fe(II) and ultrasound/H(2)O(2) combinations.

PubMed

Ghodbane, Houria; Hamdaoui, Oualid

2009-06-01

In this work, the sonolytic degradation of an anthraquinonic dye, C.I. Acid Blue 25 (AB25), in aqueous phase using high frequency ultrasound waves (1700kHz) for an acoustic power of 14W was investigated. The sonochemical efficiency of the reactor was evaluated by potassium iodide dosimeter, Fricke reaction and hydrogen peroxide production yield. The three investigated methods clearly show the production of oxidizing species during sonication and well reflect the sonochemical effects of high frequency ultrasonic irradiation. The effect of operational conditions such as the initial AB25 concentration, solution temperature and pH on the degradation of AB25 was studied. Additionally, the influence of addition of salts on the degradation of dye was examined. The rate of AB25 degradation was dependent on initial dye concentration, pH and temperature. Addition of salts increased the degradation of dye. Experiments conducted using distilled and natural waters demonstrated that the degradation was more efficient in the natural water compared to distilled water. To increase the efficiency of AB25 degradation, experiments combining ultrasound with Fe(II) or H(2)O(2) were conducted. Fe(II) induced the dissociation of ultrasonically produced hydrogen peroxide, leading to additional OH radicals which enhance the degradation of dye. The combination of ultrasound with hydrogen peroxide looks to be a promising option to increase the generation of free radicals. The concentration of hydrogen peroxide plays a crucial role in deciding the extent of enhancement obtained for the combined process. The results of the present work indicate that ultrasound/H(2)O(2) and ultrasound/Fe(II) processes are efficient for the degradation of AB25 in aqueous solutions by high frequency ultrasonic irradiation.

Simultaneous production of 2,3-butanediol, ethanol and hydrogen with a Klebsiella sp. strain isolated from sewage sludge.

PubMed

Wu, Ken-Jer; Saratale, Ganesh D; Lo, Yung-Chung; Chen, Wen-Ming; Tseng, Ze-Jing; Chang, Ming-Ching; Tsai, Ben-Ching; Su, Ay; Chang, Jo-Shu

2008-11-01

A Klebsiella sp. HE1 strain isolated from hydrogen-producing sewage sludge was examined for its ability to produce H2 and other valuable soluble metabolites (e.g., ethanol and 2,3-butanediol) from sucrose-based medium. The effect of pH and carbon substrate concentration on the production of soluble and gaseous products was investigated. The major soluble metabolite produced from Klebsiella sp. HE1 was 2,3-butanediol, accounting for over 42-58% of soluble microbial products (SMP) and its production efficiency enhanced after increasing the initial culture pH to 7.3 (without pH control). The HE1 strain also produced ethanol (contributing to 29-42% of total SMP) and a small amount of lactic acid and acetic acid. The gaseous products consisted of H2 (25-36%) and CO2 (64-75%). The optimal cumulative hydrogen production (2.7 l) and hydrogen yield (0.92mol H2 mol sucrose(-1)) were obtained at an initial sucrose concentration of 30g CODl(-1) (i.e., 26.7gl(-1)), which also led to the highest production rate for H2 (3.26mmol h(-1)l(-1)), ethanol (6.75mmol h(-1)l(-1)) and 2,3-butanediol (7.14mmol h(-1)l(-1)). The highest yield for H2, ethanol and 2,3-butanediol was 0.92, 0.81 and 0.59molmol-sucrose(-1), respectively. As for the overall energy production performance, the highest energy generation rate was 27.7kJ h(-1)l(-1) and the best energy yield was 2.45kJmolsucrose(-1), which was obtained at a sucrose concentration of 30 and 20g CODl(-1), respectively.

Evaluation of Lighting Systems, Carbon Sources, and Bacteria Cultures on Photofermentative Hydrogen Production.

PubMed

Hu, Chengcheng; Choy, Sing-Ying; Giannis, Apostolos

2018-05-01

Fluorescent and incandescent lighting systems were applied for batch photofermentative hydrogen production by four purple non-sulfur photosynthetic bacteria (PNSB). The hydrogen production efficiency of Rhodopseudomonas palustris, Rhodobacter sphaeroides, Rhodobacter capsulatus, and Rhodospirillum rubrum was evaluated using different carbon sources (acetate, butyrate, lactate, and malate). Incandescent light was found to be more effective for bacteria cell growth and hydrogen production. It was observed that PNSB followed substrate selection criteria for hydrogen production. Only R. palustris was able to produce hydrogen using most carbon sources. Cell density was almost constant, but cell growth rate and hydrogen production were significantly varied under the different lighting systems. The kinetics study suggested that initial substrate concentration had a positive correlation with lag phase duration. Among the PNSB, R. palustris grew faster and had higher hydrogen yields of 1.58, 4.92, and 2.57 mol H 2 /mol using acetate, butyrate, and lactate, respectively. In the integrative approach with dark fermentation effluents rich in organic acids, R. palustris should be enriched in the phototrophic microbial consortium of the continuous hydrogen production system.

Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei

Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevantmore » step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H-insertion steps in the aqueous phase, unlike those in the vapor phase, during the hydrogenation of acetic acid on Ru clusters.« less

Removal of pharmaceuticals from MWTP effluent by nanofiltration and solar photo-Fenton using two different iron complexes at neutral pH.

PubMed

Miralles-Cuevas, S; Oller, I; Pérez, J A Sánchez; Malato, S

2014-11-01

In recent years, membrane technologies (nanofiltration (NF)/reverse osmosis (RO)) have received much attention for micropollutant separation from Municipal Wastewater Treatment Plant (MWTP) effluents. Practically all micropollutants are retained in the concentrate stream, which must be treated. Advanced Oxidation Processes (AOPs) have been demonstrated to be a good option for the removal of microcontaminants from water systems. However, these processes are expensive, and therefore, are usually combined with other techniques (such as membrane systems) in an attempt at cost reduction. One of the main costs in solar photo-Fenton comes from reagent consumption, mainly hydrogen peroxide and chemicals for pH adjustment. Thus, in this study, solar photo-Fenton was used to treat a real MWTP effluent with low initial iron (less than 0.2 mM) and hydrogen peroxide (less than 2 mM) concentrations. In order to work at neutral pH, iron complexing agents (EDDS and citrate) were used in the two cases studied: direct treatment of the MWTP effluent and treatment of the concentrate stream generated by NF. The degradation of five pharmaceuticals (carbamazepine, flumequine, ibuprofen, ofloxacin and sulfamethoxazole) spiked in the effluent at low initial concentrations (μg L(-1)) was monitored as the main variable in the pilot-plant-scale photo-Fenton experiments. In both effluents, pharmaceuticals were efficiently removed (>90%), requiring low accumulated solar energy (2 kJUV L(-1), key parameter in scaling up the CPC photoreactor) and low iron and hydrogen peroxide concentrations (reagent costs, 0.1 and 1.5 mM, respectively). NF provided a clean effluent, and the concentrate was positively treated by solar photo-Fenton with no significant differences between the direct MWTP effluent and NF concentrate treatments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biohythane production from marine macroalgae Sargassum sp. coupling dark fermentation and anaerobic digestion.

PubMed

Costa, José C; Oliveira, João V; Pereira, Maria A; Alves, Maria M; Abreu, Angela A

2015-08-01

Potential biohythane production from Sargassum sp. was evaluated in a two stage process. In the first stage, hydrogen dark fermentation was performed by Caldicellulosiruptor saccharolyticus. Sargassum sp. concentrations (VS) of 2.5, 4.9 and 7.4gL(-1) and initial inoculum concentrations (CDW) of 0.04 and 0.09gL(-1) of C. saccharolyticus were used in substrate/inoculum ratios ranging from 28 to 123. The end products from hydrogen production process were subsequently used for biogas production. The highest hydrogen and methane production yields, 91.3±3.3Lkg(-1) and 541±10Lkg(-1), respectively, were achieved with 2.5gL(-1) of Sargassum sp. (VS) and 0.09gL(-1)of inoculum (CDW). The biogas produced contained 14-20% of hydrogen. Potential energy production from Sargassum sp. in two stage process was estimated in 242GJha(-1)yr(-1). A maximum energy supply of 600EJyr(-1) could be obtained from the ocean potential area for macroalgae production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of a gas-liquid film plasma reactor for organic compound oxidation.

PubMed

Hsieh, Kevin; Wang, Huijuan; Locke, Bruce R

2016-11-05

A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas and a liquid water film was analyzed using methylene blue as a liquid phase hydroxyl radical scavenger and simultaneous measurements of hydrogen peroxide formation. The effects of liquid flow rate, liquid conductivity, concentration of dye, and the addition of ferrous ion on dye decoloration and degradation were determined. Higher liquid flow rates and concentrations of dye resulted in less decoloration percentages and hydrogen peroxide formation due to initial liquid conductivity effects and lower residence times in the reactor. The highest decoloration energy yield of dye found in these studies was 5.2g/kWh when using the higher liquid flow rate and adding the catalyst. The non-homogeneous nature of the plasma discharge favors the production of hydrogen peroxide in the plasma-liquid interface over the chemical oxidation of the organic in the bulk liquid phase and post-plasma reactions with the Fenton catalyst lead to complete utilization of the plasma-formed hydrogen peroxide. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of the mineralization of a mixture of phenolic pollutants under a ferrioxalate-induced solar photo-Fenton process.

PubMed

Monteagudo, J M; Durán, A; Aguirre, M; San Martín, I

2011-01-15

The mineralization of solutions containing a mixture of three phenolic compounds, gallic, p-coumaric and protocatechuic acids, in a ferrioxalate-induced solar photo-Fenton process was investigated. The reactions were carried out in a pilot plant consisting of a compound parabolic collector (CPC) solar reactor. An optimization study was performed combining a multivariate experimental design and neuronal networks that included the following variables: pH, temperature, solar power, air flow and initial concentrations of H(2)O(2), Fe(II) and oxalic acid. Under optimal conditions, total elimination of the original compounds and 94% TOC removal of the mixture were achieved in 5 and 194 min, respectively. pH and initial concentrations of H(2)O(2) and Fe(II) were the most significant factors affecting the mixture mineralization. The molar correlation between consumed hydrogen peroxide and removed TOC was always between 1 and 3. A detailed analysis of the reaction was presented. The values of the pseudo-first-order mineralization kinetic rate constant, k(TOC), increased as initial Fe(II) and H(2)O(2) concentrations and temperature increased. The optimum pH value also slightly increased with greater Fe(II) and hydrogen peroxide concentrations but decreased when temperature increased. OH and O(2)(-) radicals were the main oxidative intermediate species in the process, although singlet oxygen ((1)O(2)) also played a role in the mineralization reaction. Copyright © 2010 Elsevier B.V. All rights reserved.

Biohydrogen production from lactose: influence of substrate and nitrogen concentration.

PubMed

Moreno, R; Fierro, J; Fernández, C; Cuetos, M J; Gómez, X

2015-01-01

Hydrogen produced from renewable sources may be considered the energy vector of the future. However, reducing process costs is imperative in order to achieve this goal. In the present research, the effect of nitrogen (N), initial pH and substrate content for starting up the dark fermentative process was studied using the response surface methodology. Anaerobic digested dried sludge (biosolid pellets) was used as the inoculum. Synthetic wastewater was used as the substrate in batch reactors. A decrease in H2 production was observed with the increase in N and lactose concentrations. This drop was considerably greater when the concentration of lactose was at its lower level. Although the increase in lactose concentration results in a lower H2 production, the effect of N on the response is attenuated at higher levels of lactose. On the other hand, the effect of initial pH on the fermentation system was not significant. The evaluation on the process under semi-continuous conditions was performed using anaerobic sequencing batch reactors (ASBRs). The process was evaluated at different C/N ratios using synthetic wastewater. Results showed higher hydrogen yields with the gradual decrease in nitrogen content. The addition of cheese whey to the ASBR resulted in a H2 production rate of 0.18 L H2 L(-1) d(-1).

Dosimetry determines the initial OH radical concentration in fast photochemical oxidation of proteins (FPOP).

PubMed

Niu, Ben; Zhang, Hao; Giblin, Daryl; Rempel, Don L; Gross, Michael L

2015-05-01

Fast photochemical oxidation of proteins (FPOP) employs laser photolysis of hydrogen peroxide to give OH radicals that label amino acid side-chains of proteins on the microsecond time scale. A method for quantitation of hydroxyl radicals after laser photolysis is of importance to FPOP because it establishes a means to adjust the yield of •OH, offers the opportunity of tunable modifications, and provides a basis for kinetic measurements. The initial concentration of OH radicals has yet to be measured experimentally. We report here an approach using isotope dilution gas chromatography/mass spectrometry (GC/MS) to determine quantitatively the initial •OH concentration (we found ~0.95 mM from 15 mM H2O2) from laser photolysis and to investigate the quenching efficiencies for various •OH scavengers.

Activation of c-Jun N-terminal kinase and apoptosis in endothelial cells mediated by endogenous generation of hydrogen peroxide

NASA Technical Reports Server (NTRS)

Ramachandran, Anup; Moellering, Douglas; Go, Young-Mi; Shiva, Sruti; Levonen, Anna-Liisa; Jo, Hanjoong; Patel, Rakesh P.; Parthasarathy, Sampath; Darley-Usmar, Victor M.

2002-01-01

Reactive oxygen species have been implicated in the activation of signal transduction pathways. However, extracellular addition of oxidants such as hydrogen peroxide (H2O2) often requires concentrations that cannot be readily achieved under physiological conditions to activate biological responses such as apoptosis. Explanations for this discrepancy have included increased metabolism of H2O2 in the extracellular environment and compartmentalization within the cell. We have addressed this issue experimentally by examining the induction of apoptosis of endothelial cells induced by exogenous addition of H2O2 and by a redox cycling agent, 2,3-dimethoxy-1,4-naphthoquinone, that generates H2O2 in cells. Here we show that low nanomolar steady-state concentrations (0.1-0.5 nmol x min(-1) x 10(6) cells) of H2O2 generated intracellularly activate c-Jun N terminal kinase and initiate apoptosis in endothelial cells. A comparison with bolus hydrogen peroxide suggests that the low rate of intracellular formation of this reactive oxygen species results in a similar profile of activation for both c-Jun N terminal kinase and the initiation of apoptosis. However, a detailed analysis reveals important differences in both the duration and profile for activation of these signaling pathways.

Estimation of the hydrogen concentration in rat tissue using an airtight tube following the administration of hydrogen via various routes

PubMed Central

Liu, Chi; Kurokawa, Ryosuke; Fujino, Masayuki; Hirano, Shinichi; Sato, Bunpei; Li, Xiao-Kang

2014-01-01

Hydrogen exerts beneficial effects in disease animal models of ischemia-reperfusion injury as well as inflammatory and neurological disease. Additionally, molecular hydrogen is useful for various novel medical and therapeutic applications in the clinical setting. In the present study, the hydrogen concentration in rat blood and tissue was estimated. Wistar rats were orally administered hydrogen super-rich water (HSRW), intraperitoneal and intravenous administration of hydrogen super-rich saline (HSRS), and inhalation of hydrogen gas. A new method for determining the hydrogen concentration was then applied using high-quality sensor gas chromatography, after which the specimen was prepared via tissue homogenization in airtight tubes. This method allowed for the sensitive and stable determination of the hydrogen concentration. The hydrogen concentration reached a peak at 5 minutes after oral and intraperitoneal administration, compared to 1 minute after intravenous administration. Following inhalation of hydrogen gas, the hydrogen concentration was found to be significantly increased at 30 minutes and maintained the same level thereafter. These results demonstrate that accurately determining the hydrogen concentration in rat blood and organ tissue is very useful and important for the application of various novel medical and therapeutic therapies using molecular hydrogen. PMID:24975958

Degradation kinetics and mechanism of trace nitrobenzene by granular activated carbon enhanced microwave/hydrogen peroxide system.

PubMed

Tan, Dina; Zeng, Honghu; Liu, Jie; Yu, Xiaozhang; Liang, Yanpeng; Lu, Lanjing

2013-07-01

The kinetics of the degradation of trace nitrobenzene (NB) by a granular activated carbon (GAC) enhanced microwave (MW)/hydrogen peroxide (H202) system was studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiency were examined. It was found that the reaction rate fits well to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced the degradation rate of NB in water. Under a given condition (MW power 300 W, H202 dosage 10 mg/L, pH 6.85 and temperature (60 +/- 5)degrees C), the degradation rate of NB was 0.05214 min-1when 4 g/L GAC was added. In general, alkaline pH was better for NB degradation; however, the optimum pH was 8.0 in the tested pH value range of 4.0-12.0. At H202 dosage of 10 mg/L and GAC dosage of 4 g/L, the removal of NB was decreased with increasing initial concentrations of NB, indicating that a low initial concentration was beneficial for the degradation of NB. These results indicated that the MW/GAC/H202 process was effective for trace NB degradation in water. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction and dehydrogenation reaction enhanced NB degradation.

Hydrogen-Induced Plastic Deformation in ZnO

NASA Astrophysics Data System (ADS)

Lukáč, F.; Čížek, J.; Vlček, M.; Procházka, I.; Anwand, W.; Brauer, G.; Traeger, F.; Rogalla, D.; Becker, H.-W.

In the present work hydrothermally grown ZnO single crystals covered with Pd over-layer were electrochemically loaded with hydrogen and the influence of hydrogen on ZnO micro structure was investigated by positron annihilation spectroscopy (PAS). Nuclear reaction analysis (NRA) was employed for determination of depth profile of hydrogen concentration in the sample. NRA measurements confirmed that a substantial amount of hydrogen was introduced into ZnO by electrochemical charging. The bulk hydrogen concentration in ZnO determined by NRA agrees well with the concentration estimated from the transported charge using the Faraday's law. Moreover, a subsurface region with enhanced hydrogen concentration was found in the loaded crystals. Slow positron implantation spectroscopy (SPIS) investigations of hydrogen-loaded crystal revealed enhanced concentration of defects in the subsurface region. This testifies hydrogen-induced plastic deformation of the loaded crystal. Absorbed hydrogen causes a significant lattice expansion. At low hydrogen concentrations this expansion is accommodated by elastic straining, but at higher concentrations hydrogen-induced stress exceeds the yield stress in ZnO and plastic deformation of the loaded crystal takes place. Enhanced hydrogen concentration detected in the subsurface region by NRA is, therefore, due to excess hydrogen trapped at open volume defects introduced by plastic deformation. Moreover, it was found that hydrogen-induced plastic deformation in the subsurface layer leads to typical surface modification: formation of hexagonal shape pyramids on the surface due to hydrogen-induced slip in the [0001] direction.

Effects of furan derivatives on biohydrogen fermentation from wet steam-exploded cornstalk and its microbial community.

PubMed

Liu, Zhidan; Zhang, Chong; Wang, Linjun; He, Jianwei; Li, Baoming; Zhang, Yuanhui; Xing, Xin-Hui

2015-01-01

Understanding the role of furan derivatives, furfural (FUR) and 5-hydroxymethyl furfural (HMF), is important for biofuel production from lignocellulosic biomass. In this study, the effects of furan derivatives on hydrogen fermentation from wet steam-exploded cornstalk were investigated. The control experiments with only seed sludge indicated that HMF addition of up to 1g/L stimulated hydrogen production. Similar results were obtained using steam-exploded cornstalk as the feedstock. Hydrogen productivity was increased by up to 40% with the addition of HMF. In addition, over 90% of furan derivatives with an initial concentration below 1g/L were degraded. Pyosequencing showed that the addition of HMF and FUR resulted in different microbial communities. HMF led to a higher proportion of the genera Clostridium and Ruminococcaceae, supporting the increased hydrogen production. This study suggested that hydrogen fermentation could be a detoxifying step for steam-exploded cornstalk, and HMF and FUR exhibited different functions for hydrogen fermentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrocarbon polymeric binder for advanced solid propellant

NASA Technical Reports Server (NTRS)

Potts, J. E. (Editor)

1972-01-01

A series of DEAB initiated isoprene polymerizations were run in the 5-gallon stirred autoclave reactor. Polymerization run parameters such as initiator concentration and feed rate were correlated with the molecular weight to provide a basis for molecular weight control in future runs. Synthetic methods were developed for the preparation of n-1,3-alkadienes. By these methods, 1,3-nonadiene was polymerized using DEAB initiator to give an ester-telechelic polynonadiene. This was subsequently hydrogenated with copper chromite catalyst to give a hydroxyl terminated saturated liquid hydrocarbon prepolymer having greatly improved viscosity characteristics and a Tg 18 degrees lower than that of the hydrogenated polyisoprenes. The hydroxyl-telechelic saturated polymers prepared by the hydrogenolysis of ester-telechelic polyisoprene were reached with diisocyanates under conditions favoring linear chain extension gel permeation chromatography was used to monitor this condensation polymerization. Fractions having molecular weights above one million were produced.

Organic metamorphism in the California petroleum basins; Chapter B, Insights from extractable bitumen and saturated hydrocarbons

USGS Publications Warehouse

Price, Leigh C.

2000-01-01

Seventy-five shales from the Los Angeles, Ventura, and Southern San Joaquin Valley Basins were extracted and analyzed. Samples were chosen on the basis of ROCK-EVAL analyses of a much larger sample base. The samples ranged in burial temperatures from 40 ? to 220 ? C, and contained hydrogen-poor to hydrogen-rich organic matter (OM), based on OM visual typing and a correlation of elemental kerogen hydrogen to carbon ratios with ROCK-EVAL hydrogen indices. By extractable bitumen measurements, rocks with hydrogen- poor OM in the Los Angeles Basin began mainstage hydrocarbon (HC) generation by 90 ? C. The HC concentrations maximized by 165 ? C, and beyond 165 ? C, HC and bitumen concentrations and ROCK-EVAL hydrogen indices all began decreasing to low values reached by 220 ? C, where HC generation was largely complete. Rocks with hydrogen-poor OM in the Southern San Joaquin Valley Basin commenced mainstage HC generation at 135 ? C and HC concentrations maximized by 180 ? C. Above 180 ? C, HC and bitumen concentrations and ROCK-EVAL hydrogen indices all decreased to low values reached by 214 ? C, again the process of HC generation being largely complete. In both cases, bell-shaped HC-generation curves were present versus depth (burial temperature). Mainstage HC generation had not yet begun in Ventura Basin rocks with hydrogen-poor OM by 140 ? C. The apparent lower temperature for initiation of mainstage generation in the Los Angeles Basin is attributed to very recent cooling in that basin from meteoric-water flow. Thus, HC generation there most probably occurred at higher burial temperatures. In contrast, mainstage HC generation, and all aspects of organic metamorphism, were strongly suppressed in rocks with hydrogen-rich OM at temperatures as high as 198 ? C. For example, shales from the Wilmington field (Los Angeles Basin) from 180 ? to 198 ? C retained ROCK-EVAL hydrogen indices of 550- 700 and had saturated-HC coefficients of only 4-15 mg/g organic carbon. The rocks with hydrogen-rich OM were subjected to the same burial conditions as the rocks with hydrogenpoor OM. We attribute this suppression of organic metamorphism in this study primarily to much stronger bonds in the hydrogen-rich OM compared to the bonds in hydrogen-poor OM. Trends in bitumen compositions (qualitative characteristics) versus burial temperature were also very different for rocks with hydrogen-poor OM compared to that in rocks with hydrogen- rich OM. This observation demonstrated that the two OM types also had significantly different reaction pathways, in addition to different reaction kinetics. Strong exploration implications arise from these observations. Above 40?C, but before mainstage HC generation, a lowtemperature (pre-mainstage) HC generation occurred in all rocks, and all OM types, studied. This low-temperature generation resulted in significant qualitative changes in the bitumen and HCS (hydrocarbons) from rocks of all OM types, especially in rocks with hydrogen-rich OM, from 40 ? to 70 ? C. This, and previous studies, document that very high carbon-normalized concentrations of indigenous bitumen and HCS occur in late Neogene immature rocks of any OM type in all southern California basins. This characteristic is attributed to the low-temperature generation occurring in both sulfur-poor and sulfur-rich kerogens, which originally had unusually high concentrations of weak (15-40 Kcal/mole) bonds. These observations and considerations have marked relevance to exploration regarding the possible formation of commercial oil deposits at immature ranks in these basins. Other significant geochemical observations also result from this study.

Horseradish peroxidase-mediated decolourization of Orange II: modelling hydrogen peroxide utilization efficiency at different pH values.

PubMed

Morales Urrea, Diego Alberto; Haure, Patricia Mónica; García Einschlag, Fernando Sebastián; Contreras, Edgardo Martín

2018-05-09

Enzymatic decolourization of azo-dyes could be a cost-competitive alternative compared to physicochemical or microbiological methods. Stoichiometric and kinetic features of peroxidase-mediated decolourization of azo-dyes by hydrogen peroxide (P) are central for designing purposes. In this work, a modified version of the Dunford mechanism of peroxidases was developed. The proposed model takes into account the inhibition of peroxidases by high concentrations of P, the substrate-dependant catalatic activity of peroxidases (e.g. the decomposition of P to water and oxygen), the generation of oxidation products (OP) and the effect of pH on the decolourization kinetics of the azo-dye Orange II (OII). To obtain the parameters of the proposed model, two series of experiments were performed. In the first set, the effects of initial P concentration (0.01-0.12 mM) and pH (5-10) on the decolourization degree were studied at a constant initial OII concentration (0.045 mM). Obtained results showed that at pH 9-10 and low initial P concentrations, the consumption of P was mainly to oxidize OII. From the proposed model, an expression for the decolourization degree was obtained. In the second set of experiments, the effect of the initial concentrations of OII (0.023-0.090 mM), P (0.02-4.7 mM), HRP (34-136 mg/L) and pH (5-10) on the initial specific decolourization rate (q 0 ) was studied. As a general rule, a noticeable increase in q 0 was observed for pHs higher than 7. For a given pH, q 0 increased as a function of the initial OII concentration. Besides, there was an inhibitory effect of high P concentrations on q 0 . To asses the possibility of reusing the enzyme, repeated additions of OII and P were performed. Results showed that the enzyme remained active after six reuse cycles. A satisfactory accordance between the change of the absorbance during these experiments and absorbances calculated using the proposed model was obtained. Considering that this set of data was not used during the fitting procedure of the model, the agreement between predicted and experimental absorbances provides a powerful validation of the model developed in the present work.

30 CFR 250.490 - Hydrogen sulfide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... where neither the presence nor absence of H2S has been confirmed. Well-control fluid means drilling mud..., well logs, formation tests, cores and analysis of formation fluids; and (4) Submit a request for... initiate when the SO2 concentration in the atmosphere reaches 5 ppm; (20) Engineering controls to protect...

KOH concentration effect on the cycle life of nickel-hydrogen cells. 4: Results of failure analyse

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1989-01-01

Effects of KOH concentrations on failure modes and mechanisms of nickel-hydrogen cells were studied using long cycled boiler plate cells containing electrolytes of various KOH concentrations ranging 21 to 36 percent. Life of these cells were up to 40,000 cycles in an accelerated low earth orbit (LEO) cycle regime at 80 percent depth of discharge. An interim life test results were reported earlier in J. Power Sources, 22, 213-220, 1988. The results of final life test, end-of-life cell performance, and teardown analyses are discussed. These teardown analyses included visual observations, measurements of nickel electrode capacity in an electrolyte-flooded cell, dimensional changes of cell components, SEM studies on cell cross section, BET surface area and pore volume distribution in cycled nickel electrodes, and chemical analyses. Cycle life of a nickel-hydrogen cell was improved tremendously as KOH concentration was decreased from 36 to 31 percent and from 31 to 26 percent while effect of further concentration decrease was complicated as described in our earlier report. Failure mode of high concentration (31 to 36 percent) cells was gradual capacity decrease, while that of low concentration (21 to 26 percent) cells was mainly formation of a soft short. Long cycled (25,000 to 40,000 cycles) nickel electrodes were expanded more than 50 percent of the initial value, but no correlation was found between this expansion and measured capacity. All electrodes cycled in low concentration (21 to 26 percent) cells had higher capacity than those cycled in high concentration (31 to 36 percent) cells.

Modeling of the steam hydrolysis in a two-step process for hydrogen production by solar concentrated energy

NASA Astrophysics Data System (ADS)

Valle-Hernández, Julio; Romero-Paredes, Hernando; Pacheco-Reyes, Alejandro

2017-06-01

In this paper the simulation of the steam hydrolysis for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 to lower-valence cerium oxide, at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. The modeling of endothermic reduction step was presented at the Solar Paces 2015. This work shows the modeling of the exothermic step; the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For this model, three sections of the pipe where the reaction occurs were considered; the steam water inlet, the porous medium and the hydrogen outlet produced. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

Release of hydrogen from nanoconfined hydrides by application of microwaves

NASA Astrophysics Data System (ADS)

Sanz-Moral, Luis Miguel; Navarrete, Alexander; Sturm, Guido; Link, Guido; Rueda, Miriam; Stefanidis, Georgios; Martín, Ángel

2017-06-01

The release of hydrogen from solid hydrides by thermolysis can be improved by nanoconfinement of the hydride in a suitable micro/mesoporous support, but the slow heat transfer by conduction through the support can be a limitation. In this work, a C/SiO2 mesoporous material has been synthesized and employed as matrix for nanoconfinement of hydrides. The matrix showed high surface area and pore volume (386 m2/g and 1.41 cm3/g), which enabled the confinement of high concentrations of hydride. Furthermore, by modification of the proportion between C and SiO2, the dielectric properties of the complex could be modified, making it susceptible to microwave heating. As with this heating method the entire sample is heated simultaneously, the heat transfer resistances associated to conduction were eliminated. To demonstrate this possibility, ethane 1,2-diaminoborane (EDAB) was embedded on the C/SiO2 matrix at concentrations ranging from 11 to 31%wt using a wet impregnation method, and a device appropriate for hydrogen release from this material by application of microwaves was designed with the aid of a numerical simulation. Hydrogen liberation tests by conventional heating and microwaves were compared, showing that by microwave heating hydrogen release can be initiated and stopped in shorter times.

Innovative self-powered submersible microbial electrolysis cell (SMEC) for biohydrogen production from anaerobic reactors.

PubMed

Zhang, Yifeng; Angelidaki, Irini

2012-05-15

A self-powered submersible microbial electrolysis cell (SMEC), in which a specially designed anode chamber and external electricity supply were not needed, was developed for in situ biohydrogen production from anaerobic reactors. In batch experiments, the hydrogen production rate reached 17.8 mL/L/d at the initial acetate concentration of 410 mg/L (5 mM), while the cathodic hydrogen recovery ( [Formula: see text] ) and overall systemic coulombic efficiency (CE(os)) were 93% and 28%, respectively, and the systemic hydrogen yield ( [Formula: see text] ) peaked at 1.27 mol-H(2)/mol-acetate. The hydrogen production increased along with acetate and buffer concentration. The highest hydrogen production rate of 32.2 mL/L/d and [Formula: see text] of 1.43 mol-H(2)/mol-acetate were achieved at 1640 mg/L (20 mM) acetate and 100 mM phosphate buffer. Further evaluation of the reactor under single electricity-generating or hydrogen-producing mode indicated that further improvement of voltage output and reduction of electron losses were essential for efficient hydrogen generation. In addition, alternate exchanging the electricity-assisting and hydrogen-producing function between the two cell units of the SMEC was found to be an effective approach to inhibit methanogens. Furthermore, 16S rRNA genes analysis showed that this special operation strategy resulted same microbial community structures in the anodic biofilms of the two cell units. The simple, compact and in situ applicable SMEC offers new opportunities for reactor design for a microbial electricity-assisted biohydrogen production system. Copyright © 2012 Elsevier Ltd. All rights reserved.

21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining the...

21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining the...

21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining the...

21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining the...

21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining the...

Modelling of hydrogen transport in silicon solar cell structures under equilibrium conditions

NASA Astrophysics Data System (ADS)

Hamer, P.; Hallam, B.; Bonilla, R. S.; Altermatt, P. P.; Wilshaw, P.; Wenham, S.

2018-01-01

This paper presents a model for the introduction and redistribution of hydrogen in silicon solar cells at temperatures between 300 and 700 °C based on a second order backwards difference formula evaluated using a single Newton-Raphson iteration. It includes the transport of hydrogen and interactions with impurities such as ionised dopants. The simulations lead to three primary conclusions: (1) hydrogen transport across an n-type emitter is heavily temperature dependent; (2) under equilibrium conditions, hydrogen is largely driven by its charged species, with the switch from a dominance of negatively charged hydrogen (H-) to positively charged hydrogen (H+) within the emitter region critical to significant transport across the junction; and (3) hydrogen transport across n-type emitters is critically dependent upon the doping profile within the emitter, and, in particular, the peak doping concentration. It is also observed that during thermal processes after an initial high temperature step, hydrogen preferentially migrates to the surface of a phosphorous doped emitter, drawing hydrogen out of the p-type bulk. This may play a role in several effects observed during post-firing anneals in relation to the passivation of recombination active defects and even the elimination of hydrogen-related defects in the bulk of silicon solar cells.

Mathematical model of a parallel plate ammonia electrolyzer for combined wastewater remediation and hydrogen production.

PubMed

Estejab, Ali; Daramola, Damilola A; Botte, Gerardine G

2015-06-15

A mathematical model was developed for the simulation of a parallel plate ammonia electrolyzer to convert ammonia in wastewater to nitrogen and hydrogen under basic conditions. The model consists of fundamental transport equations, the ammonia oxidation kinetics at the anode, and the hydrogen evolution kinetics at the cathode of the electrochemical reactor. The model shows both qualitative and quantitative agreement with experimental measurements at ammonia concentrations found within wastewater (200-1200 mg L(-1)). The optimum electrolyzer performance is dependent on both the applied voltage and the inlet concentrations. Maximum conversion of ammonia to nitrogen at the rates of 0.569 and 0.766 mg L(-1) min(-1) are achieved at low (0.01 M NH4Cl and 0.1 M KOH) and high (0.07 M NH4Cl and 0.15 M KOH) inlet concentrations, respectively. At high and low concentrations, an initial increase in the cell voltage will cause an increase in the system response - current density generated and ammonia converted. These system responses will approach a peak value before they start to decrease due to surface blockage and/or depletion of solvated species at the electrode surface. Furthermore, the model predicts that by increasing the reactant and electrolyte concentrations at a certain voltage, the peak current density will plateau, showing an asymptotic response. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrogen speciation in synthetic quartz

USGS Publications Warehouse

Aines, R.D.; Kirby, S.H.; Rossman, G.R.

1984-01-01

The dominant hydrogen impurity in synthetic quartz is molecular H2O. H-OH groups also occur, but there is no direct evidence for the hydrolysis of Si-O-Si bonds to yield Si-OH HO-Si groups. Molecular H2O concentrations in the synthetic quartz crystals studied range from less than 10 to 3,300 ppm (H/Si), and decrease smoothly by up to an order of magnitude with distance away from the seed. OH- concentrations range from 96 to 715 ppm, and rise smoothly with distance away from the seed by up to a factor of three. The observed OH- is probably all associated with cationic impurities, as in natural quartz. Molecular H2O is the dominant initial hydrogen impurity in weak quartz. The hydrolytic weakening of quartz may be caused by the transformation H2O + Si-O-Si ??? 2SiOH, but this may be a transitory change with the SiOH groups recombining to form H2O, and the average SiOH concentration remaining very low. Synthetic quartz is strengthened when the H2O is accumulated into fluid inclusions and cannot react with the quartz framework. ?? 1984 Springer-Verlag.

Coupled laboratory experiments and numerical models for generating ice-depth profiles of steady-state hydrogen peroxide concentrations on radiolytically processed icy worlds.

NASA Astrophysics Data System (ADS)

Hand, K. P.; Carlson, R. W.

2007-12-01

The presence of hydrogen peroxide and condensed phase molecular oxygen on the surface of Europa is now well established [1,2] and laboratory experiments have repeatedly demonstrated the viability of various radiolytic processes for explaining the observations [see e.g. 3, 4]. To date, however, both the Europa observations and the laboratory work have been limited to only the upper few, or few tens of microns, of ice. The spectrum of charged particles incident on the surface of Europa penetrates deeper, and deposits energy over a much greater range, than any laboratory experiment has aimed to replicate [5, 6]. Here we present results from laboratory work on hydrogen peroxide production using energetic electrons (4 keV - 16 keV) and couple these results with a numerical model for the integrated steady-state density of hydrogen peroxide as a function of depth into the ice. Production rates and steady-state peroxide levels for a range of initial electron energies are used to generate functions for the number of peroxide molecules produced per initial electron as it penetrates through the ice. We examined the electron energy spectrum from 0.01 MeV to 10 MeV and accounted for electrons incident to the surface over the solid angle from cosine(theta) = 0.3-1.0, where theta is the angle from the normal to the surface. We found that, accounting for production and destruction as a function of energy deposition, steady-state hydrogen peroxide concentrations resulting from electron radiolysis likely increases by a factor of a few to an order of magnitude at a depth of a few hundred microns. In other words, the 0.13 percent by number abundance of peroxide observed by NIMS [1] may be a low-end value; at depth the peroxide concentration could increase to a few percent by number relative to water. [1] Carlson et al. 1999. [2] Spencer and Calvin, 2002. [3] Moore and Hudson, 2000. [4] Loeffler et al., 2006. [5] Cooper et al., 2001 [6] Paranicas et al., 2001.

Shifting the balance of fermentation products between hydrogen and volatile fatty acids: microbial community structure and function.

PubMed

Miceli, Joseph F; Torres, César I; Krajmalnik-Brown, Rosa

2016-12-01

Fermentation is a key process in many anaerobic environments. Varying the concentration of electron donor fed to a fermenting community is known to shift the distribution of products between hydrogen, fatty acids and alcohols. Work to date has focused mainly on the fermentation of glucose, and how the microbial community structure is affected has not been explored. We fed ethanol, lactate, glucose, sucrose or molasses at 100 me- eq. L -1 , 200 me- eq. L -1 or 400 me- eq. L -1 to batch-fed cultures with fermenting, methanogenic communities. In communities fed high concentrations of electron donor, the fraction of electrons channeled to methane decreased, from 34% to 6%, while the fraction of electrons channeled to short chain fatty acids increased, from 52% to 82%, averaged across all electron donors. Ethanol-fed cultures did not produce propionate, but did show an increase in electrons directed to acetate as initial ethanol concentration increased. In glucose, sucrose, molasses and lactate-fed cultures, propionate accumulation co-occurred with known propionate producing organisms. Overall, microbial communities were determined by the substrate provided, rather than its initial concentration, indicating that a change in community function, rather than community structure, is responsible for shifts in the fermentation products produced. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Consequences of CO2 solubility for hydrate formation from carbon dioxide containing water and other impurities.

PubMed

Kvamme, Bjørn; Kuznetsova, Tatiana; Jensen, Bjørnar; Stensholt, Sigvat; Bauman, Jordan; Sjøblom, Sara; Nes Lervik, Kim

2014-05-14

Deciding on the upper bound of water content permissible in a stream of dense carbon dioxide under pipeline transport conditions without facing the risks of hydrate formation is a complex issue. In this work, we outline and analyze ten primary routes of hydrate formation inside a rusty pipeline, with hydrogen sulfide, methane, argon, and nitrogen as additional impurities. A comprehensive treatment of equilibrium absolute thermodynamics as applied to multiple hydrate phase transitions is provided. We also discuss in detail the implications of the Gibbs phase rule that make it necessary to consider non-equilibrium thermodynamics. The analysis of hydrate formation risk has been revised for the dominant routes, including the one traditionally considered in industrial practice and hydrate calculators. The application of absolute thermodynamics with parameters derived from atomistic simulations leads to several important conclusions regarding the impact of hydrogen sulfide. When present at studied concentrations below 5 mol%, the presence of hydrogen sulfide will only support the carbon-dioxide-dominated hydrate formation on the phase interface between liquid water and hydrate formers entering from the carbon dioxide phase. This is in contrast to a homogeneous hydrate nucleation and growth inside the aqueous solution bulk. Our case studies indicate that hydrogen sulfide at higher than 0.1 mol% concentration in carbon dioxide can lead to growth of multiple hydrate phases immediately adjacent to the adsorbed water layers. We conclude that hydrate formation via water adsorption on rusty pipeline walls will be the dominant contributor to the hydrate formation risk, with initial concentration of hydrogen sulfide being the critical factor.

Direct hydrogen production from dilute-acid pretreated sugarcane bagasse hydrolysate using the newly isolated Thermoanaerobacterium thermosaccharolyticum MJ1.

PubMed

Hu, Bin-Bin; Zhu, Ming-Jun

2017-05-03

Energy shortage and environmental pollution are two severe global problems, and biological hydrogen production from lignocellulose shows great potential as a promising alternative biofuel to replace the fossil fuels. Currently, most studies on hydrogen production from lignocellulose concentrate on cellulolytic microbe, pretreatment method, process optimization and development of new raw materials. Due to no effective approaches to relieve the inhibiting effect of inhibitors, the acid pretreated lignocellulose hydrolysate was directly discarded and caused environmental problems, suggesting that isolation of inhibitor-tolerant strains may facilitate the utilization of acid pretreated lignocellulose hydrolysate. Thermophilic bacteria for producing hydrogen from various kinds of sugars were screened, and the new strain named MJ1 was isolated from paper sludge, with 99% identity to Thermoanaerobacterium thermosaccharolyticum by 16S rRNA gene analysis. The hydrogen yields of 11.18, 4.25 and 2.15 mol-H 2 /mol sugar can be reached at an initial concentration of 5 g/L cellobiose, glucose and xylose, respectively. The main metabolites were acetate and butyrate. More important, MJ1 had an excellent tolerance to inhibitors of dilute-acid (1%, g/v) pretreated sugarcane bagasse hydrolysate (DAPSBH) and could efficiently utilize DAPSBH for hydrogen production without detoxication, with a production higher than that of pure sugars. The hydrogen could be quickly produced with the maximum hydrogen production reached at 24 h. The hydrogen production reached 39.64, 105.42, 111.75 and 110.44 mM at 20, 40, 60 and 80% of DAPSBH, respectively. Supplementation of CaCO 3 enhanced the hydrogen production by 21.32% versus the control. These results demonstrate that MJ1 could directly utilize DAPSBH for biohydrogen production without detoxication and can serve as an excellent candidate for industrialization of hydrogen production from DAPSBH. The results also suggest that isolating unique strains from a particular environment offers an ideal way to conquer the related problems.

Measuring Hydrogen Concentrations in Metals

NASA Technical Reports Server (NTRS)

Danford, M. D.

1985-01-01

Commercial corrosion-measurement system adapted to electrochemical determination of hydrogen concentrations in metals. New technique based on diffusion of hydrogen through foil specimen of metal. In sample holder, hydrogen produced on one side of foil, either by corrosion reaction or by cathodic current. Hydrogen diffused through foil removed on other side by constant anode potential, which leads to oxidation of hydrogen to water. Anode current is measure of concentration of hydrogen diffusing through foil. System used to study hydrogen uptake, hydrogen elimination by baking, effect of heat treatment, and effect of electroplating on high-strength steels.

Leaching under Oxygen Pressure with Carbonate Solution Reduction by Hydrogen; LIXIVIATION OXYDANTE DES PECHBLENDES ET PRECIPITATION DE L'URANIUM PAR L'HYDROGENE. APPLICATION AUX MINERAIS PAUVRES FRANCAIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balaceanu, J.C.; Coussemant, F.; Mouret, P.

1959-10-31

A study was made of the basic characteristics of the leaching with carbonate solution under oxygen pressure and of the catalytic hydrogen reduction of low-grade French ores. Pure U/sub 3/O/sub 8/ was used in the investigations on leaching. The effects of oxygen pressure, temperature, initial surface of the oxide, surfuce during the course of the reaction, and concentration of the carbonate solution were determined. It was shown that the heterogeneous reactions involve a constant surface and two steps. A pilot plant experiment was made on a number of low-grade French ores. With ores the leaching is not sensitive to oxygenmore » pressure. Dilute solutions of sodium uranyl carbonate are obtained from the leaching. The uranium can be precipitated as an oxide of a lower valent state by catalytic reduction with hydrogen. The study of this step was made on pure solutions of sodium uranyl carbonate in the presence of nickel and platinum catalysts. The reaction is strongly modified by the presence of even low concentrations of sodium bicarbonate. The reaction velocity increases with hydrogen pressure up to 5 atm, but then becomes independent of the pressure. The precipitation is accelerated by an increase in temperature. (J.S.R.)« less

The influence of calcium supplementation on immobilised mixed microflora for biohydrogen production

NASA Astrophysics Data System (ADS)

Lutpi, Nabilah Aminah; Shian, Wong Yee; Izhar, Tengku Nuraiti Tengku; Zainol, Noor Ainee; Kiong, Yiek Wee

2017-04-01

This study is aim to study the effect of calcium as supplement in attached growth system towards the enhancement of the hydrogen production performance. The effects of calcium ion for thermophilic biohydrogen production were studied by using a mixed culture, from palm oil mill effluent sludge and granular activated carbon (GAC) as the support material. Batch experiments were carried out at 60°C by feeding the anaerobic sludge bacteria with sucrose-containing synthetic medium at an initial pH of 5.5 under anaerobic conditions. The repeated batch cultivation process was conducted by adding different concentration of calcium at range 0.025g/L to 0.15g/L. The results showed that the calcium at 0.1 g/L was the optimal concentration to enhance the fermentative hydrogen production under thermophilic (60°C) conditions.

Effect of hydrogen peroxide concentration on enamel color and microhardness.

PubMed

Borges, A B; Zanatta, R F; Barros, A C S M; Silva, L C; Pucci, C R; Torres, C R G

2015-01-01

The aim of this study was to investigate the effect of hydrogen peroxide gels with different concentrations (20%, 25%, 30%, and 35%) on enamel Knoop microhardness (KNH) as well as on changes in dental color (C). Cylindrical specimens of enamel/dentin (3-mm diameter and 2-mm thickness) were obtained from bovine incisors and randomly divided into six groups (n=20), according to the concentration of the whitening gel (20%, 25%, 30%, 35%, control, thickener). After polishing, initial values of KNH0 and color measurement, assessed by spectrophotometry using the CIE L*a*b* system, were taken from the enamel surface. The gels were applied on the enamel surface for 30 minutes, and immediate values of KNHi were taken. After seven days of being stored in artificial saliva, new measures of KNH7 and color (L7* a7* b7*, for calculating ΔE, ΔL, and Δb) were made. Data were submitted to statistical analysis of variance, followed by Tukey test (p<0.05). Differences in gel concentration and time did not influence the microhardness (p=0.54 and p=0.29, respectively). In relation to color changes, ΔE data showed that the 35% gel presented a higher color alteration than the 20% gel did (p=0.006). Bleaching with 35% hydrogen peroxide gel was more effective than with the 20% gel, without promoting significant adverse effects on enamel surface microhardness.

Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

NASA Technical Reports Server (NTRS)

Molnar, Melissa; Marek, C. John

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

A hydrogen-ferric ion rebalance cell operating at low hydrogen concentrations for capacity restoration of iron-chromium redox flow batteries

NASA Astrophysics Data System (ADS)

Zeng, Y. K.; Zhao, T. S.; Zhou, X. L.; Zou, J.; Ren, Y. X.

2017-06-01

To eliminate the adverse impacts of hydrogen evolution on the capacity of iron-chromium redox flow batteries (ICRFBs) during the long-term operation and ensure the safe operation of the battery, a rebalance cell that reduces the excessive Fe(III) ions at the positive electrolyte by using the hydrogen evolved from the negative electrolyte is designed, fabricated and tested. The effects of the flow field, hydrogen concentration and H2/N2 mixture gas flow rate on the performance of the hydrogen-ferric ion rebalance cell have been investigated. Results show that: i) an interdigitated flow field based rebalance cell delivers higher limiting current densities than serpentine flow field based one does; ii) the hydrogen utilization can approach 100% at low hydrogen concentrations (≤5%); iii) the apparent exchange current density of hydrogen oxidation reaction in the rebalance cell is proportional to the square root of the hydrogen concentration at the hydrogen concentration from 1.3% to 50%; iv) a continuous rebalance process is demonstrated at the current density of 60 mA cm-2 and hydrogen concentration of 2.5%. Moreover, the cost analysis shows that the rebalance cell is just approximately 1% of an ICRFB system cost.

FT-IR and computer modeling study of hydrogen bonding in N-alkyl acrylamide-toluene binary mixtures

NASA Astrophysics Data System (ADS)

Rumyantsev, Misha; Kazantsev, Oleg A.; Kamorina, Sofia I.; Kamorin, Denis M.; Sivokhin, Alexey P.

2016-10-01

Degree of hydrogen bonding driven self-association of N-(n-butyl)acrylamide, N-(n-octyl)acrylamide, N-(sec-octyl)acrylamide and N-(tert-octyl)acrylamide in toluene was investigated using IR spectroscopy and computer modeling methods. Consistent results were demonstrated in the treatment of the Amide-I (νC=O), Amide-II (δN-H and νC-N) and Amide-A (νN-H) absorption bands in IR spectra. Thus, the content of non-bonded (free) amide groups decreases from 83-98% to 8-20% and the content of linear polyassociates increases to 80-90% with an increase in monomer concentration from 0.5 wt% to 50 wt%. The content of cyclic dimers was equal to the value between 5 and 10% regardless of the initial monomer concentration. Dependences of the association degree and the content of the linear polyassociates on the concentration were found to be similar for all of the studied amides.

Biohydrogen production and wastewater treatment from organic wastewater by anaerobic fermentation with UASB

NASA Astrophysics Data System (ADS)

Wang, Lu; Li, Yong-feng; Wang, Yi-xuan; Yang, Chuan-ping

2010-11-01

In order to discuss the ability of H2-production and wastewater treatment, an up-flow anaerobic sludge bed (UASB) using a synthesized substrate with brown sugar wastewater was conducted to investigate the hydrogen yield, hydrogen producing rate, fermentation type of biohydrogen production, and the chemical oxygen demand (COD) removal rate, respectively. The results show that when the biomass of inoculants was 22.5 g SSṡL-1 and the influent concentration, hydraulic retention time (HRT) and initial pH were within the ranges of 4000˜6000 mg CODṡL-1, 8 h and 5-5.5, respectively, and the biohydrogen producing reactor could work effectively. The maximum hydrogen production rate is 5.98 Lṡd-1. Simultaneously, the concentration of ethanol and acetic acid is around 80% of the aqueous terminal production in the system, which presents the typical ethanol type fermentation. pH is at the range of 4˜4.5 during the whole performing process, however, the removal rate of COD is just about 20%. Therefore, it's still needs further research to successfully achieve the biohydrogen production and wastewater treatment, simultaneously.

Biotransformation of furanic and phenolic compounds with hydrogen gas production in a microbial electrolysis cell

DOE PAGES

Zeng, Xiaofei; Borole, Abhijeet P.; Pavlostathis, Spyros G.

2015-10-27

In this study, furanic and phenolic compounds are problematic byproducts resulting from the decomposition of lignocellulosic biomass during biofuel production. This study assessed the capacity of a microbial electrolysis cell (MEC) to produce hydrogen gas (H 2) using a mixture of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as the sole carbon and energy source in the bioanode. The rate and extent of biotransformation of the five compounds, efficiency of H 2 production, as well as the anode microbial community structure were investigated. The five compoundsmore » were completely transformed within 7-day batch runs and their biotransformation rate increased with increasing initial concentration. At an initial concentration of 1,200 mg/L (8.7 mM) of the mixture of the five compounds, their biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode coulombic efficiency was 44-69%, which is comparable to wastewater-fed MECs. The H 2 yield varied from 0.26 to 0.42 g H 2-COD/g COD removed in the anode, and the bioanode volume-normalized H 2 production rate was 0.07-0.1 L/L-d. The major identified fermentation products that did not transform further were catechol and phenol. Acetate was the direct substrate for exoelectrogenesis. Current and H 2 production were inhibited at an initial substrate concentration of 1,200 mg/L, resulting in acetate accumulation at a much higher level than that measured in other batch runs conducted with a lower initial concentration of the five compounds. The anode microbial community consisted of exoelectrogens, putative degraders of the five compounds, and syntrophic partners of exoelectrogens. The H 2 production route demonstrated in this study has proven to be an alternative to the currently used process of reforming natural gas to supply H 2 needed to upgrade bio-oils to stable hydrocarbon fuels.« less

Biotransformation of Furanic and Phenolic Compounds with Hydrogen Gas Production in a Microbial Electrolysis Cell.

PubMed

Zeng, Xiaofei; Borole, Abhijeet P; Pavlostathis, Spyros G

2015-11-17

Furanic and phenolic compounds are problematic byproducts resulting from the breakdown of lignocellulosic biomass during biofuel production. The capacity of a microbial electrolysis cell (MEC) to produce hydrogen gas (H2) using a mixture of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as the substrate in the bioanode was assessed. The rate and extent of biotransformation of the five compounds and efficiency of H2 production, as well as the structure of the anode microbial community, were investigated. The five compounds were completely transformed within 7-day batch runs and their biotransformation rate increased with increasing initial concentration. At an initial concentration of 1200 mg/L (8.7 mM) of the mixture of the five compounds, their biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode Coulombic efficiency was 44-69%, which is comparable to that of wastewater-fed MECs. The H2 yield varied from 0.26 to 0.42 g H2-COD/g COD removed in the anode, and the bioanode volume-normalized H2 production rate was 0.07-0.1 L/L-d. The biotransformation of the five compounds took place via fermentation followed by exoelectrogenesis. The major identified fermentation products that did not transform further were catechol and phenol. Acetate was the direct substrate for exoelectrogenesis. Current and H2 production were inhibited at an initial substrate concentration of 1200 mg/L, resulting in acetate accumulation at a much higher level than that measured in other batch runs conducted with a lower initial concentration of the five compounds. The anode microbial community consisted of exoelectrogens, putative degraders of the five compounds, and syntrophic partners of exoelectrogens. The MEC H2 production demonstrated in this study is an alternative to the currently used process of reforming natural gas to supply H2 needed to upgrade bio-oils to stable hydrocarbon fuels.

Enhanced hydrogen production from formic acid by formate hydrogen lyase-overexpressing Escherichia coli strains.

PubMed

Yoshida, Akihito; Nishimura, Taku; Kawaguchi, Hideo; Inui, Masayuki; Yukawa, Hideaki

2005-11-01

Genetic recombination of Escherichia coli in conjunction with process manipulation was employed to elevate the efficiency of hydrogen production in the resultant strain SR13 2 orders of magnitude above that of conventional methods. The formate hydrogen lyase (FHL)-overexpressing strain SR13 was constructed by combining FHL repressor (hycA) inactivation with FHL activator (fhlA) overexpression. Transcription of large-subunit formate dehydrogenase, fdhF, and large-subunit hydrogenase, hycE, in strain SR13 increased 6.5- and 7.0-fold, respectively, compared to the wild-type strain. On its own, this genetic modification effectively resulted in a 2.8-fold increase in hydrogen productivity of SR13 compared to the wild-type strain. Further enhancement of productivity was attained by using a novel method involving the induction of the FHL complex with high-cell-density filling of a reactor under anaerobic conditions. Continuous hydrogen production was achieved by maintaining the reactor concentration of the substrate (free formic acid) under 25 mM. An initial productivity of 23.6 g hydrogen h(-1) liter(-1) (300 liters h(-1) liter(-1) at 37 degrees C) was achieved using strain SR13 at a cell density of 93 g (dry weight) cells/liter. The hydrogen productivity reported in this work has great potential for practical application.

Small-scale, hydrogen-oxidizing-denitrifying bioreactor for treatment of nitrate-contaminated drinking water.

PubMed

Smith, Richard L; Buckwalter, Seanne P; Repert, Deborah A; Miller, Daniel N

2005-05-01

Nitrate removal by hydrogen-coupled denitrification was examined using flow-through, packed-bed bioreactors to develop a small-scale, cost effective system for treating nitrate-contaminated drinking-water supplies. Nitrate removal was accomplished using a Rhodocyclus sp., strain HOD 5, isolated from a sole-source drinking-water aquifer. The autotrophic capacity of the purple non-sulfur photosynthetic bacterium made it particularly adept for this purpose. Initial tests used a commercial bioreactor filled with glass beads and countercurrent, non-sterile flow of an autotrophic, air-saturated, growth medium and hydrogen gas. Complete removal of 2 mM nitrate was achieved for more than 300 days of operation at a 2-h retention time. A low-cost hydrogen generator/bioreactor system was then constructed from readily available materials as a water treatment approach using the Rhodocyclus strain. After initial tests with the growth medium, the constructed system was tested using nitrate-amended drinking water obtained from fractured granite and sandstone aquifers, with moderate and low TDS loads, respectively. Incomplete nitrate removal was evident in both water types, with high-nitrite concentrations in the bioreactor output, due to a pH increase, which inhibited nitrite reduction. This was rectified by including carbon dioxide in the hydrogen stream. Additionally, complete nitrate removal was accomplished with wastewater-impacted surface water, with a concurrent decrease in dissolved organic carbon. The results of this study using three chemically distinct water supplies demonstrate that hydrogen-coupled denitrification can serve as the basis for small-scale remediation and that pilot-scale testing might be the next logical step.

Small-scale, hydrogen-oxidizing-denitrifying bioreactor for treatment of nitrate-contaminated drinking water

USGS Publications Warehouse

Smith, R.L.; Buckwalter, S.P.; Repert, D.A.; Miller, D.N.

2005-01-01

Nitrate removal by hydrogen-coupled denitrification was examined using flow-through, packed-bed bioreactors to develop a small-scale, cost effective system for treating nitrate-contaminated drinking-water supplies. Nitrate removal was accomplished using a Rhodocyclus sp., strain HOD 5, isolated from a sole-source drinking-water aquifer. The autotrophic capacity of the purple non-sulfur photosynthetic bacterium made it particularly adept for this purpose. Initial tests used a commercial bioreactor filled with glass beads and countercurrent, non-sterile flow of an autotrophic, air-saturated, growth medium and hydrogen gas. Complete removal of 2 mM nitrate was achieved for more than 300 days of operation at a 2-h retention time. A low-cost hydrogen generator/bioreactor system was then constructed from readily available materials as a water treatment approach using the Rhodocyclus strain. After initial tests with the growth medium, the constructed system was tested using nitrate-amended drinking water obtained from fractured granite and sandstone aquifers, with moderate and low TDS loads, respectively. Incomplete nitrate removal was evident in both water types, with high-nitrite concentrations in the bioreactor output, due to a pH increase, which inhibited nitrite reduction. This was rectified by including carbon dioxide in the hydrogen stream. Additionally, complete nitrate removal was accomplished with wastewater-impacted surface water, with a concurrent decrease in dissolved organic carbon. The results of this study using three chemically distinct water supplies demonstrate that hydrogen-coupled denitrification can serve as the basis for small-scale remediation and that pilot-scale testing might be the next logical step.

Titanium hydride and hydrogen concentration in acid-etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems.

PubMed

Szmukler-Moncler, S; Bischof, M; Nedir, R; Ermrich, M

2010-09-01

Acid etching is a popular method to texture the surface of dental implants. During etching, the titanium oxide protective layer is dissolved and small native hydrogen ions diffuse into the unprotected implant surface. They enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH). The aim of this study was to measure the concentration of TiH at the implant surface and the total concentration of Hydrogen at five commercially available implant systems, made of either commercially pure (cp) titanium or titanium alloy. X-Ray diffraction (XRD) was conducted on each implant system to determine the compounds present at the implant surface. Following a TiH(2)/Ti calibration curve, the concentration of TiH was determined. Concentration of hydrogen in the implants was measured by the inert gas fusion thermal conductivity/infrared detection method. XRD data showed that TiH was present on all cp titanium implants but not on the alloyed implants. TiH concentration varied between 5% and 37%. Hydrogen concentration varied between 43 and 108 ppm, no difference in uptake was found between the cp titanium and alloyed implants. Low solubility of hydrogen in alpha-titanium is responsible for precipitation into TiH. Stronger etching conditions led to higher concentration of TiH2-x. High solubility of hydrogen in the beta-phase of the alloy is preventing hydrogen from precipitating into TiH. All implants, even those lacking TiH at the surface, were enriched with hydrogen. In all implants, hydrogen concentration was within the normative limit of 130 ppm.

Modeling of a CeO2 thermochemistry reduction process for hydrogen production by solar concentrated energy

NASA Astrophysics Data System (ADS)

Valle-Hernández, Julio; Romero-Paredes, Hernando; Arancibia-Bulnes, Camilo A.; Villafan-Vidales, Heidi I.; Espinosa-Paredes, Gilberto

2016-05-01

In this paper the simulation of the thermal reduction for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. For the thermochemical process, a solar reactor prototype is proposed; consisting of a cubic receptacle made of graphite fiber thermally insulated. Inside the reactor a pyramidal arrangement with nine tungsten pipes is housed. The pyramidal arrangement is made respect to the focal point where the reflected energy is concentrated. The solar energy is concentrated through the solar furnace of high radiative flux. The endothermic step is the reduction of the cerium oxide to lower-valence cerium oxide, at very high temperature. The exothermic step is the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For the modeling, three sections of the pipe where the reaction occurs were considered; the carrier gas inlet, the porous medium and the reaction products outlet. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

Exospheric hydrogen above St-Santin /France/

NASA Technical Reports Server (NTRS)

Derieux, A.; Lejeune, G.; Bauer, P.

1975-01-01

The temperature and hydrogen concentration of the exosphere was determined using incoherent scatter measurements performed above St. Santin from 1969 to 1972. The hydrogen concentration was deduced from measurements of the number density of positive hydrogen and oxygen ions. A statistical analysis is given of the hydrogen concentration as a function of the exospheric temperature and the diurnal variation of the hydrogen concentration is investigated for a few selected days of good quality observation. The data averaged with respect to the exospheric temperature without consideration of the local time exhibits a distribution consistent with a constant effective Jeans escape flux of about 9 x 10 to the 7 cu cm/s. The local time variation exhibits a maximum to minimum concentration ratio of at least 3.5.

Preparation and evaluation of tilmicosin-loaded hydrogenated castor oil nanoparticle suspensions of different particle sizes.

PubMed

Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong

2014-01-01

Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development.

Preparation and evaluation of tilmicosin-loaded hydrogenated castor oil nanoparticle suspensions of different particle sizes

PubMed Central

Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong

2014-01-01

Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development. PMID:24920902

Glycerophosphate-dependent peroxide production by brown fat mitochondria from newborn rats.

PubMed

Drahota, Z; Rauchova, H; Jesina, P; Vojtísková, A; Houstek, J

2003-03-01

Glycerophosphate (GP)-dependent, ferricyanide-induced hydrogen peroxide production was studied in brown adipose tissue mitochondria from newborn rats. Relations between the rate of hydrogen peroxide production and total amount of hydrogen peroxide produced at different GP and ferricyanide concentrations were determined. It was found that the rate of hydrogen peroxide production increases with increasing GP concentration and decreases with increasing ferricyanide concentration. Total amount of hydrogen peroxide produced increases with increasing ferricyanide concentration, however, not proportionally, and the efficiency of this process (oxygen/ferricyanide ratio) strongly declines. Data presented provide further information on the character and kinetics of hydrogen peroxide production by mammalian mitochondrial glycerophosphate dehydrogenase.

Effect of substrate concentration on hydrogen production by photo-fermentation in the pilot-scale baffled bioreactor.

PubMed

Lu, Chaoyang; Zhang, Zhiping; Zhou, Xuehua; Hu, Jianjun; Ge, Xumeng; Xia, Chenxi; Zhao, Jia; Wang, Yi; Jing, Yanyan; Li, Yameng; Zhang, Quanguo

2018-01-01

Effect of substrate concentration on photo-fermentative hydrogen production was studied with a self-designed 4m 3 pilot-scale baffled photo-fermentative hydrogen production reactor (BPHR). The relationships between parameters, such as hydrogen production rate (HPR, mol H 2 /m 3 /d), hydrogen concentration, pH value, oxidation-reduction potential, biomass concentration (volatile suspended solids, VSS) and reducing sugar concentration, during the photo-fermentative hydrogen production process were investigated. The highest HPR of 202.64±8.83mol/m 3 /d was achieved in chamber #3 at a substrate concentration of 20g/L. Hydrogen contents were in the range of 42.19±0.94%-49.71±0.27%. HPR increased when organic loading rate was increased from 3.3 to 20g/L/d, then decreased when organic loading rate was further increased to 25g/L/d. A maximum HPR of 148.65±4.19mol/m 3 /d was obtained when organic loading rate was maintained at 20g/L/d during continuous bio-hydrogen production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Steady-state generation of hydrogen peroxide: kinetics and stability of alcohol oxidase immobilized on nanoporous alumina.

PubMed

Kjellander, Marcus; Götz, Kathrin; Liljeruhm, Josefine; Boman, Mats; Johansson, Gunnar

2013-04-01

Alcohol oxidase from Pichia pastoris was immobilized on nanoporous aluminium oxide membranes by silanization and activation by carbonyldiimidazole to create a flow-through enzyme reactor. Kinetic analysis of the hydrogen peroxide generation was carried out for a number of alcohols using a subsequent reaction with horseradish peroxidase and ABTS. The activity data for the immobilized enzyme showed a general similarity with literature data in solution, and the reactor could generate 80 mmol H2O2/h per litre reactor volume. Horseradish peroxidase was immobilized by the same technique to construct bienzymatic modular reactors. These were used in both single pass mode and circulating mode. Pulsed injections of methanol resulted in a linear relation between response and concentration, allowing quantitative concentration measurement. The immobilized alcohol oxidase retained 58 % of initial activity after 3 weeks of storage and repeated use.

Heterogeneous photo-Fenton decolorization of Orange II over Al-pillared Fe-smectite: response surface approach, degradation pathway, and toxicity evaluation.

PubMed

Li, Huiyuan; Li, Yanli; Xiang, Luojing; Huang, Qianqian; Qiu, Juanjuan; Zhang, Hui; Sivaiah, Matte Venkata; Baron, Fabien; Barrault, Joel; Petit, Sabine; Valange, Sabine

2015-04-28

A ferric smectite clay material was synthesized and further intercalated with Al2O3 pillars for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the photo-Fenton decolorization of azo dye Orange II. UV irradiation was found to enhance the activity of the catalyst in the heterogeneous photo-Fenton process. Catalyst loading of 0.5g/L and hydrogen peroxide concentration of 13.5mM yielded a remarkable color removal, accompanied by excellent catalyst stability. The decolorization of Orange II followed the pseudo-first-order kinetics for initial dye concentrations from 20 to 160mg/L. The central composite design (CCD) based on the response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely initial pH, catalyst loading and hydrogen peroxide concentration, on the decolorization efficiency. The RSM model was derived and the response surface plots were developed based on the results. Moreover, the main intermediate products were separated and identified using gas chromatography-mass spectrometry (GC-MS) and a possible degradation pathway was proposed accordingly. The acute toxicity experiments illustrated that the Daphniamagna immobilization rate continuously decreased during 150min reaction, indicating that the effluent was suitable for sequential biological treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative analysis of hydrogen in SiO{sub 2}/SiN/SiO{sub 2} stacks using atom probe tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunimune, Yorinobu, E-mail: yorinobu.kunimune.vz@renesas.com; Shimada, Yasuhiro; Sakurai, Yusuke

2016-04-15

We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO{sub 2}/SiN/SiO{sub 2} (ONO) stack structure using ultraviolet laser-assisted atom probe tomography (APT). The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at. %). Thus, by subtracting the concentration of adsorbed hydrogen, the actualmore » hydrogen concentration in the SiN layer was quantified as approximately 1.0 at. %. This result was consistent with that obtained by elastic recoil detection analysis (ERDA), which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.« less

Computational Study of Near-limit Propagation of Detonation in Hydrogen-air Mixtures

NASA Technical Reports Server (NTRS)

Yungster, S.; Radhakrishnan, K.

2002-01-01

A computational investigation of the near-limit propagation of detonation in lean and rich hydrogen-air mixtures is presented. The calculations were carried out over an equivalence ratio range of 0.4 to 5.0, pressures ranging from 0.2 bar to 1.0 bar and ambient initial temperature. The computations involved solution of the one-dimensional Euler equations with detailed finite-rate chemistry. The numerical method is based on a second-order spatially accurate total-variation-diminishing (TVD) scheme, and a point implicit, first-order-accurate, time marching algorithm. The hydrogen-air combustion was modeled with a 9-species, 19-step reaction mechanism. A multi-level, dynamically adaptive grid was utilized in order to resolve the structure of the detonation. The results of the computations indicate that when hydrogen concentrations are reduced below certain levels, the detonation wave switches from a high-frequency, low amplitude oscillation mode to a low frequency mode exhibiting large fluctuations in the detonation wave speed; that is, a 'galloping' propagation mode is established.

Heterogeneous hydrogen distribution in orthopyroxene from veined mantle peridotite (San Carlos, Arizona): Impact of melt-rock interactions

NASA Astrophysics Data System (ADS)

Denis, Carole M. M.; Demouchy, Sylvie; Alard, Olivier

2018-03-01

Experimental studies have shown that hydrogen embedded as a trace element in mantle mineral structures affects the physical properties of mantle minerals and rocks. Nevertheless, hydrogen concentrations in mantle minerals are much lower than predicted by hydrogen solubilities obtained experimentally at high pressure and temperature. Here, we report textural analyses and major and trace element concentrations (including hydrogen) in upper mantle minerals from a spinel-bearing composite xenolith (dunite and pyroxenite) transported by silica-undersaturated mafic alkaline lavas from the San Carlos volcanic field (Arizona, USA). Our results suggest that the composite xenolith results from the percolation-reaction of a basaltic liquid within dunite channels, and is equilibrated with respect to trace elements. Equilibrium temperatures range between 1011 and 1023 °C. Hydrogen concentrations (expressed in ppm H2O by weight) obtained from unpolarized and polarized Fourier transform infrared spectroscopy are low, with average values <2 ppm H2O, 24 ppm H2O, and 53 ppm H2O for olivine, orthopyroxene, and clinopyroxene, respectively; hydrogen concentrations in olivine are below the detection limit. These low hydrogen concentrations are consistent with depletion by high melt-rock ratio interactions. Clinopyroxene hydrogen concentrations are homogeneous, whereas polarized infrared profile measurements across single-crystals of orthopyroxene reveal hydrogen-depleted rims, which are interpreted as the result of dehydration by ionic diffusion, possibly triggered by melt-rock interactions. We conclude that pyroxenes, like olivine, are unreliable hydrogen proxies, and that the remaining hydrogen concentrations observed in peridotites might only represent the 'tip of the iceberg' of the water stored in the Earth's upper mantle.

Bulk hydrogen abundances in the lunar highlands: Measurements from orbital neutron data

NASA Astrophysics Data System (ADS)

Lawrence, David J.; Peplowski, Patrick N.; Plescia, Jeffrey B.; Greenhagen, Benjamin T.; Maurice, Sylvestre; Prettyman, Thomas H.

2015-07-01

The first map of bulk hydrogen concentrations in the lunar highlands region is reported. This map is derived using data from the Lunar Prospector Neutron Spectrometer (LP-NS). We resolve prior ambiguities in the interpretation of LP-NS data with respect to non-polar hydrogen concentrations by comparing the LP-NS data with maps of the 750 nm albedo reflectance, optical maturity, and the wavelength position of the thermal infrared Christiansen Feature. The best explanation for the variations of LP-NS epithermal neutron data in the lunar highlands is variable amounts of solar-wind-implanted hydrogen. The average hydrogen concentration across the lunar highlands and away from the lunar poles is 65 ppm. The highest hydrogen values range from 120 ppm to just over 150 ppm. These values are consistent with the range of hydrogen concentrations from soils and regolith breccias at the Apollo 16 highlands landing site. Based on a moderate-to-strong correlation of epithermal neutrons and orbit-based measures of surface maturity, the map of highlands hydrogen concentration represents a new global maturity index that can be used for studies of the lunar soil maturation process. We interpret these hydrogen concentrations to represent a bulk soil property related to the long-term impact of the space environment on the lunar surface. Consequently, the derived hydrogen concentrations are not likely related to the surficial enhancements (top tens to hundreds of microns) or local time variations of OH/H2O measured with spectral reflectance data.

Effects of lithium-implantation on the hydrogen retention in both a-C:H and a-SiC:H materials submitted to deuterium bombardment

NASA Astrophysics Data System (ADS)

Barbier, G.; Ross, G. G.; El Khakani, M. A.; Chevarier, N.; Chevarier, A.

1997-02-01

The hydrogen release in plasma facing materials is a challenging problem for the hydrogen recycling. The hydrogen desorption from the a-C:H and a-SiC:H materials induced by deuterium bombardment has been investigated. Prior to the deuterium bombardment, both materials were implanted with different fluences of lithium ions. Before and after each irradiation, depth profiles of H, Li and deuterium were determined by nuclear microanalysis. After deuterium bombardment, it is shown that the retention of the initial hydrogen in both materials was enhanced by increasing the total dose of the implanted Li. For the a-C:H samples, the hydrogen desorption under deuterium bombardment was strongly reduced by lithium implantation. This effect was also evidenced in a-SiC:H samples, even though it is less spectacular than in a-C:H. Also, nuclear analyses showed that the retained dose of deuterium decreases when the lithium concentration increases. This could be a result of the formation of LiH bonds which occurs to the detriment of deuterium retention in both a-C:H and a-SiC:H materials. Preliminary results of both materials exposed to TdeV tokamak discharges confirms the role of Li in hydrogen retention, already observed in deuterium bombardment exposure.

Biodegradation of PCE and TCE in landfill leachate predicted from concentrations of molecular hydrogen: a case study.

PubMed

Gonsoulin, Mary E; Wilson, Barbara H; Wilson, John T

2004-12-01

The Refuse Hideaway Landfill (23-acre) received municipal, commercial, and industrial waste between 1974 and 1988. It was designed as a "natural attenuation" landfill and no provision was made to collect and treat contaminated water. Natural biological degradation through sequential reductive dechlorination had been an important mechanism for natural attenuation at the site. We used the concentration of hydrogen to forecast whether reductive dechlorination would continue over time at particular locations in the plume. Based on published literature, reductive dechlorination and natural attenuation of PCE, TCE, and cis-DCE can be expected in the aquifer if the concentration of molecular hydrogen in monitoring wells are adequate (> 1 nanomolar). Reductive dechlorination can be expected to continue as the ground water moves down gradient. Natural attenuation through reductive dechlorination is not expected in flow paths that originate at down gradient monitoring wells with low concentrations of molecular hydrogen (< 1 nanomolar). In three monitoring wells at the margin of the landfill and in five monitoring wells down gradient of the landfill, ground water maintained a molecular hydrogen concentration, ranging from 1.30 to 9.17 nanomolar, that is adequate for reductive dechlorination. In three of the monitoring wells far down gradient of the landfill, the concentration of molecular hydrogen (0.33 to 0.83 nanomolar) was not adequate to support reductive dechlorination. In wells with adequate concentrations of hydrogen, the concentrations of chlorinated volatile organic compounds were attenuated over time, or concentrations of chlorinated volatile organics were below the detection limit. In wells with inadequate concentrations of hydrogen, the concentrations of chlorinated organic compounds attenuated at a slower rate over time. In wells with adequate hydrogen the first order rate of attenuation of PCE, TCE, cis-DCE and total chlorinated volatile organic compounds varies from 0.38 to 0.18 per year. In wells without adequate hydrogen the rate varies from 0.015 to 0.006 per year.

Microstructural characterization of hydrogen induced cracking in TRIP-assisted steel by EBSD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laureys, A., E-mail: Aurelie.Laureys@UGent.be; Depover, T.; Petrov, R.

2016-02-15

The present work evaluates hydrogen induced cracking by performing an elaborate EBSD (Electron BackScatter Diffraction) study in a steel with transformation induced plasticity (TRIP-assisted steel). This type of steel exhibits a multiphase microstructure which undergoes a deformation induced phase transformation. Additionally, each microstructural constituent displays a different behavior in the presence of hydrogen. The aim of this study is to obtain a better understanding on the mechanisms governing hydrogen induced crack initiation and propagation in the hydrogen saturated multiphase structure. Tensile tests on notched samples combined with in-situ electrochemical hydrogen charging were conducted. The tests were interrupted at stresses justmore » after reaching the tensile strength, i.e. before macroscopic failure of the material. This allowed to study hydrogen induced crack initiation and propagation by SEM (Scanning Electron Microscopy) and EBSD. A correlation was found between the presence of martensite, which is known to be very susceptible to hydrogen embrittlement, and the initiation of hydrogen induced cracks. Initiation seems to occur mostly by martensite decohesion. High strain regions surrounding the hydrogen induced crack tips indicate that further crack propagation may have occurred by the HELP (hydrogen-enhanced localized plasticity) mechanism. Small hydrogen induced cracks located nearby the notch are typically S-shaped and crack propagation was dominantly transgranularly. The second stage of crack propagation consists of stepwise cracking by coalescence of small hydrogen induced cracks. - Highlights: • Hydrogen induced cracking in TRIP-assisted steel is evaluated by EBSD. • Tensile tests were conducted on notched hydrogen saturated samples. • Crack initiation occurs by a H-Enhanced Interface DEcohesion (HEIDE) mechanism. • Crack propagation involves growth and coalescence of small cracks. • Propagation is governed by the characteristics of phases on the crack path.« less

Experimental design applied to photo-Fenton treatment of highly methomyl-concentrated water.

PubMed

Micó, María M; Bacardit, Jordi; Sans, Carme

2010-01-01

This work is focused on the study of the suitability of the photo-Fenton process as a pretreatment for water highly contaminated with a methomyl commercial formulation in Advanced Greenhouses devices. Initial concentrations of reagents and pesticide were evaluated according to a central composite experimental design, with methomyl depletion and biocompatibility of the final effluent as response functions. A triad of optimal operation conditions could be determined, [Met.](0)=50 mg L(-1), [H(2)O(2)](0)=254 mg L(-1) and [Fe(2+)](0)=77 mg L(-1) for the best elimination yield and an acceptable BOD(5)/COD value, and initial concentration of methomyl can be established as the most important parameter for the performance of the treatment due to the limitations that impose on the hydrogen peroxide doses in the presence of the excipients of the commercial formulation.

Effect of hydrogen on the mechanical properties of titanium and its alloys

NASA Technical Reports Server (NTRS)

Beck, F. H.

1975-01-01

Occluded hydrogen resulting from cathodic charging of commercially pure titanium and titanium alloys, Ti-8Al-1Mo-1V and Ti-6Al-4V, was shown to cause embrittlement of the alloys. Embrittlement was a function of the interstitial hydrogen content rather than the amount of precipitated titanium hydride. The effects of hydrogen concentration on the critical strain for plastic instability along pure shear directions was determined for alloys Ti-8Al-1Mo-1V and Ti-5Al-2.5Sn. Hydrogen, in concentrations below that necessary for spontaneous hydride precipitation, increased the strain necessary for instability formation or instability failure. The strain rate sensitivity also increased with increasing hydrogen concentration. The effect of hydrogen on slip and twinning was determined for titanium single crystals. The critical resolved shear stress for prism slip was increased and the critical resolved shear stress for twinning was decreased with increasing hydrogen concentration.

The Use of Cryogenically Cooled 5A Molecular Sieves for Large Volume Reduction of Tritiated Hydrogen Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antoniazzi, A.B.; Bartoszek, F.E.; Sherlock, A.M.

2006-07-01

A commercial hydrogen isotope separation system based on gas chromatography (AGC-ISS) has been built. The system operates in two modes: stripping and volume reduction. The purpose of the stripping mode is to reduce a large volume of tritiated hydrogen gas to a small volume of tritium rich hydrogen gas. The results here illustrate the effectiveness of the AGC-ISS in the stripping and volume reduction phases. Column readiness for hydrogen isotope separation is confirmed by room temperature air separation tests. Production runs were initially carried out using natural levels of deuterium (110-160 ppm) in high purity hydrogen. After completion of themore » deuterium/hydrogen runs the system began operations with tritiated hydrogen. The paper presents details of the AGC-ISS design and results of tritium tests. The heart of the AGC-ISS consists of two packed columns (9 m long, 3.8 cm OD) containing 5A molecular sieve material of 40/60 mesh size. Each column has 5 individually controlled heaters along the length of the column and is coiled around an inverted inner dewar. The coiled column and inner dewar are both contained within an outer dewar. In this arrangement liquid nitrogen, used to cryogenically cool the columns, flows into and out off the annular space defined by the two dewars, allowing for alternate heating and cooling cycles. Tritiated hydrogen feed is injected in batch quantities. The batch size is variable with the maximum quantity restricted by the tritium concentration in the exhausted hydrogen. The stripping operations can be carried out in full automated mode or in full manual mode. The average cycle time between injections is about 75 minutes. To date, the maximum throughput achieved is 10.5 m{sup 3}/day. A total of 37.8 m{sup 3} of tritiated hydrogen has been processed during commissioning. The system has demonstrated that venting of >99.95% of the feed gas is possible while retaining 99.98% of the tritium. At a maximum tritium concentration of {approx}7 GBq/m{sup 3} (190 mCi/m{sup 3}), processing tritiated hydrogen gas at a rate of 8.1 m{sup 3} (NTP)/day results in an average tritium concentration in the process effluent line of 1.4 MBq/m{sup 3} (37 {mu}Ci/m{sup 3}). The average process exhaust flow, split between helium and hydrogen, is 10.6 litre/min. Product from the stripping phase is stored on a 5 kg depleted uranium bed. A 250 g depleted uranium bed is available for storage of enriched product. Several, ionization type, tritium sensors are located throughout the process to control emissions, control valve switching, and monitor evolution of tritiated species from the columns. (authors)« less

Enhanced Hydrogen Production from Formic Acid by Formate Hydrogen Lyase-Overexpressing Escherichia coli Strains

PubMed Central

Yoshida, Akihito; Nishimura, Taku; Kawaguchi, Hideo; Inui, Masayuki; Yukawa, Hideaki

2005-01-01

Genetic recombination of Escherichia coli in conjunction with process manipulation was employed to elevate the efficiency of hydrogen production in the resultant strain SR13 2 orders of magnitude above that of conventional methods. The formate hydrogen lyase (FHL)-overexpressing strain SR13 was constructed by combining FHL repressor (hycA) inactivation with FHL activator (fhlA) overexpression. Transcription of large-subunit formate dehydrogenase, fdhF, and large-subunit hydrogenase, hycE, in strain SR13 increased 6.5- and 7.0-fold, respectively, compared to the wild-type strain. On its own, this genetic modification effectively resulted in a 2.8-fold increase in hydrogen productivity of SR13 compared to the wild-type strain. Further enhancement of productivity was attained by using a novel method involving the induction of the FHL complex with high-cell-density filling of a reactor under anaerobic conditions. Continuous hydrogen production was achieved by maintaining the reactor concentration of the substrate (free formic acid) under 25 mM. An initial productivity of 23.6 g hydrogen h−1 liter−1 (300 liters h−1 liter−1 at 37°C) was achieved using strain SR13 at a cell density of 93 g (dry weight) cells/liter. The hydrogen productivity reported in this work has great potential for practical application. PMID:16269707

Hot-electron-induced hydrogen redistribution and defect generation in metal-oxide-semiconductor capacitors

NASA Astrophysics Data System (ADS)

Buchanan, D. A.; Marwick, A. D.; Dimaria, D. J.; Dori, L.

1994-09-01

Redistribution of hydrogen caused by hot-electron injection has been studied by hydrogen depth profiling with N-15 nuclear reaction analysis and electrical methods. Internal photoemission and Fowler-Nordheim injection were used for electron injection into large Al-gate and polysilicon-gate capacitors, respectively. A hydrogen-rich layer (about 10(exp 15) atoms/sq cm) observed at the Al/SiO2 interface was found to serve as the source of hydrogen during the hot-electron stress. A small fraction of the hydrogen released from this layer was found to be retrapped near the Si/SiO2 interface for large electron fluences in the Al-gate samples. Within the limit of detectability, about 10(exp 14)/sq cm, no hydrogen was measured using nuclear reaction analysis in the polysilicon-gate samples. The buildup of hydrogen at the Si/SiO2 interface exhibits a threshold at about 1 MV/cm, consistent with the threshold for electron heating in SiO2. In the 'wet' SiO2 films with purposely introduced excess hydrogen, the rate of hydrogen buildup at the Si/SiO2 interface is found to be significantly greater than that found in the 'dry' films. During electron injection, hydrogen redistribution was also confirmed via the deactivation of boron dopant in the silicon substrate. The generation rates of interface states, neutral electron traps, and anomalous positive charge are found to increase with increasing hydrogen buildup in the substrate and the initial hydrogen concentration in the film. It is concluded that the generation of defects is preceded by the hot-electron-induced release and transport of atomic hydrogen and it is the chemical reaction of this species within the metal-oxide-semiconductor structure that generates the electrically active defects.

Degradation of bisphenol A in water by the heterogeneous photo-Fenton.

PubMed

Jiang, Chuanrui; Xu, Zhencheng; Guo, Qingwei; Zhuo, Qiongfang

2014-01-01

Bisphenol A (BPA) is a kind of a controversial endocrine disruptor, and is ubiquitous in environment. The degradation of BPA with the heterogeneous photo-Fenton system was demonstrated in this study. The Fe-Y molecular sieve catalyst was prepared with the ion exchange method, and it was characterized by X-ray radiation diffraction (XRD). The effects ofpH, initial concentration of H2O2, initial BPA concentration, and irradiation intensity on the degradation of BPA were investigated. The service life and iron solubility of catalyst were also tested. XRD test shows that the major phase of the Fe-Y catalyst was Fe2O3. The method of heterogeneous photo-Fenton with Fe-Y catalyst was superior to photolysis, photo-oxidation with only hydrogen, heterogeneous Fenton, and homogeneous photo-Fenton approaches. pH value had no obvious effects on BPA degradation over the range of 2.2-7.2. The initial concentration of H2O2 had an optimal value of 20 x 10(-4) mol/L. The decrease in initial concentration of BPA was favourable for degradation. The intensity of ultraviolet irradiation has no obvious effect on the BPA removal. The stability tests indicated that the Fe-Y catalyst can be reused and iron solubility concentration ranged from NA to 0.0062 mg/L. Based on the results, the heterogeneous photo-Fenton treatment is the available method for the degradation of BPA.

Feasibility of oxidation-biodegradation serial foam spraying for total petroleum hydrocarbon removal without soil disturbance.

PubMed

Bajagain, Rishikesh; Park, Yoonsu; Jeong, Seung-Woo

2018-06-01

This study evaluated surface foam spraying technology, which avoids disturbing the soil, to deliver chemical oxidant and oil-degrading microbes to unsaturated soil for 30 days. Hydrogen peroxide foam was sprayed once onto diesel contaminated soil for oxidation of soil total petroleum hydrocarbon (TPH). Periodic bioaugmentation foam was sprayed every three days for biodegradation of soil TPH. Foam spraying employing oxidation-bioaugmentation serial application significantly reduced soil TPH concentrations to 550 mg·kg -1 from an initial 7470 mg·kg -1 . This study selected an optimal hydrogen peroxide concentration of 5%, which is capable of treating diesel oil contaminated soil following biodegradation without supplementary iron. Application of hydrogen peroxide by foam spraying increased the infiltration of hydrogen peroxide into the unsaturated soil. Surface foam spraying provided the aqueous phase of remediation agents evenly to the unsaturated soil and resulted in relatively similar soil water content throughout the soil. The easy and even infiltration of remediation reagents increased their contact with contaminants, resulting in enhanced oxidation and biodegradation. Fractional analysis of TPH showed C18-C22 present in diesel as biodegradation recalcitrant hydrocarbons. Recalcitrant hydrocarbons were reduced by 92% using oxidation-biodegradation serial foam, while biodegradation alone only reduced the recalcitrant fraction by 25%. Copyright © 2018 Elsevier B.V. All rights reserved.

Hydrous pyrolysis of polycyclic aromatic hydrocarbons and implications for the origin of PAH in hydrothermal petroleum

NASA Technical Reports Server (NTRS)

McCollom, T. M.; Simoneit, B. R.; Shock, E. L.

1999-01-01

Polycyclic aromatic hydrocarbons (PAH) are found at high concentrations in thermally altered organic matter and hydrothermally generated petroleum from sediment-covered seafloor hydro-thermal systems. To better understand the factors controlling the occurrence of PAH in thermally altered environments, the reactivities of two PAH, phenanthrene and anthracene, were investigated in hydrothermal experiments. The compounds were heated with water at 330 degrees C in sealed reaction vessels for durations ranging from 1 to 17 days. Iron oxide and sulfide minerals, formic acid, or sodium for-mate were included in some experiments to vary conditions within the reaction vessel. Phenanthrene was unreactive both in water alone and in the presence of minerals for up to 17 days, while anthracene was partially hydrogenated (5-10%) to di- and tetrahydroanthracene. In the presence of 6-21 vol % formic acid, both phenanthrene and anthracene reacted extensively to form hydrogenated and minor methylated derivatives, with the degree of hydrogenation and methylation increasing with the amount of formic acid. Phenanthrene was slightly hydrogenated in sodium formate solutions. The hydrogenation reactions could be readily reversed; heating a mixture of polysaturated phenanthrenes resulted in extensive dehydrogenation (aromatization) after 3 days at 330 degrees C. While the experiments demonstrate that reaction pathways for the hydrogenation of PAH under hydrothermal conditions exist, the reactions apparently require higher concentrations of H2 than are typical of geologic settings. The experiments provide additional evidence that PAH may be generated in hydrothermal systems from progressive aromatization and dealkylation of biologically derived polycyclic precursors such as steroids and terpenoids. Furthermore, the results indicate that PAH initially present in sediments or formed within hydrothermal systems are resistant to further thermal degradation during hydrothermal alteration.

WTP Waste Feed Qualification: Hydrogen Generation Rate Measurement Apparatus Testing Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stone, M. E.; Newell, J. D.; Smith, T. E.

The generation rate of hydrogen gas in the Hanford tank waste will be measured during the qualification of the staged tank waste for processing in the Hanford Tank Waste Treatment and Immobilization Plant. Based on a review of past practices in measurement of the hydrogen generation, an apparatus to perform this measurement has been designed and tested for use during waste feed qualification. The hydrogen generation rate measurement apparatus (HGRMA) described in this document utilized a 100 milliliter sample in a continuously-purged, continuously-stirred vessel, with measurement of hydrogen concentration in the vent gas. The vessel and lid had a combinedmore » 220 milliliters of headspace. The vent gas system included a small condenser to prevent excessive evaporative losses from the sample during the test, as well as a demister and filter to prevent particle migration from the sample to the gas chromatography system. The gas chromatograph was an on line automated instrument with a large-volume sample-injection system to allow measurement of very low hydrogen concentrations. This instrument automatically sampled the vent gas from the hydrogen generation rate measurement apparatus every five minutes and performed data regression in real time. The fabrication of the hydrogen generation rate measurement apparatus was in accordance with twenty three (23) design requirements documented in the conceptual design package, as well as seven (7) required developmental activities documented in the task plan associated with this work scope. The HGRMA was initially tested for proof of concept with physical simulants, and a remote demonstration of the system was performed in the Savannah River National Laboratory Shielded Cells Mockup Facility. Final verification testing was performed using non-radioactive simulants of the Hanford tank waste. Three different simulants were tested to bound the expected rheological properties expected during waste feed qualification testing. These simulants were tested at different temperatures using purge gas spiked with varying amounts of hydrogen to provide verification that the system could accurately measure the hydrogen in the vent gas at steady state.« less

THE RÔLE OF CERTAIN METALLIC IONS AS OXIDATION CATALYSTS

PubMed Central

Cook, S. F.

1926-01-01

1. When iron and copper are allowed to act on hydrogen peroxide and pyrogallol, enough carbon dioxide is produced to be readily measured. 2. The curve of the production of carbon dioxide may be fitted by an empirical equation, by the use of which the initial rate and the total amount of the oxidation may be determined. 3. The effect of the concentration of the reagents is different in each case, the effect varying as a fractional power of the copper and pyrogallol concentrations and as a logarithmic function of the hydrogen peroxide concentration. 4. When gold or silver is used the rate changes suddenly during the course of the reaction due to the precipitation of colloidal metal. 5. Mercury, cadmium, zinc, tin, and some other metals have no effect. 6. A theoretical set of equations is assumed to account for the action of the metals. 7. The metals are assumed to act by means of the formation of intermediate peroxides. 8. Experiments on the action of gold indicate that the metals are active in the ionic and not in the colloidal state. PMID:19872322

Effect of toluene concentration and hydrogen peroxide on Pseudomonas plecoglossicida cometabolizing mixture of cis-DCE and TCE in soil slurry.

PubMed

Li, Junhui; Lu, Qihong; de Toledo, Renata Alves; Lu, Ying; Shim, Hojae

2015-12-01

An indigenous Pseudomonas sp., isolated from the regional contaminated soil and identified as P. plecoglossicida, was evaluated for its aerobic cometabolic removal of cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE) using toluene as growth substrate in a laboratory-scale soil slurry. The aerobic simultaneous bioremoval of the cis-DCE/TCE/toluene mixture was studied under different conditions. Results showed that an increase in toluene concentration level from 300 to 900 mg/kg prolonged the lag phase for the bacterial growth, while the bioremoval extent for cis-DCE, TCE, and toluene declined as the initial toluene concentration increased. In addition, the cometabolic bioremoval of cis-DCE and TCE was inhibited by the presence of hydrogen peroxide as the additional oxygen source, while the bioremoval of toluene (900 mg/kg) was enhanced after 9 days of incubation. The subsequent addition of toluene did not improve the cometabolic bioremoval of cis-DCE and TCE. The obtained results would help to enhance the applicability of bioremediation technology to the mixed waste contaminated sites.

Generation of cavitation luminescence by laser-induced exothermic chemical reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung Park, Han; Diebold, Gerald J.

2013-08-14

Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxidemore » concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.« less

Sensitive Capacitive-type Hydrogen Sensor Based on Ni Thin Film in Different Hydrogen Concentrations.

PubMed

Pour, Ghobad Behzadi; Aval, Leila Fekri; Eslami, Shahnaz

2018-04-01

Hydrogen sensors are micro/nano-structure that are used to locate hydrogen leaks. They are considered to have fast response/recovery time and long lifetime as compared to conventional gas sensors. In this paper, fabrication of sensitive capacitive-type hydrogen gas sensor based on Ni thin film has been investigated. The C-V curves of the sensor in different hydrogen concentrations have been reported. Dry oxidation was done in thermal chemical vapor deposition furnace (TCVD). For oxidation time of 5 min, the oxide thickness was 15 nm and for oxidation time 10 min, it was 20 nm. The Ni thin film as a catalytic metal was deposited on the oxide film using electron gun deposition. Two MOS sensors were compared with different oxide film thickness and different hydrogen concentrations. The highest response of the two MOS sensors with 15 nm and 20 nm oxide film thickness in 4% hydrogen concentration was 87.5% and 65.4% respectively. The fast response times for MOS sensors with 15 nm and 20 nm oxide film thickness in 4% hydrogen concentration was 8 s and 21 s, respectively. By increasing the hydrogen concentration from 1% to 4%, the response time for MOS sensor (20nm oxide thickness), was decreased from 28s to 21s. The recovery time was inversely increased from 237s to 360s. The experimental results showed that the MOS sensor based on Ni thin film had a quick response and a high sensitivity.

The effect of stress on hydrogen uptake and desorption by A-286

NASA Technical Reports Server (NTRS)

Danford, Merlin D.

1991-01-01

The uptake and desorption of hydrogen by A-286 as a function of stress was studied using electrochemical methods. It was found that the apparent surface hydrogen concentration, the mean hydrogen concentration, and the hydrogen distribution uniformity all increased up to a stress level 50 percent of yield and decreased thereafter. The value of the hydrogen diffusion coefficient was relatively unaffected by stress while the percent of trapped hydrogen appeared to decrease with increasing stress.

Assessment of Potential Health Hazards During Emission of Hydrogen Sulphide from the Mine Exploiting Copper Ore Deposit - Case Study.

PubMed

Kupczewska-Dobecka, Małgorzata; Czerczak, Sławomir; Gromiec, Jan P; Konieczko, Katarzyna

2015-06-01

The aim of this study was to determine hydrogen sulphide concentration emitted from the mine extracting copper ore, to evaluate potential adverse health effects to the population living in four selected villages surrounding the exhaust shaft. Maximum measured concentration of hydrogen sulphide in the emitter is 286 µg/m³. Maximum emission calculated from the results of determinations of concentrations in the emitter is 0.44 kg/h. In selected villages hydrogen sulphide at concentrations exceeding 4 µg/m³ was not detected in any of the 5-hour air samples. In all locations, the estimated maximum 1-hour concentrations of hydrogen sulphide were below 1 µg/m³, and the estimated mean annual concentrations were below 0.53 µg/m³. Any risk to the health of people in the selected area is not expected. As indicated by the available data on the threshold odour, the estimated concentrations of hydrogen sulphide may be sensed by humans. Copyright© by the National Institute of Public Health, Prague 2015.

Meso-scale anisotropic hydrogen segregation near grain-boundaries in polycrystalline nickel characterized by EBSD/SIMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oudriss, A.; Le Guernic, Solenne; Wang, Zhaoying

2016-02-15

To study anisotropic hydrogen segregation and diffusion in nickel polycrystalline, Secondary Ion Mass Spectrometry (SIMS) and Electron Back Scattered Diffraction (EBSD) are integrated to investigate hydrogen distribution around grain boundaries. Hydrogen distribution in pre-charged samples were correlated with grain boundary character by integrating high-resolution grain microstructure from EBSD inverse pole figure map and low-resolution hydrogen concentration profile map from SIMS. This multimodal imaging instrumentation shows that grain boundaries in nickel can be categorized into two families based on behavior of hydrogen distribution crossing grain boundary: the first one includes random grain boundaries with fast hydrogen diffusivity, showing a sharp gapmore » for hydrogen concentration profile cross the grain boundaries. The second family are special Σ3n grain boundaries with low hydrogen diffusivity, showing a smooth gradient of hydrogen concentration cross the grain boundary. Heterogeneous hydrogen distributions due to grain boundary family revealed by SIMS/EBSD on mesoscale further validate the recent hydrogen permeation data and anisotropic ab-initio calculations in nanoscale. The results highlight the fact that grain boundaries character impacts hydrogen distribution significantly.« less

Long-term biological hydrogen production by agar immobilized Rhodobacter capsulatus in a sequential batch photobioreactor.

PubMed

Elkahlout, Kamal; Alipour, Siamak; Eroglu, Inci; Gunduz, Ufuk; Yucel, Meral

2017-04-01

In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar. Cell concentration was increased from 2.5 to 5 mg dcw mL -1 agar and it was found that increasing cell concentration of wild-type strain caused decrease in yield and productivity while these parameters improved by increasing cell concentration of mutant strain. Also, the hydrogen production time has extended from 17 days up to 60 days according to the process conditions and parameters. Hydrogen production by immobilized photosynthetic bacteria is a convenient technology for hydrogen production as it enables to produce hydrogen with high organic acid concentrations comparing to suspended cultures. Besides, immobilization increases the stability of the system and allowed sequential batch operation for long-term application.

40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

Code of Federal Regulations, 2013 CFR

2013-07-01

...-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated. 721...+) sodium zinc salt, hydrogen peroxide-initiated. (a) Chemical substance and significant new uses subject to... furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated (PMN P-09-388; CAS No...

40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

Code of Federal Regulations, 2014 CFR

2014-07-01

...-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated. 721...+) sodium zinc salt, hydrogen peroxide-initiated. (a) Chemical substance and significant new uses subject to... furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated (PMN P-09-388; CAS No...

40 CFR 721.10253 - Butanedioic acid, 2-methylene-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium...

Code of Federal Regulations, 2012 CFR

2012-07-01

...-, polymer with 2,5 furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated. 721...+) sodium zinc salt, hydrogen peroxide-initiated. (a) Chemical substance and significant new uses subject to... furanedione, copper(2+) manganese(2+) sodium zinc salt, hydrogen peroxide-initiated (PMN P-09-388; CAS No...

Lunar prospector epithermal neutrons from impact craters and landing sites: Implications for surface maturity and hydrogen distribution

USGS Publications Warehouse

Johnson, J. R.; Feldman, W.C.; Lawrence, D.J.; Maurice, S.; Swindle, T.D.; Lucey, P.G.

2002-01-01

Initial studies of neutron spectrometer data returned by Lunar Prospector concentrated on the discovery of enhanced hydrogen abundances near both lunar poles. However, the nonpolar data exhibit intriguing patterns that appear spatially correlated with surface features such as young impact craters (e.g., Tycho). Such immature crater materials may have low hydrogen contents because of their relative lack of exposure to solar wind-implanted volatiles. We tested this hypothesis by comparing epithermal* neutron counts (i.e., epithermal -0.057 ?? thermal neutrons) for Copernican-age craters classified as relatively young, intermediate, and old (as determined by previous studies of Clementine optical maturity variations). The epithermal* counts of the crater and continuous ejecta regions suggest that the youngest impact materials are relatively devoid of hydrogen in the upper 1 m of regolith. We also show that the mean hydrogen contents measured in Apollo and Luna landing site samples are only moderately well correlated to the epithermal* neutron counts at the landing sites, likely owing to the effects of rare earth elements. These results suggest that further work is required to define better how hydrogen distribution can be revealed by epithermal neutrons in order to understand more fully the nature and sources (e.g., solar wind, meteorite impacts) of volatiles in the lunar regolith.

Hydrogen generation via anaerobic fermentation of paper mill wastes.

PubMed

Valdez-Vazquez, Idania; Sparling, Richard; Risbey, Derek; Rinderknecht-Seijas, Noemi; Poggi-Varaldo, Héctor M

2005-11-01

The objective of this work was to determine the hydrogen production from paper mill wastes using microbial consortia of solid substrate anaerobic digesters. Inocula from mesophilic, continuous solid substrate anaerobic digestion (SSAD) reactors were transferred to small lab scale, batch reactors. Milled paper (used as a surrogate paper waste) was added as substrate and acetylene or 2-bromoethanesulfonate (BES) was spiked for methanogenesis inhibition. In the first phase of experiments it was found that acetylene at 1% v/v in the headspace was as effective as BES in inhibiting methanogenic activity. Hydrogen gas accumulated in the headspace of the bottles, reaching a plateau. Similar final hydrogen concentrations were obtained for reactors spiked with acetylene and BES. In the second phase of tests the headspace of the batch reactors was flushed with nitrogen gas after the first plateau of hydrogen was reached, and subsequently incubated, with no further addition of inhibitor nor substrate. It was found that hydrogen production resumed and reached a second plateau, although somewhat lower than the first one. This procedure was repeated a third time and an additional amount of hydrogen was obtained. The plateaux and initial rates of hydrogen accumulation decreased in each subsequent incubation cycle. The total cumulative hydrogen harvested in the three cycles was much higher (approx. double) than in the first cycle alone. We coined this procedure as IV-SSAH (intermittently vented solid substrate anaerobic hydrogen generation). Our results point out to a feasible strategy for obtaining higher hydrogen yields from the fermentation of industrial solid wastes, and a possible combination of waste treatment processes consisting of a first stage IV-SSAH followed by a second SSAD stage. Useful products of this approach would be hydrogen, organic acids or methane, and anaerobic digestates that could be used as soil amenders after post-treatment.

Ion cyclotron resonance heating for tungsten control in various JET H-mode scenarios

NASA Astrophysics Data System (ADS)

Goniche, M.; Dumont, R. J.; Bobkov, V.; Buratti, P.; Brezinsek, S.; Challis, C.; Colas, L.; Czarnecka, A.; Drewelow, P.; Fedorczak, N.; Garcia, J.; Giroud, C.; Graham, M.; Graves, J. P.; Hobirk, J.; Jacquet, P.; Lerche, E.; Mantica, P.; Monakhov, I.; Monier-Garbet, P.; Nave, M. F. F.; Noble, C.; Nunes, I.; Pütterich, T.; Rimini, F.; Sertoli, M.; Valisa, M.; Van Eester, D.; Contributors, JET

2017-05-01

Ion cyclotron resonance heating (ICRH) in the hydrogen minority scheme provides central ion heating and acts favorably on the core tungsten transport. Full wave modeling shows that, at medium power level (4 MW), after collisional redistribution, the ratio of power transferred to the ions and the electrons vary little with the minority (hydrogen) concentration n H/n e but the high-Z impurity screening provided by the fast ions temperature increases with the concentration. The power radiated by tungsten in the core of the JET discharges has been analyzed on a large database covering the 2013-2014 campaign. In the baseline scenario with moderate plasma current (I p = 2.5 MA) ICRH modifies efficiently tungsten transport to avoid its accumulation in the plasma centre and, when the ICRH power is increased, the tungsten radiation peaking evolves as predicted by the neo-classical theory. At higher current (3-4 MA), tungsten accumulation can be only avoided with 5 MW of ICRH power with high gas injection rate. For discharges in the hybrid scenario, the strong initial peaking of the density leads to strong tungsten accumulation. When this initial density peaking is slightly reduced, with an ICRH power in excess of 4 MW,very low tungsten concentration in the core (˜10-5) is maintained for 3 s. MHD activity plays a key role in tungsten transport and modulation of the tungsten radiation during a sawtooth cycle is correlated to the fishbone activity triggered by the fast ion pressure gradient.

Bactericidal Efficacy of Hydrogen Peroxide-Based Disinfectants Against Gram-Positive and Gram-Negative Bacteria on Stainless Steel Surfaces.

PubMed

Ríos-Castillo, Abel G; González-Rivas, Fabián; Rodríguez-Jerez, José J

2017-10-01

In order to develop disinfectant formulations that leverage the effectiveness of hydrogen peroxide (H 2 O 2 ), this study evaluated the bactericidal efficacy of hydrogen peroxide-based disinfectants against Gram-positive and Gram-negative bacteria on stainless steel surfaces. Low concentration of hydrogen peroxide as 0.5% with a cationic polymer, ethoxylated fatty alcohol, and ethyl alcohol had bactericidal efficacy (reductions ≥ 4 log 10 CFU/mL) against Escherichia coli, Staphylococcus aureus, Enterococcus hirae, and Pseudomonas aeruginosa. Hydrogen peroxide-based disinfectants were more effective against E. hirae and P. aeruginosa than to S. aureus. However, the efficacy of hydrogen peroxide against catalase positive bacteria such as S. aureus was increased when this compound was formulated with low concentrations of benzalkonium chloride or ethyl alcohol, lactic acid, sodium benzoate, cationic polymer, and salicylic acid. This study demonstrates that the use of hydrogen peroxide with other antimicrobial products, in adequate concentrations, had bactericidal efficacy in Gram-positive and Gram-negative bacteria on stainless steel surfaces, enabling to reduce the effective concentration of hydrogen peroxide. In the same way, the use of hydrogen peroxide-based disinfectants could reduce the concentrations of traditional disinfectants as quaternary ammonium compounds and therefore a reduction of their chemical residues in the environment after being used. The study of the bactericidal properties of environmentally nontoxic disinfectants such as hydrogen peroxide, sole or in formulations with other disinfectants against Gram-positive and Gram-negative bacteria can enhance the efficacy of various commonly used disinfectant formulations with the hygiene benefits that it entails. Also, the use of hydrogen peroxide formulations can reduce the concentration levels of products that generate environmental residues. © 2017 Institute of Food Technologists®.

Relationship of Hydrogen Bioavailability to Chromate Reduction in Aquifer Sediments

PubMed Central

Marsh, Tamara L.; McInerney, Michael J.

2001-01-01

Biological Cr(VI) reduction was studied in anaerobic sediments from an aquifer in Norman, Okla. Microcosms containing sediment and mineral medium were amended with various electron donors to determine those most important for biological Cr(VI) reduction. Cr(VI) (about 340 μM) was reduced with endogenous substrates (no donor), or acetate was added. The addition of formate, hydrogen, and glucose stimulated Cr(VI) reduction compared with reduction in unamended controls. From these sediments, an anaerobic Cr(VI)-utilizing enrichment was obtained that was dependent upon hydrogen for both growth and Cr(VI) reduction. No methane was produced by the enrichment, which reduced about 750 μM Cr(VI) in less than six days. The dissolved hydrogen concentration was used as an indicator of the terminal electron accepting process occurring in the sediments. Microcosms with sediments, groundwater, and chromate metabolized hydrogen to a concentration below the detection limits of the mercury vapor gas chromatograph. In microcosms without chromate, the hydrogen concentration was about 8 nM, a concentration comparable to that under methanogenic conditions. When these microcosms were amended with 500 μM Cr(VI), the dissolved hydrogen concentration quickly fell below the detection limits. These results showed that the hydrogen concentration under chromate-reducing conditions became very low, as low as that reported under nitrate- and manganese-reducing conditions, a result consistent with the free energy changes for these reactions. The utilization of formate, lactate, hydrogen, and glucose as electron donors for Cr(VI) reduction indicates that increasing the availability of hydrogen results in a greater capacity for Cr(VI) reduction. This conclusion is supported by the existence of an enrichment dependent upon hydrogen for growth and Cr(VI) reduction. PMID:11282599

High-concentration sugars production from corn stover based on combined pretreatments and fed-batch process.

PubMed

Yang, Maohua; Li, Wangliang; Liu, Binbin; Li, Qiang; Xing, Jianmin

2010-07-01

In this paper, high-concentration sugars were produced from pretreated corn stover. The raw corn stover was pretreated in a process combining steam explosion and alkaline hydrogen-peroxide. The hemicellulose and lignin were removed greatly. The cellulose content increased to 73.2%. Fed-batch enzymatic hydrolysis was initiated with 12% (w/v) solids loading and 20 FPU/g solids. Then, 6% solids were fed consecutively at 12, 36 and 60 h. After 144 h, the final concentrations of reducing sugar, glucose, cellobiose and xylose reached 220, 175, 22 and 20 g/L, respectively. The final total biomass conversion was 60% in fed-batch process. Copyright 2009 Elsevier Ltd. All rights reserved.

Non-linear dynamics of stable carbon and hydrogen isotope signatures based on a biological kinetic model of aerobic enzymatic methane oxidation.

PubMed

Vavilin, Vasily A; Rytov, Sergey V; Shim, Natalia; Vogt, Carsten

2016-06-01

The non-linear dynamics of stable carbon and hydrogen isotope signatures during methane oxidation by the methanotrophic bacteria Methylosinus sporium strain 5 (NCIMB 11126) and Methylocaldum gracile strain 14 L (NCIMB 11912) under copper-rich (8.9 µM Cu(2+)), copper-limited (0.3 µM Cu(2+)) or copper-regular (1.1 µM Cu(2+)) conditions has been described mathematically. The model was calibrated by experimental data of methane quantities and carbon and hydrogen isotope signatures of methane measured previously in laboratory microcosms reported by Feisthauer et al. [ 1 ] M. gracile initially oxidizes methane by a particulate methane monooxygenase and assimilates formaldehyde via the ribulose monophosphate pathway, whereas M. sporium expresses a soluble methane monooxygenase under copper-limited conditions and uses the serine pathway for carbon assimilation. The model shows that during methane solubilization dominant carbon and hydrogen isotope fractionation occurs. An increase of biomass due to growth of methanotrophs causes an increase of particulate or soluble monooxygenase that, in turn, decreases soluble methane concentration intensifying methane solubilization. The specific maximum rate of methane oxidation υm was proved to be equal to 4.0 and 1.3 mM mM(-1) h(-1) for M. sporium under copper-rich and copper-limited conditions, respectively, and 0.5 mM mM(-1) h(-1) for M. gracile. The model shows that methane oxidation cannot be described by traditional first-order kinetics. The kinetic isotope fractionation ceases when methane concentrations decrease close to the threshold value. Applicability of the non-linear model was confirmed by dynamics of carbon isotope signature for carbon dioxide that was depleted and later enriched in (13)C. Contrasting to the common Rayleigh linear graph, the dynamic curves allow identifying inappropriate isotope data due to inaccurate substrate concentration analyses. The non-linear model pretty adequately described experimental data presented in the two-dimensional plot of hydrogen versus carbon stable isotope signatures.

In situ Removal of Hydrogen Sulfide During Biogas Fermentation at Microaerobic Condition.

PubMed

Wu, Mengmeng; Zhang, Yima; Ye, Yuanyuan; Lin, Chunmian

2016-11-01

In this paper, rice straw was used as a raw material to produce biogas by anaerobic batch fermentation at 35 °C (mesophilic) or 55 °C (thermophilic). The hydrogen sulfide in biogas can be converted to S 0 or sulfate and removed in-situ under micro-oxygen environment. Trace oxygen was conducted to the anaerobic fermentation tank in amount of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, or 10.0 times stoichiometric equivalence, respectively, and the control experiment without oxygen addition was carried out. The results showed that the initial H 2 S concentrations of biogas are about 3235 ± 185 mg/m 3 (mesophilic) or 3394 ± 126 mg/m 3 (thermophilic), respectively. The desulfurization efficiency is 72.3 % (mesophilic) or 65.6 % (thermophilic), respectively, with oxygen addition by stoichiometric relation. When the oxygen feeded in amount of 2∼4 times, theoretical quantity demanded the removal efficiency of hydrogen sulfide could be over 92 %, and the oxygen residue in biogas could be maintained less than 0.5 %, which fit the requirement of biogas used as vehicle fuel or combined to the grid. Though further more oxygen addition could promote the removal efficiency of hydrogen sulfide (about 93.6 %), the oxygen residue in biogas would be higher than the application limit concentration (0.5 %). Whether mesophilic or thermophilic fermentation with the extra addition of oxygen, there were no obvious changes in the gas production and methane concentration. In conclusion, in-situ desulfurization can be achieved in the anaerobic methane fermentation system under micro-oxygen environment. In addition, air could be used as a substitute oxygen resource on the situation without strict demand for the methane content of biogas.

PEROXIDE DESTRUCTION TESTING FOR THE 200 AREA EFFLUENT TREATMENT FACILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

HALGREN DL

2010-03-12

The hydrogen peroxide decomposer columns at the 200 Area Effluent Treatment Facility (ETF) have been taken out of service due to ongoing problems with particulate fines and poor destruction performance from the granular activated carbon (GAC) used in the columns. An alternative search was initiated and led to bench scale testing and then pilot scale testing. Based on the bench scale testing three manganese dioxide based catalysts were evaluated in the peroxide destruction pilot column installed at the 300 Area Treated Effluent Disposal Facility. The ten inch diameter, nine foot tall, clear polyvinyl chloride (PVC) column allowed for the samemore » six foot catalyst bed depth as is in the existing ETF system. The flow rate to the column was controlled to evaluate the performance at the same superficial velocity (gpm/ft{sup 2}) as the full scale design flow and normal process flow. Each catalyst was evaluated on peroxide destruction performance and particulate fines capacity and carryover. Peroxide destruction was measured by hydrogen peroxide concentration analysis of samples taken before and after the column. The presence of fines in the column headspace and the discharge from carryover was generally assessed by visual observation. All three catalysts met the peroxide destruction criteria by achieving hydrogen peroxide discharge concentrations of less than 0.5 mg/L at the design flow with inlet peroxide concentrations greater than 100 mg/L. The Sud-Chemie T-2525 catalyst was markedly better in the minimization of fines and particle carryover. It is anticipated the T-2525 can be installed as a direct replacement for the GAC in the peroxide decomposer columns. Based on the results of the peroxide method development work the recommendation is to purchase the T-2525 catalyst and initially load one of the ETF decomposer columns for full scale testing.« less

One Step Biomass Gas Reforming-Shift Separation Membrane Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, Michael J.; Souleimanova, Razima

2012-12-28

GTI developed a plan where efforts were concentrated in 4 major areas: membrane material development, membrane module development, membrane process development, and membrane gasifier scale-up. GTI assembled a team of researchers to work in each area. Task 1.1 Ceramic Membrane Synthesis and Testing was conducted by Arizona State University (ASU), Task 1.2 Metallic Membrane Synthesis and Testing was conducted by the U.S. National Energy Technology Laboratory (NETL), Task 1.3 was conducted by SCHOTT, and GTI was to test all membranes that showed potential. The initial focus of the project was concentrated on membrane material development. Metallic and glass-based membranes weremore » identified as hydrogen selective membranes under the conditions of the biomass gasification, temperatures above 700C and pressures up to 30 atmospheres. Membranes were synthesized by arc-rolling for metallic type membranes and incorporating Pd into a glass matrix for glass membranes. Testing for hydrogen permeability properties were completed and the effects of hydrogen sulfide and carbon monoxide were investigated for perspective membranes. The initial candidate membrane of Pd80Cu20 chosen in 2008 was selected for preliminary reactor design and cost estimates. Although the H2A analysis results indicated a $1.96 cost per gge H2 based on a 5A (micron) thick PdCu membrane, there was not long-term operation at the required flux to satisfy the go/no go decision. Since the future PSA case yielded a $2.00/gge H2, DOE decided that there was insufficient savings compared with the already proven PSA technology to further pursue the membrane reactor design. All ceramic membranes synthesized by ASU during the project showed low hydrogen flux as compared with metallic membranes. The best ceramic membrane showed hydrogen permeation flux of 0.03 SCFH/ft2 at the required process conditions while the metallic membrane, Pd80Cu20 showed a flux of 47.2 SCFH/ft2 (3 orders of magnitude difference). Results from NETL showed Pd80Cu20 with the highest flux, therefore it was chosen as the initial and eventually, final candidate membrane. The criteria for choice were high hydrogen flux, long-term stability, and H2S tolerance. Results from SCHOTT using glass membranes showed a maximum of 0.25 SCFH/ft2, that is an order of magnitude better than the ceramic membrane but still two orders of magnitude lower than the metallic membrane. A membrane module was designed to be tested with an actual biomass gasifier. Some parts of the module were ordered but the work was stopped when a no go decision was made by the DOE.« less

Stress development in thin yttrium films on hard substrates during hydrogen loading

NASA Astrophysics Data System (ADS)

Dornheim, M.; Pundt, A.; Kirchheim, R.; Molen, S. J. v. d.; Kooij, E. S.; Kerssemakers, J.; Griessen, R.; Harms, H.; Geyer, U.

2003-06-01

Polycrystalline (0002)-textured yttrium (Y) films of 50-500 nm thickness on sapphire substrates were loaded electrolytically with hydrogen (H). The stresses which build up in these films were measured in situ using curvature measurements. The results are compared to the behavior of bulk Y-H. A linear elastic model is used to predict the behavior of clamped thin films. Basic properties of the bulk Y-H phase diagram and elastic constants resemble the measured values of the thin films. Compressive stress builds up during H-loading in the α-Y phase and in the (α-Y+β-YH2) two-phase field, showing an initial stress increase of -1.3 GPa per hydrogen concentration XH (compressive stress). While bulk Y-H samples are known to show a contraction in the β-YH2 phase during H loading, thin films show no evidence for such a contraction during the first loading cycle of the film. The stress remains constant in the bulk β-phase concentration range (ΔXH=0.1 H/Y). This is attributed to the narrow β-phase field (ΔXH=0.02 H/Y) of the thin film during the first loading. Only samples which have been kept at a hydrogen concentration of about 1.5 H/Y for weeks show tensile stress in the concentration range of the bulk β phase. Amazingly a stress increase of about +0.5 GPa/XH (tensile stress) is measured in the β+γ two-phase field. This is attributed to the smaller in-plane nearest-neighbor distance in the γ phase compared to the β phase. In the γ-phase field compressive stress is built up again, compensating the tensile stress. It increases by -1.3 GPa/XH. In total, the net stress in Y-H films remains comparably small. This could be a reason for the good mechanical stability of such Y-H switchable mirrors during H cycling.

In-situ synthesis of hydrogen peroxide in a novel Zn-CNTs-O2 system

NASA Astrophysics Data System (ADS)

Gong, Xiao-bo; Yang, Zhao; Peng, Lin; Zhou, An-lan; Liu, Yan-lan; Liu, Yong

2018-02-01

A novel strategy of in-situ synthesis of hydrogen peroxide (H2O2) was formulated and evaluated. Oxygen was selectively reduced to H2O2 combined with electrochemical corrosion of zinc in the Zn-CNTs-O2 system. The ratio of zinc and CNTs, heat treatment temperature, and operational parameters such as composite dosage, initial pH, solution temperature, oxygen flow rate were systematically investigated to improve the efficiency of H2O2 generation. The Zn-CNTs composite (weight ratio of 2.5:1) prepared at 500 °C showed the maximum H2O2 accumulation concentration of 293.51 mg L-1 within 60 min at the initial pH value of 3.0, Zn-CNTs dosage of 0.4 g and oxygen flow rate of 400 mL min-1. The oxygen was reduced through two-electron pathway to hydrogen peroxide on CNTs while the zinc was oxidized in the system and the dissolved zinc ions convert to zinc hydroxide and depositing on the surface of CNTs. It was proposed that the increment of direct H2O2 production was caused by the improvement of the formed Zn/CNTs corrosion cell. This provides promising strategy for in-situ synthesis and utilization of hydrogen peroxide in the novel Zn-CNTs-O2 system, which enhances the environmental and economic attractiveness of the use of H2O2 as green oxidant for wastewater treatments.

Ion and laser microprobes applied to the measurement of corrosion produced hydrogen on a microscopic scale.

NASA Technical Reports Server (NTRS)

Gray, H. R.

1972-01-01

Use of an ion microprobe and a laser microprobe to measure concentrations of corrosion-produced hydrogen on a microscopic scale. Hydrogen concentrations of several thousand ppm were measured by both analytical techniques below corroded and fracture surfaces of hot salt stress corroded titanium alloy specimens. This extremely high concentration compares with only about 100 ppm hydrogen determined by standard vacuum fusion chemical analyses of bulk samples. Both the ion and laser microprobes were used to measure hydrogen concentration profiles in stepped intervals to substantial depths below the original corroded and fracture surfaces. For the ion microprobe, the area of local analysis was 22 microns in diameter and for the laser microprobe, the area of local analysis was about 300 microns in diameter. The segregation of hydrogen below fracture surfaces supports a previously proposed theory that corrosion-produced hydrogen is responsible for hot salt stress corrosion embrittlement and cracking of titanium alloys. These advanced analytical techniques suggest great potential for many areas of stress corrosion and hydrogen embrittlement research, quality control, and field inspection of corrosion problems. For example, it appears possible that a contour map of hydrogen distribution at notch roots and crack tips could be quantitatively determined. Such information would be useful in substantiating current theories of stress corrosion and hydrogen embrittlement.

FY 2005 Annual Progress Report for the DOE Hydrogen Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

In cooperation with industry, academia, national laboratories, and other government agencies, the Department of Energy's Hydrogen Program is advancing the state of hydrogen and fuel cell technologies in support of the President's Hydrogen Fuel Initiative. The initiative seeks to develop hydrogen, fuel cell, and infrastructure technologies needed to make it practical and cost-effective for Americans to choose to use fuel cell vehicles by 2020. Significant progress was made in fiscal year 2005 toward that goal.

Hydrogen-Detection Apparatus

NASA Technical Reports Server (NTRS)

Ross, H. Richard; Bourgeois, Chris M.

1995-01-01

Apparatus continuously monitors concentration of hydrogen, at level ranging from few parts per million to several percent, in mixture of gases. Simple and fast, providing high sensitivity and linear response. Used to alert technicians to potentially explosive concentrations of residual hydrogen.

Was Ferrocyanide a Prebiotic Reagent?

NASA Technical Reports Server (NTRS)

Keefe, Anthony D.; Miller, Stanley L.

1996-01-01

Hydrogen cyanide is the starting material for a diverse array of prebiotic syntheses, including those of amino acids and purines. Hydrogen cyanide also reacts with ferrous ions to give ferrocyanide, and so it is possible that ferrocyanide was common in the early ocean. This can only be true if the hydrogen cyanide concentration was high enough and the rate of reaction of cyanide with ferrous ions was fast enough. We show experimentally that the rate of formation of ferrocyanide is rapid even at low concentrations of hydrogen cyanide in the pH range 6-8, and therefore an equilibrium calculation is valid. The equilibrium concentrations of ferrocyanide are calculated as a function of hydrogen cyanide concentration, pH and temperature. The steady state concentration of hydrogen cyanide depends on the rate of synthesis by electric discharges and ultraviolet light and the rate of hydrolysis, which depends on pH and temperature. Our conclusions show that ferrocyanide was a major species in the prebiotic ocean only at the highest production rates of hydrogen cyanide in a strongly reducing atmosphere and at temperatures of 0 C or less, although small amounts would have been present at lower hydrogen cyanide production rates. The prebiotic application of ferrocyanide as a source of hydrated electrons, as a photochemical replication process, and in semi-permeable membranes is discussed.

Sulfate and organic matter concentration in relation to hydrogen sulfide generation at inert solid waste landfill site - Limit value for gypsum.

PubMed

Asakura, Hiroshi

2015-09-01

In order to suggest a limit value for gypsum (CaSO4) for the suppression of hydrogen sulfide (H2S) generation at an inert solid waste landfill site, the relationship between raw material (SO4 and organic matter) for H2S generation and generated H2S concentration, and the balance of raw material (SO4) and product (H2S) considering generation and outflow were investigated. SO4 concentration should be less than approximately 100mg-SO4/L in order to suppress H2S generation to below 2000ppm. Total organic carbon (TOC) concentration should be less than approximately 200mg-C/L assuming a high SO4 concentration. The limit value for SO4 in the ground is 60mg-SO4/kg with 0.011wt% as gypsum dihydrate, i.e., approximately 1/10 of the limit value in inert waste as defined by the EU Council Decision (560mg-SO4/kg-waste). The limit value for SO4 in inert waste as defined by the EU Council Decision is high and TOC is strictly excluded. The cumulative amount of SO4 outflow through the liquid phase is much larger than that through the gas phase. SO4 concentration in pore water decreases with time, reaching half the initial concentration around day 100. SO4 reduction by rainfall can be expected in the long term. Copyright © 2015 Elsevier Ltd. All rights reserved.

Water-wetting surfaces as hydrate promoters during transport of carbon dioxide with impurities.

PubMed

Kuznetsova, Tatiana; Jensen, Bjørnar; Kvamme, Bjørn; Sjøblom, Sara

2015-05-21

Water condensing as liquid drops within the fluid bulk has traditionally been the only scenario accepted in the industrial analysis of hydrate risks. We have applied a combination of absolute thermodynamics and molecular dynamics modeling to analyze the five primary routes of hydrate formation in a rusty pipeline carrying dense carbon dioxide with methane, hydrogen sulfide, argon, and nitrogen as additional impurities. We have revised the risk analysis of all possible routes in accordance with the combination of the first and the second laws of thermodynamics to determine the highest permissible content of water. It was found that at concentrations lower than five percent, hydrogen sulfide will only support the formation of carbon dioxide-dominated hydrate from adsorbed water and hydrate formers from carbon dioxide phase rather than formation in the aqueous phase. Our results indicate that hydrogen sulfide leaving carbon dioxide for the aqueous phase will be able to create an additional hydrate phase in the aqueous region adjacent to the first adsorbed water layer. The growth of hydrate from different phases will decrease the induction time by substantially reducing the kinetically limiting mass transport across the hydrate films. Hydrate formation via adsorption of water on rusty walls will play the decisive role in hydrate formation risk, with the initial concentration of hydrogen sulfide being the critical factor. We concluded that the safest way to eliminate hydrate risks is to ensure that the water content of carbon dioxide is low enough to prevent water dropout via the adsorption mechanism.

Methods and apparatuses for deoxygenating pyrolysis oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baird, Lance Awender; Brandvold, Timothy A.; Frey, Stanley Joseph

Methods and apparatuses are provided for deoxygenating pyrolysis oil. A method includes contacting a pyrolysis oil with a deoxygenation catalyst in a first reactor at deoxygenation conditions to produce a first reactor effluent. The first reactor effluent has a first oxygen concentration and a first hydrogen concentration, based on hydrocarbons in the first reactor effluent, and the first reactor effluent includes an aromatic compound. The first reactor effluent is contacted with a dehydrogenation catalyst in a second reactor at conditions that deoxygenate the first reactor effluent while preserving the aromatic compound to produce a second reactor effluent. The second reactormore » effluent has a second oxygen concentration lower than the first oxygen concentration and a second hydrogen concentration that is equal to or lower than the first hydrogen concentration, where the second oxygen concentration and the second hydrogen concentration are based on the hydrocarbons in the second reactor effluent.« less

Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

DOE PAGES

Yan, Y.; Qian, S.; Littrell, K.; ...

2015-02-13

A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distributionmore » of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. This study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor will be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.« less

Porous media for catalytic renewable energy conversion

NASA Astrophysics Data System (ADS)

Hotz, Nico

2012-05-01

A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

Measurement of the para-hydrogen concentration in the ISIS moderators using neutron transmission and thermal conductivity

NASA Astrophysics Data System (ADS)

Romanelli, Giovanni; Rudić, Svemir; Zanetti, Matteo; Andreani, Carla; Fernandez-Alonso, Felix; Gorini, Giuseppe; Krzystyniak, Maciej; Škoro, Goran

2018-04-01

We present an experimental study to determine the para-hydrogen concentration in the hydrogen moderators at the ISIS pulsed neutron and muon source. The experimental characterisation is based on neutron transmission experiments performed on the VESUVIO spectrometer, and thermal conductivity measurements using the TOSCA para-hydrogen rig. A reliable estimation of the level of para-hydrogen concentration in the hydrogen moderators is of crucial importance in the framework of a current project to completely refurbish the first target station at ISIS. Moreover, we report a new measurement of the total neutron cross section for normal hydrogen at 15 K on the broad energy range 3 meV -10 eV suggesting a revision of the most recent nuclear libraries for incident neutron energies lower than 10 meV. Finally, we characterise systematic errors affecting the para-hydrogen level estimation due to conversion from para to ortho hydrogen, as a function of the time a batch of gas spends in every component of our gas panel and apparatus.

Real-Time Prediction of Tropical Cyclone Intensity Using COAMPS-TC

DTIC Science & Technology

2012-01-01

tropospheric (UT) cloud fields (i.e., cirrus clouds) long after the initial eruption cycle from gradual particle settling and re-entrainment back into the... troposphere . Volcanic sul- fur dioxide and hydrogen sulfide vapor molecules are photo-oxidized in the LS, forming gaseous sulphuric acid, which in...concentration over the eastern United States at 1815 UTC on the 17th shown in Fig. 5(a), derived from NASA Ozone Monitoring Instrument (OMI) measurements

Process for hydrogen isotope concentration between liquid water and hydrogen gas

DOEpatents

Stevens, William H.

1976-09-21

A process for hydrogen isotope exchange and concentration between liquid water and hydrogen gas, wherein liquid water and hydrogen gas are contacted, in an exchange section, with one another and with at least one catalyst body comprising at least one metal selected from Group VIII of the Periodic Table and preferably a support therefor, the catalyst body has a liquid-water-repellent, gas permeable polymer or organic resin coating, preferably a fluorinated olefin polymer or silicone coating, so that the isotope concentration takes place by two simultaneously occurring steps, namely, ##EQU1## WHILE THE HYDROGEN GAS FED TO THE EXCHANGE SECTION IS DERIVED IN A REACTOR VESSEL FROM LIQUID WATER THAT HAS PASSED THROUGH THE EXCHANGE SECTION.

Cellulosic hydrogen production with a sequencing bacterial hydrolysis and dark fermentation strategy.

PubMed

Lo, Yung-Chung; Bai, Ming-Der; Chen, Wen-Ming; Chang, Jo-Shu

2008-11-01

In this study, cellulose hydrolysis activity of two mixed bacterial consortia (NS and QS) was investigated. Combination of NS culture and BHM medium exhibited better hydrolytic activity under the optimal condition of 35 degrees C, initial pH 7.0, and 100rpm agitation. The NS culture could hydrolyze carboxymethyl cellulose (CMC), rice husk, bagasse and filter paper, among which CMC gave the best hydrolysis performance. The CMC hydrolysis efficiency increased with increasing CMC concentration from 5 to 50g/l. With a CMC concentration of 10g/l, the total reducing sugar (RS) production and the RS producing rate reached 5531.0mg/l and 92.9mg/l/h, respectively. Furthermore, seven H2-producing bacterial isolates (mainly Clostridium species) were used to convert the cellulose hydrolysate into H2 energy. With an initial RS concentration of 0.8g/l, the H2 production and yield was approximately 23.8ml/l and 1.21mmol H2/g RS (0.097mmol H2/g cellulose), respectively.

Theoretical studies of the decomposition mechanisms of 1,2,4-butanetriol trinitrate.

PubMed

Pei, Liguan; Dong, Kehai; Tang, Yanhui; Zhang, Bo; Yu, Chang; Li, Wenzuo

2017-12-06

Density functional theory (DFT) and canonical variational transition-state theory combined with a small-curvature tunneling correction (CVT/SCT) were used to explore the decomposition mechanisms of 1,2,4-butanetriol trinitrate (BTTN) in detail. The results showed that the γ-H abstraction reaction is the initial pathway for autocatalytic BTTN decomposition. The three possible hydrogen atom abstraction reactions are all exothermic. The rate constants for autocatalytic BTTN decomposition are 3 to 10 40 times greater than the rate constants for the two unimolecular decomposition reactions (O-NO 2 cleavage and HONO elimination). The process of BTTN decomposition can be divided into two stages according to whether the NO 2 concentration is above a threshold value. HONO elimination is the main reaction channel during the first stage because autocatalytic decomposition requires NO 2 and the concentration of NO 2 is initially low. As the reaction proceeds, the concentration of NO 2 gradually increases; when it exceeds the threshold value, the second stage begins, with autocatalytic decomposition becoming the main reaction channel.

Method for charging a hydrogen getter

DOEpatents

Tracy, C. Edwin; Keyser, Matthew A.; Benson, David K.

1998-01-01

A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10.sup.-4 torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures.

Deposition and separation of W and Mo from aqueous solutions with simultaneous hydrogen production in stacked bioelectrochemical systems (BESs): Impact of heavy metals W(VI)/Mo(VI) molar ratio, initial pH and electrode material.

PubMed

Huang, Liping; Li, Ming; Pan, Yuzhen; Quan, Xie; Yang, Jinhui; Puma, Gianluca Li

2018-04-16

The deposition and separation of W and Mo from aqueous solutions with simultaneous hydrogen production was investigated in stacked bioelectrochemical systems (BESs) composed of microbial electrolysis cell (1#) serially connected with parallel connected microbial fuel cell (2#). The impact of W/Mo molar ratio (in the range 0.01 mM : 1 mM and vice-versa), initial pH (1.5 to 4.0) and cathode material (stainless steel mesh (SSM), carbon rod (CR) and titanium sheet (TS)) on the BES performance was systematically investigated. The concentration of Mo(VI) was more influential than W(VI) in determining the rate of deposition of both metals and the rate of hydrogen production. Complete metal recovery was achieved at equimolar W/Mo ratio of 0.05 mM : 0.05 mM. The rates of metal deposition and hydrogen production increased at acidic pH, with the fastest rates at pH 1.5. The morphology of the metal deposits and the valence of the Mo were correlated with W/Mo ratio and pH. CR cathodes (2#) coupled with SSM cathodes (1#) achieved a significant rate of hydrogen production (0.82 ± 0.04 m 3 /m 3 /d) with W and Mo deposition (0.049 ± 0.003 mmol/L/h and 0.140 ± 0.004 mmol/L/h (1#); 0.025 ± 0.001 mmol/L/h and 0.090 ± 0.006 mmol/L/h (2#)). Copyright © 2018 Elsevier B.V. All rights reserved.

Thermodynamic Calculations of Hydrogen-Oxygen Detonation Parameters for Various Initial Pressures

NASA Technical Reports Server (NTRS)

Bollinger, Loren E.; Edse, Rudolph

1961-01-01

Composition, temperature, pressure and density behind a stable detonation wave and its propagation rate have been calculated for seven hydrogen-oxygen mixture at 1, 5, 25 and 100 atm initial pressure, and at an initial temperature of 40C. For stoichiometric mixtures that calculations also include an initial temperature of 200C. According to these calculations the detonation velocities of hydrogen-oxygen mixtures increase with increasing initial pressure, but decrease slightly when the initial temperature is raised from 40 to 200 C. The calculated detonation velocities agree satisfactorily with values determined experimentally. These values will be published in the near future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benson, D.K.; Tracy, C.E.

The real and perceived risks of hydrogen fuel use, particularly in passenger vehicles, will require extensive safety precautions including hydrogen leak detection. Conventional hydrogen gas sensors require electrical wiring and may be too expensive for deployment in multiple locations within a vehicle. In this recently initiated project, we are attempting to develop a reversible, thin-film, chemochromic sensor that can be applied to the end of a polymer optical fiber. The presence of hydrogen gas causes the film to become darker. A light beam transmitted from a central instrument in the vehicle along the sensor fibers will be reflected from themore » ends of the fiber back to individual light detectors. A decrease in the reflected light signal will indicate the presence and concentration of hydrogen in the vicinity of the fiber sensor. The typical thin film sensor consists of a layer of transparent, amorphous tungsten oxide covered by a very thin reflective layer of palladium. When the sensor is exposed to hydrogen, a portion of the hydrogen is dissociated, diffuses through the palladium and reacts with the tungsten oxide to form a blue insertion compound, H{sub X}WO{sub 3}- When the hydrogen gas is no longer present, the hydrogen will diffuse out of the H{sub X}WO{sub 3} and oxidize at the palladium/air interface, restoring the tungsten oxide film and the light signal to normal. The principle of this detection scheme has already been demonstrated by scientists in Japan. However, the design of the sensor has not been optimized for speed of response nor tested for its hydrogen selectivity in the presence of hydrocarbon gases. The challenge of this project is to modify the basic sensor design to achieve the required rapid response and assure sufficient selectivity to avoid false readings.« less

Integrated Temperature and Hydrogen Sensors with MEMS Technology

PubMed Central

Jiang, Hongchuan; Huang, Min; Yu, Yibing; Tian, Xiaoyu; Zhang, Wanli; Zhang, Jianfeng; Huang, Yifan; Yu, Kun

2017-01-01

In this work, a PdNi thin film hydrogen gas sensor with integrated Pt thin film temperature sensor was designed and fabricated using the micro-electro-mechanical system (MEMS) process. The integrated sensors consist of two resistors: the former, based on Pt film, is used as a temperature sensor, while the latter had the function of hydrogen sensing and is based on PdNi alloy film. The temperature coefficient of resistance (TCR) in both devices was measured and the output response of the PdNi film hydrogen sensor was calibrated based on the temperature acquired by the Pt temperature sensor. The SiN layer was deposited on top of Pt film to inhibit the hydrogen diffusion and reduce consequent disturbance on temperature measurement. The TCR of the PdNi film and the Pt film was about 0.00122/K and 0.00217/K, respectively. The performances of the PdNi film hydrogen sensor were investigated with hydrogen concentrations from 0.3% to 3% on different temperatures from 294.7 to 302.2 K. With the measured temperature of the Pt resistor and the TCR of the PdNi film, the impact of the temperature on the performances of the PdNi film hydrogen sensor was reduced. The output response, response time and recovery time of the PdNi film hydrogen sensors under the hydrogen concentration of 0.5%, 1.0%, 1.5% and 2.0% were measured at 313 K. The output response of the PdNi thin film hydrogen sensors increased with increasing hydrogen concentration while the response time and recovery time decreased. A cycling test between pure nitrogen and 3% hydrogen concentration was performed at 313 K and PdNi thin film hydrogen sensor demonstrated great repeatability in the cycling test. PMID:29301220

Study on gold concentrate leaching by iodine-iodide

NASA Astrophysics Data System (ADS)

Wang, Hai-xia; Sun, Chun-bao; Li, Shao-ying; Fu, Ping-feng; Song, Yu-guo; Li, Liang; Xie, Wen-qing

2013-04-01

Gold extraction by iodine-iodide solution is an effective and environment-friendly method. In this study, the method using iodine-iodide for gold leaching is proved feasible through thermodynamic calculation. At the same time, experiments on flotation gold concentrates were carried out and encouraging results were obtained. Through optimizing the technological conditions, the attained high gold leaching rate is more than 85%. The optimum process conditions at 25°C are shown as follows: the initial iodine concentration is 1.0%, the iodine-to-iodide mole ratio is 1:8, the solution pH value is 7, the liquid-to-solid mass ratio is 4:1, the leaching time is 4 h, the stirring intensity is 200 r/mim, and the hydrogen peroxide consumption is 1%.

E. S. R. determination of atomic hydrogen distribution in oxy-fuel flames burning at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bregeon, B.G.; Kadirgan, M.A.N.; Lamy, C.

1981-01-01

The authors have derived an experimental technique, using ESR spectroscopy, that allows this determination. A quartz burner equipped with an appropriate cooling system is placed directly in the ESR cavity. We obtained the hydrogen resonance signal and studied its variation for different positions of the flame inside the cavity. Hydrogen concentrations cannot be calculated directly from experimental data; hence we proceed indirectly to deconvoluate the resonance signal. This allows us to overcome the present severe handicap in obtaining atomic hydrogen concentrations in oxy-fuel flames from ESR measurements. Data obtained in this work, after temperature correction, give us the axial distributionmore » of hydrogen radicals for different oxy-propane and hydrogen-oxygen flames. These results show clearly that for all flames, the hydrogen radical concentration is maximum in a zone immediately above the inner cone. 13 refs.« less

Use of Response Surface Methodology to Optimize Culture Conditions for Hydrogen Production by an Anaerobic Bacterial Strain from Soluble Starch

NASA Astrophysics Data System (ADS)

Kieu, Hoa Thi Quynh; Nguyen, Yen Thi; Dang, Yen Thi; Nguyen, Binh Thanh

2016-05-01

Biohydrogen is a clean source of energy that produces no harmful byproducts during combustion, being a potential sustainable energy carrier for the future. Therefore, biohydrogen produced by anaerobic bacteria via dark fermentation has attracted attention worldwide as a renewable energy source. However, the hydrogen production capability of these bacteria depends on major factors such as substrate, iron-containing hydrogenase, reduction agent, pH, and temperature. In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by an anaerobic bacterial strain isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8 g L-1 to 12 g L-1), ferrous iron concentration (100 mg L-1 to 200 mg L-1), and l-cysteine concentration (300 mg L-1 to 500 mg L-1). RSM analysis showed that all three factors significantly influenced hydrogen production. Among them, the ferrous iron concentration presented the greatest influence. The optimum hydrogen concentration of 1030 mL L-1 medium was obtained with 10 g L-1 soluble starch, 150 mg L-1 ferrous iron, and 400 mg L-1 l-cysteine after 48 h of anaerobic fermentation. The hydrogen concentration produced by the PL strain was doubled after using RSM. The obtained results indicate that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacterial strain. Hydrogen production from low-cost organic substrates such as soluble starch using anaerobic fermentation methods may be one of the most promising approaches.

Method for charging a hydrogen getter

DOEpatents

Tracy, C.E.; Keyser, M.A.; Benson, D.K.

1998-09-15

A method for charging a sample of either a permanent or reversible getter material with a high concentration of hydrogen while maintaining a base pressure below 10{sup {minus}4} torr at room temperature involves placing the sample of hydrogen getter material in a chamber, activating the sample of hydrogen getter material, overcharging the sample of getter material through conventional charging techniques to a high concentration of hydrogen, and then subjecting the sample of getter material to a low temperature vacuum bake-out process. Application of the method results in a reversible hydrogen getter which is highly charged to maximum capacities of hydrogen and which concurrently exhibits minimum hydrogen vapor pressures at room temperatures. 9 figs.

Composition and method for polymer moderated catalytic water formation

DOEpatents

Shepodd, Timothy Jon

1999-01-01

A composition suitable for safely removing hydrogen from gaseous mixtures containing hydrogen and oxygen, particularly those mixtures wherein the hydrogen concentration is within the explosive range. The composition comprises a hydrogenation catalyst, preferably Pd dispersed on carbon, wherein the concentration of Pd is from about 1-10 wt %, dispersed in a polymeric material matrix. As well as serving as a matrix to contain the hydrogenation catalyst, the polymeric material, which is substantially unreactive to hydrogen, provides both a diffusion restriction to hydrogen and oxygen, thereby limiting the rate at which the reactants (hydrogen and oxygen) can diffuse to the catalyst surface and thus, the production of heat from the recombination reaction and as a heat sink.

Method for selectively preparing evoglucosenone (LGO) and other anhydrosugars from biomass in polar aprotic solvents

DOEpatents

Huber, George W.; Cao, Fei; Dumesic, James A.; Schwartz, Thomas J.

2016-06-28

A method to produce 5-hydroxymethylfurfural (HMF) is described in which a reactant including cellulose, lignocellulose, or a combination thereof, in a reaction mixture of a polar, aprotic solvent and an acid is reacted for a time, at a temperature, and at a hydrogen ion concentration wherein at least a portion of the cellulose or lignocellulose present in the reactant is converted to HMF. The reaction mixture is initially substantially devoid of water. As the reaction proceeds, dehydration of intermediates causes the water concentration in the reaction mixture to rise to no more than about 2.0 wt % water.

Method for selectively preparing 5-hydroxymethylfurfual (HMF) from biomass in polar aprotic solvents

DOEpatents

Dumesic, James A.; Huber, George W.; Weingarten, Ronen

2016-01-26

A method to produce 5-hydroxymethylfurfural (HMF) is described in which a reactant including cellulose, lignocellulose, or a combination thereof, in a reaction mixture of a polar, aprotic solvent and an acid is reacted for a time, at a temperature, and at a hydrogen ion concentration wherein at least a portion of the cellulose or lignocellulose present in the reactant is converted to HMF. The reaction mixture is initially substantially devoid of water. As the reaction proceeds, dehydration of intermediates causes the water concentration in the reaction mixture to rise to no more than about 0.2 wt % water.

Fermentative hydrogen production from Jerusalem artichoke by Clostridium tyrobutyricum expressing exo-inulinase gene.

PubMed

Jiang, Ling; Wu, Qian; Xu, Qing; Zhu, Liying; Huang, He

2017-08-11

Clostridium tyrobutyricum ATCC25755 has been reported as being able to produce significant quantities of hydrogen. In this study, the exo-inulinase encoding gene cloned from Paenibacillus polymyxa SC-2 was into the expression plasmid pSY6 and expressed in the cells of C. tyrobutyricum. The engineered C. tyrobutyricum strain efficiently fermented the inulin-type carbohydrates from Jerusalem artichoke, without any pretreatment being necessary for the production of hydrogen. A comparatively high hydrogen yield (3.7 mol/mol inulin-type sugar) was achieved after 96 h in a batch process with simultaneous saccharification and fermentation (SSF), with an overall volumetric productivity rate of 620 ± 60 mL/h/L when the initial total sugar concentration of the inulin extract was increased to 100 g/L. Synthesis of inulinase in the batch SSF culture was closely associated with strain growth until the end of the exponential phase, reaching a maximum activity of 28.4 ± 0.26 U/mL. The overall results show that the highly productive and abundant biomass crop Jerusalem artichoke can be a good substrate for hydrogen production, and that the application of batch SSF for its conversion has the potential to become a cost-effective process in the near future.

Hydrodynamical Modeling of Hydrogen Escape from Rocky Planets

NASA Astrophysics Data System (ADS)

Barringer, Daniel; Zugger, M.; Kasting, J.

2013-01-01

Hydrogen escape affects both the composition of primitive atmospheres of terrestrial planets and the planet’s state of oxidation. On Mars, hydrogen escape played a critical role in how long the planet remained in a warm wet state amenable to life. For both solar and extrasolar planets, hydrogen-rich atmospheres are better candidates for originating life by way of Miller-Urey-type prebiotic synthesis. However, calculating the rate of atmospheric hydrogen escape is difficult, for a number of reasons. First, the escape can be controlled either by diffusion through the homopause or by conditions in the upper atmosphere, whichever is slower. Second, both thermal and non-thermal escape mechanisms are typically important. Third, thermal escape itself can be subdivided into Jeans escape (thin upper atmosphere), and hydrodynamic escape, and hydrodynamic escape can be further subdivided into transonic escape and slower subsonic escape, depending on whether the exobase occurs above or below the sonic point. Additionally, the rate of escape for real terrestrial planet atmospheres, which are not 100% hydrogen, depends upon the concentration of infrared coolants, and upon heating and photochemistry driven largely by extreme ultraviolet (EUV) radiation. We have modified an existing 1-D model of hydrodynamic escape (F. Tian et al., JGR, 2008) to work in the high- hydrogen regime. Calculations are underway to determine hydrogen escape rates as a function of atmospheric H2 mixing ratio and the solar EUV flux. We will compare these rates with the estimated upper limit on the escape rate based on diffusion. Initial results for early Earth and Mars will later be extended to rocky exoplanets.

A dynamic system for the simulation of fasting luminal pH-gradients using hydrogen carbonate buffers for dissolution testing of ionisable compounds.

PubMed

Garbacz, Grzegorz; Kołodziej, Bartosz; Koziolek, Mirko; Weitschies, Werner; Klein, Sandra

2014-01-23

The hydrogen carbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions and covers the physiological pH range of the luminal fluids from pH 5.5 to about pH 8.4. The pH value of a hydrogen carbonate buffer is the result of a complex and dynamic interplay of the concentration of hydrogen carbonate ions, carbonic acid, the concentration of dissolved and solvated carbon dioxide and its partial pressure above the solution. The complex equilibrium between the different ions results in a thermodynamic instability of hydrogen carbonate solutions. In order to use hydrogen carbonate buffers with pH gradients in the physiological range and with the dynamics observed in vivo without changing the ionic strength of the solution, we developed a device (pHysio-grad®) that provides both acidification of the dissolution medium by microcomputer controlled carbon dioxide influx and alkalisation by degassing. This enables a continuous pH control and adjustment during dissolution of ionisable compounds. The results of the pH adjustment indicate that the system can compensate even rapid pH changes after addition of a basic or acidic moiety in amounts corresponding up to 90% of the overall buffer capacity. The results of the dissolution tests performed for a model formulation containing ionizable compounds (Nexium 20mg mups) indicate that both the simulated fasting intraluminal pH-profiles and the buffer species can significantly affect the dissolution process by changing the lag time prior to initial drug release and the release rate of the model compound. A prediction of the in vivo release behaviour of this formulation is thus most likely strongly related to the test conditions such as pH and buffer species. Copyright © 2013 Elsevier B.V. All rights reserved.

Application of Fenton oxidation to cosmetic wastewaters treatment.

PubMed

Bautista, P; Mohedano, A F; Gilarranz, M A; Casas, J A; Rodriguez, J J

2007-05-08

The removal of organic matter (TOC and COD) from a cosmetic wastewater by Fenton oxidation treatment has been evaluated. The operating conditions (temperature as well as ferrous ion and hydrogen peroxide dosage) have been optimized. Working at an initial pH equal to 3.0, a Fe(2+) concentration of 200 mg/L and a H(2)O(2) concentration to COD initial weight ratio corresponding to the theoretical stoichiometric value (2.12), a TOC conversion higher than 45% at 25 degrees C and 60% at 50 degrees C was achieved. Application of the Fenton oxidation process allows to reach the COD regional limit for industrial wastewaters discharges to the municipal sewer system. A simple kinetic analysis based on TOC was carried out. A second-order equation describes well the overall kinetics of the process within a wide TOC conversion range covering up to the 80-90% of the maximum achievable conversion.

Degradation of n-butylparaben and 4- tert-octylphenol in H 2O 2/UV system

NASA Astrophysics Data System (ADS)

BŁędzka, Dorota; Gryglik, Dorota; Olak, Magdalena; Gębicki, Jerzy L.; Miller, Jacek S.

2010-04-01

The degradation of two endocrine disrupting compounds: n-butylparaben (BP) and 4- tert-octylphenol (OP) in the H 2O 2/UV system was studied. The effect of operating variables: initial hydrogen peroxide concentration, initial substrate concentration, pH of the reaction solution and photon fluency rate of radiation at 254 nm on reaction rate was investigated. The influence of hydroxyl radical scavengers, humic acid and nitrate anion on reaction course was also studied. A very weak scavenging effect during BP degradation was observed indicating reactions different from hydroxyl radical oxidation. The second-order rate constants of BP and OP with OH radicals were estimated to be 4.8×10 9 and 4.2×10 9 M -1 s -1, respectively. For BP the rate constant equal to 2.0×10 10 M -1 s -1was also determined using water radiolysis as a source of hydroxyl radicals.

Deposition of amorphous silicon using a tubular reactor with concentric-electrode confinement

NASA Astrophysics Data System (ADS)

Conde, J. P.; Chan, K. K.; Blum, J. M.; Arienzo, M.; Cuomo, J. J.

1992-04-01

High-quality, hydrogenated amorphous silicon (a-Si:H) is deposited at room temperature by rf glow discharge at a high deposition rate using a tubular reactor with cylindrical symmetry (concentric-electrode plasma-enhanced chemical vapor deposition, CE-PECVD). Using the novel CE-PECVD design, room-temperature deposition of a-Si:H with growth rates up to 14 Å s-1, low hydrogen concentration (≲10%), and the bonded hydrogen in the Si-H monohydride configuration, is achieved for the first time using an rf glow-discharge technique. The influence of the deposition parameters (silane flow rate, pressure, and power density) on the growth rate, optical band gap, and silicon-hydrogen bonding configuration, is quantitatively predicted using a deposition mechanism based on the additive contribution of three growth precursors, SiH2, SiH3, and Si2H6, with decreasing sticking coefficients of 0.7, 0.1, and 0.001, respectively. The low hydrogen concentration is due to the enhanced ion bombardment resulting from the concentric electrode design.

21 CFR 173.370 - Peroxyacids.

Code of Federal Regulations, 2010 CFR

2010-04-01

... conditions: (a) The additive is a mixture of peroxyacetic acid, octanoic acid, acetic acid, hydrogen peroxide... the maximum concentration of hydrogen peroxide is 75 ppm. (2) The additive is used as an antimicrobial... million (ppm) as peroxyacetic acid, the maximum concentration of hydrogen peroxide is 110 ppm, and the...

21 CFR 173.370 - Peroxyacids.

Code of Federal Regulations, 2011 CFR

2011-04-01

... conditions: (a) The additive is a mixture of peroxyacetic acid, octanoic acid, acetic acid, hydrogen peroxide... the maximum concentration of hydrogen peroxide is 75 ppm. (2) The additive is used as an antimicrobial... million (ppm) as peroxyacetic acid, the maximum concentration of hydrogen peroxide is 110 ppm, and the...

Kinetics of hydrogen peroxide decomposition by catalase: hydroxylic solvent effects.

PubMed

Raducan, Adina; Cantemir, Anca Ruxandra; Puiu, Mihaela; Oancea, Dumitru

2012-11-01

The effect of water-alcohol (methanol, ethanol, propan-1-ol, propan-2-ol, ethane-1,2-diol and propane-1,2,3-triol) binary mixtures on the kinetics of hydrogen peroxide decomposition in the presence of bovine liver catalase is investigated. In all solvents, the activity of catalase is smaller than in water. The results are discussed on the basis of a simple kinetic model. The kinetic constants for product formation through enzyme-substrate complex decomposition and for inactivation of catalase are estimated. The organic solvents are characterized by several physical properties: dielectric constant (D), hydrophobicity (log P), concentration of hydroxyl groups ([OH]), polarizability (α), Kamlet-Taft parameter (β) and Kosower parameter (Z). The relationships between the initial rate, kinetic constants and medium properties are analyzed by linear and multiple linear regression.

Yield of H2O2 in Gas-Liquid Phase with Pulsed DBD

NASA Astrophysics Data System (ADS)

Jiang, Song; Wen, Yiyong; Liu, Kefu

2014-01-01

Electric discharge in water can generate a large number of oxidants such as ozone, hydrogen peroxide and hydroxyl radicals. In this paper, a non-thermal plasma processing system was established by means of pulsed dielectric barrier discharge in gas-liquid phase. The electrodes of discharge reactor were staggered. The yield of H2O2 was enhanced after discharge. The effects of discharge time, discharge voltage, frequency, initial pH value, and feed gas were investigated. The concentration of hydrogen peroxide and ozone was measured after discharge. The experimental results were fully analyzed. The chemical reaction equations in water were given as much as possible. At last, the water containing Rhodamine B was tested in this system. The degradation rate came to 94.22% in 30 min.

Experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source spectrum of the NBSR reactor at the NIST Center for Neutron Research

NASA Astrophysics Data System (ADS)

Cook, J. C.; Barker, J. G.; Rowe, J. M.; Williams, R. E.; Gagnon, C.; Lindstrom, R. M.; Ibberson, R. M.; Neumann, D. A.

2015-08-01

The recent expansion of the National Institute of Standards and Technology (NIST) Center for Neutron Research facility has offered a rare opportunity to perform an accurate measurement of the cold neutron spectrum at the exit of a newly-installed neutron guide. Using a combination of a neutron time-of-flight measurement, a gold foil activation measurement, and Monte Carlo simulation of the neutron guide transmission, we obtain the most reliable experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source brightness to date. Time-of-flight measurements were performed at three distinct fuel burnup intervals, including one immediately following reactor startup. Prior to the latter measurement, the hydrogen was maintained in a liquefied state for an extended period in an attempt to observe an initial radiation-induced increase of the ortho (o)-hydrogen fraction. Since para (p)-hydrogen has a small scattering cross-section for neutron energies below 15 meV (neutron wavelengths greater than about 2.3 Å), changes in the o- p hydrogen ratio and in the void distribution in the boiling hydrogen influence the spectral distribution. The nature of such changes is simulated with a continuous-energy, Monte Carlo radiation-transport code using 20 K o and p hydrogen scattering kernels and an estimated hydrogen density distribution derived from an analysis of localized heat loads. A comparison of the transport calculations with the mean brightness function resulting from the three measurements suggests an overall o- p ratio of about 17.5(±1) % o- 82.5% p for neutron energies<15 meV, a significantly lower ortho concentration than previously assumed.

Validation of the role of bulk charging of hydrogen in the corrosion fatigue cracking of a low alloy steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffiths, A.J.; Hutchings, R.B.; Turnbull, A.

1993-09-01

The enhanced corrosion fatigue crack growth rates of low alloy steels cathodically protected in marine environments results from absorbed hydrogen atoms. Hydrogen atoms are generated at the crack tip, crack walls and the external surface of the specimen (bulk charging). In previous work, Turnbull and Saenz de Santa Maria developed a model to predict the rate of generation of hydrogen atoms at the tips of fatigue cracks for steels cathodically polarized in marine environments. The main prediction from this work was that the external surface of the specimen can be the dominant source of hydrogen atoms at potentials more negativemore » than about [minus]900 mV (SCE), at a cyclic frequency of 0.1 Hz and a stress ratio of 0.5. The relative importance of bulk charging depends on the specific test conditions and is influenced by the applied potential, bulk chemistry, cyclic frequency, specimen thickness, temperature and use of coatings. Since laboratory test times are usually short in relation to the time required for hydrogen transport measured crack growth rates may be lower than those occurring in practice, for which there is sufficient time for full hydrogen charging. The purpose of this study is to verify experimentally the importance of bulk charging. Since the sensitivity of cracking to variations in hydrogen concentration will be material dependent a high strength steel was selected in this initial study because of its sensitivity to hydrogen. This will enable validation of the basic premise that bulk charging can be important, prior to more extensive studies using lower strength alloys.« less

Inhalation of water electrolysis-derived hydrogen ameliorates cerebral ischemia-reperfusion injury in rats - A possible new hydrogen resource for clinical use.

PubMed

Cui, Jin; Chen, Xiao; Zhai, Xiao; Shi, Dongchen; Zhang, Rongjia; Zhi, Xin; Li, Xiaoqun; Gu, Zhengrong; Cao, Liehu; Weng, Weizong; Zhang, Jun; Wang, Liping; Sun, Xuejun; Ji, Fang; Hou, Jiong; Su, Jiacan

2016-10-29

Hydrogen is a kind of noble gas with the character to selectively neutralize reactive oxygen species. Former researches proved that low-concentration of hydrogen can be used to ameliorating cerebral ischemia/reperfusion injury. Hydrogen electrolyzed from water has a hydrogen concentration of 66.7%, which is much higher than that used in previous studies. And water electrolysis is a potential new hydrogen resource for regular clinical use. This study was designed and carried out for the determination of safety and neuroprotective effects of water electrolysis-derived hydrogen. Sprague-Dawley rats were used as experimental animals, and middle cerebral artery occlusion was used to make cerebral ischemia/reperfusion model. Pathologically, tissues from rats in hydrogen inhalation group showed no significant difference compared with the control group in HE staining pictures. The blood biochemical findings matched the HE staining result. TTC, Nissl, and TUNEL staining showed the significant improvement of infarction volume, neuron morphology, and neuron apoptosis in rat with hydrogen treatment. Biochemically, hydrogen inhalation decreased brain caspase-3, 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine-positive cells and inflammation factors concentration. Water electrolysis-derived hydrogen inhalation had neuroprotective effects on cerebral ischemia/reperfusion injury in rats with the effect of suppressing oxidative stress and inflammation, and it is a possible new hydrogen resource to electrolyze water at the bedside clinically. Copyright © 2016. Published by Elsevier Ltd.

Hydrogen production from sugar beet juice using an integrated biohydrogen process of dark fermentation and microbial electrolysis cell.

PubMed

Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Hafez, Hisham; Lee, Hyung-Sool

2015-12-01

An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice. Different substrate to inoculum (S/X) ratios were tested for dark fermentation, and the maximum hydrogen yield was 13% of initial COD at the S/X ratio of 2 and 4 for dark fermentation. Hydrogen yield was 12% of initial COD in the MEC using fermentation liquid end products as substrate, and butyrate only accumulated in the MEC. The overall hydrogen production from the integrated biohydrogen process was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded), and the energy recovery from sugar beet juice was 57% using the combined biohydrogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selective deposition of a crystalline Si film by a chemical sputtering process in a high pressure hydrogen plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohmi, Hiromasa, E-mail: ohmi@prec.eng.osaka-u.ac.jp; Yasutake, Kiyoshi; Research Center for Ultra-Precision Science and Technology, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871

2015-07-28

The selective deposition of Si films was demonstrated using a chemical sputtering process induced by a high pressure hydrogen plasma at 52.6 kPa (400 Torr). In this chemical sputtering process, the initial deposition rate (R{sub d}) is dependent upon the substrate type. At the initial stage of Si film formation, R{sub d} on glass substrates increased with elapsed time and reached to a constant value. In contrast, R{sub d} on Si substrates remained constant during the deposition. The selective deposition of Si films can be achieved by adjusting the substrate temperature (T{sub sub}) and hydrogen concentration (C{sub H2}) in the process atmosphere.more » For any given deposition time, it was found that an optimum C{sub H2} exists for a given T{sub sub} to realize the selective deposition of a Si film, and the optimum T{sub sub} value tends to increase with decreasing C{sub H2}. According to electron diffraction patterns obtained from the samples, the selectively prepared Si films showed epitaxial-like growth, although the Si films contained many defects. It was revealed by Raman scattering spectroscopy that some of the defects in the Si films were platelet defects induced by excess hydrogen incorporated during Si film formation. Raman spectrum also suggested that Si related radicals (SiH{sub 2}, SiH, Si) with high reactivity contribute to the Si film formation. Simple model was derived as the guideline for achieving the selective growth.« less

Improved vacuum-UV (VUV)-initiated photomineralization of organic compounds in water with a xenon excimer flow-through photoreactor (Xe2* lamp, 172 nm) containing an axially centered ceramic oxygenator.

PubMed

Oppenländer, Thomas; Walddörfer, Carsten; Burgbacher, Jens; Kiermeier, Martin; Lachner, Klaus; Weinschrott, Helga

2005-07-01

Xenon excimer (Xe2*) lamps can be used for the oxidation and mineralization of organic compounds in aqueous solution. This vacuum-ultraviolet (VUV) photochemical method is mainly based on the photochemically initiated homolysis of water that produces hydrogen atoms and hydroxyl radicals. The efficiency of substrate oxidation and mineralization is limited markedly due to the high absorbance of water at the emission maximum of the Xe2* lamp (lambda(max)=172 nm). This photochemical condition generates an extreme heterogeneity between the irradiated volume V(irr) and the non-irradiated ("dark") bulk solution. During VUV-initiated photomineralization of organic substrates, the fast scavenging of hydrogen atoms and of carbon-centered radicals by dissolved molecular oxygen produces a permanent oxygen deficit within V(irr) and adjacent compartments. Hence, at a constant photon flux the concentration of dissolved molecular oxygen within the zones of photo and thermal radical reactions limits the rate of mineralization, i.e. the rate of TOC diminution. Thus, a simple and convenient technique is presented that overcomes this limitation by injection of molecular oxygen (or air) into the irradiated volume by use of a ceramic oxygenator (aerator). The tube oxygenator was centered axially within the xenon excimer flow-through lamp. Consequently, the oxygen or air bubbles enhanced the transfer of dissolved molecular oxygen into the VUV-irradiated volume leading to an increased rate of mineralization of organic model compounds, e.g. 1-heptanol, benzoic acid and potassium hydrogen phthalate.

Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope

NASA Astrophysics Data System (ADS)

Deng, Yun; Hajilou, Tarlan; Barnoush, Afrooz

2017-06-01

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10-4 Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane. This article is part of the themed issue 'The challenges of hydrogen and metals'.

Corrosion characteristics of Ni-base superalloys in high temperature steam with and without hydrogen

NASA Astrophysics Data System (ADS)

Kim, Donghoon; Kim, Daejong; Lee, Ho Jung; Jang, Changheui; Yoon, Duk Joo

2013-10-01

The hot steam corrosion behavior of Alloy 617 and Haynes 230 were evaluated in corrosion tests performed at 900 °C in steam and steam + 20 vol.% H2 environments. Corrosion rates of Alloy 617 was faster than that of Haynes 230 at 900 °C in steam and steam + 20 vol.% H2 environments. When hydrogen was added to steam, the corrosion rate was accelerated because added hydrogen increased the concentration of Cr interstitial defects in the oxide layer. Isolated nodular MnTiO3 oxides were formed on the MnCr2O4/Cr2O3 oxide layer and sub-layer Cr2O3 was formed in steam and steam + 20 vol.% H2 for Alloy 617. On the other hand, a MnCr2O4 layer was formed on top of the Cr2O3 oxide layer for Haynes 230. The extensive sub-layer Cr2O3 formation resulted from the oxygen or hydroxide inward diffusion in such environments. When hydrogen was added, the initial surface oxide morphology was changed from a convex shape to platelets because of the accelerated diffusion of cations under the oxide layer.

Micro-structured femtosecond laser assisted FBG hydrogen sensor.

PubMed

Karanja, Joseph Muna; Dai, Yutang; Zhou, Xian; Liu, Bin; Yang, Minghong

2015-11-30

We discuss hydrogen sensors based on fiber Bragg gratings (FBGs) micro-machined by femtosecond laser to form microgrooves and sputtered with Pd/Ag composite film. The atomic ratio of the two metals is controlled at Pd:Ag = 3:1. At room temperature, the hydrogen sensitivity of the sensor probe micro-machined by 75 mW laser power and sputtered with 520 nm of Pd/Ag film is 16.5 pm/%H. Comparably, the standard FBG hydrogen sensitivity becomes 2.5 pm/%H towards the same 4% hydrogen concentration. At an ambient temperature of 35°C, the processed sensor head has a dramatic rise in hydrogen sensitivity. Besides, the sensor shows good response and repeatability during hydrogen concentration test.

The impact of biostimulation on the fate of sulfate and associated sulfur dynamics in groundwater

NASA Astrophysics Data System (ADS)

Miao, Ziheng; Carreón-Diazconti, Concepcion; Carroll, Kenneth C.; Brusseau, Mark L.

2014-08-01

The impact of electron-donor addition on sulfur dynamics for a groundwater system with low levels of metal contaminants was evaluated with a pilot-scale biostimulation test conducted at a former uranium mining site. Geochemical and stable-isotope data collected before, during, and after the test were analyzed to evaluate the sustainability of sulfate reducing conditions induced by the test, the fate of hydrogen sulfide, and the impact on aqueous geochemical conditions. The results of site characterization activities conducted prior to the test indicated the absence of measurable bacterial sulfate reduction. The injection of an electron donor (ethanol) induced bacterial sulfate reduction, as confirmed by an exponential decrease of sulfate concentration in concert with changes in oxidation-reduction potential, redox species, alkalinity, production of hydrogen sulfide, and fractionation of δ34S-sulfate. High, stoichiometrically-equivalent hydrogen sulfide concentrations were not observed until several months after the start of the test. It is hypothesized that hydrogen sulfide produced from sulfate reduction was initially sequestered in the form of iron sulfides until the exhaustion of readily reducible iron oxides within the sediment. The fractionation of δ34S for sulfate was atypical, wherein the enrichment declined in the latter half of the experiment. It was conjectured that mixing effects associated with the release of sulfate from sulfate minerals associated with the sediments, along with possible sulfide re-oxidation contributed to this behavior. The results of this study illustrate the biogeochemical complexity that is associated with in-situ biostimulation processes involving bacterial sulfate reduction.

THE IMPACT OF BIOSTIMULATION ON THE FATE OF SULFATE AND ASSOCIATED SULFUR DYNAMICS IN GROUNDWATER

PubMed Central

Miao, Ziheng; Carreón-Diazconti, Concepcion; Carroll, Kenneth C.; Brusseau, Mark L.

2014-01-01

The impact of electron-donor addition on sulfur dynamics for a groundwater system with low levels of metal contaminants was evaluated with a pilot-scale biostimulation test conducted at a former uranium mining site. Geochemical and stable-isotope data collected before, during, and after the test were analyzed to evaluate the sustainability of sulfate reducing conditions induced by the test, the fate of hydrogen sulfide, and the impact on aqueous geochemical conditions. The results of site characterization activities conducted prior to the test indicated the absence of measurable bacterial sulfate reduction. The injection of an electron donor (ethanol) induced bacterial sulfate reduction, as confirmed by an exponential decrease of sulfate concentration in concert with changes in oxidation-reduction potential, redox species, alkalinity, production of hydrogen sulfide, and fractionation of δ34S-sulfate. High, stoichiometrically-equivalent hydrogen sulfide concentrations were not observed until several months after the start of the test. It is hypothesized that hydrogen sulfide produced from sulfate reduction was initially sequestered in the form of iron sulfides until the exhaustion of readily reducible iron oxides associated with the sediment. The fractionation of δ34S for sulfate was atypical, wherein the enrichment declined in the latter half of the experiment. It was conjectured that mixing effects associated with the release of sulfate from sulfate minerals associated with the sediments, along with possible sulfide re-oxidation contributed to this behavior. The results of this study illustrate the biogeochemical complexity that is associated with in-situ biostimulation processes involving bacterial sulfate reduction. PMID:25016586

Thermal desorption of hydrogen from Mg2Ni hydrogen storage materials.

PubMed

Hur, Tae Hong; Han, Jeong Seb; Kim, Jin Ho; Kim, Byung Kwan

2011-07-01

In order to investigate the influence of HCS on the hydrogen occupation site of Mg2Ni alloy, the thermal desorption technique has been applied to Mg2Ni hydride made by hydriding combustion synthesis (HCS). Mg2Ni was made under low temperature in a short time by the HCS compared to conventional melting process. At various initial hydride wt% from 0.91 to 3.52, the sample was heated to 623 K at a rate of 1.0 K/min. The starting temperature of the evolution of hydrogen goes higher as the initial hydride wt% increases. Only one peak is shown in the case of the small initial hydride wt%. But two peaks appeared with increasing initial hydride wt%. The activation energies obtained by the first and second peaks are 113.0 and 99.5 kJ/mol respectively. The two site occupation model by Darriet et al. was proved. The influence of HCS on the hydrogen occupation site of Mg2Ni alloy is nonexistent.

Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil

PubMed Central

Luo, Ying-Ting; Wang, Hong-Bin; Ma, Guo-Ming; Song, Hong-Tu; Li, Chengrong; Jiang, Jun

2016-01-01

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis. PMID:27782034

Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil.

PubMed

Luo, Ying-Ting; Wang, Hong-Bin; Ma, Guo-Ming; Song, Hong-Tu; Li, Chengrong; Jiang, Jun

2016-10-04

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis.

Enhanced radiation resistant fiber optics

DOEpatents

Lyons, Peter B.; Looney, Larry D.

1993-01-01

A process for producing an optical fiber having enhanced radiation resitance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation.

Enhanced radiation resistant fiber optics

DOEpatents

Lyons, P.B.; Looney, L.D.

1993-11-30

A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

Designing supported palladium-on-gold bimetallic nano-catalysts for controlled hydrogenation of acetylene in large excess of ethylene

NASA Astrophysics Data System (ADS)

Malla, Pavani

Ethylene is used as a starting point for many chemical intermediates in the petrochemical industry. It is predominantly produced through steam cracking of higher hydrocarbons (ethane, propane, butane, naphtha, and gas oil). During the cracking process, a small amount of acetylene is produced as a side product. However, acetylene must be removed since it acts as a poison for ethylene polymerization catalysts at even ppm concentrations (>5 ppm). Thus, the selective hydrogenation of acetylene to ethylene is an important process for the purification of ethylene. Conventional, low weight loading Pd catalysts are used for this selective reaction in high concentration ethylene streams. Gold was initially considered to be catalytically inactive for a long time. This changed when gold was seen in the context of the nanometric scale, which has indeed shown it to have excellent catalytic activity as a homogeneous or a heterogeneous catalyst. Gold is proved to have high selectivity to ethylene but poor at conversion. Bimetallic Au and Pd catalysts have exhibited superior activity as compared to Pd particles in semi-hydrogenation. Hydrogenation of acetylene was tested using this bimetallic combination. The Pd-on-Au bimetallic catalyst structure provides a new synthesis approach in improving the catalytic properties of monometallic Pd materials. TiO 2 as a support material and 0.05%Pd loading on 1%Au on titania support and used different treatment methods like washing plasma and reduction between the two metal loadings and was observed under 2:1 ratio. In my study there were two set of catalysts which were prepared by a modified incipient wetness impregnation technique. Out of all the reaction condition the catalyst which was reduced after impregnating gold and then impregnating palladium which was further treated in non-thermal hydrogen plasma and then pretreated in hydrogen till 250°C for 1 hour produced the best activity of 76% yield at 225°C. Stability tests were conducted on the catalysts which were followed by TGA analysis to analyze the coke formation on the catalyst in a period of time at a particular temperature. The catalysts were characterized by the hydrogen chemisorption and atomic absorption spectroscopy.

Hydrogen sensors based on catalytic metals

NASA Astrophysics Data System (ADS)

Beklemyshev, V. I.; Berezine, V.; Bykov, Victor A.; Kiselev, L.; Makhonin, I.; Pevgov, V.; Pustovoy, V.; Semynov, A.; Sencov, Y.; Shkuropat, I.; Shokin, A.

1999-11-01

On the base of microelectronical and micromechanical technology were designed and developed converters of hydrogen concentration to electrical signals. The devices of controlling concentration of hydrogen in the air were developed. These devices were applied for ensuring fire and explosion security of complex technological teste of missile oxygen-hydrogen engine, developed for cryogenic accelerations block. The sensor block of such device was installed directly on the armor-plate, to which was attached tested engine.

Determination of diffusion coefficients of hydrogen in fused silica between 296 and 523 K by Raman spectroscopy and application of fused silica capillaries in studying redox reactions

USGS Publications Warehouse

Shang, L.; Chou, I-Ming; Lu, W.; Burruss, Robert; Zhang, Y.

2009-01-01

Diffusion coefficients (D) of hydrogen in fused silica capillaries (FSC) were determined between 296 and 523 K by Raman spectroscopy using CO2 as an internal standard. FSC capsules (3.25 × 10−4 m OD, 9.9 × 10−5 m ID, and ∼0.01 m long) containing CO2 and H2were prepared and the initial relative concentrations of hydrogen in these capsules were derived from the Raman peak-height ratios between H2 (near 587 cm−1) and CO2 (near 1387 cm−1). The sample capsules were then heated at a fixed temperature (T) at one atmosphere to let H2 diffuse out of the capsule, and the changes of hydrogen concentration were monitored by Raman spectroscopy after quench. This process was repeated using different heating durations at 296 (room T), 323, 375, 430, 473, and 523 K; the same sample capsule was used repeatedly at each temperature. The values of D (in m2 s−1) in FSC were obtained by fitting the observed changes of hydrogen concentration in the FSC capsule to an equation based on Fick’s law. Our D values are in good agreement with the more recent of the two previously reported experimental data sets, and both can be represented by:lnD=-(16.471±0.035)-44589±139RT(R2=0.99991)">lnD=-(16.471±0.035)-44589±139RT(R2=0.99991)where R is the gas constant (8.3145 J/mol K), T in Kelvin, and errors at 1σ level. The slope corresponds to an activation energy of 44.59 ± 0.14 kJ/mol.The D in FSC determined at 296 K is about an order of magnitude higher than that in platinum at 723 K, indicating that FSC is a suitable membrane for hydrogen at temperature between 673 K and room temperature, and has a great potential for studying redox reactions at these temperatures, especially for systems containing organic material and/or sulphur.

The effect of cathodic polarization on the corrosion fatigue behavior of a precipitation hardened aluminum alloy

NASA Astrophysics Data System (ADS)

Smith, E. F.; Duquette, D. J.

1986-02-01

Fatigue experiments were conducted on polycrystalline and monocrystalline samples of a high purity Al, 5.5 wt pct Zn, 2.5 wt pct Mg, 1.5 wt pct Cu alloy in the peak-hardened heat treatment condition. These experiments were conducted in dry laboratory air and in 0.5 N NaCl solutions at the corrosion potential and at applied potentials cathodic to the corrosion potential. It has been shown that saline solutions severely reduce the fatigue resistance of the alloy, resulting in considerable amounts of intergranular crack initiation and propagation under freely corroding conditions for polycrystalline samples. Applied cathodic potentials resulted in still larger decreases in fatigue resistance and, for poly crystals, increases in the degree of transgranular crack initiation and propagation. Increasing amounts of intergranular cracking were observed when applied cyclic stresses were reduced (longer test times). The characteristics of cracking, combined with results obtained on tensile tests of deformed and hydrogen charged samples, suggest that environmental cracking of these alloys is associated with a form of hydrogen embrittlement of the process zones of growing cracks. Further, it is suggested that stress corrosion cracking and corrosion fatigue of these alloys occurs by essentially the same mechanism, but that the often observed transgranular cracking under cyclic loading conditions occurs due to enhanced hydrogen transport and/or concentrations associated with mobile dislocations at growing crack tips.

Design of an integrated fuel processor for residential PEMFCs applications

NASA Astrophysics Data System (ADS)

Seo, Yu Taek; Seo, Dong Joo; Jeong, Jin Hyeok; Yoon, Wang Lai

KIER has been developing a novel fuel processing system to provide hydrogen rich gas to residential PEMFCs system. For the effective design of a compact hydrogen production system, each unit process for steam reforming and water gas shift, has a steam generator and internal heat exchangers which are thermally and physically integrated into a single packaged hardware system. The newly designed fuel processor (prototype II) showed a thermal efficiency of 78% as a HHV basis with methane conversion of 89%. The preferential oxidation unit with two staged cascade reactors, reduces, the CO concentration to below 10 ppm without complicated temperature control hardware, which is the prerequisite CO limit for the PEMFC stack. After we achieve the initial performance of the fuel processor, partial load operation was carried out to test the performance and reliability of the fuel processor at various loads. The stability of the fuel processor was also demonstrated for three successive days with a stable composition of product gas and thermal efficiency. The CO concentration remained below 10 ppm during the test period and confirmed the stable performance of the two-stage PrOx reactors.

A finite element model of a MEMS-based surface acoustic wave hydrogen sensor.

PubMed

El Gowini, Mohamed M; Moussa, Walied A

2010-01-01

Hydrogen plays a significant role in various industrial applications, but careful handling and continuous monitoring are crucial since it is explosive when mixed with air. Surface Acoustic Wave (SAW) sensors provide desirable characteristics for hydrogen detection due to their small size, low fabrication cost, ease of integration and high sensitivity. In this paper a finite element model of a Surface Acoustic Wave sensor is developed using ANSYS12© and tested for hydrogen detection. The sensor consists of a YZ-lithium niobate substrate with interdigital electrodes (IDT) patterned on the surface. A thin palladium (Pd) film is added on the surface of the sensor due to its high affinity for hydrogen. With increased hydrogen absorption the palladium hydride structure undergoes a phase change due to the formation of the β-phase, which deteriorates the crystal structure. Therefore with increasing hydrogen concentration the stiffness and the density are significantly reduced. The values of the modulus of elasticity and the density at different hydrogen concentrations in palladium are utilized in the finite element model to determine the corresponding SAW sensor response. Results indicate that with increasing the hydrogen concentration the wave velocity decreases and the attenuation of the wave is reduced.

Direct Method for Continuous Determination of Iron Oxidation by Autotrophic Bacteria

PubMed Central

Steiner, Michael; Lazaroff, Norman

1974-01-01

A method for direct, continuous determination of ferric ions produced in autotrophic iron oxidation, which depends upon the measurement of ferric ion absorbance at 304 nm, is described. The use of initial rates is shown to compensate for such changes in extinction during oxidation, which are due to dependence of the extinction coefficient on the ratio of complexing anions to ferric ions. A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO42+ and hydrogen ion concentrations. Some examples are discussed of the applicability of these methods to study of the rates of ferrous ion oxidation related to sulfate concentration. PMID:4441066

Chromium (VI) purification using pine sawdust in batch systems

NASA Astrophysics Data System (ADS)

Politi, Dorothea; Sidiras, Dimitris

2012-12-01

Pine sawdust, a waste generated in furniture industry, has been used as low-cost potential adsorbent. This low-cost adsorbent was used for the removal of chromium (VI) from an aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbent and adsorbate. The effect of hydrogen ion concentration, contact time, adsorbent dose and initial concentration of adsorbate on the uptake of chromium were studied in batch experiments. The adsorption data has been correlated with Lagergren - Eldridge pseudofirst order kinetic model. The efficiency of adsorbent material for the removal of Cr(VI) was found to be between 13.1 and 95.6%, respectively. These results depend on the conditions of pH, contact time, sawdust dose and Cr(VI) concentration.

Steam gasification of waste tyre: influence of process temperature on yield and product composition.

PubMed

Portofino, Sabrina; Donatelli, Antonio; Iovane, Pierpaolo; Innella, Carolina; Civita, Rocco; Martino, Maria; Matera, Domenico Antonio; Russo, Antonio; Cornacchia, Giacinto; Galvagno, Sergio

2013-03-01

An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850-1000°C, holding all the other operational parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86 wt%) and a lower char yield, due to an enhancement of the solid-gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000°C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature. Copyright © 2012 Elsevier Ltd. All rights reserved.

Radiolytic Hydrogen Production in the South Pacific Subseafloor Basaltic Aquifer

NASA Astrophysics Data System (ADS)

Dzaugis, M. E.; Spivack, A. J.; Dunlea, A. G.; Murray, R. W.; D'Hondt, S.

2015-12-01

Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from natural radioactive decay of uranium (238U, 235U), thorium (232Th) and potassium (40K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we calculate radiolytic H2 production rates in basement fractures utilizing measured radionuclide concentrations in 42 basalt samples from IODP Expedition 329. The samples are from three sites with very different basement ages and a wide range of alteration types. Major and trace element concentrations vary by up to an order of magnitude from sample to sample. Comparison of our samples to each other and to previous studies of fresh East Pacific Rise basalt suggests that between-sample variation in radionuclide concentrations is primarily due to differences in initial (pre-alteration) concentrations (which can vary between eruptive events), rather than to alteration type or extent. Local maxima in radionuclide (U, Th, and K) concentrations produce 'hotspots' of radiolytic H2 production; calculated radiolytic rates differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production. Due to the low penetration distance of alpha radiation, microfractures are 'hotpots' for radiolytic H2 production. For example, radiolytic H2 production rates normalized to water volume are 170 times higher in 1μm-wide fractures than in 10cm-wide fractures.

Impact of fermentation rate changes on potential hydrogen sulfide concentrations in wine.

PubMed

Butzke, Christian E; Park, Seung Kook

2011-05-01

The correlation between alcoholic fermentation rate, measured as carbon dioxide (CO2) evolution, and the rate of hydrogen sulfide (H2S) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace H2S were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; H2S was quantitatively trapped in realtime using a pre-calibrated H2S detection tube which was inserted into a fermentor gas relief port. Evolution rates for CO2 and H2S as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated H2S formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of H2S when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained CO2 production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the H2S formation was marginal.

Benefits of slush hydrogen for space missions

NASA Technical Reports Server (NTRS)

Friedlander, Alan; Zubrin, Robert; Hardy, Terry L.

1991-01-01

A study was performed to quantify the benefits of using slush hydrogen instead of normal boiling point liquid hydrogen as a fuel for several space missions. Vehicles considered in the study included the Space Shuttle/Shuttle-C, LEO to GEO transfer vehicles, Lunar and Mars transfer vehicles, and cryogenic depots in low Earth orbit. The advantages of using slush hydrogen were expressed in terms of initial mass differences at a constant payload, payload differences at a constant tank volume, and increases in fuel storage time for cryogenic depots. Both chemical oxygen/hydrogen and hydrogen nuclear thermal rocket propulsion were considered in the study. The results indicated that slush hydrogen offers the potential for significant decreases in initial mass and increases in payload for most missions studied. These advantages increase as the mission difficulty, or energy, increases.

Hydrogen gas storage in fluorinated ultramicroporous tunnel crystal

NASA Astrophysics Data System (ADS)

Kataoka, Keisuke; Katagiri, Toshimasa

2012-07-01

We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder.We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder. Electronic supplementary information (ESI) available. CCDC 246922. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30940h

Highly hydrogen-sensitive thermal desorption spectroscopy system for quantitative analysis of low hydrogen concentration (˜1 × 1016 atoms/cm3) in thin-film samples

NASA Astrophysics Data System (ADS)

Hanna, Taku; Hiramatsu, Hidenori; Sakaguchi, Isao; Hosono, Hideo

2017-05-01

We developed a highly hydrogen-sensitive thermal desorption spectroscopy (HHS-TDS) system to detect and quantitatively analyze low hydrogen concentrations in thin films. The system was connected to an in situ sample-transfer chamber system, manipulators, and an rf magnetron sputtering thin-film deposition chamber under an ultra-high-vacuum (UHV) atmosphere of ˜10-8 Pa. The following key requirements were proposed in developing the HHS-TDS: (i) a low hydrogen residual partial pressure, (ii) a low hydrogen exhaust velocity, and (iii) minimization of hydrogen thermal desorption except from the bulk region of the thin films. To satisfy these requirements, appropriate materials and components were selected, and the system was constructed to extract the maximum performance from each component. Consequently, ˜2000 times higher sensitivity to hydrogen than that of a commercially available UHV-TDS system was achieved using H+-implanted Si samples. Quantitative analysis of an amorphous oxide semiconductor InGaZnO4 thin film (1 cm × 1 cm × 1 μm thickness, hydrogen concentration of 4.5 × 1017 atoms/cm3) was demonstrated using the HHS-TDS system. This concentration level cannot be detected using UHV-TDS or secondary ion mass spectroscopy (SIMS) systems. The hydrogen detection limit of the HHS-TDS system was estimated to be ˜1 × 1016 atoms/cm3, which implies ˜2 orders of magnitude higher sensitivity than that of SIMS and resonance nuclear reaction systems (˜1018 atoms/cm3).

Vacancy-hydrogen complexes in ammonothermal GaN

NASA Astrophysics Data System (ADS)

Tuomisto, F.; Kuittinen, T.; Zając, M.; Doradziński, R.; Wasik, D.

2014-10-01

We have applied positron annihilation spectroscopy to study in-grown vacancy defects in bulk GaN crystals grown by the ammonothermal method. We observe a high concentration of Ga vacancy related defects in n-type samples with varying free electron and oxygen content. The positron lifetimes found in these samples suggest that the Ga vacancies are complexed with hydrogen impurities. The number of hydrogen atoms in each vacancy decreases with increasing free electron concentration and oxygen and hydrogen content. The local vibrational modes observed in infrared absorption support this conclusion. Growth of high-quality ammonothermal GaN single crystals with varying electron concentrations. Identification of defect complexes containing a Ga vacancy and 1 or more hydrogen atoms, and possibly O. These vacancy complexes provide a likely explanation for electrical compensation in ammonothermal GaN.

Study on Molasses Concentration from Sugarcanne Bagasse for Biohydrogen Production using Enriched Granular Activated Carbon (GAC) Immobilised Cells by Repeated Batch Cultivation

NASA Astrophysics Data System (ADS)

Idris, Norfatiha; Aminah Lutpi, Nabilah; Ruhaizul Che Ridzuan, Che Mohd; Shian, Wong Yee; Nuraiti Tengku Izhar, Tengku

2018-03-01

Repeated batch cultivation is known as most attractive method in improving hydrogen productivity, due to the facts that this approach could minimize the reuse of the cell and the inoculum preparation. In addition, with the combination of attach growth system during the fermentation processes to produce biohydrogen, the density of cells will be increased and the cell washout could be avoided. Therefore, this study aimed to examine the effectiveness of repeated batch cultivation for enrichment of anaerobic mixed culture onto granular activated carbon (GAC) and investigate the effect of molasses concentration during immobilization of mixed culture onto the GAC. The molasses concentration using 50 %, 40 %, 30 %, 20 % and 10 % of diluted molasses were used as feedstock in the fermentation process. The maximum hydrogen production of 60 ml was obtained at 30 % of molasses concentration with 831 ppm of hydrogen concentration. Thus, the kinetic parameter obtained from the batch profiling based on modified Gompertz equation are, Hm= 58 ml for the maximum hydrogen production and Rm= 2.02 ml/h representing the hydrogen production rate.

Organosolv delignification of Eucalyptus globulus: Kinetic study of autocatalyzed ethanol pulping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliet, M.; Rodriguez, F.; Santos, A.

2000-01-01

The autocatalyzed delignification of Eucalyptus globulus in 50% ethanol (w/w) was modeled as the irreversible and consecutive dissolution of initial, bulk, and residual lignin. Their respective contributions to total lignin was estimated as 9, 75, and 16%. Isothermal pulping experiments were carried out to evaluate an empirical kinetic model among eight proposals corresponding to different reaction schemes. The calculated activation energy was found to be 96.5, 98.5, and 40.8 kJ/mol for initial, bulk, and residual delignification, respectively. The influence of hydrogen ion concentration was expressed by a power-law function model. The kinetic model developed here was validated using data frommore » nonisothermal pulping runs.« less

Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

PubMed Central

Laptev, Roman; Abzaev, Yuri; Lider, Andrey; Ivashutenko, Alexander

2018-01-01

The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation. PMID:29324712

Destruction of 4-phenolsulfonic acid in water by anodic contact glow discharge electrolysis.

PubMed

Yang, Haiming; An, Baigang; Wang, Shaoyan; Li, Lixiang; Jin, Wenjie; Li, Lihua

2013-06-01

Destruction of 4-phenolsulfonic acid (4-PSA) in water was carried out using anodic contact glow discharge electrolysis. Accompanying the decay of 4-PSA, the amount of total organic carbon (TOC) in water correspondingly decreased, while the sulfonate group of 4-PSA was released as sulfate ion. Oxalate and formate were obtained as minor by-products. Additionally, phenol, 1,4-hydroquinone, hydroxyquinol and 1,4-benzoquinone were detected as primary intermediates in the initial stages of decomposition of 4-PSA. A reaction pathway involving successive attacks of hydroxyl and hydrogen radicals was assumed on the basis of the observed products and kinetics. It was revealed that the decay of both 4-PSA and TOC obeyed a first-order rate law. The effects of different Fe ions and initial concentrations of 4-PSA on the degradation rate were investigated. It was found that the presence of Fe ions could increase the degradation rate of 4-PSA, while initial concentrations lower than 80 mmol/L had no significant effect on kinetic behaviour. The disappearance rate of 4-PSA was significantly affected by pH.

The study of hydrogen peroxide level under cisplatin action using genetically encoded sensor hyper

NASA Astrophysics Data System (ADS)

Belova, A. S.; Orlova, A. G.; Maslennikova, A. V.; Brilkina, A. A.; Balalaeva, I. V.; Antonova, N. O.; Mishina, N. M.; Shakhova, N. M.; Belousov, V. V.

2014-03-01

The aim of the work was to study the participation of hydrogen peroxide in reaction of cervical cancer cell line HeLa Kyoto on cisplatin action. Determination of hydrogen peroxide level was performed using genetically encoded fluorescent sensor HyPer2. The dependence of cell viability on cisplatin concentration was determined using MTT assay. Mechanisms of cell death as well as HyPer2 reaction was revealed by flow cytometry after 6-hours of incubation with cisplatin in different concentrations. Cisplatin used in low concentrations had no effect on hydrogen peroxide level in HeLa Kyoto cells. Increase of HyPer2 fluorescence was detected only after exposure with cisplatin in high concentration. The reaction was not the consequence of cell death.

Variation of molecular hydrogen tropospheric concentration over Southern Poland - results of the continuous chromatographic measurements.

NASA Astrophysics Data System (ADS)

Necki, J.; Chmura, L.

2012-04-01

Although hydrogen is one of the fundamental constituents of the earth's atmosphere its global balance is still poorly clarified. A few developed inventories diverging values for efficiency of sources and sinks of this gas. The European network for the hydrogen concentrations measurement is based on several unevenly spaced measurement points. While in 2009 MPI Jena has delivered accurate scale for hydrogen measurements and the techniques of analyses are well described, still large areas of Central Europe is uncovered by representative stations. The first measurement point, established under the EUROHYDROS EU program, on the territory of Poland was Kraków city. Different laboratory setups was tested there and compared to each other. The Kraków area has significant car traffic and its geographical location implies frequent temperature inversions in lower troposphere leading to the accumulation of trace gases in atmosphere of the city. Observations launched in 2007 revealed that the concentration of hydrogen fluctuates strongly within diurnal and seasonal timescales. Its average concentration is three times larger than this, observed at the other stations. The European "background" concentrations of hydrogen are not reflected in the Krakow record. An ideal place to carry out observation of the regional air composition for Central Europe is a research station located in the meteorological observatory at Kasprowy Wierch. Measurement point at the top of mountain peak with elevation of 2000m a.s.l. gives an access to the well mixed troposphere. The station delivers also the necessary facilities and logistics. Since year 1996 greenhouse gas measurement program has been operating at this point. The first measurements of atmospheric concentrations of hydrogen at Kasprowy Wierch were performed in year 2010, based on dedicated gas chromatograph using RGD detector installed at the station. Analysis of hydrogen content in the outside air is performed without any enrichment process with precision better than 1ppb. But a temporary problems with UV lamp power supply module considerably hampers the research and adversely affect the reproducibility of the analysis. The results should be treated as a preliminary diagnosis of the diurnal and seasonal variation of the hydrogen concentration at the mountain site. The average short term variation of hydrogen concentrations does not exceed 50ppb and reveals the periodic nature except special situations when the concentration abruptly rises up by 150ppb and returns to an average of 480-520ppb. It is possible to observe the variations with larger time constant probably related with mezzo-scale circulation in atmosphere and slight seasonality in the level of hydrogen observed in autumn and in winter (with amplitude of 50ppb). Measurements carried out at Kasprowy Wierch were also used to balance the hydrogen for the city of Kraków. The work was partly financed from Polish national grant N N305 400939.

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

NASA Technical Reports Server (NTRS)

Gregory, G. L.; Emerson, B. R., Jr.; Hudgins, C. H.

1978-01-01

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.

Sorption of poly(hexamethylenebiguanide) on cellulose: mechanism of binding and molecular recognition.

PubMed

Blackburn, Richard S; Harvey, Anna; Kettle, Lorna L; Payne, John D; Russell, Stephen J

2006-06-20

Antimicrobial agents such as poly(hexamethylene biguanide) (PHMB) find application in medical, apparel, and household textile sectors; although it is understood that certain concentrations need to be applied to achieve suitable performance, there has been very little work published concerning the interactions of the polymer and its adsorption mechanism on cellulose. In this paper, such physical chemistry parameters are examined and related to computational chemistry studies. Adsorption isotherms were constructed: at low concentrations, these were typical Langmuir isotherms; at higher concentrations, they were more indicative of Freundlich isotherms, attributed to a combination of electrostatic and hydrogen-bonding forces, which endorsed computational chemistry proposals. At lower concentrations, electrostatic interactions between PHMB and carboxylic acid groups in the cellulose dominate with a contribution to binding through hydrogen bonding; as the concentration of PHMB increases, hydrogen bonding with cellulose becomes increasingly dominant. At high PHMB concentrations, observations of increasing PHMB adsorption are attributed to monolayer aggregation and multilayer stacking of PHMB through electrostatic interactions with counterions and hydrogen bonding of biguanide groups.

High Resolution Neutron Radiography and Tomography of Hydrided Zircaloy-4 Cladding Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Tyler S; Bilheux, Hassina Z; Ray, Holly B

2015-01-01

Neutron radiography for hydrogen analysis was performed with several Zircaloy-4 cladding samples with controlled hydrogen concentrations up to 1100 ppm. Hydrogen charging was performed in a process tube that was heated to facilitate hydrogen absorption by the metal. A correlation between the hydrogen concentration in the hydrided tubes and the neutron intensity was established, by which hydrogen content can be determined precisely in a small area (55 m x 55 m). Radiography analysis was also performed to evaluate the heating rate and its correlation with the hydrogen distribution through hydrided materials. In addition to radiography analysis, tomography experiments were performedmore » on Zircaloy-4 tube samples to study the local hydrogen distribution. Through tomography analysis a 3D reconstruction of the tube was evaluated in which an uneven hydrogen distribution in the circumferential direction can be observed.« less

Cadmium removal from wastewater by sponge iron sphere prepared by hydrogen reduction.

PubMed

Li, Junguo; Wei, Linghong; Li, Yungang; Bi, Na; Song, Fangfang

2011-06-01

A new type of sponge iron sphere (NSIS) with 1-5 mm diameter, made of concentrated iron powder and possessed high activity and intension, was prepared by mini-pellet sintering integrated with H2 direct reduction. Static state experiment has been carried on to investigate the Cd(2+) removal efficiency from wastewater by the NSIS and to explore the Cd(2+) removal reaction kinetics. It was suggested that initial pH value and Cd(2+) original concentration had significant influence on Cd(2+) removal percentage. Cd(2+) removal percentage decreased significantly with the increasing of Cd(2+)original concentration whether the original pH value be adjusted to 3.0 or without adjustment. The results showed that the Cd(2+) removal process followed the first order reaction because the reaction order was from 0.803 to 0.996. The apparent reaction rate constant between Cd(2+) and NSIS was from 0.0025 to 0.1000 (mg·L(-1))(1-n)·min(-1). Compared with SIS reduced by charcoal reduction, NSIS deoxided by hydrogen possessed higher activity, and could remove the same quantity of Cd(2+) within a shorter period of time. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Hydrogen production by sodium borohydride in NaOH aqueous solution

NASA Astrophysics Data System (ADS)

Wang, Q.; Zhang, L. F.; Zhao, Z. G.

2018-01-01

The kinetics of hydrolysis reaction of NaBH4 in NaOH aqueous solution is studied. The influence of pH of the NaOH aqueous solution on the rate of hydrogen production and the hydrogen production efficiency are studied for the hydrolysis reaction of NaBH4. The results show that the activation energy of hydrolysis reaction of NaBH4 increased with the increase of the initial pH of NaOH aqueous solution.With the increasing of the initial pH of NaOH aqueous solution, the rate of hydrogen production and hydrogen production efficiency of NaBH4 hydrolysis decrease.

Sonochemical degradation of ofloxacin in aqueous solutions.

PubMed

Hapeshi, E; Achilleos, A; Papaioannou, A; Valanidou, L; Xekoukoulotakis, N P; Mantzavinos, D; Fatta-Kassinos, D

2010-01-01

The use of low frequency (20 kHz), high energy ultrasound for the degradation of the antibiotic ofloxacin in water was investigated. Experiments were performed with a horn-type ultrasound generator at varying applied power densities (130-640 W/L), drug concentrations (5-20 mg/L), hydrogen peroxide concentrations (0-100 mM) and sparging gases (air, oxygen, nitrogen and argon). In general, conversion (which was assessed following sample absorbance at 288 nm) increased with increasing ultrasound energy and peroxide concentration and decreasing initial drug concentration. Moreover, reactions under an argon atmosphere were faster than with diatomic gases, possibly due to argon's physical properties (e.g. solubility, thermal conductivity and specific heat ratio) favoring sonochemical activity. Overall, low to moderate levels of ofloxacin degradation were achieved (i.e. it never exceeded 50%), thus indicating that radical reactions in the liquid bulk rather than thermal reactions in the vicinity of the cavitation bubble are responsible for ofloxacin degradation.

40 CFR 62.15390 - What equations must I use?

Code of Federal Regulations, 2011 CFR

2011-07-01

... reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen... of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as measured at the air pollution control device inlet, corrected to 7 percent oxygen, dry basis Eo = hydrogen...

40 CFR 62.15390 - What equations must I use?

Code of Federal Regulations, 2010 CFR

2010-07-01

... reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen... of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as measured at the air pollution control device inlet, corrected to 7 percent oxygen, dry basis Eo = hydrogen...

Evaluating different concentrations of hydrogen peroxide in an automated room disinfection system.

PubMed

Murdoch, L E; Bailey, L; Banham, E; Watson, F; Adams, N M T; Chewins, J

2016-09-01

A comparative study was made on the efficacy of 5, 10 and 35% weight by weight (w/w) hydrogen peroxide solutions when applied using an automated room disinfection system. Six-log biological indicators of methicillin-resistant Staphylococcus aureus (MRSA) and Geobacillus stearothermophilus were produced on stainless steel coupons and placed within a large, sealed, environmentally controlled enclosure. Five percent hydrogen peroxide was distributed throughout the enclosure using a Bioquell hydrogen peroxide vapour generator (BQ-50) for 40 min and left to reside for a further 200 min. Biological indicators were removed at 10-min intervals throughout the first 120 min of the process. The experiment was repeated for 10 and 35% hydrogen peroxide solutions. Five percent and 10% hydrogen peroxide solutions failed to achieve any reduction of MRSA, but achieved full kill of G. stearothermophilus spores at 70 and 40 min respectively. Thirty-five percent hydrogen peroxide achieved a 6-log reduction of MRSA after 30 min and full kill of G. stearothermophilus at 20 min. The concentration of 5% hydrogen peroxide within the enclosure after the 200-min dwell was measured at 9·0 ppm. This level exceeds the 15-min Short Term Exposure Limit (STEL) for hydrogen peroxide of 2·0 ppm. Users of automated hydrogen peroxide disinfection systems should review system efficacy and room re-entry protocols in light of these results. This research allows hospital infection control teams to consider the impact and risks of using low concentrations of hydrogen peroxide for disinfection within their facilities, and to question automated room disinfection system providers on the efficacy claims they make. The evidence that low concentration hydrogen peroxide solutions do not rapidly, autonomously break down, is in contradiction to the claims made by some hydrogen peroxide equipment providers and raises serious health and safety concerns. Facilities using hydrogen peroxide systems that claim autonomous break down of hydrogen peroxide should introduce monitoring procedures to ensure rooms are safe for re-entry and patient occupation. © 2016 The Society for Applied Microbiology.

Groundwater quality data in 15 GAMA study units: results from the 2006–10 Initial sampling and the 2009–13 resampling of wells, California GAMA Priority Basin Project

USGS Publications Warehouse

Kent, Robert

2015-08-31

Most constituents that were detected in groundwater samples from the trend wells were found at concentrations less than drinking-water benchmarks. Two volatile organic compounds (VOCs)—tetrachloroethene and trichloroethene—were detected in samples from one or more wells at concentrations greater than their health-based benchmarks, and three VOCs—chloroform, tetrachloroethene, and trichloroethene—were detected in at least 10 percent of the trend-well samples from the initial sampling period and the later trend sampling period. No pesticides were detected at concentrations near or greater than their health-based benchmarks. Three pesticide constituents—atrazine, deethylatrazine, and simazine—were detected in more than 10 percent of the trend-well samples in both sampling periods. Perchlorate, a constituent of special interest, was detected at a concentration greater than its health-based benchmark in samples from one trend well in the initial sampling and trend sampling periods, and in an additional trend well sample only in the trend sampling period. Most detections of nutrients, major and minor ions, and trace elements in samples from trend wells were less than health-based benchmarks in both sampling periods. Exceptions included nitrate, fluoride, arsenic, boron, molybdenum, strontium, and uranium; these were all detected at concentrations greater than their health-based benchmarks in at least one well sample in both sampling periods. Lead and vanadium were detected above their health-based benchmarks in one sample each collected in the initial sampling period only. The isotopic ratios of oxygen and hydrogen in water and the activities of tritium and carbon-14 generally changed little between sampling periods.

Nanoindentation of silicon implanted with hydrogen: effect of implantation dose on silicon’s mechanical properties and nanoindentation-induced phase transformation

NASA Astrophysics Data System (ADS)

Jelenković, Emil V.; To, Suet; Goncharova, Lyudmila V.; Wong, Sing Fai

2017-07-01

Implantation of hydrogen in single-crystal silicon (c-Si) is known to affect its machining. However, very little is reported on the material and mechanical properties of hydrogen-implanted silicon (Si). In this article, near-surface regions (~0-500 nm) of lightly doped (1 0 0) Si were modified by varying the hydrogen concentration using ion implantation. The maximum hydrogen concentration was varied from ~4  ×  1020 to ~3.2  ×  1021 cm-3. The implanted Si was investigated by nanoindentation. From the dynamic nanoindentation test, it was found that in hydrogen-implanted Si hardness is increased significantly, while the elastic modulus is reduced. The nanoindentation-induced Si phase transformation was studied under different load/unload rates and loads. Raman spectroscopy revealed that the hydrogen implantation tends to suppress Si-XII and Si-III phases and facilitates amorphous Si formation during the unloading stage of nanoindentation. Both the mechanical properties and phase transformations were qualitatively related not only to the hydrogen concentration, but also to the implantation-generated defects and strain.

Operational characteristics of the J-PARC cryogenic hydrogen system for a spallation neutron source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatsumoto, Hideki; Ohtsu, Kiichi; Aso, Tomokazu

2014-01-29

The J-PARC cryogenic hydrogen system provides supercritical hydrogen with the para-hydrogen concentration of more than 99 % and the temperature of less than 20 K to three moderators so as to provide cold pulsed neutron beams of a higher neutronic performance. Furthermore, the temperature fluctuation of the feed hydrogen stream is required to be within ± 0.25 K. A stable 300-kW proton beam operation has been carried out since November 2012. The para-hydrogen concentrations were measured during the cool-down process. It is confirmed that para-hydrogen always exists in the equilibrium concentration because of the installation of an ortho-para hydrogen convertor.more » Propagation characteristics of temperature fluctuation were measured by temporarily changing the heater power under off-beam condition to clarify the effects of a heater control for thermal compensation on the feed temperature fluctuation. The experimental data gave an allowable temperature fluctuation of ± 1.05 K. It is clarified through a 286-kW and a 524-kW proton beam operations that the heater control would be applicable for the 1-MW proton beam operation by extrapolating from the experimental data.« less

Highly sensitive hydrogen detection of catalyst-free ZnO nanorod networks suspended by lithography-assisted growth.

PubMed

Huh, Junghwan; Park, Jonghyurk; Kim, Gyu Tae; Park, Jeong Young

2011-02-25

We have successfully demonstrated a ZnO nanorod-based 3D nanostructure to show a high sensitivity and very fast response/recovery to hydrogen gas. ZnO nanorods have been synthesized selectively over the pre-defined area at relatively low temperature using a simple self-catalytic solution process assisted by a lithographic method. The conductance of the ZnO nanorod device varies significantly as the concentration of the hydrogen is changed without any additive metal catalyst, revealing a high sensitivity to hydrogen gas. Its superior performance can be explained by the porous structure of its three-dimensional network and the enhanced surface reaction of the hydrogen molecules with the oxygen defects resulting from a high surface-to-volume ratio. It was found that the change of conductance follows a power law depending on the hydrogen concentration. A Langmuir isotherm following an ideal power law and a cross-over behavior of the activation energy with respect to hydrogen concentration were observed. This is a very novel and intriguing phenomenon on nanostructured materials, which suggests competitive surface reactions in ZnO nanorod gas sensors.

Mechanical Behavior and Fractography of 304 Stainless Steel with High Hydrogen Concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Au, M.

2003-02-05

Hydrogen embrittlement of 304 stainless steel with different hydrogen concentrations has been investigated. An electrochemical technique was used to effectively charge the high level of hydrogen into 304 stainless steel in a short period of time. At 25 ppm of hydrogen, 304 stainless steel loses 10 percent of its original mechanical strength and 20 percent plasticity. Although the ductile feature dominates the fractography, the brittle crown area near the outer surface shows the intergranular rupture effected by hydrogen. At 60 ppm of hydrogen, 304 stainless steel loses 23 percent of its strength and 38 percent plasticity, where the brittle modemore » dominates the fracture of the materials. Experimental results show that hydrogen damage to the performance of 304 stainless steel is significant even at very low levels. The fractograph analysis indicates the high penetration ability of hydrogen in 304 stainless steel. This work also demonstrates the advantages of the electrochemical charging technique in the study of hydrogen embrittlement.« less

Phenol abatement using persulfate activated by nZVI, H2O2 and NaOH and development of a kinetic model for alkaline activation.

PubMed

Lominchar, Miguel A; Rodríguez, Sergio; Lorenzo, David; Santos, Noelia; Romero, Arturo; Santos, Aurora

2018-01-01

Three persulfate (PS) activation methods (nanoparticles of zero-valent iron (nZVI), hydrogen peroxide and alkali) were compared using phenol as target pollutant. Firstly, four experiments were conducted at 25°C in a batch way using the same initial phenol and oxidant concentrations (10 mM and 420 mM, respectively), being the molar ratio activator/PS fixed to 0.005 with nZVI (mass ratio 0.0011 nZVI/PS), to 2 using hydrogen peroxide and to 2 and 4 with NaOH. Phenol and PS conversions and aromatic byproducts profiles during 168 h reaction time were measured and compared, as well as mineralization and ecotoxicity of the samples. It was found that both phenol and aromatic byproducts (catechol and hydroquinone) totally disappeared using PS activated by alkali before 24 h, while a significant amount of aromatic intermediates was obtained with nZVI and H 2 O 2 . Additional runs were carried out using shorter times (0-2 h) to discriminate the oxidation route and the kinetic model of phenol abatement by using PS activated by alkali. Different initial concentrations of phenol (5-15 mM), PS (210 and 420 mM) and molar ratio NaOH/PS (2 and 4) were employed. The kinetic model obtained predicts accurately the evolution of phenol, persulfate, hydroquinone and catechol.

Hormetic concentrations of hydrogen peroxide but not ethanol induce cross-adaptation to different stresses in budding yeast.

PubMed

Semchyshyn, Halyna M

2014-01-01

The biphasic-dose response of microorganisms to hydrogen peroxide is a phenomenon of particular interest in hormesis research. In different animal models, the dose-response curve for ethanol is also nonlinear showing an inhibitory effect at high doses but a stimulatory effect at low doses. In this study, we observed the hormetic-dose response to ethanol in budding yeast S. cerevisiae. Cross-protection is a phenomenon in which exposure to mild stress results in the acquisition of cellular resistance to lethal stress induced by different factors. Since both hydrogen peroxide and ethanol at low concentrations were found to stimulate yeast colony growth, we evaluated the role of one substance in cell cross-adaptation to the other substance as well as some weak organic acid preservatives. This study demonstrates that, unlike ethanol, hydrogen peroxide at hormetic concentrations causes cross-resistance of S. cerevisiae to different stresses. The regulatory protein Yap1 plays an important role in the hormetic effects by low concentrations of either hydrogen peroxide or ethanol, and it is involved in the yeast cross-adaptation by low sublethal doses of hydrogen peroxide.

Time-resolved, nonequilibrium carrier dynamics in Si-on-glass thin films for photovoltaic cells

DOE PAGES

Serafini, John; Akbas, Yunus; Crandall, Lucas; ...

2016-03-02

Here, a femtosecond pump–probe spectroscopy method was used to characterize the growth process and transport properties of amorphous silicon-on-glass, thin films, intended as absorbers for photovoltaic cells. We collected normalized transmissivity change (ΔT/T) waveforms and interpreted them using a comprehensive three-rate equation electron trapping and recombination model. Optically excited ~300–500 nm thick Si films exhibited a bi-exponential carrier relaxation with the characteristic times varying from picoseconds to nanoseconds depending on the film growth process. From our comprehensive trapping model, we could determine that for doped and intrinsic films with very low hydrogen dilution the dominant relaxation mode was carrier trapping;more » while for intrinsic films with large hydrogen content and some texture, it was the standard electron–phonon cooling. In both cases, the initial nonequilibrium relaxation was followed by Shockley–Read–Hall recombination. An excellent fit between the model and the ΔT/T experimental transients was obtained and a correlation between the Si film growth process, its hydrogen content, and the associated trap concentration was demonstrated.« less

Hydrogen calibration of GD-spectrometer using Zr-1Nb alloy

NASA Astrophysics Data System (ADS)

Mikhaylov, Andrey A.; Priamushko, Tatiana S.; Babikhina, Maria N.; Kudiiarov, Victor N.; Heller, Rene; Laptev, Roman S.; Lider, Andrey M.

2018-02-01

To study the hydrogen distribution in Zr-1Nb alloy (Э110 alloy) GD-OES was applied in this work. Qualitative analysis needs the standard samples with hydrogen. However, the standard samples with high concentrations of hydrogen in the zirconium alloy which would meet the requirements of the shape, size are absent. In this work method of Zr + H calibration samples production was performed at the first time. Automated Complex Gas Reaction Controller was used for samples hydrogenation. To calculate the parameters of post-hydrogenation incubation of the samples in an inert gas atmosphere the diffusion equations were used. Absolute hydrogen concentrations in the samples were determined by melting in the inert gas atmosphere using RHEN602 analyzer (LECO Company). Hydrogen distribution was studied using nuclear reaction analysis (HZDR, Dresden, Germany). RF GD-OES was used for calibration. The depth of the craters was measured with the help of a Hommel-Etamic profilometer by Jenoptik, Germany.

Detection of hydrogen peroxide with chemiluminescent micelles

PubMed Central

Lee, Dongwon; Erigala, Venkata R; Dasari, Madhuri; Yu, Junhua; Dickson, Robert M; Murthy, Niren

2008-01-01

The overproduction of hydrogen peroxide is implicated in the progress of numerous life-threatening diseases and there is a great need for the development of contrast agents that can detect hydrogen peroxide in vivo. In this communication, we present a new contrast agent for hydrogen peroxide, termed peroxalate micelles, which detect hydrogen peroxide through chemiluminescence, and have the physical/chemical properties needed for in vivo imaging applications. The peroxalate micelles are composed of amphiphilic peroxalate based copolymers and the fluorescent dye rubrene, they have a ‘stealth’ polyethylene glycol (PEG) corona to evade macrophage phagocytosis, and a diameter of 33 nm to enhance extravasation into permeable tissues. The peroxalate micelles can detect nanomolar concentrations of hydrogen peroxide (>50 nM) and thus have the sensitivity needed to detect physiological concentrations of hydrogen peroxide. We anticipate numerous applications of the peroxalate micelles for in vivo imaging of hydrogen peroxide, given their high sensitivity, small size, and biocompatible PEG corona. PMID:19337415

Steam gasification of waste tyre: Influence of process temperature on yield and product composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Portofino, Sabrina, E-mail: sabrina.portofino@enea.it; Donatelli, Antonio; Iovane, Pierpaolo

Highlights: ► Steam gasification of waste tyre as matter and energy recovery treatment. ► Process temperature affects products yield and gas composition. ► High temperature promotes hydrogen production. ► Char exploitation as activated carbon or carbon source. - Abstract: An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850–1000 °C, holding all the other operationalmore » parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86 wt%) and a lower char yield, due to an enhancement of the solid–gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000 °C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature.« less

Anaerobic biotransformation of explosives in aquifer slurries amended with ethanol and propylene glycol.

PubMed

Adrian, Neal R; Arnett, Clint M

2007-01-01

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,4,6-trinitrotoluene (TNT) are explosives that are frequently found as environmental contaminants on military installations. Hydrogen has been shown to support the anaerobic transformation of these explosives. We investigated ethanol and propylene glycol as electron donors for providing syntrophically produced H2 for stimulating the anaerobic biodegradation of explosives in contaminated soil. The study was conducted using anoxic microcosms constructed with slurries of the contaminated soil and groundwater. The addition of 5mM ethanol and propylene glycol enhanced the biodegradation of RDX and HMX relative to the control bottles. Ethanol was depleted within about 20 days, resulting in the transient formation of hydrogen, acetate, and methane. The hydrogen headspace concentration increased from 8 ppm to 1838 ppm before decreasing to background concentrations. Propylene glycol was completely degraded after 15 days, forming hydrogen, propionate, and acetate as end-products. The hydrogen headspace concentrations increased from 56 ppm to 628 ppm before decreasing to background concentrations. No methane formation was observed during the incubation period of 48 days. Our findings indicate the addition of ethanol and propylene to the aquifer slurries increased the hydrogen concentrations and enhanced the biotransformation of RDX and HMX in the explosive-contaminated soil.

Experimental study of the transient hydrogen jet - Using a fast response probe

NASA Astrophysics Data System (ADS)

Tanabe, H.; Ohnishi, M.; Sato, G. T.; Fujimoto, H.

Mixing processes of a transient hydrogen jet, such as those of a hydrogen-injection internal combustion engine, are studied by means of a concentration probe having a response time of less than 200 microsec. Hydrogen was injected into quiescent air by means of (1) a single-shot device, in order to study the air interactions of the jet with schlieren photography and smoke wire methods, and (2) a hydrogen diesel engine injection nozzle to determine jet shape with high speed schlieren photography. The concentration probe's response time was found to be adequate for the very short injection period, and it was determined that air-hydrogen mixing in the case of high jet momentum is governed by eddy diffusion.

Hydrogen absorption and its effect on magnetic properties of Nd2Fe14B

NASA Astrophysics Data System (ADS)

Bezdushnyi, R.; Damianova, R.; Tereshina, I. S.; Pankratov, N. Yu.; Nikitin, S. A.

2018-05-01

Magnetic properties of hydrides of the intermetallic compound Nd2Fe14BHx are investigated in the temperature range covering the Curie temperatures (TC) of the compounds (up to 670 K). The temperature dependencies of magnetization are measured under continuous control of hydrogen content in the investigated samples. The dependencies of Curie and spin-reorientation transition (TSR) temperatures on the hydrogen concentration are studied in detail. The dependence of hydrogen concentration on pressure at a constant temperature (near TC) and on the temperature at various pressures are obtained. We attempted to estimate the contributions of the unit cell volume increase upon hydrogenation and the electronic structure change in the variation of TC of the hydrogenated Nd2Fe14 B .

Analytical chemical kinetic investigation of the effects of oxygen, hydrogen, and hydroxyl radicals on hydrogen-air combustion

NASA Technical Reports Server (NTRS)

Carson, G. T., Jr.

1974-01-01

Quantitative values were computed which show the effects of the presence of small amounts of oxygen, hydrogen, and hydroxyl radicals on the finite-rate chemical kinetics of premixed hydrogen-air mixtures undergoing isobaric autoignition and combustion. The free radicals were considered to be initially present in hydrogen-air mixtures at equivalence ratios of 0.2, 0.6, 1.0, and 1.2. Initial mixture temperatures were 1100 K, 1200 K, and 1500 K, and pressures were 0.5, 1.0, 2.0, and 4.0 atm. Of the radicals investigated, atomic oxygen was found to be the most effective for reducing induction time, defined as the time to 5 percent of the total combustion temperature rise. The reaction time, the time between 5 percent and 95 percent of the temperature rise, is not decreased by the presence of free radicals in the initial hydrogen-air mixture. Fuel additives which yield free radicals might be used to effect a compact supersonic combustor design for efficient operation in an otherwise reaction-limited combustion regime.

Hydrogen peroxide catalytic decomposition

NASA Technical Reports Server (NTRS)

Parrish, Clyde F. (Inventor)

2010-01-01

Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

Combined on-board hydride slurry storage and reactor system and process for hydrogen-powered vehicles and devices

DOEpatents

Brooks, Kriston P; Holladay, Jamelyn D; Simmons, Kevin L; Herling, Darrell R

2014-11-18

An on-board hydride storage system and process are described. The system includes a slurry storage system that includes a slurry reactor and a variable concentration slurry. In one preferred configuration, the storage system stores a slurry containing a hydride storage material in a carrier fluid at a first concentration of hydride solids. The slurry reactor receives the slurry containing a second concentration of the hydride storage material and releases hydrogen as a fuel to hydrogen-power devices and vehicles.

Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope.

PubMed

Deng, Yun; Hajilou, Tarlan; Barnoush, Afrooz

2017-07-28

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10 -4  Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane.This article is part of the themed issue 'The challenges of hydrogen and metals'. © 2017 The Author(s).

Modeling of local steam condensation on walls in presence of non-condensable gases. Application to a loca calculation in reactor containment using the multidimensional geyser/tonus code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benet, L.V.; Caroli, C.; Cornet, P.

1995-09-01

This paper reports part of a study of possible severe pressurized water reactor (PWR) accidents. The need for containment modeling, and in particular for a hydrogen risk study, was reinforced in France after 1990, with the requirement that severe accidents must be taken into account in the design of future plants. This new need of assessing the transient local hydrogen concentration led to the development, in the Mechanical Engineering and Technology Department of the French Atomic Energy Commission (CEA/DMT), of the multidimensional code GEYSER/TONUS for containment analysis. A detailed example of the use of this code is presented. The mixturemore » consisted of noncondensable gases (air or air plus hydrogen) and water vapor and liquid water. This is described by a compressible homogeneous two-phase flow model and wall condensation is based on the Chilton-Colburn formula and the analogy between heat and mass transfer. Results are given for a transient two-dimensional axially-symmetric computation for the first hour of a simplified accident sequence. In this there was an initial injection of a large amount of water vapor followed by a smaller amount and by hydrogen injection.« less

An effective temperature compensation approach for ultrasonic hydrogen sensors

NASA Astrophysics Data System (ADS)

Tan, Xiaolong; Li, Min; Arsad, Norhana; Wen, Xiaoyan; Lu, Haifei

2018-03-01

Hydrogen is a kind of promising clean energy resource with a wide application prospect, which will, however, cause a serious security issue upon the leakage of hydrogen gas. The measurement of its concentration is of great significance. In a traditional approach of ultrasonic hydrogen sensing, a temperature drift of 0.1 °C results in a concentration error of about 250 ppm, which is intolerable for trace amount of gas sensing. In order to eliminate the influence brought by temperature drift, we propose a feasible approach named as linear compensation algorithm, which utilizes the linear relationship between the pulse count and temperature to compensate for the pulse count error (ΔN) caused by temperature drift. Experimental results demonstrate that our proposed approach is capable of improving the measurement accuracy and can easily detect sub-100 ppm of hydrogen concentration under variable temperature conditions.

[Acatalasemia and type 2 diabetes mellitus].

PubMed

Góth, László; Nagy, Teréz; Káplár, Miklós

2015-03-08

The catalase enzyme decomposes the toxic concentrations of hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly reactive small molecule and its excessive concentration may cause significant damages to proteins, deoxyribonucleic acid, ribonucleic acid and lipids. Acatalasemia refers to inherited deficiency of the catalase enzyme. In this review the authors discuss the possible role of the human catalase enzyme, the metabolism of hydrogen peroxide, and the phenomenon of hydrogen peroxide paradox. In addition, they review data obtained from Hungarian acatalasemic patients indicating an increased frequency of type 2 diabetes mellitus, especially in female patients, and an early onset of type 2 diabetes in these patients. There are 10 catalase gene variants which appear to be responsible for decreased blood catalase activity in acatalasemic patients with type 2 diabetes. It is assumed that low levels of blood catalase may cause an increased concentration of hydrogen peroxide which may contribute to the pathogenesis of type 2 diabetes mellitus.

Light-induced changes in silicon nanocrystal based solar cells: Modification of silicon-hydrogen bonding on silicon nanocrystal surface under illumination

NASA Astrophysics Data System (ADS)

Kim, Ka-Hyun; Johnson, Erik V.; Cabarrocas, Pere Roca i.

2016-07-01

Hydrogenated polymorphous silicon (pm-Si:H) is a material consisting of a small volume fraction of nanocrystals embedded in an amorphous matrix. pm-Si:H solar cells demonstrate interesting initial degradation behaviors such as rapid initial change in photovoltaic parameters and self-healing after degradation during light-soaking. The precise dynamics of the light-induced degradation was studied in a series of light-soaking experiments under various illumination conditions such as AM1.5G and filtered 570 nm yellow light. Hydrogen effusion experiment before and after light-soaking further revealed that the initial degradation of pm-Si:H solar cells originate from the modification of silicon-hydrogen bonding on the surface of silicon nanocrystals in pm-Si:H.

Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

DOEpatents

Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

2010-04-13

A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

Enhanced thermophilic fermentative hydrogen production from cassava stillage by chemical pretreatments.

PubMed

Wang, Wen; Luo, Gang; Xie, Li; Zhou, Qi

2013-01-01

Acid and alkaline pretreatments for enhanced hydrogen production from cassava stillage were investigated in the present study. The result showed that acid pretreatment was suitable for enhancement of soluble carbohydrate while alkaline pretreatment stimulated more soluble total organic carbon production from cassava stillage. Acid pretreatment thereby has higher capacity to promote hydrogen production compared with alkaline pretreatment. Effects of pretreatment temperature, time and acid concentration on hydrogen production were also revealed by response surface methodology. The results showed that the increase of all factors increased the soluble carbohydrate production, whereas hydrogen production was inhibited when the factors exceeded their optimal values. The optimal conditions for hydrogen production were pretreatment temperature 89.5 °C, concentration 1.4% and time 69 min for the highest hydrogen production of 434 mL, 67% higher than raw cassava stillage.

BUBBLE STRIPPING TO DETERMINE HYDROGEN CONCENTRATIONS IN GROUND WATER: A PRACTICAL APPLICATION OF HENRY'S LAW

EPA Science Inventory

The Bubble Stripping Method is a chemical testing method that operates on the principle of Henry's Law. It is useful for determining concentrations of hydrogen in well water, and it is capable of detecting concentrations on the order of nanomoles per liter. The method provides ...

Venus nighttime hydrogen bulge

NASA Technical Reports Server (NTRS)

Brinton, H. C.; Taylor, H. A., Jr.; Niemann, H. B.; Mayr, H. G.; Nagy, A. F.; Cravens, T. E.; Strobel, D. F.

1980-01-01

The concentration of atomic hydrogen in the Venus thermosphere near 165 km altitude and approximately 18 deg north latitude has been derived from Pioneer Venus in situ measurements of H(+), O(+), O and CO2 concentrations, under the assumption of chemical equilibrium. Altitude profiles of derived H concentration suggest that chemical equilibrium prevails to an altitude of at least 200 km on the dayside and to 165 km on the nightside. Measurements below these limits were made by the ion and neutral mass spectrometers on the orbiter spacecraft between December 1978 and July 1979, while periapsis traversed a complete diurnal cycle. The hydrogen concentration is found to rise sharply at both terminators from a dayside value of approximately 50,000/cu cm, and to exhibit an asymmetric nightside distribution with a peak density in the predawn sector approximately 400 times greater than the dayside value. Analysis suggests that wind-induced diffusion, combined with exospheric return flow, can account for the observed hydrogen behavior. The large day-night temperature contrast enhances advective transport, which produces the large H concentration diurnal variation; the shift of the H concentration nighttime maximum toward dawn is caused by atmospheric superrotation.

Fluidic hydrogen detector production prototype development

NASA Technical Reports Server (NTRS)

Roe, G. W.; Wright, R. E.

1976-01-01

A hydrogen gas sensor that can replace catalytic combustion sensors used to detect leaks in the liquid hydrogen transfer systems at Kennedy Space Center was developed. A fluidic sensor concept, based on the principle that the frequency of a fluidic oscillator is proportional to the square root of the molecular weight of its operating fluid, was utilized. To minimize sensitivity to pressure and temperature fluctuations, and to make the sensor specific for hydrogen, two oscillators are used. One oscillator operates on sample gas containing hydrogen, while the other operates on sample gas with the hydrogen converted to steam. The conversion is accomplished with a small catalytic converter. The frequency difference is taken, and the hydrogen concentration computed with a simple digital processing circuit. The output from the sensor is an analog signal proportional to hydrogen content. The sensor is shown to be accurate and insensitive to severe environmental disturbances. It is also specific for hydrogen, even with large helium concentrations in the sample gas.

Long-term acclimatory response to excess excitation energy: evidence for a role of hydrogen peroxide in the regulation of photosystem II antenna size.

PubMed

Borisova-Mubarakshina, Maria M; Ivanov, Boris N; Vetoshkina, Daria V; Lubimov, Valeriy Y; Fedorchuk, Tatyana P; Naydov, Ilya A; Kozuleva, Marina A; Rudenko, Natalia N; Dall'Osto, Luca; Cazzaniga, Stefano; Bassi, Roberto

2015-12-01

Higher plants possess the ability to trigger a long-term acclimatory response to different environmental light conditions through the regulation of the light-harvesting antenna size of photosystem II. The present study provides an insight into the molecular nature of the signal which initiates the high light-mediated response of a reduction in antenna size. Using barley (Hordeum vulgare) plants, it is shown (i) that the light-harvesting antenna size is not reduced in high light with a low hydrogen peroxide content in the leaves; and (ii) that a decrease in the antenna size is observed in low light in the presence of an elevated concentration of hydrogen peroxide in the leaves. In particular, it has been demonstrated that the ability to reduce the antenna size of photosystem II in high light is restricted to photosynthetic apparatus with a reduced level of the plastoquinone pool and with a low hydrogen peroxide content. Conversely, the reduction of antenna size in low light is induced in photosynthetic apparatus possessing elevated hydrogen peroxide even when the reduction level of the plastoquinone pool is low. Hydrogen peroxide affects the relative abundance of the antenna proteins that modulate the antenna size of photosystem II through a down-regulation of the corresponding lhcb mRNA levels. This work shows that hydrogen peroxide contributes to triggering the photosynthetic apparatus response for the reduction of the antenna size of photosystem II by being the molecular signal for the long-term acclimation of plants to high light. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Thermodynamic analysis on the role of hydrogen in anodic stress corrosion cracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, L.; Mao, X.

1995-11-01

A synergistic effect of hydrogen and stress on a corrosion rate was analyzed with thermodynamics. The results showed that an interaction of stress and hydrogen could increase the corrosion rate remarkably. Stress corrosion cracking (SCC) of austenitic stainless steel (ASS) was investigated in boiling chloride solution to confirm the analysis. Hydrogen could be introduced into the specimen concentrated at the crack tip during SCC in boiling LiCl solution (143 C). The concentrating factor is about 3 which is consistent with calculated results according to stress induced diffusion.

Diffusion of hydrogen in a hydrogen-saturated tungsten

NASA Astrophysics Data System (ADS)

Krstic, Predrag; Kaganovich, Igor

2015-11-01

Hydrogen diffusion in monoscrystalline tungsten is studied by molecular dynamics with BOP potential in function of hydrogen concentration and temperature. Tungsten surface is prepared by cumulative irradiation of the 25 eV deuterium atoms at various fluences. The diffusion coefficients for T>500K and various D concentrations were calculated from the average slope of the mean square displacements of deuterium as functions of time. The accumulation of deuterium suppresses its diffusion at all temperatures. The results are in a reasonable agreement with the existing experiments. Supported by the LDRD of PPPL.

Degradation of 4-Chloro-3,5-Dimethylphenol by a Heterogeneous Fenton-Like Reaction Using Nanoscale Zero-Valent Iron Catalysts

PubMed Central

Xu, Lejin; Wang, Jianlong

2013-01-01

Abstract Degradation of 4-chloro-3,5-dimethylphenol (PCMX) by a heterogeneous Fenton-like process using nanoparticulate zero-valent iron (nZVI) and hydrogen peroxide (H2O2) at pH 6.3 was investigated. Interactive effects of three factors—initial PCMX concentration, nZVI dosage, and H2O2 concentration—were investigated using the response surface method based on the Box–Behnken design. Experimental results showed that complete decomposition of PCMX and 65% of total organic carbon removal were observed after 30 min of reaction at neutral pH under recommended reaction conditions: nZVI, 1.0 g/L; H2O2, 18 mM; and initial PCMX concentration, 0.15 g/L. Based on the effects of scavengers n-butanol and KI, removal of PCMX was mainly attributed to the attack of •OH, especially the surface-bonded •OH. A possible degradation pathway of PCMX was proposed. PMID:23781127

Sequential solar photo-fenton-biological system for the treatment of winery wastewaters.

PubMed

Mosteo, R; Sarasa, J; Ormad, Maria P; Ovelleiro, J L

2008-08-27

In this study, winery wastewaters are considered for degradation using heterogeneous photo-Fenton as a preliminary step before biotreatment. The heterogeneous photo-Fenton process assisted by solar light is able to partially degrade the organic matter present in winery wastewaters. When an initial hydrogen peroxide concentration of 0.1 M is used over 24 h of treatment, a degradation yield of organic matter (measured as TOC) of around 50% is reached. The later treatment (activated sludge process) allows the elimination of 90% of the initial TOC present in pretreated winery wastewaters without producing nondesired side-effects, such as the bulking phenomenon, which is usually detected when this treatment is used alone. The final effluent contains a concentration of organic matter (measured as COD) of 128 mg O2/L. The coupled system comprising the heterogeneous photo-Fenton process and biological treatment based on activated sludge in simple stage is a real alternative for the treatment of winery wastewater.

Analysis of hydrogen isotope mixtures

DOEpatents

Villa-Aleman, Eliel

1994-01-01

An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

Real-time elucidation of catalytic pathways in CO hydrogenation on Ru

DOE PAGES

LaRue, Jerry; Krejci, Ondrej; Yu, Liang; ...

2017-07-31

Here, the direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast timescales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO 2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time x-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.

Impact of temperature and substrate concentration on degradation rates of acetate, propionate and hydrogen and their links to microbial community structure.

PubMed

Zhao, Jing; Westerholm, Maria; Qiao, Wei; Yin, Dongmin; Bi, Shaojie; Jiang, Mengmeng; Dong, Renjie

2018-05-01

The present study investigates the conversion of acetate, propionate and hydrogen consumption linked to the microbial community structure and related to temperature and substrate concentration. Biogas reactors were continuously fed with coffee powder (20 g-COD/L) or acetate (20, 40, and 60 g-COD/L) and operated for 193 days at 37 °C or 55 °C conditions. Starting HRT was 23 days which was then reduced to 7 days. The kinetics of acetate and propionate degradation and hydrogen consumption rates were measured in batch assays. At HRT 7 days, the degradation rate of propionate was higher in thermophilic batches, while acetate degradation rate was higher at mesophilic conditions. The gaseous hydrogen consumption in acetate reactors increased proportionally with temperature and substrate concentration, while the dissolved hydrogen was not affected. The relative high abundance of hydrogentrophic methanogens indicated that the methanogenesis was directed towards the syntrophic acetate oxidation pathway at high acetate concentration and high temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impact of Lactic Acid and Hydrogen Ion on the Simultaneous Fermentation of Glucose and Xylose by the Carbon Catabolite Derepressed Lactobacillus brevis ATCC 14869.

PubMed

Jeong, Kyung Hun; Israr, Beenish; Shoemaker, Sharon P; Mills, David A; Kim, Jaehan

2016-07-28

Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite de-repressed (CCR) phenotype which has ability to consume fermentable sugar simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effect of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration has been reduced. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Moreover; utilization of other compounds were also observed along with hydrogen ion and lactic acid concentration simultaneously. It has been found that substrate preference changes significantly regarding to utilization of compounds in media. That could result into formation of two-carbon products. In particular, acetic acid present in the media as sodium acetate were consumed by L. brevis ATCC 14869 under extreme pH of both acid and alkaline conditions.

Reactive oxygen species regulate DNA copy number in isolated yeast mitochondria by triggering recombination-mediated replication.

PubMed

Hori, Akiko; Yoshida, Minoru; Shibata, Takehiko; Ling, Feng

2009-02-01

Mitochondrial DNA (mtDNA) encodes proteins that are essential for cellular ATP production. Reactive oxygen species (ROS) are respiratory byproducts that damage mtDNA and other cellular components. In Saccharomyces cerevisiae, the oxidized base excision-repair enzyme Ntg1 introduces a double-stranded break (DSB) at the mtDNA replication origin ori5; this DSB initiates the rolling-circle mtDNA replication mediated by the homologous DNA pairing protein Mhr1. Thus, ROS may play a role in the regulation of mtDNA copy number. Here, we show that the treatment of isolated mitochondria with low concentrations of hydrogen peroxide increased mtDNA copy number in an Ntg1- and Mhr1-dependent manner. This treatment elevated the DSB levels at ori5 of hypersuppressive [rho(-)] mtDNA only if Ntg1 was active. In vitro Ntg1-treatment of hypersuppressive [rho(-)] mtDNA extracted from hydrogen peroxide-treated mitochondria revealed increased oxidative modifications at ori5 loci. We also observed that purified Ntg1 created breaks in single-stranded DNA harboring oxidized bases, and that ori5 loci have single-stranded character. Furthermore, chronic low levels of hydrogen peroxide increased in vivo mtDNA copy number. We therefore propose that ROS act as a regulator of mtDNA copy number, acting through the Mhr1-dependent initiation of rolling-circle replication promoted by Ntg1-induced DSB in the single-stranded regions at ori5.

Photocatalytic Treatment of a Synthetic Wastewater

NASA Astrophysics Data System (ADS)

Yerkinova, Azat; Balbayeva, Gaukhar; Inglezakis, Vassilis J.; Poulopoulos, Stavros G.

2018-01-01

This work aimed at investigating the photocatalytic treatment of a synthetic wastewater using UV light (254 nm, 6 W), TiO2 catalyst and H2O2 in a batch recycle annular photoreactor. The total volume of the solution was 250 mL while the irradiated volume in the annular photoreactor with 55.8 mL. Each experiment lasted 120 min and samples were sent for Total Carbon and HPLC analysis. The stock wastewater had initial total carbon 1118 mg L-1. The effect of the presence of phenol in the wastewater on total carbon (TC) removal was also studied. It was shown that the photocatalytic treatment was effective only when initial TC was decreased to 32 mg L-1, whereas the optimum TiO2 concentration was 0.5 g L-1, leading to a TC removal up to 56%. For the same initial carbon load, the optimum H2O2 concentration was found to be 67 mg L-1 resulting in 55% TC removal. Combining, however, TiO2 and H2O2 did not lead to better performance, as 51% TC removal was observed. In contrast, when initial carbon in the wastewater was partially substituted by phenol, the combination of catalyst and hydrogen peroxide was beneficial. Specifically, when 10 ppm of phenol were added keeping the same initial TC concentration, UV/TiO2 treatment resulted in 46% TC removal and 98% phenol conversion, whereas using additionally H2O2 led to 100% phenol conversion after 45 minutes and 81% TC removal.

The effect of hydrogen and microstructure on the deformation and fracture behavior of a single crystal nickel-base superalloy. Final Report Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Walston, William S.

1990-01-01

A study was conducted on the effects of internal hydrogen and microstructure on the deformation and fracture of a single crystal nickel-base superalloy. In particular, room temperature plane strain fracture toughness and tensile tests were performed on hydrogen-free and hydrogen charged samples of PWA 1480. The role of microstructure was incorporated by varying the levels of porosity and eutectic gamma/gamma prime through hot isostatic pressing and heat treatment. The room temperature behavior of PWA 1480 was unusual because precipitate shearing was not the primary deformation mechanism at all strains. At strains over 1 percent, dislocations were trapped in the gamma matrix and an attempt was made to relate this behavior to compositional differences between PWA 1480 and other superalloys. Another unique feature of the tensile behavior was cleavage of the eutectic gamma/gamma prime, which is believed to initiate the failure process. Fracture occurred on (111) planes and is likely a result of shear localization along these planes. Elimination of the eutectic gamma/gamma prime greatly improved the tensile ductility, but pososity had no effect on tensile properties. Large quantities of hydrogen (1.74 at. percent) were gas-phase charged into the material, but surprisingly this was not a function of the amount of porosity or eutectic gamma/gamma prime present. Desorption experiments suggest that the vast majority of hydrogen is at reversible lattice trapping sites. This large, uniform concentration of hydrogen dramatically reduced the tensile strain to failure, but only slightly affected the reduction in area. Available hydrogen embrittlement models were examined in light of these results and it was found that the hydrogen enhanced localized plasticity model can explain much of the tensile behavior. K(IC) fracture toughness tests were conducted, but it was necessary to also perform J(IC) tests to provide valid data.

Hydrogen environment embrittlement

NASA Technical Reports Server (NTRS)

Gray, H. R.

1972-01-01

Hydrogen embrittlement is classified into three types: internal reversible hydrogen embrittlement, hydrogen reaction embrittlement, and hydrogen environment embrittlement. Characteristics of and materials embrittled by these types of hydrogen embrittlement are discussed. Hydrogen environment embrittlement is reviewed in detail. Factors involved in standardizing test methods for detecting the occurrence of and evaluating the severity of hydrogen environment embrittlement are considered. The effect of test technique, hydrogen pressure, purity, strain rate, stress concentration factor, and test temperature are discussed. Additional research is required to determine whether hydrogen environment embrittlement and internal reversible hydrogen embrittlement are similar or distinct types of embrittlement.

Investigating Elevated Concentrations of Hydrogen in the LAX region

NASA Astrophysics Data System (ADS)

Rund, P.; Hughes, S.; Blake, D. R.

2017-12-01

The growing interest in hydrogen (H2) fuel cell vehicles has created a need to study the atmospheric H2 budget. While there is resounding agreement that hydrogen would escape into the atmosphere due to fuel transport/storage processes, there is disagreement over the amount that would be leaked in a hydrogen fuel economy. Leakage rate estimates range from 2% to 10% for total hydrogen production and transport. A hydrogen based energy infrastructure seems a viable clean alternative to oil because, theoretically, the only waste products are H2O and heat. However, hydrogen leads to the formation of water vapor, polar stratospheric clouds, and a decrease in stratospheric temperatures, which contribute to the depletion of stratospheric ozone. Whole air samples (WAS) collected aboard the NASA Sherpa C-23 during the Student Airborne Research Program (SARP) showed elevated concentrations of hydrogen near LAX (950 ± 110 ppbv) compared to global average concentrations of 560 ± 20 ppbv. Trace gas analysis along with wind trajectories obtained with the NOAA HySPLIT models indicate that the source of elevated mixing ratios was leakage from H2 fuel stations in the surrounding areas. Correlation and ratio analyses eliminate the potential for common photochemical sources of H2 in the LAX area. This project could elucidate new and potential factors that contribute to the global atmospheric hydrogen budget.

Hydrogen sulfide generation in simulated construction and demolition debris landfills: impact of waste composition.

PubMed

Yang, Kenton; Xu, Qiyong; Townsend, Timothy G; Chadik, Paul; Bitton, Gabriel; Booth, Matthew

2006-08-01

Hydrogen sulfide (H2S) generation in construction and demolition (C&D) debris landfills has been associated with the biodegradation of gypsum drywall. Laboratory research was conducted to observe H2S generation when drywall was codisposed with different C&D debris constituents. Two experiments were conducted using simulated landfill columns. Experiment 1 consisted of various combinations of drywall, wood, and concrete to determine the impact of different waste constituents and combinations on H2S generation. Experiment 2 was designed to examine the effect of concrete on H2S generation and migration. The results indicate that decaying drywall, even alone, leached enough sulfate ions and organic matter for sulfate-reducing bacteria (SRB) to generate large H2S concentrations as high as 63,000 ppmv. The codisposed wastes show some effect on H2S generation. At the end of experiment 1, the wood/drywall and drywall alone columns possessed H2S concentrations > 40,000 ppmv. Conversely, H2S concentrations were < 1 ppmv in those columns containing concrete. Concrete plays a role in decreasing H2S by increasing pH out of the range for SRB growth and by reacting with H2S. This study also showed that wood lowered H2S concentrations initially by decreasing leachate pH values. Based on the results, two possible control mechanisms to mitigate H2S generation in C&D debris landfills are suggested.

Two-photon laser-induced fluorescence of atomic hydrogen in a diamond-depositing dc arcjet.

PubMed

Juchmann, Wolfgang; Luque, Jorge; Jeffries, Jay B

2005-11-01

Atomic hydrogen in the plume of a dc-arcjet plasma is monitored by use of two-photon excited laser-induced fluorescence (LIF) during the deposition of diamond film. The effluent of a dc-arc discharge in hydrogen and argon forms a luminous plume as it flows through a converging-diverging nozzle into a reactor. When a trace of methane (< 2%) is added to the flow in the diverging part of the nozzle, diamond thin film grows on a water-cooled molybdenum substrate from the reactive mixture. LIF of atomic hydrogen in the arcjet plume is excited to the 3S and 3D levels with two photons near 205 nm, and the subsequent fluorescence is observed at Balmer-alpha near 656 nm. Spatially resolved LIF measurements of atomic hydrogen are made as a function of the ratio of hydrogen to argon feedstock gas, methane addition, and reactor pressure. At lower reactor pressures, time-resolved LIF measurements are used to verify our collisional quenching correction algorithm. The quenching rate coefficients for collisions with the major species in the arcjet (Ar, H, and H2) do not change with gas temperature variations in the plume (T < 2300 K). Corrections of the LIF intensity measurements for the spatial variation of collisional quenching are important to determine relative distributions of the atomic hydrogen concentration. The relative atomic hydrogen concentrations measured here are calibrated with an earlier calorimetric determination of the feedstock hydrogen dissociation to provide quantitative hydrogen-atom concentration distributions.

Misoriented grain boundaries vicinal to the ? twin in Nickel part II: thermodynamics of hydrogen segregation

NASA Astrophysics Data System (ADS)

O'Brien, Christopher J.; Foiles, Stephen M.

2016-05-01

Grain boundary engineered materials are of immense interest for their resistance to hydrogen embrittlement. This work builds on the work undertaken in Part I on the thermodynamic stability and structure of misoriented grain boundaries vicinal to the ?? (coherent-twin) boundary to examine hydrogen segregation to those boundaries. The segregation of hydrogen reflects the asymmetry of the boundary structure with the sense of rotation of the grains about the coherent-twin boundary, and the temperature-dependent structural transition present in one sense of misorientation. This work also finds that the presence of hydrogen affects a change in structure of the boundaries with increasing concentration. The structural change effects only one sense of misorientation and results in the reduction in length of the emitted stacking faults. Moreover, the structural change results in the generation of occupied sites populated by more strongly bound hydrogen. The improved understanding of misoriented twin grain boundary structure and the effect on hydrogen segregation resulting from this work is relevant to higher length-scale models. To that end, we examine commonly used metrics such as free volume and atomic stress at the boundary. Free volume is found not to be useful as a surrogate for predicting the degree of hydrogen segregation, whereas the volumetric virial stress reliably predicts the locations of hydrogen segregation and exclusion at concentrations below saturation or the point where structural changes are induced by increasing hydrogen concentration.

Electrochemical removal of hydrogen atoms in Mg-doped GaN epitaxial layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, June Key, E-mail: junekey@jnu.ac.kr, E-mail: hskim7@jbnu.ac.kr; Hyeon, Gil Yong; Tawfik, Wael Z.

2015-05-14

Hydrogen atoms inside of an Mg-doped GaN epitaxial layer were effectively removed by the electrochemical potentiostatic activation (EPA) method. The role of hydrogen was investigated in terms of the device performance of light-emitting diodes (LEDs). The effect of the main process parameters for EPA such as solution type, voltage, and time was studied and optimized for application to LED fabrication. In optimized conditions, the light output of 385-nm LEDs was improved by about 26% at 30 mA, which was caused by the reduction of the hydrogen concentration by ∼35%. Further removal of hydrogen seems to be involved in the breaking ofmore » Ga-H bonds that passivate the nitrogen vacancies. An EPA process with high voltage breaks not only Mg-H bonds that generate hole carriers but also Ga-H bonds that generate electron carriers, thus causing compensation that impedes the practical increase of hole concentration, regardless of the drastic removal of hydrogen atoms. A decrease in hydrogen concentration affects the current-voltage characteristics, reducing the reverse current by about one order and altering the forward current behavior in the low voltage region.« less

A CFD Analysis of Hydrogen Leakage During On-Pad Purge in the ORION/ARES I Shared Volume

NASA Technical Reports Server (NTRS)

Ajmani, Kumud; Edwards, Daryl A.

2011-01-01

A common open volume is created by the stacking of the Orion vehicle onto the Ares I Upper Stage. Called the Shared Volume, both vehicles contribute to its gas, fluid, and thermal environment. One of these environments is related to hazardous hydrogen gas. While both vehicles use inert purge gas to mitigate any hazardous gas buildup, there are concerns that hydrogen gas may still accumulate and that the Ares I Hazardous Gas Detection System will not be sufficient for monitoring the integrated volume. This Computational Fluid Dynamics (CFD) analysis has been performed to examine these topics. Results of the analysis conclude that the Ares I Hazardous Gas Detection System will be able to sample the vent effluent containing the highest hydrogen concentrations. A second conclusion is that hydrogen does not accumulate under the Orion Service Module (SM) avionics ring as diffusion and purge flow mixing sufficiently dilute the hydrogen to safe concentrations. Finally the hydrogen concentrations within the Orion SM engine nozzle may slightly exceed the 1 percent volume fraction when the entire worse case maximum full leak is directed vertically into the engine nozzle.

Electrochemical removal of hydrogen atoms in Mg-doped GaN epitaxial layers

NASA Astrophysics Data System (ADS)

Lee, June Key; Hyeon, Gil Yong; Tawfik, Wael Z.; Choi, Hee Seok; Ryu, Sang-Wan; Jeong, Tak; Jung, Eunjin; Kim, Hyunsoo

2015-05-01

Hydrogen atoms inside of an Mg-doped GaN epitaxial layer were effectively removed by the electrochemical potentiostatic activation (EPA) method. The role of hydrogen was investigated in terms of the device performance of light-emitting diodes (LEDs). The effect of the main process parameters for EPA such as solution type, voltage, and time was studied and optimized for application to LED fabrication. In optimized conditions, the light output of 385-nm LEDs was improved by about 26% at 30 mA, which was caused by the reduction of the hydrogen concentration by ˜35%. Further removal of hydrogen seems to be involved in the breaking of Ga-H bonds that passivate the nitrogen vacancies. An EPA process with high voltage breaks not only Mg-H bonds that generate hole carriers but also Ga-H bonds that generate electron carriers, thus causing compensation that impedes the practical increase of hole concentration, regardless of the drastic removal of hydrogen atoms. A decrease in hydrogen concentration affects the current-voltage characteristics, reducing the reverse current by about one order and altering the forward current behavior in the low voltage region.

Hydrogen Fuel Cell Electric Vehicle Learning Demonstration | Hydrogen and

Science.gov Websites

Fuel Cells | NREL Fuel Cell Electric Vehicle Learning Demonstration Hydrogen Fuel Cell Electric Vehicle Learning Demonstration Initiated in 2004, DOE's Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project-later dubbed the Fuel Cell Electric Vehicle (FCEV) Learning Demonstration

The Effect of the Presence of Ozone on the Lower Flammability Limit (LFL) of Hydrogen in Vessels Containing Savannah River Site High Level Waste - 12387

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherburne, Carol; Osterberg, Paul

The Enhanced Chemical Cleaning (ECC) process uses ozone to effect the oxidation of metal oxalates produced during the dissolution of sludge in the Savannah River Site (SRS) waste tanks. The ozone reacts with the metal oxalates to form metal oxide and hydroxide precipitants, and the CO{sub 2}, O{sub 2}, H{sub 2}O and any unreacted O{sub 3} gases are discharged into the vapor space. In addition to the non-radioactive metals in the waste, however, the SRS radioactive waste also contains a variety of radionuclides, hence, hydrogen gas is also present in the vapor space of the ECC system. Because hydrogen ismore » flammable, the impact of this resultant gas stream on the Lower Flammability Limit (LFL) of hydrogen must be understood for all possible operating scenarios of both normal and off-normal situations, with particular emphasis at the elevated temperatures and pressures of the typical ECC operating conditions. Oxygen is a known accelerant in combustion reactions, but while there are data associated with the behavior of hydrogen/oxygen environments, recent, relevant studies addressing the effect of ozone on the flammability limit of hydrogen proved scarce. Further, discussions with industry experts verified the absence of data in this area and indicated that laboratory testing, specific to defined operating parameters, was needed to comprehensively address the issue. Testing was thus designed and commissioned to provide the data necessary to support safety related considerations for the ECC process. A test matrix was developed to envelope the bounding conditions considered credible during ECC processing. Each test consists of combining a gas stream of high purity hydrogen with a gas stream comprised of a specified mixture of ozone and oxygen in a temperature and pressure regulated chamber such that the relative compositions of the two streams are controlled. The gases are then stirred to obtain a homogeneous mixture and ignition attempted by applying 10J of energy to a fuse wire. A gas combination is considered flammable when a pressure rise of 7% of the initial absolute pressure is observed. The specified testing methodology is consistent with guidelines established in ASTM E-918-83 (2005) 'Standard Practices for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure'. The LFL of hydrogen in air was determined and is in good agreement with the literature data. Ozone-oxygen mixtures were found to be flammable at concentrations above 8.3 vol.% based on the ASTM E918 7% pressure rise criteria for flame propagation. This result is lower than previously reported values which can be explained through the variations in the test setup and procedure. It is believed that the lower values obtained in this work are a result of improvements of the test methodology. Tests performed with hydrogen in various concentrations of ozone in oxygen have shown that the LFL of hydrogen decreases as the concentration of ozone in the mixture increases. This testing was designed to provide data under the conditions considered most optimal to produce deflagration. The geometry and materials of construction of the testing vessel; the location of the fuse wire; the magnitude of the supplied energy; the careful minimization of diluents and other contaminants; and meticulous procedural detail to maintain integrity of the ozone to the maximum extent practical, result in data that reflect not the expected process conditions, but those that enhance the possibility of flame propagation. For this reason, there is believed to be considerable conservatism in the indicated results. Per the vendor, the maximum possible ozone concentration producible by the planned ECC Ozone generator is 8 volume percent (the typical maximum operating setpoint concentration is 6.8 vol%), less than the 8.3 minimum volume % concentration shown to be flammable in a 99.999% pure O{sub 2} environment at the optimally conservative conditions established in this testing. Further, the feed to the ECC ozone generator is only 87% oxygen, the remainder, water vapor and nitrogen, both powerful diluents. It is, thus, believed not credible that deflagration can occur at this maximum feed concentration condition. In addition, once the ozone stream contacts the waste stream, the many simultaneous oxidizing reactions will rapidly decompose available ozone to well below flammable levels. Further, because the radiolytically generated hydrogen quantity is negligible compared to the supplied ozone/oxygen stream (0.0004 moles per minute H{sub 2} vs 76 moles per minute ozone/oxygen), even the total H{sub 2}/O{sub 3} mixture, without crediting decomposition reactions, does not approach flammable concentrations. Finally, even at the 'end' of the ECC batch cycle, when most of the metal oxalates have been decomposed, testing has indicated that the ozone concentration in the vapor space of the ECC process vessel reaches a concentration of no more than 3 vol%, remaining well below concentrations of concern. The major issue for the ECC operation established by this testing is the impact of the data when applied to off normal conditions. While it is possible to discontinue ozone addition to the reaction vessel at any time, the radiolytic hydrogen generation rate continues, varying slightly as ambient pressures and temperatures change. Relative to the data generated and analyzed in this testing, the ECC hazards analysis team will re-evaluate off normal conditions (e.g. those during which process exhaust ventilation is lost) such that issues involving mixtures of hydrogen and ozone in the vapor space can be appropriately controlled. (authors)« less

Generalized platform for antibody detection using the antibody catalyzed water oxidation pathway.

PubMed

Welch, M Elizabeth; Ritzert, Nicole L; Chen, Hongjun; Smith, Norah L; Tague, Michele E; Xu, Youyong; Baird, Barbara A; Abruña, Héctor D; Ober, Christopher K

2014-02-05

Infectious diseases, such as influenza, present a prominent global problem including the constant threat of pandemics that initiate in avian or other species and then pass to humans. We report a new sensor that can be specifically functionalized to detect antibodies associated with a wide range of infectious diseases in multiple species. This biosensor is based on electrochemical detection of hydrogen peroxide generated through the intrinsic catalytic activity of all antibodies: the antibody catalyzed water oxidation pathway (ACWOP). Our platform includes a polymer brush-modified surface where specific antibodies bind to conjugated haptens with high affinity and specificity. Hydrogen peroxide provides an electrochemical signal that is mediated by Resorufin/Amplex Red. We characterize the biosensor platform, using model anti-DNP antibodies, with the ultimate goal of designing a versatile device that is inexpensive, portable, reliable, and fast. We demonstrate detection of antibodies at concentrations that fall well within clinically relevant levels.

Investment in hydrogen tri-generation for wastewater treatment plants under uncertainties

NASA Astrophysics Data System (ADS)

Gharieh, Kaveh; Jafari, Mohsen A.; Guo, Qizhong

2015-11-01

In this article, we present a compound real option model for investment in hydrogen tri-generation and onsite hydrogen dispensing systems for a wastewater treatment plant under price and market uncertainties. The ultimate objective is to determine optimal timing and investment thresholds to exercise initial and subsequent options such that the total savings are maximized. Initial option includes investment in a 1.4 (MW) Molten Carbonate Fuel Cell (MCFC) fed by mixture of waste biogas from anaerobic digestion and natural gas, along with auxiliary equipment. Produced hydrogen in MCFC via internal reforming, is recovered from the exhaust gas stream using Pressure Swing Adsorption (PSA) purification technology. Therefore the expansion option includes investment in hydrogen compression, storage and dispensing (CSD) systems which creates additional revenue by selling hydrogen onsite in retail price. This work extends current state of investment modeling within the context of hydrogen tri-generation by considering: (i) Modular investment plan for hydrogen tri-generation and dispensing systems, (ii) Multiple sources of uncertainties along with more realistic probability distributions, (iii) Optimal operation of hydrogen tri-generation is considered, which results in realistic saving estimation.

Production of bioethanol and value added compounds from wheat straw through combined alkaline/alkaline-peroxide pretreatment.

PubMed

Yuan, Zhaoyang; Wen, Yangbing; Li, Guodong

2018-07-01

An efficient scheme was developed for the conversion of wheat straw (WS) into bioethanol, silica and lignin. WS was pre-extracted with 0.2 mol/L sodium hydroxide at 30 °C for 5 h to remove about 91% of initial silica. Subsequently, the alkaline-pretreated solids were subjected to alkaline hydrogen peroxide (AHP) pretreatment with 40 mg hydrogen peroxide (H 2 O 2 )/g biomass at 50 °C for 7 h to prepare highly digestible substrate. The results of enzymatic hydrolysis demonstrated that the sequential alkaline-AHP pretreated WS was efficiently hydrolyzed at 10% (w/v) solids loading using an enzyme dosage of 10 mg protein/g glucan. The total sugar conversion of 92.4% was achieved. Simultaneous saccharification and co-fermentation (SSCF) was applied to produce ethanol from the two-stage pretreated substrate using Saccharomyces cerevisiae SR8u strain. Ethanol with concentration of 31.1 g/L was produced. Through the proposed process, about 86.4% and 54.1% of the initial silica and lignin were recovered, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Safety issues of high-concentrated hydrogen peroxide production used as rocket propellant

NASA Astrophysics Data System (ADS)

Romantsova, O. V.; Ulybin, V. B.

2015-04-01

The article dwells on the possibility of production of high-concentrated hydrogen peroxide with the Russian technology of isopropyl alcohol autoxidation. Analysis of fire/explosion hazards and reasons of insufficient quality is conducted for the technology. Modified technology is shown. Non-standard fire/explosion characteristics required for integrated fire/explosion hazards rating for modified hydrogen peroxide production based on the autoxidation of isopropyl alcohol are defined.

Stabilized aqueous hydrogen peroxide solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malin, M.J.; Sciafani, L.D.

1988-05-17

This patent describes a stabilized aqueous hydrogen peroxide solution having a pH below 7 and an amount of Ferric ion up to about 2 ppm comprising hydrogen peroxide, acetanilide having a concentration which ranges between 0.74 M Mol/L and 2.22 mMol/L, and o-benzene disulfonic acid or salt thereof at a concentration between about 0.86 mMol/L to about 1.62 mMol/L.

Improved Sensitivity with Low Limit of Detection of a Hydrogen Gas Sensor Based on rGO-Loaded Ni-Doped ZnO Nanostructures.

PubMed

Bhati, Vijendra Singh; Ranwa, Sapana; Rajamani, Saravanan; Kumari, Kusum; Raliya, Ramesh; Biswas, Pratim; Kumar, Mahesh

2018-04-04

We report enhanced hydrogen-gas-sensing performance of a Ni-doped ZnO sensor decorated with the optimum concentration of reduced graphene oxide (rGO). Ni-doped ZnO nanoplates were grown by radio frequency sputtering, rGO was synthesized by Hummer's method and decorated by the drop cast method of various concentration of rGO (0-1.5 wt %). The current-voltage characteristics of the rGO-loaded sensor are highly influenced by the loading concentration of rGO, where current conduction decreases and sensor resistance increases as the rGO concentration is increased up to 0.75 wt % because of the formation of various Schottky heterojunctions at rGO/ZnO interfaces. With the combined effect of more active site availability and formation of various p-n heterojunctions due to the optimum loading concentration of rGO (0.75 wt %), the sensor shows the maximum sensing response of ∼63.8% for 100 ppm hydrogen at moderate operating temperature (150 °C). The rGO-loaded sensors were able to detect a minimum of 1 ppm hydrogen concentration and showed high selectivity. However, a further increase in the rGO concentration (1.5 wt %) leads to the reduction of the relative response of hydrogen gas, ascribed to the formation of interconnections of rGO between electrodes. Therefore, it reduces the total resistance of the sensor and minimizes the effect of p-n heterojunction on sensor response.

Thermodynamic characterization of hydrogen interaction with iridium polyhydride complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zidan, R.A.; Rocheleau, R.E.

1999-01-01

Hydrogen interaction with solid iridium complexes IrXH{sub 2}(PPr3{sup i}){sub 2} (X=Cl, I) was investigated. Gaseous hydrogen was found to react reversibly with solid chloro-iridium complex IrClH{sub 2}(PPr3{sup i}){sub 2} forming IrClH{sub 2}(PPr3{sup i}){sub 2}H{sub 2}. The relative partial molal enthalpy and entropy were obtained from equilibrium isotherms at different hydrogen concentrations. The decrease in entropy with increasing hydrogen concentration and the absence of plateaus in the equilibrium isotherms were consistent with a single phase solid solution with two chemical components. Hydrogen release from solid iodo-iridium complex IrIH{sub 2}(PPr3{sup i}){sub 2}H{sub 2} was not observed at temperatures up to 350 K,more » indicating stronger hydrogen bonding. {copyright} {ital 1999 Materials Research Society.}« less

Preparation of ZnO/SnO2 Composite Nanometer Photocatalyst and Photocatalytic Treatment of Marine Diesel Pollution

NASA Astrophysics Data System (ADS)

Zhang, J.; Yu, X. C.; Nie, Z. W.; Guo, M. C.; Liu, J. H.; Wang, L. P.

2017-12-01

The ZnO/SnO2 composite nanophotocatalyst studied in this paper was prepared by a chemical precipitation method, which were characterized by XRD and SEM. The results show that the prepared samples were rutile SnO2 particles and the average grain size is 8.41 nm. In this paper, the factors for the degradation efficiency of marine diesel oil degraded by ZnO/SnO2 composite nanophotocatalyst are the catalysts’ doping ratio, the initial concentration of oil, the pH value of seawater, the dosage of catalyst and the dosage of hydrogen peroxide. The results show that the ZnO/SnO2 composite nanophotocatalyst can effectively degrade seawater diesel oil under UV light. When the doping ratio of ZnO and SnO2 is 0.35, the reaction time is 2.5 hours, the pH value of seawater with oil is 7, The concentration of diesel oil is 0.1g/L, the dosage of catalyst is 0.3g/L and the dosage of hydrogen peroxide is 0.1 g/L, the highest degradation rate is 91.54%.

Field-rugged sensitive hydrogen peroxide sensor based on tunable diode laser absorption spectroscopy (TDLAS)

NASA Astrophysics Data System (ADS)

Frish, M. B.; Morency, J. R.; Laderer, M. C.; Wainner, R. T.; Parameswaran, K. R.; Kessler, W. J.; Druy, M. A.

2010-04-01

This paper reports the development and initial testing of a field-portable sensor for monitoring hydrogen peroxide (H2O2) and water (H2O) vapor concentrations during building decontamination after accidental or purposeful exposure to hazardous biological materials. During decontamination, a sterilization system fills ambient air with water and peroxide vapor to near-saturation. The peroxide concentration typically exceeds several hundred ppm for tens of minutes, and subsequently diminishes below 1 ppm. The H2O2/ H2O sensor is an adaptation of a portable gas-sensing platform based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. By capitalizing on its spectral resolution, the TDLAS analyzer isolates H2O2 and H2O spectral lines to measure both vapors using a single laser source. It offers a combination of sensitivity, specificity, fast response, dynamic range, linearity, ease of operation and calibration, ruggedness, and portability not available in alternative H2O2 detectors. The H2O2 range is approximately 0- 5,000 ppm. The autonomous and rugged instrument provides real-time data. It has been tested in a closed-loop liquid/vapor equilibrium apparatus and by comparison against electrochemical sensors.

Hydrogen combustion in a flat semi-confined layer with respect to the Fukushima Daiichi accident

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuznetsov, M.; Yanez, J.; Grune, J.

2012-07-01

The hydrogen accumulation at the top of containment or reactor building may occur due to an interaction of molten corium and water followed by a severe accident of a nuclear reactor (TMI, Chernobyl, Fukushima Daiichi). The hydrogen, released from the reactor, accumulates usually as a stratified semi-confined layer of hydrogen-air mixture. A series of large scale experiments on hydrogen combustion and explosion in a semi-confined layer of uniform and non-uniform hydrogen-air mixtures in presence of obstructions or without them was performed at the Karlsruhe Inst. of Technology (KIT). Different flame propagation regimes from slow subsonic to relative fast sonic flamesmore » and then to the detonations were experimentally investigated in different geometries and then simulated with COMSD code with respect to evaluate amount of burnt hydrogen taken place during the Fukushima Daiichi Accident (FDA). The experiments were performed in a horizontal semi-confined layer with dimensions of 9x3x0.6 m with/without obstacles opened from below. The hydrogen concentration in the mixtures with air was varied in the range of 0-34 vol. % without or with a gradient of 0-60 vol. %H{sub 2}/m. Effects of hydrogen concentration gradient, thickness of the layer, geometry of the obstructions, average and maximum hydrogen concentration on flame propagation regimes were investigated with respect to evaluate the maximum pressure loads of internal structures. Blast wave strength and dynamics of propagation after explosion of the layer of hydrogen-air mixture was numerically simulated to reproduce the hydrogen explosion process during the Fukushima Daiichi Accident. (authors)« less

Development of a technique for the in vivo assessment of flatulence in dogs.

PubMed

Collins, S B; Perez-Camargo, G; Gettinby, G; Butterwick, R F; Batt, R M; Giffard, C J

2001-07-01

To develop a noninvasive method for the in vivo assessment of flatulence in dogs. 8 adult dogs. Rectal gases were collected via a perforated tube held close to each dog's anus and attached to a monitoring pump fitted with a sensor that recorded hydrogen sulfide concentrations every 20 seconds. Patterns of flatulence were monitored for 14 hours after feeding on 4 days, and within- and between-dog variation was assessed over 4 hours on 4 consecutive days. Rate of hydrogen sulfide production (flatulence index) and frequency and number of emissions were evaluated as potential indicators of flatus characteristics. An odor judge assigned an odor rating to each flatulence episode, and the relationship between that rating and hydrogen sulfide concentration was determined. Flatulence patterns varied within and between dogs. Variation was most pronounced for flatulence index; mean coefficients of variance within dogs over time and between dogs on each day were 75 and 103%, respectively. Flatus with hydrogen sulfide concentrations > 1 parts per million could be detected by the odor judge, and severity of malodor was highly correlated with hydrogen sulfide concentration. Odor ratings were accurately predicted by use of the equation 1.51 X hydrogen sulfide concentration(0.28). The technique described in this report appears to provide sensitive, reliable, and relevant data and will enable further studies of the factors that influence flatulence in dogs. Use of this technique also has the potential to aid in investigations of colonic physiology and pathology.

Biohydrogen production by dark fermentation of glycerol using Enterobacter and Citrobacter Sp.

PubMed

Maru, Biniam T; Constanti, Magda; Stchigel, Alberto M; Medina, Francesc; Sueiras, Jesus E

2013-01-01

Glycerol is an attractive substrate for biohydrogen production because, in theory, it can produce 3 mol of hydrogen per mol of glycerol. Moreover, glycerol is produced in substantial amounts as a byproduct of producing biodiesel, the demand for which has increased in recent years. Therefore, hydrogen production from glycerol was studied by dark fermentation using three strains of bacteria: namely, Enterobacter spH1, Enterobacter spH2, and Citrobacter freundii H3 and a mixture thereof (1:1:1). It was found that, when an initial concentration of 20 g/L of glycerol was used, all three strains and their mixture produced substantial amounts of hydrogen ranging from 2400 to 3500 mL/L, being highest for C. freundii H3 (3547 mL/L) and Enterobacter spH1 (3506 mL/L). The main nongaseous fermentation products were ethanol and acetate, albeit in different ratios. For Enterobacter spH1, Enterobacter spH2, C. freundii H3, and the mixture (1:1:1), the ethanol yields (in mol EtOH/mol glycerol consumed) were 0.96, 0.67, 0.31, and 0.66, respectively. Compared to the individual strains, the mixture (1:1:1) did not show a significantly higher hydrogen level, indicating that there was no synergistic effect. Enterobacter spH1 was selected for further investigation because of its higher yield of hydrogen and ethanol. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

An efficient on-board metal-free nanocatalyst for controlled room temperature hydrogen production† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00162b Click here for additional data file.

PubMed Central

Das, Debanjan; Das, Nirmalya Sankar

2017-01-01

Positively charged functionalized carbon nanodots (CNDs) with a variety of different effective surface areas (ESAs) are synthesized via a cheap and time effective microwave method and applied for the generation of hydrogen via hydrolysis of sodium borohydride. To the best of our knowledge, this is the first report of metal-free controlled hydrogen generation. Our observation is that a positively charged functional group is essential for the hydrolysis for hydrogen production, but the overall activity is found to be enhanced with the ESA. A maximum value of 1066 ml g–1 min–1 as the turnover frequency is obtained which is moderate in comparison to other catalysts. However, the optimum activation energy is found to be 22.01 kJ mol–1 which is comparable to well-known high cost materials like Pt and Ru. All of the samples showed good reusability and 100% conversion even after the 10th cycle. The effect of H+ and OH– is also studied to control the on-board and on-demand hydrogen production (“on–off switching”). It is observed that H2 production decreases inversely with NaOH concentration and ceases completely when 10–1 M NaOH is added. With the addition of HCl, H2 production can be initiated again, which confirms the on/off control over production. PMID:28451366

Symmetry analysis of the behavior of the family R6M23 compounds upon hydrogenation

NASA Astrophysics Data System (ADS)

Kuna, Agnieszka; Sikora, Wiesława

2011-06-01

Symmetry analysis was applied in this work to discuss the behavior of the family R6M23 compounds upon hydrogenation (deuteration), where different structural transformations and magnetic properties, depending on the type of R and M atoms and hydrogen (deuterium) concentrations, have been found. The crystallographic structure of these compounds is described by the Fm3m space group and contain 116 atoms per unit cell occupying the positions 24e(R), 4b, 24d, 32f1 and 32f2(M). Additionally in the elementary cell, there could be up to 100 atoms of hydrogen (or deuterium) occupying the interstitial positions 4a, 32f3, 96j1 and 96k1. The symmetry analysis in the frame of the theory of space groups and their representation gives the opportunity to find all possible transformations from high symmetry parent structure to the structures with symmetry belonging to one of its subgroups. For a given transformation it indicates possible displacements of atoms from initial positions in the parent structure, ordering of hydrogen over interstitial sites and also ordering of magnetic moments, described by the smallest possible number of free parameters. The analysis was carried out by means of the MODY computer program for vectors k = (0; 0; 0) and k = (0; 0; 1) describing the changes of translational symmetry and all positions occupied by the R, M and D atoms.

On the effect of hydrogen on the mechanical behavior of Beta-C titanium in aged condition

NASA Astrophysics Data System (ADS)

Alvarez, Anna-Maria

The effect of hydrogen in solid solution on the mechanical behavior of the metastable beta-titanium alloy Beta-C was studied. The samples were aged at 482°C for 28 h prior to hydrogen charging in order to obtain a microstructure of alpha-precipitates in a beta-phase matrix. The kinetics and thermodynamics of hydrogen uptake in the alloy were studied in order to determine the required parameters to gas charge the samples with hydrogen, without altering the microstructure. The mechanical samples were hydrogen charged at 350°C to hydrogen concentrations between 0.6 and 24 at%. The samples were thereafter tested under tensile and alternating loading in order to study the effect of hydrogen on the tensile properties, fatigue properties and crack propagation rate. The fracture surfaces were then studied by using SEM, TEM and X-ray diffraction techniques. The macroscopic mechanical properties were compared with the micromechanisms of deformation and fracture in order to obtain information about the operating hydrogen-enhanced fracture mechanism. It was found that the tensile behavior was sensitive to hydrogen. A sharp ductile-to-brittle transition (DBT) occurred when hydrogen in solid solution reached a concentration of about 3.5 at%. TEM and X-ray analysis showed that stress-induced hydrides form in areas of low stress intensities at hydrogen concentrations above the DBT, and it is therefore believed that this is the cause of the hydrogen embrittlement in this alloy. However, at higher stress intensities, slip localization and enhanced slip band fracture were observed. Since slip localization and hydrogen-induced slip band fracture have previously been connected with a large decrease in ductility it can not be excluded that these effects of hydrogen affects the DBT. The cyclic stress strain behavior was not affected by hydrogen; the non-linear elastic behavior and the cyclic softening did not change with introduction of hydrogen up to a level of 10.8 at%. The fatigue life was, however, reduced when hydrogen charged samples were tested at low frequency (0.00032 Hz).

Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Vetter, Tiffany A.; Colombo, D. Philip, Jr.

2003-07-01

CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

Determination of Hydrogen Diffusion Coefficients in Fused Silica From 23 to 250°C Using Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Shang, L.; Chou, I.; Lu, W.; Burruss, R. C.

2008-12-01

The oxygen buffer technique is routinely used in experimental studies of redox sensitive geochemical reactions at elevated pressures (P) and temperatures (T). However, this technique is limited to T above about 400°C due to the low permeability of sample containers (Pt or Ag-Pd alloys) to hydrogen at lower T. Preliminary results of Chou et al. (Geochim. Cosmochim. Acta, 2008, doi:10.1016/j.gca.2008.07.030) indicate that the use of fused silica capillary (FSC) container may extend this technique to lower T. In this study, hydrogen diffusion coefficients (D) in FSC were determined from 23 to 250°C by measuring the loss of hydrogen from the FSC containers (0.3 mm OD, 0.1 mm ID, and ~10 mm long) with Raman spectroscopy using CO2 as an internal standard. First, CO2 was loaded cryogenically in a FSC capsule (Chou et al., ibid.). The capsule was then inserted in a protective ceramic tube, sealed in a gold capsule containing Fe powder and water, and heated at 300°C under 100 MPa of Ar external P in a cold-seal pressure vessel for several days allowing H2 to diffuse into the capsule. After quench, the Raman spectra were collected and the initial relative concentration of hydrogen in the silica capsule was derived from the peak height ratios between H2 (near 587 cm-1) and CO2 (near 1387 cm- 1). The sample capsule was then heated at a fixed T at one atmosphere to let H2 diffuse out of the capsule, and the changes of hydrogen concentration were monitored by Raman spectroscopy after quench. This process was repeated with different heating durations at 23 (room T), 50, 102, 157, 200, and 250°C. The values of D (in cm2s-1) in FSC were obtained by fitting the observed changes of hydrogen concentration to an equation based on Fick's second law. Our results can be represented by: Ln D (±0.14) = (-39810/RT) - 9.5491 (r2 = 0.9985) where R is the gas constant, and T in Kelvin. The slope corresponds to an activation energy of 39.81 kJ/mol. Our D values are about a half order of magnitude lower than those extrapolated from the values of Lee et al. (1962, J. Chem. Phys., 36, 1062) measured between 300 and 500°C, and about a half order of magnitude higher than those reported by Berrer (1941, Diffusion in and through solids, Cambridge Univ. Press, 141). The D in FSC determined at 23°C is about three times higher than that of Pt at 500°C, indicating that FSC is a suitable membrane for hydrogen at T below 400°C, even at room T, and has a great potential for studying redox reactions at these T, especially for the systems containing organic material.

Effects of Internal and External Hydrogen on Inconel 718

NASA Technical Reports Server (NTRS)

Walter, R. J.; Frandsen, J. D.

1999-01-01

Internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE) tensile and bend crack growth tests were performed on Inconel 718. For the IHE tests, the specimens were precharged to approximately 90 ppm hydrogen by exposure to 34.5 MPa H2 at 650 C. The HEE tests were performed in 34.5 MPa H2. Parameters evaluated were test temperature, strain rate for smooth and notch specimen geometries. The strain rate effect was very significant at ambient temperature for both IHE and HEE and decreased with increasing temperatures. For IHE, the strain rate effect was neglible at 260'C, and for HEE the strain rate effect was neglible at 400 C. At low temperatures, IHE was more severe than HEE, and at high temperatures HEE was more severe than IHE with a cross over temperature about 350 C. At 350 C, the equilibrium hydrogen concentration in Inconel 718 is about 50% lower than the hydrogen content of the precharged IHE specimens. Dislocation hydrogen sweeping of surface absorbed hydrogen was the likely transport mechanism for increasing the hydrogen concentration in the HEE tests sufficiently to produce the same degree of embrittlement as that of the more highly hydrogen charged IHE specimens. The main IHE fracture characteristic was formation of large, brittle flat facets, which decreased with increasing test temperature. The IHE fracture matrix surrounding the large facets ranged between brittle fine faceted to microvoid ductility depending upon strain rate, specimen geometry as well as temperature. The HEE fractures were characteristically fine featured, transgranular and brittle with a significant portion forming a "saw tooth" crystallographic pattern. Both IHE and HEE fractures were predominantly along the {1 1 1) slip and twin boundaries. With respect to embrittlement mechanism, it was postulated that dislocation hydrogen sweeping and hydrogen enhanced localized plasticity were active in HEE and IHE for concentrating hydrogen along (1 1 1) slip and twin planes. Final brittle failure occurred by hydrogen induced planer decohesion.

40 CFR 60.1935 - What equations must I use?

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Percent reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen chloride emissions (%PHC1) using equation 3 of this section: ER06DE00.005 Where: %PHC1 = percent reduction of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as...

40 CFR 60.1935 - What equations must I use?

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Percent reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen chloride emissions (%PHC1) using equation 3 of this section: ER06DE00.005 Where: %PHC1 = percent reduction of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as...

X-ray characterization of short-pulse laser illuminated hydrogen storage alloys having very high performance

NASA Astrophysics Data System (ADS)

Daido, Hiroyuki; Abe, Hiroshi; Shobu, Takahisa; Shimomura, Takuya; Tokuhira, Shinnosuke; Takenaka, Yusuke; Furuyama, Takehiro; Nishimura, Akihiko; Uchida, Hirohisa; Ohshima, Takeshi

2015-09-01

Hydrogen storage alloys become more and more important in the fields of electric energy production and stage and automobiles such as Ni-MH batteries. The vacancies introduced in hydrogen absorption alloy by charged particle beams were found to be positive effect on the increase in the initial hydrogen absorption reaction rate in the previous study. The initial reaction rates of hydrogen absorption and desorption of the alloy are one of the important performances to be improved. Here, we report on the characterization of the hydrogen absorption reaction rate directly illuminated by a femtosecond and nanosecond lasers instead of particle beam machines. A laser illuminates the whole surface sequentially on a tip of a few cm square LaNi4.6Al0.4 alloy resulting in significant improvement in the hydrogen absorption reaction rate. For characterization of the surface layer, we perform an x-ray diffraction experiment using a monochromatized intense x-ray beam from SPring-8 synchrotoron machine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaRue, Jerry; Krejci, Ondrej; Yu, Liang

Here, the direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast timescales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO 2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time x-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.

Comparison of field olfactometers in a controlled chamber using hydrogen sulfide as the test odorant.

PubMed

McGinley, M A; McGinley, C M

2004-01-01

A standard method for measuring and quantifying odour in the ambient air utilizes a portable odour detecting and measuring device known as a field olfactometer (US Public Health Service Project Grant A-58-541). The field olfactometer dynamically dilutes the ambient air with carbon-filtered air in distinct ratios known as "Dilutions-to-Threshold" dilution factors (D/Ts), i.e. 2, 4, 7, 15, etc. Thirteen US states and several cities in North America currently utilize field olfactometry as a key component of determining compliance to odour regulations and ordinances. A controlled environmental chamber was utilized, with hydrogen sulfide as the known test odorant. A hydrogen sulfide environment was created in this controlled chamber using an Advanced Calibration Designs, Inc. Cal2000 Hydrogen Sulfide Generator. The hydrogen sulfide concentration inside the chamber was monitored using an Arizona Instruments, Inc. Jerome Model 631 H2S Analyzer. When the environmental chamber reached a desired test concentration, test operators entered the chamber. The dilution-to-threshold odour concentration was measured using a Nasal Ranger Field Olfactometer (St Croix Sensory, Inc.) and a Barnebey Sutcliffe Corp. Scentometer. The actual hydrogen sulfide concentration was also measured at the location in the room where the operators were standing while using the two types of field olfactometers. This paper presents a correlation between dilution-to-threshold values (D/T) and hydrogen sulfide ambient concentration. For example, a D/T of 7 corresponds to ambient H2S concentrations of 5.7-15.6 microg/m3 (4-11 ppbv). During this study, no significant difference was found between results obtained using the Scentometer or the Nasal Ranger (r = 0.82). Also, no significant difference was found between results of multiple Nasal Ranger users (p = 0.309). The field olfactometers yielded hydrogen sulfide thresholds of 0.7-3.0 microg/m3 (0.5-2.0 ppbv). Laboratory olfactometry yielded comparable thresholds of 0.64-1.3 microg/m3 (0.45-0.9 ppbv). These thresholds are consistent with published values.

Hydrogen storage in double clathrates with tert-butylamine.

PubMed

Prasad, Pinnelli S R; Sugahara, Takeshi; Sum, Amadeu K; Sloan, E Dendy; Koh, Carolyn A

2009-06-18

The first proof-of-concept of the formation of a double tert-butylamine (t-BuNH(2)) + hydrogen (H(2)) clathrate hydrate has been demonstrated. Binary clathrate hydrates with different molar concentrations of the large guest t-BuNH(2) (0.98-9.31 mol %) were synthesized at 13.8 MPa and 250 K, and characterized by powder X-ray diffraction and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed under hydrogen pressures. Raman spectroscopic data suggested that the hydrogen molecules occupied the small cages and had similar occupancy to hydrogen in the double tetrahydrofuran (THF) + H(2) clathrate hydrate. The hydrogen storage capacity in this system was approximately 0.7 H(2) wt % at the molar concentration of t-BuNH(2) close to the sII stoichiometry.

Misoriented grain boundaries vicinal to the (111) <11¯0> twin in nickel part II: Thermodynamics of hydrogen segregation

DOE PAGES

O’Brien, Christopher J.; Foiles, Stephen M.

2016-04-19

Grain boundary engineered materials are of immense interest for their resistance to hydrogen embrittlement. This work builds on the work undertaken in Part I on the thermodynamic stability and structure of misoriented grain boundaries vicinal to the Σ3 (111) <11¯0> (coherent-twin) boundary to examine hydrogen segregation to those boundaries. The segregation of hydrogen reflects the asymmetry of the boundary structure with the sense of rotation of the grains about the coherent-twin boundary, and the temperature-dependent structural transition present in one sense of misorientation. This work also finds that the presence of hydrogen affects a change in structure of the boundariesmore » with increasing concentration. The structural change effects only one sense of misorientation and results in the reduction in length of the emitted stacking faults. Moreover, the structural change results in the generation of occupied sites populated by more strongly bound hydrogen. The improved understanding of misoriented twin grain boundary structure and the effect on hydrogen segregation resulting from this work is relevant to higher length-scale models. To that end, we examine commonly used metrics such as free volume and atomic stress at the boundary. In conclusion, free volume is found not to be useful as a surrogate for predicting the degree of hydrogen segregation, whereas the volumetric virial stress reliably predicts the locations of hydrogen segregation and exclusion at concentrations below saturation or the point where structural changes are induced by increasing hydrogen concentration.« less

Quantifying the effect of hydrogen on dislocation dynamics: A three-dimensional discrete dislocation dynamics framework

NASA Astrophysics Data System (ADS)

Gu, Yejun; El-Awady, Jaafar A.

2018-03-01

We present a new framework to quantify the effect of hydrogen on dislocations using large scale three-dimensional (3D) discrete dislocation dynamics (DDD) simulations. In this model, the first order elastic interaction energy associated with the hydrogen-induced volume change is accounted for. The three-dimensional stress tensor induced by hydrogen concentration, which is in equilibrium with respect to the dislocation stress field, is derived using the Eshelby inclusion model, while the hydrogen bulk diffusion is treated as a continuum process. This newly developed framework is utilized to quantify the effect of different hydrogen concentrations on the dynamics of a glide dislocation in the absence of an applied stress field as well as on the spacing between dislocations in an array of parallel edge dislocations. A shielding effect is observed for materials having a large hydrogen diffusion coefficient, with the shield effect leading to the homogenization of the shrinkage process leading to the glide loop maintaining its circular shape, as well as resulting in a decrease in dislocation separation distances in the array of parallel edge dislocations. On the other hand, for materials having a small hydrogen diffusion coefficient, the high hydrogen concentrations around the edge characters of the dislocations act to pin them. Higher stresses are required to be able to unpin the dislocations from the hydrogen clouds surrounding them. Finally, this new framework can open the door for further large scale studies on the effect of hydrogen on the different aspects of dislocation-mediated plasticity in metals. With minor modifications of the current formulations, the framework can also be extended to account for general inclusion-induced stress field in discrete dislocation dynamics simulations.

Hydrogen concentration in plagioclaes as a hygrometer of magmas: Approaches from melt inclusion analyses and hydrous melting experiments

NASA Astrophysics Data System (ADS)

Hamada, M.; Ushioda, M.; Fujii, T.; Takahashi, E.

2012-12-01

Plagioclase is one of the nominally anhydrous minerals (NAMs) which accommodates hundreds wt. ppm of hydrogen. Hydrogen in igneous plagioclase (OH) can act as a proxy of dissolved H2O in silicate melt. In order to use it as a practical hygrometer of magmas, we studied partitioning of hydrogen between plagioclase and basaltic melt dis-solving H2O (0.3˜5.5 wt.%) by two approaches: analyses of plagioclase-hosted melt inclusions (H2O≈0.3 wt.%) from mid-ocean ridge basalt (MORB) and hydrogen partitioning experiments between An96 plagioclase and hydrous basaltic melt (0.8 wt.%≦H2O≦5.5 wt.%) at 0.35 GPa. Concentration hydrogen in plagioclase and concentration of H2O in basaltic glasses were analyzed by infrared spectroscopy. As a first series of this study, plagioclase-hosted melt inclusions in MORB (50.5% SiO2, 15.1% Al2O3, 7.4% MgO) from the Rodriguez triple junction in the Indian Ocean were analyzed. The hydrogen concentration of plagioclase is less than 50 wt. ppm water, and no correlation between hydrogen concentration and anorthite content is recognized. Average H2O concentrations in melt inclusions is 0.3 wt.%. Therefore, apparent partition coefficient of hydrogen between plagioclase and melt is ≈ 0.01 in molar basis. As a second series of this study, hydrous melting experiments of arc basaltic magma were performed at 350 MPa using internally-heated pressure vessel. Starting material was hydrous glass (0.8 wt.%≦H2O≦5.5 wt.%) of an undifferentiated rock from Miyakejima volcano, a frontal-arc volcano in Izu-arc (MTL rock: 50.5% SiO2, 18.1% Al2O3, 4.9% MgO). A grain of Ca-rich plagioclase (≈1 mg, about An96) and 10 mg of powdered glasses were sealed in Au80Pd20 alloy capsule, and then kept at temperature at around the liquidus. Liquidus phase of MTL rock at 350 MPa is always plagioclase with 0 to 5.5 wt.% H2O in melt, and therefore, a grain of plagioclase and hydrous melt were nearly in equilibrium. Oxygen fugacity (fO2) during the melting experiments was not controlled, which was estimated to be 3 log unit above Ni-NiO buffer. Experiments were quenched after 24 hours, long enough to attain equi-librium partitioning of hydrogen between plagioclase and melt. Combining two series of study, we formulated empirical equation to correlate hydrogen concentration in plagioclase and H2O concentration in melt as: Hydrogen in plagioclase (wt. ppm water) ≈ 94.3×√(H2O in melt, wt.%). We also determined partition coefficient of hydrogen between plagioclase and basaltic melt to be 0.01±0.005 under H2O-poor conditions (≤150 wt. ppm water in plagioclase, ≤2 wt.% H2O in melt) and to be 0.008±0.002 under H2O-rich conditions (≥150 wt. ppm water in plagioclase, ≥2 wt.% H2O in melt). Slight decrease in hydrogen partitioning with increasing H2O can be related to change in hydrogen site in crystal structure of plagioclase (possibly tetrahedral sites). Peak position of infrared absorbance spectra lies at 3200-3400 cm-1 under H2O-poor condition and at 3600 cm-1 under H2O-rich condition, suggesting expansion of O-H…O bond length with increasing H2O.

Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water

NASA Astrophysics Data System (ADS)

Moss, Tyler; Was, Gary S.

2017-04-01

The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr2O3 observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.

Unsteady planar diffusion flames: Ignition, travel, burnout

NASA Technical Reports Server (NTRS)

Fendell, F.; Wu, F.

1995-01-01

In microgravity, a thin planar diffusion flame is created and thenceforth travels so that the flame is situated at all times at an interface at which the hydrogen and oxygen meet in stoichiometric proportion. If the initial amount of hydrogen is deficient relative to the initial amount of oxygen, then the planar flame will travel further and further into the half volume initially containing hydrogen, until the hydrogen is (virtually) fully depleted. Of course, when the amount of residual hydrogen becomes small, the diffusion flame is neither vigorous nor thin; in practice, the flame is extinguished before the hydrogen is fully depleted, owing to the finite rate of the actual chemical-kinetic mechanism. The rate of travel of the hydrogen-air diffusion flame is much slower than the rate of laminar flame propagation through a hydrogen-air mixture. This slow travel facilitates diagnostic detection of the flame position as a function of time, but the slow travel also means that the time to burnout (extinction) probably far exceeds the testing time (typically, a few seconds) available in earth-sited facilities for microgravity-environment experiments. We undertake an analysis to predict (1) the position and temperature of the diffusion flame as a function of time, (2) the time at which extinction of the diffusion flame occurs, and (3) the thickness of quench layers formed on side walls (i.e., on lateral boundaries, with normal vectors parallel to the diffusion-flame plane), and whether, prior to extinction, water vapor formed by burning will condense on these cold walls.

Reactive transport model of growth and methane production by high-temperature methanogens in hydrothermal regions of the subseafloor

NASA Astrophysics Data System (ADS)

Stewart, L. C.; Algar, C. K.; Topçuoğlu, B. D.; Fortunato, C. S.; Larson, B. I.; Proskurowski, G. K.; Butterfield, D. A.; Vallino, J. J.; Huber, J. A.; Holden, J. F.

2014-12-01

Hydrogenotrophic methanogens are keystone high-temperature autotrophs in deep-sea hydrothermal vents and tracers of habitability and biogeochemical activity in the hydrothermally active subseafloor. At Axial Seamount, nearly all thermophilic methanogens are Methanothermococcus and Methanocaldococcus species, making this site amenable to modeling through pure culture laboratory experiments coupled with field studies. Based on field microcosm incubations with 1.2 mM, 20 μM, or no hydrogen, the growth of methanogens at 55°C and 80°C is limited primarily by temperature and hydrogen availability, with ammonium amendment showing no consistent effect on total methane output. The Arrhenius constants for methane production by Methanocaldococcus jannaschii (optimum 82°C) and Methanothermococcus thermolithotrophicus (optimum 65°C) were determined in pure culture bottle experiments. The Monod constants for hydrogen concentration were measured by growing both organisms in a 2-liter chemostat at two dilution rates; 55°C, 65°C and 82°C; and variable hydrogen concentrations. M. jannaschii showed higher ks and Vmax constants than M. thermolithotrophicus. In the field, hydrogen and methane concentrations in hydrothermal end-member and low-temperature diffuse fluids were measured, and the concentrations of methanogens that grow at 55°C and 80°C in diffuse fluids were determined using most-probable-number estimates. Methane concentration anomalies in diffuse fluids relative to end-member hydrothermal concentrations and methanogen cell concentrations are being used to constrain a 1-D reactive transport model using the laboratory-determined Arrhenius and Monod constants for methane production by these organisms. By varying flow path length and subseafloor cell concentrations in the model, our goal is to determine solutions for the potential depth of the subseafloor biosphere coupled with the amount of methanogenic biomass it contains.

Supercritical water gasification of landfill leachate for hydrogen production in the presence and absence of alkali catalyst.

PubMed

Weijin, Gong; Binbin, Li; Qingyu, Wang; Zuohua, Huang; Liang, Zhao

2018-03-01

Gasification of landfill leachate in supercritical water using batch-type reactor is investigated. Alkali such as NaOH, KOH, K 2 CO 3 , Na 2 CO 3 is used as catalyst. The effect of temperature (380-500 °C), retention time (5-25 min), landfill leachate concentration (1595 mg L -1 -15,225 mg L -1 ), catalyst adding amount (1-10 wt%) on hydrogen mole fraction, hydrogen yield, carbon gasification rate, COD, TOC, TN removal efficiency are investigated. The results showed that gaseous products mainly contained hydrogen, methane, carbon dioxide and carbon monoxide without addition of catalyst. However, the main gaseous products are hydrogen and methane with addition of NaOH, KOH, K 2 CO 3 , Na 2 CO 3 . In the absence of alkali catalyst, the effect of temperature on landfill leachate gasification is positive. Hydrogen mole fraction, hydrogen yield, carbon gasification ratio increase with temperature, which maximum value being 55.6%, 107.15 mol kg -1 , 71.96% is obtained at 500 °C, respectively. Higher raw landfill leachate concentration leads to lower hydrogen production and carbon gasification rate. The suitable retention time is suggested to be 15 min for higher hydrogen production and carbon gasification rate. COD, TOC and TN removal efficiency also increase with increase of temperature, decrease of landfill leachate concentration. In the presence of catalyst, the hydrogen production is obviously promoted by addition of alkali catalyst. the effect of catalysts on hydrogen production is in the following order: NaOH ＞ KOH ＞ Na 2 CO 3  ＞ K 2 CO 3 . The maximum hydrogen mole fraction and hydrogen yield being 74.40%, 70.05 mol kg -1 is obtained with adding amount of 5 wt% NaOH at 450 °C, 28 MPa, 15 min. Copyright © 2017. Published by Elsevier Ltd.

Disinfection of wastewater by hydrogen peroxide or peracetic acid: development of procedures for measurement of residual disinfectant and application to a physicochemically treated municipal effluent.

PubMed

Wagner, Monika; Brumelis, Daina; Gehr, Ronald

2002-01-01

The Montreal Urban Community Wastewater Treatment Plant (MUCWTP) located in Montreal. Quebec, Canada, uses physicochemical treatment processes prior to discharging wastewater into the St. Lawrence River via an outfall tunnel of 2 hours retention time. Although chlorination facilities exist, they are not being used, and the MUCWTP is seeking alternative methods for disinfection to achieve a 2- to 3-log fecal coliform reduction. Liquid chemical disinfectants were attractive options because of their low capital costs. This led to an investigation of the feasibility of using hydrogen peroxide or peracetic acid. A method for measuring peroxycompounds (hydrogen peroxide or peracetic acid plus hydrogen peroxide) was developed using the peroxidase-based oxidation of 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfuric acid) diammonium salt (ABTS) with hydrogen peroxide. The validity of the method was confirmed using effluent from the MUCWTP. Recovery was higher than 90% for peracetic acid levels as low as 1.0 mg/L. Quenching of hydrogen peroxide was achieved with 50-mg/L catalase; quenching of peracetic acid was achieved with 100 mg/L of sodium thiosulfate, followed by 50 mg/L of catalase. Batch disinfection tests were conducted on MUCWTP effluent. Hydrogen peroxide and peracetic acid in wastewater over time could be modeled as a second-order decay, with the decay "constant" being a function of the initial concentration of peroxycompounds. This function was the same for both hydrogen peroxide and peracetic acid, possibly indicating similar decomposition pathways in wastewater matrices. Disinfection was modeled using a modified Hom equation. Required doses of hydrogen peroxide to reach the target fecal coliform levels ranged from 106 to 285 mg/L, with the higher doses occurring when ferric chloride instead of alum was used as the coagulant. Hence, hydrogen peroxide was infeasible as a disinfectant for this application. On the other hand, the peracetic acid dose needed to achieve the target fecal coliform level was only 0.6 to 1.6 mg/L. Therefore, peracetic acid seems to be a promising disinfectant for physicochemical or primary effluent, or combined sewer overflows.

Impact of pH on hydrogen oxidizing redox processes in aquifers due to gas intrusions

NASA Astrophysics Data System (ADS)

Metzgen, Adrian; Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

2017-04-01

Hydrogen production from excess energy and its storage can help increasing the efficiency of solar and wind in the energy mix. Therefore, hydrogen needs large-scale intermediate storage independent of the intended later use as hydrogen gas or as reactant to produce methane in the Sabatier process. A possible storage solution is using the geological subsurface such as caverns built in salt deposits or aquifers that are not used for drinking water production. However, underground storage of hydrogen gas potentially leads to accidental gas leakages into near-surface potable aquifers triggering subsequent geochemical processes. These leakages pose potential risks that are currently not sufficiently understood. To close this gap in knowledge, a high-pressure laboratory column system was used to simulate a hydrogen gas intrusion into a shallow aquifer. Water and sediment were gained from a sandy Pleistocene aquifer near Neumünster, Germany. In the first stage of the experiment, 100% hydrogen gas was used to simulate dissolved hydrogen concentrations between 800 and 4000 µM by varying pH2 between 2 and 15 bars. pH values rose to between 7.9 and 10.4, partly due to stripping CO2 from the groundwater used during H2 gas addition. In a second stage, the pH was regulated in a range of 6.7 to 7.9 by using a gas mixture of 99% H2 and 1% CO2 at 5 bars of total gas pressure. Observed processes included hydrogen oxidation, sulfate reduction, acetogenesis, formate production, and methanogenesis, which were independent of the hydrogen concentration. Hydrogen oxidation and sulfate reduction showed zeroth order reaction rates and rate constants (106 to 412 µM/h and 12 to 33 µM/h, respectively) in the pH range between 8 and 10. At pH levels between 7 and 8, both reactions started out faster near the column's inflow but then seemed limited towards the columns outflow, suggesting the dependence of sulfate reduction on the pH-value. Acetogenesis dominated the pH range between 8 and 10 (first order rate constants between 0.029 and 0.036 1/h). Between pH 7 and 8, acetogenesis showed a linear trend (zeroth order rates between 3 and 5 µM/h) whereas formate production became the main process (zeroth order rates between 38 to 197 µM/h) together with methanogenesis as a minor process. The results indicated a strong dependency of the biogeochemical hydrogenotrophic redox reactions on the pH milieu. Thus, pH buffers such as dissolved or solid phase carbonates should be taken into account when predicting effects a hydrogen leakage may have on shallow aquifers. Additionally, parameters derived from the observed processes and their rates allow the design of a process based numerical model simulating a hydrogen intrusion into a shallow aquifer. Consequently the presented outcomes allow an exemplary quantification of the resulting geochemical effects. This study was carried out within the ANGUS+ project and was funded by the German Federal Ministry of Education and Research (BMBF) energy storage funding initiative.

Numerical Study of Contaminant Effects on Combustion of Hydrogen, Ethane, and Methane in Air

NASA Technical Reports Server (NTRS)

Lai, H. T.; Thomas, S. R.

1995-01-01

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NP, H2O, and a combustion of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamic effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

Numerical study of contaminant effects on combustion of hydrogen, ethane, and methane in air

NASA Technical Reports Server (NTRS)

Lai, H. T.; Thomas, S. R.

1995-01-01

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NO, H2O, and a combination of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamically effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

The effect of mixing on fermentation of primary solids, glycerol, and biodiesel waste.

PubMed

Ghasemi, Marzieh; Randall, Andrew A

2018-03-01

In this study, the effect of mixing on volatile fatty acid (VFA) production and composition was investigated through running five identical bench-scale reactors that were filled with primary solid and dosed with either pure glycerol or biodiesel waste. Experimental results revealed that there was an inverse correlation between the mixing intensity and the VFA production. The total VFA production in the un-mixed reactor was 9,787 ± 3,601 mg COD/L, whereas in the reactor mixed at 100 rpm this dropped to 3,927 ± 1,175 mg COD/L, while both types of reactor were dosed with pure glycerol at the beginning of each cycle to reach the initial concentration of 1,000 mg/L (1,217 mg COD/L). Propionic acid was the dominant VFA in all the reactors except the reactor mixed at 30 rpm. It is hypothesized that low mixing facilitated hydrogen transfer between obligate hydrogen producing acetogens (OHPA) and hydrogen consuming acidogens in these non-methanogenic reactors. Also, in a narrower range of mixing (0 or 7 rpm), the total VFA production in biodiesel waste-fed reactors was considerably higher than that of pure glycerol-fed reactors.

Hydrogen and Storage Initiatives at the NASA JSC White Sands Test Facility

NASA Technical Reports Server (NTRS)

Maes, Miguel; Woods, Stephen S.

2006-01-01

NASA WSTF Hydrogen Activities: a) Aerospace Test; b) System Certification & Verification; c) Component, System, & Facility Hazard Assessment; d) Safety Training Technical Transfer: a) Development of Voluntary Consensus Standards and Practices; b) Support of National Hydrogen Infrastructure Development.

Sulfur transformations at the hydrogen sulfide/oxygen interface in stratified waters and in cyanobacterial mats

NASA Technical Reports Server (NTRS)

Cohen, Y.

1985-01-01

Stratified water bodies allow the development of several microbial plates along the water column. The microbial plates develop in relation to nutrient availability, light penetration, and the distribution of oxygen and sulfide. Sulfide is initially produced in the sediment by sulfate-reducing bacteria. It diffuses along the water column creating a zone of hydrogen sulfide/oxygen interface. In the chemocline of Solar Lake oxygen and sulfide coexist in a 0 to 10 cm layer that moves up and down during a diurnal cycle. The microbial plate at the chemocline is exposed to oxygen and hydrogen sulfide, alternating on a diurnal basis. The cyanobacteria occupying the interface switch from anoxygenic photosynthesis in the morning to oxygenic photosynthesis during the rest of the day which results in a temporal build up of elemental sulfur during the day and disappears at night due to both oxidation to thiosulfate and sulfate by thiobacilli, and reduction to hydrogen sulfide by Desulfuromonas sp. and anaerobically respiring cyanobacteria. Sulfate reduction was enhanced in the light at the surface of the cyanobacterial mats. Microsulfate reduction measurements showed enhanced activity of sulfate reduction even under high oxygen concentrations of 300 to 800 micrometer. Apparent aerobic SO sub 4 reduction activity is explained by the co-occurrence of H sub 2. The physiology of this apparent sulfate reduction activity is studied.

Emissions of nitrogen oxides from an experimental hydrogen-fueled gas turbine combustor

NASA Technical Reports Server (NTRS)

Norgren, C. T.; Ingebo, R. D.

1974-01-01

The effect of operating variables of a hydrogen fueled combustor on exhaust concentrations of total oxides of nitrogen was determined at inlet-air temperature levels up to 810 K, pressure of 414,000N/sa m, and reference velocity of 21.3 m/sec. The combustor, which was originally designed for hydrocarbon fuel produced a NO(x) concentration of 380 ppm with hydrogen at 810 K inlet-air temperature. A reduction in NO(x) of about 30 % was obtained by modification to a lean or rich primary zone. The lowest NO(x) levels obtained with hydrogen were equivalent to those of the reference combustor burning hydrocarbon fuels.

Feasibility demonstration for hydrogen chloride detection using a chemisorption technique and a quartz crystal microbalance

NASA Technical Reports Server (NTRS)

Jex, D. W.; Workman, G. L.

1975-01-01

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.

Initial test results with a single-cylinder rhombic-drive Stirling engine. [to be applied to automobile engine design to conserve energy

NASA Technical Reports Server (NTRS)

Cairelli, J. E.; Thieme, L. G.; Walter, R. J.

1978-01-01

A 6 kW (8 hp), single-cylinder, rhombic-drive Stirling engine was restored to operating condition, and preliminary characterization tests run with hydrogen and helium as the working gases. Initial tests show the engine brake specific fuel consumption (BSFC) with hydrogen working gas to be within the range of BSFC observed by the Army at Fort Belvoir, Virginia, in 1966. The minimum system specific fuel consumption (SFC) observed during the initial tests with hydrogen was 669 g/kW hr (1.1 lb/hpx hr), compared with 620 g/kWx hr (1.02 lb/hpx hr) for the Army tests. However, the engine output power for a given mean compression-space pressure was lower than for the Army tests. The observed output power at a working-space pressure of 5 MPa (725 psig) was 3.27 kW (4.39 hp) for the initial tests and 3.80 kW (5.09 hp) for the Army tests. As expected, the engine power with helium was substantially lower than with hydrogen.

Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

PubMed

Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

2016-05-01

Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of an Inexpensive RGB Color Sensor for the Detection of Hydrogen Cyanide Gas.

PubMed

Greenawald, Lee A; Boss, Gerry R; Snyder, Jay L; Reeder, Aaron; Bell, Suzanne

2017-10-27

An inexpensive red, green, blue (RGB) color sensor was developed for detecting low ppm concentrations of hydrogen cyanide gas. A piece of glass fiber filter paper containing monocyanocobinamide [CN(H 2 O)Cbi] was placed directly above the RGB color sensor and an on chip LED. Light reflected from the paper was monitored for RGB color change upon exposure to hydrogen cyanide at concentrations of 1.0-10.0 ppm as a function of 25%, 50%, and 85% relative humidity. A rapid color change occurred within 10 s of exposure to 5.0 ppm hydrogen cyanide gas (near the NIOSH recommended exposure limit). A more rapid color change occurred at higher humidity, suggesting a more effective reaction between hydrogen cyanide and CN(H 2 O)Cbi. The sensor could provide the first real time respirator end-of-service-life alert for hydrogen cyanide gas.

Bio-immobilization of dark fermentative bacteria for enhancing continuous hydrogen production from cornstalk hydrolysate.

PubMed

Zhao, Lei; Cao, Guang-Li; Sheng, Tao; Ren, Hong-Yu; Wang, Ai-Jie; Zhang, Jian; Zhong, Ying-Juan; Ren, Nan-Qi

2017-11-01

Mycelia pellets were employed as biological carrier in a continuous stirred tank reactor to reduce biomass washout and enhance hydrogen production from cornstalk hydrolysate. Hydraulic retention time (HRT) and influent substrate concentration played critical roles on hydrogen production of the bioreactor. The maximum hydrogen production rate of 14.2mmol H 2 L -1 h -1 was obtained at optimized HRT of 6h and influent concentration of 20g/L, 2.6 times higher than the counterpart without mycelia pellets. With excellent immobilization ability, biomass accumulated in the reactor and reached 1.6g/L under the optimum conditions. Upon further energy conversion analysis, continuous hydrogen production with mycelia pellets gave the maximum energy conversion efficiency of 17.8%. These results indicate mycelia pellet is an ideal biological carrier to improve biomass retention capacity of the reactor and enhance hydrogen recovery efficiency from lignocellulosic biomass, and meanwhile provides a new direction for economic and efficient hydrogen production process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogen and sulfur recovery from hydrogen sulfide wastes

DOEpatents

Harkness, J.B.L.; Gorski, A.J.; Daniels, E.J.

1993-05-18

A process is described for generating hydrogen and elemental sulfur from hydrogen sulfide waste in which the hydrogen sulfide is [dis]associated under plasma conditions and a portion of the hydrogen output is used in a catalytic reduction unit to convert sulfur-containing impurities to hydrogen sulfide for recycle, the process also including the addition of an ionizing gas such as argon to initiate the plasma reaction at lower energy, a preheater for the input to the reactor and an internal adjustable choke in the reactor for enhanced coupling with the microwave energy input.

Hydrogen and sulfur recovery from hydrogen sulfide wastes

DOEpatents

Harkness, John B. L.; Gorski, Anthony J.; Daniels, Edward J.

1993-01-01

A process for generating hydrogen and elemental sulfur from hydrogen sulfide waste in which the hydrogen sulfide is associated under plasma conditions and a portion of the hydrogen output is used in a catalytic reduction unit to convert sulfur-containing impurities to hydrogen sulfide for recycle, the process also including the addition of an ionizing gas such as argon to initiate the plasma reaction at lower energy, a preheater for the input to the reactor and an internal adjustable choke in the reactor for enhanced coupling with the microwave energy input.

Use of an iodide-specific electrode to study lactoperoxidase-catalyzed iodination of l-tyrosine.

PubMed

Threatte, R M; Fregly, M J; Field, F P; Jones, P K

1979-12-01

An in vitro method employing an iodide-specific electrode for monitoring lactoperoxidase-catalyzed iodination is described. The method utilized lactoperoxidase, potassium iodide, and a glucose--glucose oxidase system for the generation of hydrogen peroxide and l-tyrosine. As iodination of l-tyrosine proceeded, the free iodide concentration in solution decreased and was monitored by an iodide-specific electrode. The iodide electrode was reliable when compared to a 131I-method for measuring free iodide changes in solution. Increasing concentrations of resorcinol, a well-known inhibitor of thyroid peroxidase-catalyzed iodination, in the reaction mixture resulted in graded inhibition of the initial rate of lactoperoxidase-catalyzed l-tyrosine iodination. This in vitro system can be used to assess inhibitory activity of various antithyroid substances.

238U-234U-230Th disequilibrium in hydrogenous oceanic Fe-Mn crusts: Palaeoceanographic record or diagenetic alteration?

USGS Publications Warehouse

Chabaux, F.; O'Nions, R. K.; Cohen, A.S.; Hein, J.R.

1997-01-01

A detailed TIMS study of (234Uexc/238U), (230Th/232Th), and Th/U ratios have been performed on the outermost margin of ten hydrogenous Fe-Mn crusts from the equatorial Pacific Ocean and west-central Indian Ocean. Th/U concentration ratios generally decrease from the crust's surface down to 0.5-1 mm depth and growth rates estimated by uranium and thorium isotope ratios are significantly different in Fe-Mn crusts from the Peru Basin and the west-central Indian Ocean. Fe-Mn crusts from the same geographical area define a single trend in plots of Ln (234Uexc/238U) vs. Ln(230Th/232Th) and Th/U ratios vs. age of the analysed fractions. Results suggest that (1) hydrogenous Fe-Mn crusts remain closed-systems after formation, and consequently (2) the discrepancy observed between the 230Th and 234U chronometers in Fe-Mn crusts, and the variations of the Th/U ratios through the margin of Fe-Mn crusts, are not due to redistribution of uranium and thorium isotopes after oxyhydroxide precipitation, but rather to temporal variations of both Th/U and initial thorium activity ratios recorded by the Fe-Mn layers. Implications of these observations for determination of Fe-Mn crust growth-rates are discussed. Variations of both Th/U and initial Th activity ratios in Fe-Mn crusts might be related to changes in particle input to seawater and/or changes in ocean circulation during the last 150 ka. Copyright ?? 1997 Elsevier Science Ltd.

Borax and Octabor Treatment of Stored Swine Manure: Reduction in Hydrogen Sulfide Emissions and Phytotoxicity to Agronomic Crops

USDA-ARS?s Scientific Manuscript database

Gaseous emissions from stored manure have become environmental and health issues for humans and animals as the livestock industry becomes specialized and concentrated. Of particular concern is hydrogen sulfide, which is being targeted for regulatory control in concentrated animal farm operations. ...

Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies

ERIC Educational Resources Information Center

Schenck, Heather L.; Hui, KaWai

2011-01-01

These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). The…

A convenient method for determining the concentration of hydrogen in water: use of methylene blue with colloidal platinum

PubMed Central

2012-01-01

A simple titration (oxidimetry) method using a methylene blue-platinum colloid reagent is effective in determining the concentration of hydrogen gas in an aqueous solution. The method performs as effectively as the more complex and expensive electrochemical method. PMID:22273079

The role of hydrogen in zirconium alloy corrosion

NASA Astrophysics Data System (ADS)

Ensor, B.; Lucente, A. M.; Frederick, M. J.; Sutliff, J.; Motta, A. T.

2017-12-01

Hydrogen enters zirconium metal as a result of the corrosion process and forms hydrides when present in quantities above the solubility limit at a given temperature. Zircaloy-4 coupons of different thicknesses (0.4 mm-2.3 mm) but identical chemistry and processing were corroded in autoclave at 360 °C for various times up to 2800 days. Coupons were periodically removed and weighed to determine weight gain, which allows follow of the corrosion kinetics. Coupon thickness differences resulted in different volumetric concentrations of hydrogen, as quantified using hot vacuum extraction. The thinnest coupons, having the highest concentration of hydrogen, demonstrated acceleration in their corrosion kinetics and shorter transition times when compared to thicker coupons. Furthermore, it was seen that the post-transition corrosion rate was increased with increasing hydrogen concentration. Corrosion rates increased only after the terminal solid solubility (TSS) was exceeded for hydrogen in Zircaloy-4 at 360 °C. Therefore, it is hypothesized that the corrosion acceleration is caused by the formation of hydrides. Scanning electron microscope (SEM) examinations of fractured oxide layers demonstrate the oxide morphology changed with hydrogen content, with more equiaxed oxide grains in the high hydrogen samples than in those with lower hydrogen content. Additionally, locations of advanced oxide growth were correlated with locations of hydrides in the metal. A hypothesis is proposed to explain the accelerated corrosion due to the presence of the hydrides, namely that the metal, locally, is less able to accommodate oxide growth stresses and this leads to earlier loss of oxide protectiveness in the form of more frequent oxide kinetic transitions.

Development of a Hydrogen Uptake-Release Mg-Based Alloy by Adding a Polymer CMC (Carboxymethylcellulose, Sodium Salt) via Reaction-Accompanying Milling

NASA Astrophysics Data System (ADS)

Kwak, Young Jun; Choi, Eunho; Song, Myoung Youp

2018-03-01

The addition of carboxymethylcellulose, sodium salt (CMC) might improve the hydrogen uptake and release properties of Mg since it has a relatively low melting point and the melting of CMC during milling in hydrogen (reaction-accompanying milling) may make the milled samples be in good states to absorb and release hydrogen rapidly and to have a large hydrogen-storage capacity. Samples with compositions of 95 w/o Mg + 5 w/o CMC (named Mg-5CMC) and 90 w/o Mg + 10 w/o CMC (named Mg-10CMC) were prepared by adding CMC via reaction-accompanying milling. Activation of Mg-10CMC was completed after about 3 hydrogen uptake-release cycles. Mg-10CMC had a higher initial hydrogen uptake rate and a larger amount of hydrogen absorbed in 60 min, U (60 min), than Mg-5CMC before and after activation. At the cycle number of three (CN = 3), Mg-10CMC had a very high initial hydrogen uptake rate (1.56 w/o H/min) and a large U (60 min) (5.57 w/o H) at 593 K in hydrogen of 12 bar, showing that the activated Mg-10CMC has an effective hydrogen-storage capacity of about 5.6 w/o at 593 K in hydrogen of 12 bar at CN = 3. At CN = 2, Mg-10CMC released 1.00 w/o H in 2.5 min, 4.67 w/o H in 10 min, and 4.76 w/o H in 60 min at 648 K in hydrogen of 1.0 bar. The milling in hydrogen of Mg with CMC is believed to generate imperfections and cracks and reduce the particle size. The addition of 10 w/o CMC was more effective on the initial hydrogen uptake rate and U (60 min) compared with the 10 w/o additions of NbF5, TaF5, Fe2O3, and MnO, and the 10 w/o simultaneous addition of Ni, Fe, and Ti. To the best of our knowledge, this study is the first in which a polymer CMC is added to Mg by reaction-accompanying milling to improve the hydrogen storage properties of Mg.

H2 CONSUMPTION DURING THE MICROBIAL REDUCTIVE DEHALOGENATION OF CHLORINATED PHENOLS AND TETRACHLOROETHENE

EPA Science Inventory

Competition for molecular hydrogen exists among hydrogen-utilizing microorganisms in anoxic environments, and evidence suggests that lower hydrogen concentrations are observed with more energetically favorable electron-accepting processes. The transfer of electrons to organochlor...

Equilibrium and diffusion studies of metal-hydrogen systems

NASA Astrophysics Data System (ADS)

Maroevic, Petar

Several new methods and models have been developed pertaining to equilibrium properties of hydrogen in random binary substitutional alloys at room and lower temperatures, describing both statistics and kinetics of hydrogen in them. They represent a solution to the problem of the complete Fermi-Dirac description which is physically appropriate for these systems. Hydrogen diffusion which proceeds via lattice assisted quantum tunneling at room and lower temperatures requires a new and different description from the one based on the thermal hopping picture, which pertains only to relatively high temperatures. It is also shown that the analogs of the solution to the Fermi-Dirac problem of hydrogen can be successfully applied to the description of vacancies in a hydrogenated system, a phenomena known to occur due to high hydrogen-vacancy binding energies and the creation of hydrogen-vacancy clusters. The solution based on this model applies to much lower temperatures and higher concentrations than the tradition alone. This methodology has also been applied to the surface problem where very large vacancy and hydrogen concentrations occur. This is of special importance since mechanical properties are known to be greatly affected by the surface. As another consequence of hydrogen induced vacancies, hydrogen induced lattice migration (HILM) occurs. This has been demonstrated in our electrical resistivity study of palladium wires where recrystallization and annealing effects were observed upon hydrogen-heat-treatment (HHT).

Experimental research on medium-frequency discharge cleaning in the HT-6M tokamak

NASA Astrophysics Data System (ADS)

Li, Chengfu; Guo, Wenkang; Gu, Xuemao; Luo, Nanchang; Hu, Wanfen; Cheng, Shanhua; Qian, Chao

1989-04-01

Surface cleaning experiments of the wall of HT-6M tokamak chamber by medium-frequency discharge (MFD) in hydrogen has been monitored and analysed by. QMS and AES. After 300 min discharge, the signals with mass number 12 and 18 were 100 times less than their initial values. The concentration of C and O on the wall surface decreased to 26% and 5.8%, respectively. The cleaning efficiency of MFD has been compared with that of DC glow discharge. The results showed that the former was superior to the later in ability of water release.

Isolation and Characterization of Strains CVO and FWKO B, Two Novel Nitrate-Reducing, Sulfide-Oxidizing Bacteria Isolated from Oil Field Brine

PubMed Central

Gevertz, Diane; Telang, Anita J.; Voordouw, Gerrit; Jenneman, Gary E.

2000-01-01

Bacterial strains CVO and FWKO B were isolated from produced brine at the Coleville oil field in Saskatchewan, Canada. Both strains are obligate chemolithotrophs, with hydrogen, formate, and sulfide serving as the only known energy sources for FWKO B, whereas sulfide and elemental sulfur are the only known electron donors for CVO. Neither strain uses thiosulfate as an energy source. Both strains are microaerophiles (1% O2). In addition, CVO grows by denitrification of nitrate or nitrite whereas FWKO B reduces nitrate only to nitrite. Elemental sulfur is the sole product of sulfide oxidation by FWKO B, while CVO produces either elemental sulfur or sulfate, depending on the initial concentration of sulfide. Both strains are capable of growth under strictly autotrophic conditions, but CVO uses acetate as well as CO2 as its sole carbon source. Neither strain reduces sulfate; however, FWKO B reduces sulfur and displays chemolithoautotrophic growth in the presence of elemental sulfur, hydrogen, and CO2. Both strains grow at temperatures between 5 and 40°C. CVO is capable of growth at NaCl concentrations as high as 7%. The present 16s rRNA analysis suggests that both strains are members of the epsilon subdivision of the division Proteobacteria, with CVO most closely related to Thiomicrospira denitrifcans and FWKO B most closely related to members of the genus Arcobacter. The isolation of these two novel chemolithotrophic sulfur bacteria from oil field brine suggests the presence of a subterranean sulfur cycle driven entirely by hydrogen, carbon dioxide, and nitrate. PMID:10831429

Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. Mazama, Crater Lake, Oregon

USGS Publications Warehouse

Mandeville, C.W.; Webster, J.D.; Tappen, C.; Taylor, B.E.; Timbal, A.; Sasaki, A.; Hauri, E.; Bacon, C.R.

2009-01-01

Evaluation of the extent of volatile element recycling in convergent margin volcanism requires delineating likely source(s) of magmatic volatiles through stable isotopic characterization of sulfur, hydrogen and oxygen in erupted tephra with appropriate assessment of modification by degassing. The climactic eruption of Mt. Mazama ejected approximately 50 km3 of rhyodacitic magma into the atmosphere and resulted in formation of a 10-km diameter caldera now occupied by Crater Lake, Oregon (lat. 43??N, long. 122??W). Isotopic compositions of whole-rocks, matrix glasses and minerals from Mt. Mazama climactic, pre-climactic and postcaldera tephra were determined to identify the likely source(s) of H2O and S. Integration of stable isotopic data with petrologic data from melt inclusions has allowed for estimation of pre-eruptive dissolved volatile concentrations and placed constraints on the extent, conditions and style of degassing. Sulfur isotope analyses of climactic rhyodacitic whole rocks yield ??34S values of 2.8-14.8??? with corresponding matrix glass values of 2.4-13.2???. ??34S tends to increase with stratigraphic height through climactic eruptive units, consistent with open-system degassing. Dissolved sulfur concentrations in melt inclusions (MIs) from pre-climactic and climactic rhyodacitic pumices varies from 80 to 330 ppm, with highest concentrations in inclusions with 4.8-5.2 wt% H2O (by FTIR). Up to 50% of the initial S may have been lost through pre-eruptive degassing at depths of 4-5 km. Ion microprobe analyses of pyrrhotite in climactic rhyodacitic tephra and andesitic scoria indicate a range in ??34S from -0.4??? to 5.8??? and from -0.1??? to 3.5???, respectively. Initial ??34S values of rhyodacitic and andesitic magmas were likely near the mantle value of 0???. Hydrogen isotope (??D) and total H2O analyses of rhyodacitic obsidian (and vitrophyre) from the climactic fall deposit yielded values ??f -103 to -53??? and 0.23-1.74 wt%, respectively. Values of ??D and wt% H2O of obsidian decrease towards the top of the fall deposit. Samples with depleted ??D, and mantle ??18O values, have elevated ??34S values consistent with open-system degassing. These results imply that more mantle-derived sulfur is degassed to the Earth's atmosphere/hydrosphere through convergent margin volcanism than previously attributed. Magmatic degassing can modify initial isotopic compositions of sulfur by >14??? (to ??34S values of 14??? or more here) and hydrogen isotopic compositions by 90??? (to ??D values of -127??? in this case). ?? 2009 Elsevier Ltd.

Sedimentary organic matter characterization of the Triassic-Jurassic boundary GSSP at Kuhjoch (Austria)

NASA Astrophysics Data System (ADS)

Ruhl, M.; Veld, H.; Kürschner, W. M.

2010-03-01

The Triassic-Jurassic (T-J) boundary interval coincides with enhanced extinction rates in the marine realm and pronounced changes in terrestrial ecosystems on the continents. It is further marked by distinct negative excursions in the δ13C org and δ13C carb signature that may represent strong perturbations of the global carbon cycle. We present integrated geochemical, stable-isotope and palynological data from the Kuhjoch section, the Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic (Northern Calcareous Alps, Austria). We show that the initial carbon isotope excursion (CIE), coinciding with the marine extinction interval and the formation of black shales in the western Tethys Eiberg Basin, is marked by only minor changes in kerogen type, which is mainly of terrestrial origin. Increased Total Organic Carbon (TOC) concentrations of 9% at the first half of the initial CIE coincide with Hydrogen Index (HI) values of over 600 mg HC/g TOC. The high correlation (with R2 = 0.93) between HI values and terrestrial Cheirolepidiaceaen conifer pollen suggests a terrestrial source for the hydrogen enriched organic compounds. The lack of major changes in source of the sedimentary organic matter suggests that changes in the δ13C org composition are genuine and represent true disturbances of the global C-cycle. The sudden decrease in total inorganic carbon (TIC) concentrations likely represents the onset of a biocalcification crisis. It coincides with a 4.5‰ negative shift in δ13C org values and possibly corresponds to the onset of CAMP related volcanic activity. The second half of the initial CIE is marked by the dramatic increase of green algae remains in the sediment. The simultaneous increase of the C org/N tot ratio suggests increased marine primary production at the final stage of black shale formation.

Kinetics of sulfate and hydrogen uptake by the thermophilic sulfate-reducing bacteria Thermodesulfobacterium sp. strain JSP and Thermodesulfovibrio sp. strain R1Ha3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sonne-Hansen, J.; Ahring, B.K.; Westermann, P.

1999-03-01

Dissimilatory sulfate reduction and methanogenesis are the main terminal processes in the anaerobic food chain. Both the sulfate-reducing bacteria (SRB) and the methane-producing archaea (MPA) use acetate and hydrogen as substrates and, therefore, compete for common electron donors in sulfate-containing natural environments. Due to a higher affinity for the electron donors acetate and hydrogen, SRB outcompete MPA for these compounds whenever sulfate is present in sufficient concentrations. Half-saturation constants (K{sub m}), maximum uptake rates (V{sub max}), and threshold concentrations for sulfate and hydrogen were determined for two thermophilic sulfate-reducing bacteria (SRB) in an incubation system without headspace. K{sub m} valuesmore » determined for the thermophilic SRB were similar to the constants described for mesophilic SRB isolated from environments with low sulfate concentrations.« less

Ignition in an Atomistic Model of Hydrogen Oxidation.

PubMed

Alaghemandi, Mohammad; Newcomb, Lucas B; Green, Jason R

2017-03-02

Hydrogen is a potential substitute for fossil fuels that would reduce the combustive emission of carbon dioxide. However, the low ignition energy needed to initiate oxidation imposes constraints on the efficiency and safety of hydrogen-based technologies. Microscopic details of the combustion processes, ephemeral transient species, and complex reaction networks are necessary to control and optimize the use of hydrogen as a commercial fuel. Here, we report estimates of the ignition time of hydrogen-oxygen mixtures over a wide range of equivalence ratios from extensive reactive molecular dynamics simulations. These data show that the shortest ignition time corresponds to a fuel-lean mixture with an equivalence ratio of 0.5, where the number of hydrogen and oxygen molecules in the initial mixture are identical, in good agreement with a recent chemical kinetic model. We find two signatures in the simulation data precede ignition at pressures above 200 MPa. First, there is a peak in hydrogen peroxide that signals ignition is imminent in about 100 ps. Second, we find a strong anticorrelation between the ignition time and the rate of energy dissipation, suggesting the role of thermal feedback in stimulating ignition.

Biological caproate production by Clostridium kluyveri from ethanol and acetate as carbon sources.

PubMed

Yin, Yanan; Zhang, Yifeng; Karakashev, Dimitar Borisov; Wang, Jianlong; Angelidaki, Irini

2017-10-01

Caproate is a valuable industrial product and chemical precursor. In this study, batch tests were conducted to investigate the fermentative caproate production through chain elongation from acetate and ethanol. The effect of acetate/ethanol ratio and initial ethanol concentration on caproate production was examined. When substrate concentration was controlled at 100mM total carbon, hydrogen was used as an additional electron donor. The highest caproate concentration of 3.11g/L was obtained at an ethanol/acetate ratio of 7:3. No additional electron donor was needed upon an ethanol/acetate ratio ≥7:3. Caproate production increased with the increase of carbon source until ethanol concentration over 700mM, which inhibited the fermentation process. The highest caproate concentration of 8.42g/L was achieved from high ethanol strength wastewater with an ethanol/acetate ratio of 10:1 (550mM total carbon). Results obtained in this study can pave the way towards efficient chain elongation from ethanol-rich wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elucidation of metal-ion accumulation induced by hydrogen bonds on protein surfaces by using porous lysozyme crystals containing Rh(III) ions as the model surfaces.

PubMed

Ueno, Takafumi; Abe, Satoshi; Koshiyama, Tomomi; Ohki, Takahiro; Hikage, Tatsuo; Watanabe, Yoshihito

2010-03-01

Metal-ion accumulation on protein surfaces is a crucial step in the initiation of small-metal clusters and the formation of inorganic materials in nature. This event is expected to control the nucleation, growth, and position of the materials. There remain many unknowns, as to how proteins affect the initial process at the atomic level, although multistep assembly processes of the materials formation by both native and model systems have been clarified at the macroscopic level. Herein the cooperative effects of amino acids and hydrogen bonds promoting metal accumulation reactions are clarified by using porous hen egg white lysozyme (HEWL) crystals containing Rh(III) ions, as model protein surfaces for the reactions. The experimental results reveal noteworthy implications for initiation of metal accumulation, which involve highly cooperative dynamics of amino acids and hydrogen bonds: i) Disruption of hydrogen bonds can induce conformational changes of amino-acid residues to capture Rh(III) ions. ii) Water molecules pre-organized by hydrogen bonds can stabilize Rh(III) coordination as aqua ligands. iii) Water molecules participating in hydrogen bonds with amino-acid residues can be replaced by Rh(III) ions to form polynuclear structures with the residues. iv) Rh(III) aqua complexes are retained on amino-acid residues through stabilizing hydrogen bonds even at low pH (approximately 2). These metal-protein interactions including hydrogen bonds may promote native metal accumulation reactions and also may be useful in the preparation of new inorganic materials that incorporate proteins.

Hydrogen-induced strain localisation in oxygen-free copper in the initial stage of plastic deformation

NASA Astrophysics Data System (ADS)

Yagodzinskyy, Yuriy; Malitckii, Evgenii; Tuomisto, Filip; Hänninen, Hannu

2018-03-01

Single crystals of oxygen-free copper oriented to easy glide of dislocations were tensile tested in order to study the hydrogen effects on the strain localisation in the form of slip bands appearing on the polished specimen surface under tensile straining. It was found that hydrogen increases the plastic flow stress in Stage I of deformation. The dislocation slip localisation in the form of slip bands was observed and analysed using an online optical monitoring system and atomic force microscopy. The fine structure of the slip bands observed with AFM shows that they consist of a number of dislocation slip offsets which spacing in the presence of hydrogen is markedly reduced as compared to that in the hydrogen-free specimens. The tensile tests and AFM observations were accompanied with positron annihilation lifetime measurements showing that straining of pure copper in the presence of hydrogen results in free volume generation in the form of vacancy complexes. Hydrogen-enhanced free-volume generation is discussed in terms of hydrogen interactions with edge dislocation dipoles forming in double cross-slip of screw dislocations in the initial stage of plastic deformation of pure copper.

Synthetic fuels for ground transportation with special emphasis on hydrogen

NASA Technical Reports Server (NTRS)

Singh, J. J.

1975-01-01

The role of various synthetic fuels, for ground transportation in the United States, was examined for the near term (by 1985) and the longer term applications (1985-2000 and beyond 2000). Feasible options include synthetic oil, methanol, electric propulsion, and hydrogen. It is concluded that (1) the competition during the next 50 years will be for the fuels of all types, rather than among the fuels; (2) extensive domestic oil and gas exploration should be initiated concurrent with the development of several alternate fuels and related ancillaries; and (3) hydrogen, as an automotive fuel, seems to be equivalent to gasoline for optimum fuel to air mixtures. As a pollution free, high energy density fuel, hydrogen deserves consideration as the logical replacement for the hydrocarbons. Several research and development requirements, essential for the implementation of hydrogen economy for ground transportation, were identified. Extensive engineering development and testing activities should be initiated to establish hydrogen as the future automotive fuel, followed by demonstration projects and concerted efforts at public education.

The effect of urea on microstructures of Ni{sub 3}S{sub 2} on nickel foam and its hydrogen evolution reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jinlong, Lv, E-mail: ljltsinghua@126.com; State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084; Tongxiang, Liang, E-mail: txliang@mail.tsinghua.edu.cn

The effects of urea concentration on microstructures of Ni{sub 3}S{sub 2}formed on nickel foam and its hydrogen evolution reaction were investigated. The Ni{sub 3}S{sub 2} nanosheets with porous structure were formed on nickel foam during hydrothermal process due to low urea concentration. While high urea concentration facilitated the forming of Ni{sub 3}S{sub 2} nanotube arrays. The resulting Ni{sub 3}S{sub 2} nanotube arrays exhibited higher catalytic activity than Ni3S2nanosheets for hydrogen evolution reaction. This was mainly attributed to a fact that Ni{sub 3}S{sub 2} nanotube arrays facilitated diffusion of electrolyte for hydrogen evolution reaction. - Graphical abstract: The resulting Ni{sub 3}S{submore » 2} nanotube arrays exhibited higher catalytic activity than Ni{sub 3}S{sub 2} nanosheets for hydrogen evolution reaction. This was mainly attributed to a fact that Ni{sub 3}S{sub 2} nanotube arrays facilitated diffusion of electrolyte for hydrogen evolution reaction and hydrogen evolution. - Highlights: • Urea promoted to forming more Ni{sub 3}S{sub 2} nanotube arrays on nickel foam. • Ni{sub 3}S{sub 2} nanotube arrays showed higher catalytic activity in alkaline solution. • Ni{sub 3}S{sub 2} nanotube arrays promoted electron transport and reaction during the HER.« less

Pilot Study to Evaluate Hydrogen Injection for Stimulating Reduction and Immobilization of Uranium in Groundwater at an ISR Mining Site

NASA Astrophysics Data System (ADS)

Clapp, L. W.; Cabezas, J.; Gamboa, Y.; Fernandez, W.

2011-12-01

State and federal regulations require that groundwater at in-situ recovery (ISR) uranium mining operations be restored to pre-mining conditions. Reverse osmosis (RO) filtration of several pore volumes of the post-leached groundwater and reinjection of the clean permeate is the most common technology currently used for restoring groundwater at uranium ISR sites. However, this approach does not revert the formation back to its initial reducing conditions, which can potentially impede timely groundwater restoration. In-situ biostimulation of indigenous iron- and sulfate reducing bacteria by injection of organic electron donors (e.g., ethanol, acetate, and lactate) to promote soluble uranium reduction and immobilization has been the subject of previous studies. However, injection of organic substrates has been observed to cause aquifer clogging near the injection point. In addition, U(VI) solubility may be enhanced through complexation with carbonate generated by organic carbon oxidation. An alternative approach that may overcome these problems involves the use of hydrogen as a reductant to promote microbial reduction and immobilization of U(VI) in situ. To test this approach, approximately 100,000 scf of compressed hydrogen gas was injected into a leached unconsolidated sand zone over two months at an ISR mining site. During this time groundwater was recirculated between injection and extraction wells (separated by 130 ft) at a rate of about 40 gpm and bromide was coinjected as a conservative tracer. A well monitoring program has been executed since June 2009 to evaluate the performance of the hydrogen injection. Current results show that U(VI) has been reduced from 4.2 to 0.05 ppm in the area surrounding the injection well and to 2.0 ± 0.3 ppm in the area surrounding the extraction well and two intermediate monitoring wells. Other water quality changes near the injection well include significant decreases in concentrations of Mo, sulfate, Fe, Mn, bicarbonate, Ca, and Eh, and increases in pH, methane, and sulfide. No significant rebound of soluble uranium concentrations was observed, but significant rebounds in molybdenum and sulfate have been observed. Ongoing studies are evaluating the effective zone of influence of the hydrogen injection.

Solar hydrogen generator

NASA Technical Reports Server (NTRS)

Sebacher, D. I.; Sabol, A. P. (Inventor)

1977-01-01

An apparatus, using solar energy to manufacture hydrogen by dissociating water molecules into hydrogen and oxygen molecules is described. Solar energy is concentrated on a globe containing water thereby heating the water to its dissociation temperature. The globe is pervious to hydrogen molecules permitting them to pass through the globe while being essentially impervious to oxygen molecules. The hydrogen molecules are collected after passing through the globe and the oxygen molecules are removed from the globe.

Collision cascades enhanced hydrogen redistribution in cobalt implanted hydrogenated diamond-like carbon films

NASA Astrophysics Data System (ADS)

Gupta, P.; Becker, H.-W.; Williams, G. V. M.; Hübner, R.; Heinig, K.-H.; Markwitz, A.

2017-03-01

Hydrogenated diamond-like carbon films produced by C3H6 deposition at 5 kV and implanted at room temperature with 30 keV Co atoms to 12 at.% show not only a bimodal distribution of Co atoms but also a massive redistribution of hydrogen in the films. Resonant nuclear reaction analysis was used to measure the hydrogen depth profiles (15N-method). Depletion of hydrogen near the surface was measured to be as low as 7 at.% followed by hydrogen accumulation from 27 to 35 at.%. A model is proposed considering the thermal energy deposited by collision cascade for thermal insulators. In this model, sufficient energy is provided for dissociated hydrogen to diffuse out of the sample from the surface and diffuse into the sample towards the interface which is however limited by the range of the incoming Co ions. At a hydrogen concentration of ∼35 at.%, the concentration gradient of the mobile unbounded hydrogen atoms is neutralised effectively stopping diffusion towards the interface. The results point towards new routes of controlling the composition and distribution of elements at the nanoscale within a base matrix without using any heat treatment methods. Exploring these opportunities can lead to a new horizon of materials and device engineering needed for enabling advanced technologies and applications.

Concentration of atomic hydrogen in a dielectric barrier discharge measured by two-photon absorption fluorescence

NASA Astrophysics Data System (ADS)

Dvořák, P.; Talába, M.; Obrusník, A.; Kratzer, J.; Dědina, J.

2017-08-01

Two-photon absorption laser-induced fluorescence (TALIF) was utilized for measuring the concentration of atomic hydrogen in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar, H2 and O2 at atmospheric pressure. The method was calibrated by TALIF of krypton diluted in argon at atmospheric pressure, proving that three-body collisions had a negligible effect on quenching of excited krypton atoms. The diagnostic study was complemented with a 3D numerical model of the gas flow and a zero-dimensional model of the chemistry in order to better understand the reaction kinetics and identify the key pathways leading to the production and destruction of atomic hydrogen. It was determined that the density of atomic hydrogen in Ar-H2 mixtures was in the order of 1021 m-3 and decreased when oxygen was added into the gas mixture. Spatially resolved measurements and simulations revealed a sharply bordered region with low atomic hydrogen concentration when oxygen was added to the gas mixture. At substoichiometric oxygen/hydrogen ratios, this H-poor region is confined to an area close to the gas inlet and it is shown that the size of this region is not only influenced by the chemistry but also by the gas flow patterns. Experimentally, it was observed that a decrease in H2 concentration in the feeding Ar-H2 mixture led to an increase in H production in the DBD.

The performance and decolourization kinetics of O3/H2O2 oxidation of reactive green 19 dye in wastewater

NASA Astrophysics Data System (ADS)

Sabri, S. N.; Abidin, C. Z. A.; Fahmi; Kow, S. H.; Razali, N. A.

2018-03-01

The degradations characteristic of azo dye Reactive Green 19 (RG19) was investigated using advanced oxidation process (AOPs). It was evaluated based on colour and chemical oxygen demand (COD) removal. The effect of operational parameters such as initial dye concentration, initial dosage of hydrogen peroxide (H2O2), contact time, and pH was also being studied. The samples were treated by ozonation (O3) and peroxone O3/H2O2 process. Advanced oxidation processes (AOPs) involve two stages of oxidation; firstly is the formation of strong oxidant and secondly the reaction of organic contaminants in water. In addition, the term advanced oxidation is referring to the processes in which oxidation of organic contaminants occurs primarily through reactions with hydroxyl radicals. There are several analyses that use to determine the efficiency of the treatment process, which are UV-Vis absorption spectra, COD, Fourier Transform Infrared (FT-IR), and pH. The results demonstrated that the ozone oxidation was efficient in decolourization and good in mineralization, based on the reduction of colour and COD. Additionally, results indicate that H2O2 is able to perform better than ozonation in order to decolourize the dye wastewater with 0.5 mL H2O2/L dye dosage of H2O2 at different initial concentration, initial pH, with contact time.

Purging of a tank-mounted multilayer insulation system by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

The investigation was conducted on a multilayer insulation (MLI) system mounted on a spherical liquid hydrogen propellant tank. The MLI consisted of two blankets of insulation each containing 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The gaseous nitrogen initially contained within the MLI system and vacuum chamber was purged with gaseous helium introduced both underneath the MLI and into the vacuum chamber. The MLI panels were assumed to be purged primarily by means of gas diffusion. Overall, test results indicated that nitrogen concentrations well below 1 percent could be achieved everywhere within the MLI system. Typical times to achieve 1 percent nitrogen concentration within the MLI panels ranged from 69 minutes at the top of the tank to 158 minutes at the bottom of the tank. Four space-hold thermal performance tests indicated no significant thermal degradation of the MLI system had occurred due to the purge tests conducted. The final measured heat input attributed to the MLI was 7.23 watts as compared to 7.18 watts for the initial baseline thermal performance test.

Solar photocatalytic degradation of some hazardous water-soluble pesticides at pilot-plant scale.

PubMed

Oller, I; Gernjak, W; Maldonado, M I; Pérez-Estrada, L A; Sánchez-Pérez, J A; Malato, S

2006-12-01

The technical feasibility and performance of photocatalytic degradation of six water-soluble pesticides (cymoxanil, methomyl, oxamyl, dimethoate, pyrimethanil and telone) have been studied at pilot-plant scale in two well-defined systems which are of special interest because natural solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. TiO(2) photocatalysis tests were performed in a 35L solar pilot plant with three Compound Parabolic Collectors (CPCs) under natural illumination and a 75L solar pilot plant with four CPC units was used for homogeneous photocatalysis tests. The initial pesticide concentration studied was 50 mg L(-1) and the catalyst concentrations employed were 200 mg L(-1) of TiO(2) and 20 mg L(-1) of iron. Both toxicity (Vibrio fischeri, Biofix) and biodegradability (Zahn-Wellens test) of the initial pesticide solutions were also measured. Total disappearance of the parent compounds and nearly complete mineralization were attained with all pesticides tested. Treatment time, hydrogen peroxide consumption and release of heteroatoms are discussed.

Hydrogen-Assisted Crack Propagation in Austenitic Stainless Steel Fusion Welds

NASA Astrophysics Data System (ADS)

Somerday, B. P.; Dadfarnia, M.; Balch, D. K.; Nibur, K. A.; Cadden, C. H.; Sofronis, P.

2009-10-01

The objective of this study was to characterize hydrogen-assisted crack propagation in gas-tungsten arc (GTA) welds of the nitrogen-strengthened, austenitic stainless steel 21Cr-6Ni-9Mn (21-6-9), using fracture mechanics methods. The fracture initiation toughness and crack growth resistance curves were measured using fracture mechanics specimens that were thermally precharged with 230 wppm (1.3 at. pct) hydrogen. The fracture initiation toughness and slope of the crack growth resistance curve for the hydrogen-precharged weld were reduced by as much as 60 and 90 pct, respectively, relative to the noncharged weld. A physical model for hydrogen-assisted crack propagation in the welds was formulated from microscopy evidence and finite-element modeling. Hydrogen-assisted crack propagation proceeded by a sequence of microcrack formation at the weld ferrite, intense shear deformation in the ligaments separating microcracks, and then fracture of the ligaments. One salient role of hydrogen in the crack propagation process was promoting microcrack formation at austenite/ferrite interfaces and within the ferrite. In addition, hydrogen may have facilitated intense shear deformation in the ligaments separating microcracks. The intense shear deformation could be related to the development of a nonuniform distribution of hydrogen trapped at dislocations between microcracks, which in turn created a gradient in the local flow stress.

Spectroscopic studies on the conformational transitions of a bovine growth hormone releasing factor analog

NASA Astrophysics Data System (ADS)

Sarver, Ronald W.; Friedman, Alan R.; Thamann, Thomas J.

1997-10-01

The secondary structure of the bovine growth hormone releasing factor analog, [Ile 2, Ser 8,28, Ala 15, Leu 27, Hse 30] bGRF(1-30)-NH-Ethyl, acetate salt (U-90699F) was studied in solution by Fourier transform infrared and Raman spectroscopies. Spectroscopic studies revealed that concentrated aqueous solutions of U-90699F (100 mg ml -1) undergo a secondary structure transition from disordered coil/α-helix to intermolecular β-sheet. Disordered coil and α-helical structure were grouped together in the infrared and Raman studies since the amide I vibrations are close in frequency and overlap in assignments was possible. Before the conformational transition, the facile exchange of the peptide's amide hydrogens for deuterium indicated that the majority of amide hydrogens were readily accessible to solvent. The kinetics of the conformational transition coincided with an increase in solution viscosity and turbidity. An initiation phase preceded the conformational transition during which only minor spectral changes were observed by infrared spectroscopy. The initiation phase and reaction kinetics were consistent with a highly cooperative nucleation ultimately leading to a network of intermolecular β-sheet structure and gel formation. Increased temperature accelerated the conformational transition. The conformational transition was thermally irreversible but the β-sheet structure of aggregated or gelled peptide could be disrupted by dilution and agitation.

Hydrogen Generation by Koh-Ethanol Plasma Electrolysis Using Double Compartement Reactor

NASA Astrophysics Data System (ADS)

Saksono, Nelson; Sasiang, Johannes; Dewi Rosalina, Chandra; Budikania, Trisutanti

2018-03-01

This study has successfully investigated the generation of hydrogen using double compartment reactor with plasma electrolysis process. Double compartment reactor is designed to achieve high discharged voltage, high concentration, and also reduce the energy consumption. The experimental results showed the use of double compartment reactor increased the productivity ratio 90 times higher compared to Faraday electrolysis process. The highest hydrogen production obtained is 26.50 mmol/min while the energy consumption can reach up 1.71 kJ/mmol H2 at 0.01 M KOH solution. It was shown that KOH concentration, addition of ethanol, cathode depth, and temperature have important effects on hydrogen production, energy consumption, and process efficiency.

A table for converting pH to hydrogen ion concentration [H+] over the range 5-9.

DOT National Transportation Integrated Search

1968-10-01

The wider use, in the future, of hydrogen ion concentration (H+) rather than pH to describe and evaluate acid-base status will require interconversion of the two notations until a final standard is adopted. The relationship between pH and (H+) is giv...

High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering

NASA Astrophysics Data System (ADS)

Arakawa, Yasuaki; Ueno, Kohei; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

2016-08-01

We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN films with residual hydrogen concentrations below 5 × 1016 cm-3, which is the detection limit of secondary ion mass spectroscopy. In the Mg profile, no memory effect or serious dopant diffusion was detected. The as-deposited Mg-doped GaN films showed clear p-type conductivity at room temperature (RT) without thermal activation. The GaN film doped with a low concentration of Mg (7.9 × 1017 cm-3) deposited by PSD showed hole mobilities of 34 and 62 cm2 V-1 s-1 at RT and 175 K, respectively, which are as high as those of films grown by a state-of-the-art metal-organic chemical vapor deposition apparatus. These results indicate that PSD is a powerful tool for the fabrication of GaN-based vertical power devices.

Growth Kinetics of the S Sub H Center on Magnesium Oxide Using Electron Paramagnetic Resonance

NASA Technical Reports Server (NTRS)

Jayne, J. P.

1971-01-01

Electron paramagnetic resonance spectroscopy was used to study the growth of S sub H centers on magnesium oxide powder which had hydrogen adsorbed on its surface. The centers were produced by ultraviolet radiation. The effects of both radiation intensity and hydrogen pressure were also studied. At constant hydrogen pressure and radiation dose, the initial S sub H center growth rate was found to be zero order. Beyond the initial region the growth rate deviated from zero order and finally approached saturation. The results are interpreted in terms of a model which assumes that the S sub H center is a hydrogen atom associated with a surface vacancy. Saturation appears to result from a limited supply of surface vacancies.

Hydrogenation of carbonyl compounds of relevance to hydrogen storage in alcohols

NASA Astrophysics Data System (ADS)

Suárez, Andrés

2018-02-01

Alcohols are a promising source for the sustainable production of hydrogen that may also serve as rechargeable liquid organic hydrogen carriers (LOHCs). Metal-catalyzed acceptorless dehydrogenation of alcohols produces carbonyl derivatives as H2-depleted by-products, which by means of a hydrogenation reaction can be reconverted to the initial alcohols. Hence, reversible H2-storage systems based on pairs of secondary alcohols/ketones and primary alcohols/carboxylic acid derivatives may be envisaged. In this contribution, the hydrogenation of carbonyl derivatives, including ketones, esters, amides and carboxylic acids, is reviewed from the perspective of the hydrogen storage in alcohols.

Hydrogen segregation to inclined Σ3 < 110 >twin grain boundaries in nickel

DOE PAGES

O’Brien, Christopher J.; Foiles, Stephen M.

2016-08-04

Low-mobility twin grain boundaries dominate the microstructure of grain boundary-engineered materials and are critical to understanding their plastic deformation behaviour. The presence of solutes, such as hydrogen, has a profound effect on the thermodynamic stability of the grain boundaries. This work examines the case of a Σ3 grain boundary at inclinations from 0° ≤ Φ ≤ 90°. The angle Φ corresponds to the rotation of the Σ3 (1 1 1) < 1 1 0 > (coherent) into the Σ3 (1 1 2) < 1 1 0 > (lateral) twin boundary. To this end, atomistic models of inclined grain boundaries, utilisingmore » empirical potentials, are used to elucidate the finite-temperature boundary structure while grand canonical Monte Carlo models are applied to determine the degree of hydrogen segregation. In order to understand the boundary structure and segregation behaviour of hydrogen, the structural unit description of inclined twin grain boundaries is found to provide insight into explaining the observed variation of excess enthalpy and excess hydrogen concentration on inclination angle, but the explanatory power is limited by how the enthalpy of segregation is affected by hydrogen concentration. At higher concentrations, the grain boundaries undergo a defaceting transition. In order to develop a more complete mesoscale model of the interfacial behaviour, an analytical model of boundary energy and hydrogen segregation that relies on modelling the boundary as arrays of discrete 1/3 < 1 1 1 > disconnections is constructed. Lastly, the complex interaction of boundary reconstruction and concentration-dependent segregation behaviour exhibited by inclined twin grain boundaries limits the range of applicability of such an analytical model and illustrates the fundamental limitations for a structural unit model description of segregation in lower stacking fault energy materials.« less

Fluorescence hydrogen peroxide probe based on a microstructured polymer optical fiber modified with a titanium dioxide film.

PubMed

Li, Dongdong; Wang, Lili

2010-05-01

A highly sensitive microstructured polymer optical fiber (MPOF) probe for hydrogen peroxide was made by forming a rhodamine 6G-doped titanium dioxide film on the side walls of array holes in an MPOF. It was found that hydrogen peroxide only has a response to the MPOF probe in a certain concentration of potassium iodide in sulfuric acid solution. The calibration graph of fluorescence intensity versus hydrogen peroxide concentration is linear in the range of 1.6 x 10(-7) mol/L to 9.6 x 10(-5) mol/L. The method, with high sensitivity and a wide linear range, has been applied to the determination of trace amounts of hydrogen peroxide in a few real samples, such as rain water and contact lens disinfectant, with satisfactory results.

Importance of analytically verifying chemical treatments

USGS Publications Warehouse

Rach, J.J.; Gaikowski, M.P.; Olson, J.J.

1997-01-01

Hydrogen peroxide is considered a low regulatory priority compound by the U.S. Food and Drug Administration. It is used to control fungal infections on fish eggs. We studied the treatment profiles of hydrogen peroxide in Heath, McDonald egg jar, and Clark-Williamson incubators during treatments intended to deliver an effective regimen of at least 500 ??L hydrogen peroxide/L (i.e., treatments of 500 and 1,000 ??L/L) for 15 min. Hydrogen peroxide concentrations decreased with increasing distance from the influent water in both Heath and Clark-Williamson incubators. The top treatment tray (tray 2) of the Heath incubator received more than 90% of the intended regimen during the 500 ??L/L treatment, whereas at 1,000 ??L/L, all trays had hydrogen peroxide concentrations at or above 500 ??L/L for 15 min. None of the compartments in the Clark-Williamson incubator received the intended therapeutic regimen when treated at 500 ??L/L. The McDonald egg jar system distributed the intended concentration for the designated treatment period in all jars, except those located directly below the influent water. Our results indicate that dilution of therapeutants applied through certain egg incubation systems significantly decreases the efficacy of treatments and may render them ineffective. The dilution characteristics of egg incubation systems should be assessed in order to ensure proper delivery of all intended chemical concentrations and exposure regimens. Suggestions for maintaining the minimum effective concentrations in evaluated incubators are included.

Study of CO2 recovery in a carbonate fuel cell tri-generation plant

NASA Astrophysics Data System (ADS)

Rinaldi, Giorgio; McLarty, Dustin; Brouwer, Jack; Lanzini, Andrea; Santarelli, Massimo

2015-06-01

The possibility of separating and recovering CO2 in a biogas plant that co-produces electricity, hydrogen, and heat is investigated. Exploiting the ability of a molten carbonate fuel cell (MCFC) to concentrate CO2 in the anode exhaust stream reduces the energy consumption and complexity of CO2 separation techniques that would otherwise be required to remove dilute CO2 from combustion exhaust streams. Three potential CO2 concentrating configurations are numerically simulated to evaluate potential CO2 recovery rates: 1) anode oxidation and partial CO2 recirculation, 2) integration with exhaust from an internal combustion engine, and 3) series connection of molten carbonate cathodes initially fed with internal combustion engine (ICE) exhaust. Physical models have been calibrated with data acquired from an operating MCFC tri-generating plant. Results illustrate a high compatibility between hydrogen co-production and CO2 recovery with series connection of molten carbonate systems offering the best results for efficient CO2 recovery. In this case the carbon capture ratio (CCR) exceeds 73% for two systems in series and 90% for 3 MCFC in series. This remarkably high carbon recovery is possible with 1.4 MWe delivered by the ICE system and 0.9 MWe and about 350 kg day-1 of H2 delivered by the three MCFC.

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

DOE PAGES

Hlova, Ihor; Goldston, Jennifer F.; Gupta, Shalabh; ...

2017-05-30

Solid-state mechanochemical synthesis of alane (AlH 3) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction,more » which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.« less

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hlova, Ihor; Goldston, Jennifer F.; Gupta, Shalabh

Solid-state mechanochemical synthesis of alane (AlH 3) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction,more » which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.« less

HYDROGEN CONCENTRATIONS IN SULFATE-REDUCING ESTUARINE SEDIMENTS DURING PCE DEHALOGENATION

EPA Science Inventory

Despite recent progress made evaluating the role of hydrogen (H2) as a key electron donor in the anaerobic remediation of chloroethenes, few studies have focused on the evaluation of hydrogen thresholds relative to reductive dehalogenation in sulfidogenic environments. Competitio...

Effects of Hydrogen Peroxide on Dental Unit Biofilms and Treatment Water Contamination

PubMed Central

Lin, Shih-Ming; Svoboda, Kathy K.H.; Giletto, Anthony; Seibert, Jeff; Puttaiah, Raghunath

2011-01-01

Objectives: To study effects of various concentrations of hydrogen peroxide on mature waterline biofilms and in controlling planktonic (free-floating) organisms in simulated dental treatment water systems; and to study in vitro the effects of 2%, 3%, and 7% hydrogen peroxide on the removal of mature biofilms and inorganic compounds in dental waterlines. Methods: Four units of an automated dental unit water system simulation device was used for 12 weeks. All units were initially cleaned to control biofilms and inorganic deposits. H2O2 at concentrations of 1%, 2%, 3% was used weekly for periodic cleaning in three treatment group units (units 1, 2 & 3), with 0.05%, 0.15% and 0.25% H2O2 in municipal water used as irrigant respectively. The control unit (unit 4) did not have weekly cleanings and used municipal water as irrigant. Laser Scanning Confocal Microscopy and Scanning Electron Microscopy were used to study deposits on lines, and weekly heterotrophic plate counts done to study effluent water contamination. A 24 hour in vitro challenge test with 7%, 3% and 2% H2O2 on mature biofilms was conducted using harvested waterlines to study biofilm and inorganic deposit removal. Results: Heterotrophic plate counts of effluent water showed that the control unit reached contamination levels in excess of 400,000 CFU/mL while all treatment units showed contamination levels <500 CFU/mL through most of the 12 weeks. All treatment units showed varying levels of biofilm and inorganic deposit control in this short 12 week study. The in vitro challenge test showed although there was biofilm control, there was no eradication even when 7% H2O2 was used for 24 hours. Conclusions: 2% H2O2 used as a periodic cleaner, and diluted to 0.05% in municipal water for irrigation was beneficial in controlling biofilm and planktonic contamination in dental unit water systems. However, to remove well established biofilms, it may take more than 2 months when initial and multiple periodic cleanings are performed using H2O2. PMID:21228956

Hydrogen Permeation in Cold-Rolled High-Mn Twinning-Induced Plasticity Steels

NASA Astrophysics Data System (ADS)

Han, Do Kyeong; Hwang, A. In; Byeon, Woo Jun; Noh, Seung Jeong; Suh, Dong-Woo

2017-11-01

Hydrogen permeation is investigated in cold-rolled Fe-0.6C-18Mn-(1.5Al) alloys. The hydrogen mobility is lower in cold-rolled alloys compared with annealed alloys. Al-containing alloy shows less deceleration of hydrogen mobility compared with the Al-free alloy. This is attributed to the reduced formation of mechanical twins and dislocations. Mechanical twins trap hydrogen strongly but are vulnerable to crack initiation; suppression of these is thought to be a major favorable influence of Al on hydrogen-induced mechanical degradation.

Dynamics of Molecular Hydrogen in Hypersaline Microbial Mars

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Bebout, Brad M.; Visscher, Pieter T.; DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Early Earth microbial communities that centered around the anaerobic decomposition of organic molecular hydrogen as a carrier of electrons, regulator of energy metabolism, and facilitator of syntroph'c microbial interactions. The advent of oxygenic photosynthetic organisms added a highly dynamic and potentially dominant term to the hydrogen economy of these communities. We have examined the daily variations of hydrogen concentrations in cyanobacteria-dominated microbial mats from hypersaline ponds in Baja California Sur, Mexico. These mats bring together phototrophic and anaerobic bacteria (along with virtually all other trophic groups) in a spatially ordered and chemically dynamic matrix that provides a good analog for early Earth microbial ecosystems. Hydrogen concentrations in the photic zone of the mat can be three orders of magnitude or more higher than in the photic zone, which are, in turn, an order of magnitude higher than in the unconsolidated sediments underlying the mat community. Within the photic zone, hydrogen concentrations can fluctuate dramatically during the diel (24 hour day-night) cycle, ranging from less than 0.001% during the day to nearly 10% at night. The resultant nighttime flux of hydrogen from the mat to the environment was up to 17% of the daytime oxygen flux. The daily pattern observed is highly dependent on cyanobacterial species composition within the mat, with Lyngbya-dominated systems having a much greater dynamic range than those dominated by Microcoleus; this may relate largely to differing degrees of nitrogen-fixing and fermentative activity in the two mats. The greatest H2 concentrations and fluxes were observed in the absence of oxygen, suggesting an important potential feedback control in the context of the evolution of atmospheric composition. The impact of adding this highly dynamic photosynthetic term to the hydrogen economy of early microbial ecosystems must have been substantial. From an evolutionary standpoint, the H2 generated in mats could have represented a very important new source of electrons and energy - but one that could not be harnessed without substantial adaptation to the highly variable chemistry of the mat surface. In addition, the emergent chemistry of anaerobic communities is often highly dependent on ambient hydrogen concentrations, so that incorporation of these communities into photosynthetic mats could have significantly affected the composition and flux of reduced "biosignature' gases to the environment.

Hydrogen coadministration slows the development of COPD-like lung disease in a cigarette smoke-induced rat model.

PubMed

Liu, Xiaoyu; Ma, Cuiqing; Wang, Xiaoyu; Wang, Wenjing; Li, Zhu; Wang, Xiansheng; Wang, Pengyu; Sun, Wuzhuang; Xue, Baojian

2017-01-01

Chronic obstructive pulmonary disease (COPD) is a progressive pulmonary disease caused by harmful gases or particles. Recent studies have shown that 2% hydrogen or hydrogen water is effective in the treatment and prevention of a variety of diseases. This study investigated the beneficial effects and the possible mechanisms of different hydrogen concentrations on COPD. A rat COPD model was established through smoke exposure methods, and inhalation of different concentrations of hydrogen was used as the intervention. The daily condition of rats and the weight changes were observed; lung function and right ventricular hypertrophy index were assessed. Also, white blood cells were assessed in bronchoalveolar lavage fluid. Pathologic changes in the lung tissue were analyzed using light microscopy and electron microscopy; cardiovascular structure and pulmonary arterial pressure changes in rats were observed using ultrasonography. Tumor necrosis factor alpha, interleukin (IL)-6, IL-17, IL-23, matrix metalloproteinase-12, tissue inhibitor of metalloproteinase-1, caspase-3, caspase-8 protein, and mRNA levels in the lung tissue were determined using immunohistochemistry, Western blot, and real-time polymerase chain reaction. The results showed that hydrogen inhalation significantly reduced the number of inflammatory cells in the bronchoalveolar lavage fluid, and the mRNA and protein expression levels of tumor necrosis factor alpha, IL-6, IL-17, IL-23, matrix metalloproteinase-12, caspase-3, and caspase-8, but increased the tissue inhibitor of metalloproteinase-1 expression. Furthermore, hydrogen inhalation ameliorated lung pathology, lung function, and cardiovascular function and reduced the right ventricular hypertrophy index. Inhalation of 22% and 41.6% hydrogen showed better outcome than inhalation of 2% hydrogen. These results suggest that hydrogen inhalation slows the development of COPD-like lung disease in a cigarette smoke-induced rat model. Higher concentrations of hydrogen may represent a more effective way for the rat model.

Hydrogen coadministration slows the development of COPD-like lung disease in a cigarette smoke-induced rat model

PubMed Central

Liu, Xiaoyu; Ma, Cuiqing; Wang, Xiaoyu; Wang, Wenjing; Li, Zhu; Wang, Xiansheng; Wang, Pengyu; Sun, Wuzhuang; Xue, Baojian

2017-01-01

Background Chronic obstructive pulmonary disease (COPD) is a progressive pulmonary disease caused by harmful gases or particles. Recent studies have shown that 2% hydrogen or hydrogen water is effective in the treatment and prevention of a variety of diseases. This study investigated the beneficial effects and the possible mechanisms of different hydrogen concentrations on COPD. Methods A rat COPD model was established through smoke exposure methods, and inhalation of different concentrations of hydrogen was used as the intervention. The daily condition of rats and the weight changes were observed; lung function and right ventricular hypertrophy index were assessed. Also, white blood cells were assessed in bronchoalveolar lavage fluid. Pathologic changes in the lung tissue were analyzed using light microscopy and electron microscopy; cardiovascular structure and pulmonary arterial pressure changes in rats were observed using ultrasonography. Tumor necrosis factor alpha, interleukin (IL)-6, IL-17, IL-23, matrix metalloproteinase-12, tissue inhibitor of metalloproteinase-1, caspase-3, caspase-8 protein, and mRNA levels in the lung tissue were determined using immunohistochemistry, Western blot, and real-time polymerase chain reaction. Results The results showed that hydrogen inhalation significantly reduced the number of inflammatory cells in the bronchoalveolar lavage fluid, and the mRNA and protein expression levels of tumor necrosis factor alpha, IL-6, IL-17, IL-23, matrix metalloproteinase-12, caspase-3, and caspase-8, but increased the tissue inhibitor of metalloproteinase-1 expression. Furthermore, hydrogen inhalation ameliorated lung pathology, lung function, and cardiovascular function and reduced the right ventricular hypertrophy index. Inhalation of 22% and 41.6% hydrogen showed better outcome than inhalation of 2% hydrogen. Conclusion These results suggest that hydrogen inhalation slows the development of COPD-like lung disease in a cigarette smoke-induced rat model. Higher concentrations of hydrogen may represent a more effective way for the rat model. PMID:28496315

Dehydrogenation of liquid fuel in microchannel catalytic reactor

DOEpatents

Toseland, Bernard Allen; Pez, Guido Peter; Puri, Pushpinder Singh

2010-08-03

The present invention is an improved process for the storage and delivery of hydrogen by the reversible hydrogenation/dehydrogenation of an organic compound wherein the organic compound is initially in its hydrogenated state. The improvement in the route to generating hydrogen is in the dehydrogenation step and recovery of the dehydrogenated organic compound resides in the following steps: introducing a hydrogenated organic compound to a microchannel reactor incorporating a dehydrogenation catalyst; effecting dehydrogenation of said hydrogenated organic compound under conditions whereby said hydrogenated organic compound is present as a liquid phase; generating a reaction product comprised of a liquid phase dehydrogenated organic compound and gaseous hydrogen; separating the liquid phase dehydrogenated organic compound from gaseous hydrogen; and, recovering the hydrogen and liquid phase dehydrogenated organic compound.

Dehydrogenation of liquid fuel in microchannel catalytic reactor

DOEpatents

Toseland, Bernard Allen [Allentown, PA; Pez, Guido Peter [Allentown, PA; Puri, Pushpinder Singh [Emmaus, PA

2009-02-03

The present invention is an improved process for the storage and delivery of hydrogen by the reversible hydrogenation/dehydrogenation of an organic compound wherein the organic compound is initially in its hydrogenated state. The improvement in the route to generating hydrogen is in the dehydrogenation step and recovery of the dehydrogenated organic compound resides in the following steps: introducing a hydrogenated organic compound to a microchannel reactor incorporating a dehydrogenation catalyst; effecting dehydrogenation of said hydrogenated organic compound under conditions whereby said hydrogenated organic compound is present as a liquid phase; generating a reaction product comprised of a liquid phase dehydrogenated organic compound and gaseous hydrogen; separating the liquid phase dehydrogenated organic compound from gaseous hydrogen; and, recovering the hydrogen and liquid phase dehydrogenated organic compound.

Revisited reaction-diffusion model of thermal desorption spectroscopy experiments on hydrogen retention in material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guterl, Jerome, E-mail: jguterl@ucsd.edu; Smirnov, R. D.; Krasheninnikov, S. I.

Desorption phase of thermal desorption spectroscopy (TDS) experiments performed on tungsten samples exposed to flux of hydrogen isotopes in fusion relevant conditions is analyzed using a reaction-diffusion model describing hydrogen retention in material bulk. Two regimes of hydrogen desorption are identified depending on whether hydrogen trapping rate is faster than hydrogen diffusion rate in material during TDS experiments. In both regimes, a majority of hydrogen released from material defects is immediately outgassed instead of diffusing deeply in material bulk when the evolution of hydrogen concentration in material is quasi-static, which is the case during TDS experiments performed with tungsten samplesmore » exposed to flux of hydrogen isotopes in fusion related conditions. In this context, analytical expressions of the hydrogen outgassing flux as a function of the material temperature are obtained with sufficient accuracy to describe main features of thermal desorption spectra (TDSP). These expressions are then used to highlight how characteristic temperatures of TDSP depend on hydrogen retention parameters, such as trap concentration or activation energy of detrapping processes. The use of Arrhenius plots to characterize retention processes is then revisited when hydrogen trapping takes place during TDS experiments. Retention processes are also characterized using the shape of desorption peaks in TDSP, and it is shown that diffusion of hydrogen in material during TDS experiment can induce long desorption tails visible aside desorption peaks at high temperature in TDSP. These desorption tails can be used to estimate activation energy of diffusion of hydrogen in material.« less

Estimating Background and Lunar Contribution to Neutrons Detected by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) Instrument

NASA Astrophysics Data System (ADS)

Livengood, T. A.; Mitrofanov, I. G.; Chin, G.; Boynton, W. V.; Evans, L. G.; Litvak, M. L.; McClanahan, T. P.; Sagdeev, R.; Sanin, A. B.; Starr, R. D.; Su, J. J.

2014-12-01

The fraction of hydrogen-bearing species embedded in planetary regolith can be determined from the ratio between measured epithermal neutron leakage flux and the flux measured from similar dry regolith. The Lunar Reconnaissance Orbiter (LRO) spacecraft is equipped with the Lunar Exploration Neutron Detector (LEND) instrument to measure embedded hydrogen in the Moon's polar regions and elsewhere. We have investigated the relative contribution of lunar and non-lunar (spacecraft-sourced) neutrons by modeling maps of the measured count rate from three of the LEND detector systems using linear combinations of maps compiled from the Lunar Prospector Neutron Spectrometer (LPNS) and the LEND detectors, demonstrating that the two systems are compatible and enabling reference signal to be inferred to enable detecting hydrogen and hydrogen-bearing volatiles. The pole-to-equator contrast ratio in epithermal neutrons indicates that the average concentration of hydrogen in the Moon's polar regolith above 80° north or south latitude is ~110 ppmw, or 0.10±0.01 wt% water-equivalent hydrogen. Above 88° north or south, the concentration increases to ~140 ppmw, or 0.13±0.02 wt% water-equivalent hydrogen. Nearly identical suppression of neutron flux at both the north and south poles, despite differences in topography and distribution of permanently-shadowed regions, supports the contention that hydrogen is broadly distributed in the polar regions and increasingly concentrated approaching the poles. Similarity in the degree of neutron suppression in low-energy and high-energy epithermal neutrons suggests that the hydrogen fraction is relatively uniform with depth down to ~1 m; the neutron leakage flux is insensitive to greater depth.

Organic silicon compounds anf hydrogen sulfide removal from biogas by mineral and adsorbent

NASA Astrophysics Data System (ADS)

Choi, J.

2015-12-01

Biogas utilized for energy production needs to be free from organic silicon compounds and hydrogen sulfide , as their burning has damaging effects on utilities and humans; organic silicon compounds and hydrogen sulfide can be found in biogas produced from biomass wastes, due to their massive industrial use in synthetic product,such as cosmetics, detergents and paints.Siloxanes and hydrogen sulfide removal from biogas can be carried out by various methods (Ajhar et al., 2010); aim of the present work is to find a single practical andeconomic way to drastically and simultaneously reduce both hydrogen sulfide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleoneet al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing both hydrogen sulphide and volatile siloxane (Decamethycyclopentasiloxane or D5) in a nitrogen stream,typically 25-300 ppm D5 over N2, through an clay minerals, Fe oxides and Silica; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best silica shows an adsorption capacity of 0.2 g D5 per gram of silica. The next thermo gravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests.The capacity results depend on D5 and hydrogen sulphide concentrations. A regenerative silica process is then carried out byheating the silica bed up to 200 ° C and flushing out the adsorbed D5 and hydrogen sulphide samples in a nitrogen stream in athree step heating procedure up to 200 ° C. The adsorption capacity is observed to degrade after cyclingthe samples through several adsorption-desorption cycles.

Subneurotoxic copper(II)-induced NF-κB-dependent microglial activation is associated with mitochondrial ROS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Zhuqin; Yu, Fengxiang; Gong, Ping

2014-04-15

Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-α (TNF-α) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxicmore » concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-α and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-α and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced IkB-α expression as well as phosphorylation and translocation of nuclear factor-κB (NF-κB) p65 and was blocked by NF-κB inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-α and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-κB-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation. - Highlights: • Subneurotoxic copper(II) triggers NF-κB-dependent microglial activation. • This activation leads to hippocampal neuronal death. • This activation may involve mitochondria-derived reactive oxygen species.« less

40 CFR 63.8234 - What equations and procedures must I use for the initial compliance demonstration?

Code of Federal Regulations, 2010 CFR

2010-07-01

... What equations and procedures must I use for the initial compliance demonstration? (a) By-product... Megagram of chlorine production (g Hg/Mg Cl2) of chlorine produced from all by-product hydrogen streams and...) Determine the mercury emission rate for each test run in grams per day for each by-product hydrogen stream...

Surface characterization of hydrogen charged and uncharged alpha-2 and gamma titanium aluminide alloys using AES and REELS

NASA Technical Reports Server (NTRS)

Shanabarger, M. R.

1990-01-01

The surfaces of selected uncharged and hydrogen charged alpha-2 and gamma titanium aluminide alloys with Nb additions were characterized by Auger electron (AES) and reflected electron energy loss (REELS) spectroscopy. The alloy surfaces were cleaned before analysis at room temperature by ion sputtering. The low energy (500 eV) ion sputtering process preferentially sputtered the surface concentration. The surface concentrations were determined by comparing AES data from the alloys with corresponding data from elemental references. No differences were observed in the Ti or Nb Auger spectra for the uncharged and hydrogen charged alloys, even though the alpha-2 alloy had 33.4 atomic percent dissolved hydrogen. Also, no differences were observed in the AES spectra when hydrogen was adsorbed from the gas phase. Bulk plasmon energy shifts were observed in all alloys. The energy shifts were induced either by dissolved hydrogen (alpha-2 alloy) or hydrogen adsorbed from the gas phase (alpha-2 and gamma alloys). The adsorption induced plasmon energy shifts were greatest for the gamma alloy and cp-Ti metal.

Hydrogen gas concentration measurement in small area using raman lidar measurement technnology

NASA Astrophysics Data System (ADS)

Sugimoto, Sachiyo; Asahi, Ippei; Shiina, Tatuso

2018-04-01

When change of hydrogen(H2) gas concentration in a certain point is measured, non-contact measurement technology with high temporal and spatial resolution is necessary. In this study, H2 concentration in the small area of <1cm2 under the gas flow was measured by using a Raman lidar. Raman scattering light at the measurement point of 750mm ahead was detected by the Raman lidar. As a result, it was proved that the H2 concentration of more than 100ppm could be successfully measured.

Polymerization model for hydrogen peroxide initiated synthesis of polypyrrole nanoparticles.

PubMed

Leonavicius, Karolis; Ramanaviciene, Almira; Ramanavicius, Arunas

2011-09-06

A very simple, environmentally friendly, one-step oxidative polymerization route to fabricate polypyrrole (Ppy) nanoparticles of fixed size and morphology was developed and investigated. The herein proposed method is based on the application of sodium dodecyl sulfate and hydrogen peroxide, both easily degradable and cheap materials. The polymerization reaction is performed on 24 h time scale under standard conditions. We monitored a polaronic peak at 465 nm and estimated nanoparticle concentration during various stages of the reaction. Using this data we proposed a mechanism for Ppy nanoparticle formation in accordance with earlier emulsion polymerization mechanisms. Rates of various steps in the polymerization mechanism were accounted for and the resulting particles identified using atomic force microscopy. Application of Ppy nanoparticles prepared by the route presented here seems very promising for biomedical applications where biocompatibility is paramount. In addition, this kind of synthesis could be suitable for the development of solar cells, where very pure and low-cost conducting polymers are required. © 2011 American Chemical Society

Optimization of Lipase-Mediated Synthesis of 1-Nonene Oxide Using Phenylacetic Acid and Hydrogen Peroxide

PubMed Central

Abdulmalek, Emilia; Arumugam, Mahashanon; Basri, Mahiran; Rahman, Mohd Basyaruddin Abdul

2012-01-01

Herein, an efficient epoxidation of 1-nonene is described. In a simple epoxidation system, commercially available Novozym 435, an immobilized Candida antarctica lipase B, and hydrogen peroxide (H2O2) were utilized to facilitate the in situ oxidation of phenylacetic acid to the corresponding peroxy acid which then reacted with 1-nonene to give 1-nonene oxide with high yield and selectivity. The aliphatic terminal alkene was epoxidised efficiently in chloroform to give an excellent yield (97%–99%) under the optimum reaction conditions, including temperature (35 °C), initial H2O2 concentration (30%), H2O2 amount (4.4 mmol), H2O2 addition rate (one step), acid amount (8.8 mmol), and stirring speed (250 rpm). Interestingly, the enzyme was stable under the single-step addition of H2O2 with a catalytic activity of 190.0 Ug−1. The entire epoxidation process was carried out within 12 h using a conventional water bath shaker. PMID:23202943

Hydrogen suppression of 'ductile' processes

NASA Technical Reports Server (NTRS)

Sisson, R. D., Jr.; Wilson, J. H.; Adler, T. A.; Mcnitt, R. P.; Louthan, M. R., Jr.

1980-01-01

Experimental results are reported for torsional fatigue specimens of high-strength steel 4370 and tensile bars of mild steel A-106 which present evidence of a hydrogen-induced strain-aided hardening effect. These results are consistent with the postulate that hydrogen suppresses ductile processes required for crack initiation at large plastic strains.

Hydrogen Highways: Lessons on the Energy Technology-Policy Interface

ERIC Educational Resources Information Center

Waegel, Alex; Byrne, John; Tobin, Daniel; Haney, Bryan

2006-01-01

The hydrogen economy has received increasing attention recently. Common reasons cited for investigating hydrogen energy options are improved energy security, reduced environmental impacts, and its contribution to a transition to sustainable energy sources. In anticipation of these benefits, national and local initiatives have been launched in the…

An electrochemical method for determining hydrogen concentrations in metals and some applications

NASA Technical Reports Server (NTRS)

Danford, M. D.

1983-01-01

An electrochemical method was developed for the determination of hydrogen in metals using the EG&G-PARC Model 350A Corrosion Measurement Console. The method was applied to hydrogen uptake, both during electrolysis and electroplating, and to studies of hydrogen elimination and the effect of heat treatment on elimination times. Results from these studies are presented.

Evaluation of dopants in hydrogen to reduce hydrogen permeation in candidate Stirling engine heater head tube alloys at 760 deg and 820 deg

NASA Technical Reports Server (NTRS)

Misencik, J. A.

1982-01-01

Alloy tubes filled with hydrogen doped with various amounts of carbon monoxide, carbon dioxide, ethane, ethylene, methane, ammonia, or water were heated in a diesel fuel-fired Stirling engine simulator materials test rig for 100 hours at 21 MPa and 760 or 820 C to determine the effectiveness of the dopants in reducing hydrogen permeation through the hot tube walls. Ultra high purity (UHP) hydrogen was used for comparison. The tube alloys were N-155, A-286, Incoloy 800, Nitronic 40, 19-9DL, 316 stainless steel, Inconel 718, and HS-188. Carbon dioxide and carbon monoxide in the concentration range 0.2 to 5 vol % were most effective in reducing hydrogen permeation through the hot tube walls for all alloys. Ethane, ethylene, methane, ammonia, and water at the concentrations investigated were not effective in reducing the permeation below that achieved with UHP hydrogen. One series of tests were conducted with UHP hydrogen in carburized tubes. Carburization of the tubes prior to exposure reduced permeation to values similar to those for carbon monoxide; however, carbon dioxide was the most effective dopant.

Theoretical study of hydrogen storage in metal hydrides.

PubMed

Oliveira, Alyson C M; Pavão, A C

2018-05-04

Adsorption, absorption and desorption energies and other properties of hydrogen storage in palladium and in the metal hydrides AlH 3 , MgH 2 , Mg(BH 4 ) 2 , Mg(BH 4 )(NH 2 ) and LiNH 2 were analyzed. The DFT calculations on cluster models show that, at a low concentration, the hydrogen atom remains adsorbed in a stable state near the palladium surface. By increasing the hydrogen concentration, the tetrahedral and the octahedral sites are sequentially occupied. In the α phase the tetrahedral site releases hydrogen more easily than at the octahedral sites, but the opposite occurs in the β phase. Among the hydrides, Mg(BH 4 ) 2 shows the highest values for both absorption and desorption energies. The absorption energy of LiNH 2 is higher than that of the palladium, but its desorption energy is too high, a recurrent problem of the materials that have been considered for hydrogen storage. The release of hydrogen, however, can be favored by using transition metals in the material structure, as demonstrated here by doping MgH 2 with 3d and 4d-transition metals to reduce the hydrogen atomic charge and the desorption energy.

Molecular mechanisms underlying the protective effects of hydrogen-saturated saline on noise-induced hearing loss.

PubMed

Chen, Liwei; Han, Mingkun; Lu, Yan; Chen, Daishi; Sun, Xuejun; Yang, Shiming; Sun, Wei; Yu, Ning; Zhai, Suoqiang

2017-10-01

This study aimed to explore the molecular mechanism of the protective effects of hydrogen-saturated saline on NIHL. Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections 3 d before and 1 h before noise exposure. ABR were tested to examine cochlear physiology changes. The changes of 8-hydroxy-desoxyguanosine (8-HOdG), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), intercellular cell adhesion molecule-1 (ICAM-1) and high mobility group box-1 protein (HMGB1) in the cochlea were also examined. The results showed that pre-treatment with hydrogen-saturated saline could significantly attenuate noise-induced hearing loss. The concentration of 8-HOdG was also significantly decreased in the hydrogen-saturated saline group compared with the normal saline group. After noise exposure, the concentrations of IL-1, IL-6, TNF-α, and ICAM-1 in the cochlea of guinea pigs in the hydrogen-saturated saline group were dramatically reduced compared to those in the normal saline group. The concentrations of HMGB-1 and IL-10 in the hydrogen-saturated saline group were significantly higher than in those in the normal saline group immediately and at 7 d after noise exposure. This study revealed for the first time the protective effects of hydrogen-saturated saline on noise-induced hearing loss (NIHL) are related to both the anti-oxidative activity and anti-inflammatory activity.

Short-Term Vitamin B-6 Restriction Does Not Affect Plasma Concentrations of Hydrogen Sulfide Biomarkers Lanthionine and Homolanthionine in Healthy Men and Women123

PubMed Central

DeRatt, Barbara N; Ralat, Maria A; Gregory, Jesse F

2016-01-01

Background: Suboptimal vitamin B-6 status is associated with increased cardiovascular disease risk, although the mechanism is unknown. The synthesis of the vasodilator hydrogen sulfide occurs through side reactions of the transsulfuration enzymes cystathionine β-synthase and cystathionine γ-lyase, with pyridoxal 5′-phosphate as a coenzyme. Two proposed hydrogen sulfide biomarkers, lanthionine and homolanthionine, are produced concurrently. Objective: To determine whether hydrogen sulfide production is reduced by vitamin B-6 deficiency, we examined the relations between plasma concentrations of lanthionine and homolanthionine, along with other components of the transsulfuration pathway (homocysteine, cystathionine, and Cys), in a secondary analysis of samples from 2 vitamin B-6 restriction studies in healthy men and women. Methods: Metabolite concentrations were measured in plasma from 23 healthy adults (12 men and 11 women) before and after 28-d controlled dietary vitamin B-6 restriction (0.37 ± 0.04 mg/d). Vitamin B-6 restriction effects on lanthionine and homolanthionine concentrations were assessed. Associations between hydrogen sulfide biomarkers, transsulfuration metabolites, and functional indicators of vitamin B-6 deficiency were analyzed by linear regression. Results: Preprandial plasma lanthionine and homolanthionine concentrations ranged from 89.0 to 372 nmol/L and 5.75 to 32.3 nmol/L, respectively, in healthy adults. Mean lanthionine and homolanthionine concentrations were not affected by vitamin B-6 restriction (P < 0.66), with marked heterogeneity of individual responses. After restriction, homolanthionine was positively associated with functional indicators of vitamin B-6 deficiency, which differed from hypothesized negative associations. Plasma lanthionine was positively correlated with the concentration of its precursor, Cys, before (R2 = 0.36; P = 0.002) and after (R2 = 0.37; P = 0.002) restriction. Likewise, homolanthionine concentration was positively correlated with its precursor homocysteine, but only in vitamin B-6 adequacy (R2 = 0.41; P < 0.001). Conclusions: The resiliency of plasma lanthionine and homolanthionine concentrations after short-term vitamin B-6 restriction suggests a minimal effect of moderate vitamin B-6 deficiency on hydrogen sulfide production. Additional research is needed to better understand the metabolism and disposal of these biomarkers in humans. This study was registered at clinicaltrials.gov as NCT00877812. PMID:26962179

Short-Term Vitamin B-6 Restriction Does Not Affect Plasma Concentrations of Hydrogen Sulfide Biomarkers Lanthionine and Homolanthionine in Healthy Men and Women.

PubMed

DeRatt, Barbara N; Ralat, Maria A; Gregory, Jesse F

2016-03-09

Suboptimal vitamin B-6 status is associated with increased cardiovascular disease risk, although the mechanism is unknown. The synthesis of the vasodilator hydrogen sulfide occurs through side reactions of the transsulfuration enzymes cystathionine β-synthase and cystathionine γ-lyase, with pyridoxal 5'-phosphate as a coenzyme. Two proposed hydrogen sulfide biomarkers, lanthionine and homolanthionine, are produced concurrently. To determine whether hydrogen sulfide production is reduced by vitamin B-6 deficiency, we examined the relations between plasma concentrations of lanthionine and homolanthionine, along with other components of the transsulfuration pathway (homocysteine, cystathionine, and Cys), in a secondary analysis of samples from 2 vitamin B-6 restriction studies in healthy men and women. Metabolite concentrations were measured in plasma from 23 healthy adults (12 men and 11 women) before and after 28-d controlled dietary vitamin B-6 restriction (0.37 ± 0.04 mg/d). Vitamin B-6 restriction effects on lanthionine and homolanthionine concentrations were assessed. Associations between hydrogen sulfide biomarkers, transsulfuration metabolites, and functional indicators of vitamin B-6 deficiency were analyzed by linear regression. Preprandial plasma lanthionine and homolanthionine concentrations ranged from 89.0 to 372 nmol/L and 5.75 to 32.3 nmol/L, respectively, in healthy adults. Mean lanthionine and homolanthionine concentrations were not affected by vitamin B-6 restriction (P < 0.66), with marked heterogeneity of individual responses. After restriction, homolanthionine was positively associated with functional indicators of vitamin B-6 deficiency, which differed from hypothesized negative associations. Plasma lanthionine was positively correlated with the concentration of its precursor, Cys, before (R 2 = 0.36; P = 0.002) and after (R 2 = 0.37; P = 0.002) restriction. Likewise, homolanthionine concentration was positively correlated with its precursor homocysteine, but only in vitamin B-6 adequacy (R 2 = 0.41; P < 0.001). The resiliency of plasma lanthionine and homolanthionine concentrations after short-term vitamin B-6 restriction suggests a minimal effect of moderate vitamin B-6 deficiency on hydrogen sulfide production. Additional research is needed to better understand the metabolism and disposal of these biomarkers in humans. This study was registered at clinicaltrials.gov as NCT00877812. © 2016 American Society for Nutrition.

Effect of plasma nitriding on the structural stability and hydrogen absorption capability of Pd-coated Nb during thermal treatment

NASA Astrophysics Data System (ADS)

Ohtsu, Naofumi; Kozuka, Taro; Shibata, Yuga; Yamane, Misao

2017-11-01

Plasma nitriding was explored for improving the thermal stability of a composite hydrogen permeable membrane comprising a Pd coating on Nb substrate. A NbN intermediate layer was formed on the Nb substrate, and the progress of interdiffusion and deterioration of hydrogen absorption behavior after a thermal treatment at 573 and 773 K, respectively, were investigated. The intermediate layer significantly suppressed the interdiffusion between the coating and the substrate. Furthermore, an increase in the NbN concentration of the intermediate layer enhanced the suppression efficiency. However, the hydrogen permeability of the intermediate layer was significantly low, and hence, an increase in NbN concentration further decreased the hydrogen permeability. We concluded that the nitride layer with a high NbN content was unsuitable as an intermediate layer owing to its low hydrogen permeability, while the partial nitride layer with a low NbN content was inefficient in suppressing the interdiffusion.

Pd/Ag coated fiber Bragg grating sensor for hydrogen monitoring in power transformers.

PubMed

Ma, G M; Jiang, J; Li, C R; Song, H T; Luo, Y T; Wang, H B

2015-04-01

Compared with conventional DGA (dissolved gas analysis) method for on-line monitoring of power transformers, FBG (fiber Bragg grating) hydrogen sensor represents marked advantages over immunity to electromagnetic field, time-saving, and convenience to defect location. Thus, a novel FBG hydrogen sensor based on Pd/Ag (Palladium/Silver) along with polyimide composite film to measure dissolved hydrogen concentration in large power transformers is proposed in this article. With the help of Pd/Ag composite coating, the enhanced performance on mechanical strength and sensitivity is demonstrated, moreover, the response time and sensitivity influenced by oil temperature are solved by correction lines. Sensitivity measurement and temperature calibration of the specific hydrogen sensor have been done respectively in the lab. And experiment results show a high sensitivity of 0.055 pm/(μl/l) with instant response time about 0.4 h under the typical operating temperature of power transformers, which proves a potential utilization inside power transformers to monitor the health status by detecting the dissolved hydrogen concentration.

Hydrogen bonding effects on the reorganization energy for photoinduced charge separation reaction between porphyrin and quinone studied by nanosecond laser flash photolysis.

PubMed

Yago, Tomoaki; Gohdo, Masao; Wakasa, Masanobu

2010-02-25

Alcohol concentration dependences of photoinduced charge separation (CS) reaction of zinc tetraphenyl-porphyrin (ZnTPP) and duroquinone (DQ) were investigated in benzonitrile by a nanosecond laser flash photolysis technique. The photoinduced CS reaction was accelerated by the addition of alcohols, whereas the addition of acetonitrile caused little effect on the CS reactions. The simple theory was developed to calculate an increase in reorganization energies induced by the hydrogen bonding interactions between DQ and alcohols using the chemical equilibrium constants for the hydrogen bonding complexes through the concerted pathway and the stepwise one. The experimental results were analyzed by using the Marcus equation where we took into account the hydrogen bonding effects on the reorganization energy and the reaction free energy for the CS reaction. The observed alcohol concentration dependence of the CS reaction rates was well explained by the formation of the hydrogen bonding complexes through the concerted pathway, demonstrating the increase in the reorganization energy by the hydrogen bonding interactions.

Thermal stability of trapped hydrogen in amorphous carbon thin films on Si substrate using ion beam scattering

NASA Astrophysics Data System (ADS)

Moore, A.; Tecos, G.; Nandasiri, M. I.; Garratt, E.; Wickey, K. J.; Gao, X.; Kayani, A.

2009-11-01

Unbalanced magnetron sputtering deposition of C-H films has been performed with various levels of negative substrate bias and with a fixed flow rate of hydrogen. Argon was used as a sputtering gas and formed the majority of the gas in the plasma. The effect of hydrogenation on the final concentration of trapped elements and their thermal stability with respect to hydrogen content is studied using ion beam analysis (IBA) techniques. The elemental concentrations of the films were measured in samples deposited on silicon substrates with a 3.3 MeV of He++ beam used to perform Rutherford Backscattering Spectroscopy (RBS), Non-Rutherford backscattering Spectroscopy (NRBS) and Elastic Recoil Detection Analysis (ERDA). Thermal stability with respect to trapped hydrogen in the film has been studied. As the films were heated in-situ in the vacuum using a o non-gassy button heater, hydrogen was found to be decreasing around 400° C.

Electrosynthesis of hydrogen peroxide via the reduction of oxygen assisted by power ultrasound.

PubMed

González-García, José; Banks, Craig E; Sljukić, Biljana; Compton, Richard G

2007-04-01

The electrosynthesis of hydrogen peroxide using the oxygen reduction reaction has been studied in the absence and presence of power ultrasound in a non-optimized sono-electrochemical flow reactor (20 cm cathodic compartment length with 6.5 cm inner diameter) with reticulated vitreous glassy carbon electrode (30 x 40 x 10 mm, 10 ppi, 7 cm(2)cm(-3)) as the cathode. The effect of several electrochemical operational variables (pH, volumetric flow, potential) and of the sono-electrochemical parameters (ultrasound amplitude and horn-to-electrode distance) on the cumulative concentration of hydrogen peroxide and current efficiency of the electrosynthesis process have been explored. The application of power ultrasound was found to increase both the cumulative concentration of hydrogen peroxide and the current efficiency. The application of ultrasound is therefore a promising approach to the increased efficiency of production of hydrogen peroxide by electrosynthesis, even in the solutions of lower pH (<12). The results demonstrate the feasibility of at-site-of-use green synthesis of hydrogen peroxide.

Validation of a reduced-order jet model for subsonic and underexpanded hydrogen jets

DOE PAGES

Li, Xuefang; Hecht, Ethan S.; Christopher, David M.

2016-01-01

Much effort has been made to model hydrogen releases from leaks during potential failures of hydrogen storage systems. A reduced-order jet model can be used to quickly characterize these flows, with low computational cost. Notional nozzle models are often used to avoid modeling the complex shock structures produced by the underexpanded jets by determining an “effective” source to produce the observed downstream trends. In our work, the mean hydrogen concentration fields were measured in a series of subsonic and underexpanded jets using a planar laser Rayleigh scattering system. Furthermore, we compared the experimental data to a reduced order jet modelmore » for subsonic flows and a notional nozzle model coupled to the jet model for underexpanded jets. The values of some key model parameters were determined by comparisons with the experimental data. Finally, the coupled model was also validated against hydrogen concentrations measurements for 100 and 200 bar hydrogen jets with the predictions agreeing well with data in the literature.« less

Laser-Based Monitoring of CH4, CO2, NH3, and H2S in Animal Farming—System Characterization and Initial Demonstration

PubMed Central

Jaworski, Piotr; Nikodem, Michał

2018-01-01

In this paper, we present a system for sequential detection of multiple gases using laser-based wavelength modulation spectroscopy (WMS) method combined with a Herriot-type multi-pass cell. Concentration of hydrogen sulfide (H2S), methane (CH4), carbon dioxide (CO2), and ammonia (NH3) are retrieved using three distributed feedback laser diodes operating at 1574.5 nm (H2S and CO2), 1651 nm (CH4), and 1531 nm (NH3). Careful adjustment of system parameters allows for H2S sensing at single parts-per-million by volume (ppmv) level with strongly reduced interference from adjacent CO2 transitions even at atmospheric pressure. System characterization in laboratory conditions is presented and the results from initial tests in real-world application are demonstrated. PMID:29425175

Titanium subhydride potassium perchlorate (TiH1.65/KClO4) burn rates from hybrid closed bomb-strand burner experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, Marcia A.; Oliver, Michael S.

2012-08-01

A hybrid closed bomb-strand burner is used to measure the burning behavior of the titanium subhydride potassium perchlorate pyrotechnic with an equivalent hydrogen concentration of 1.65. This experimental facility allows for simultaneous measurement of the closed bomb pressure rise and pyrotechnic burn rate as detected by electrical break wires over a range of pressures. Strands were formed by pressing the pyrotechnic powders to bulk densities between 60% and 90% theoretical maximum density. The burn rate dependance on initial density and vessel pressure are measured. At all initial strand densities, the burn is observed to transition from conductive to convective burningmore » within the strand. The measured vessel pressure history is further analyzed following the closed bomb analysis methods developed for solid propellants.« less

Coupling between fluid dynamics and energy addition in arcjet and microwave thrusters

NASA Technical Reports Server (NTRS)

Micci, M. M.

1986-01-01

A new approach to numerically solving the problem of the constricted electric arcjet is presented. An Euler Implicit finite difference scheme is used to solve the full compressible Navier Stokes equations in two dimensions. The boundary and initial conditions represent the constrictor section of the arcjet, and hydrogen is used as a propellant. The arc is modeled as a Gaussian distribution across the centerline of the constrictor. Temperature, pressure and velocity profiles for steady state converged solutions show both axial and radial changes in distributions resulting from their interaction with the arc energy source for specific input conditions. The temperature rise is largest at the centerline where there is a the greatest concentration arc energy. The solution does not converge for all initial inputs and the limitations in the range of obtainable solutions are discussed.

Effect of pH on lead removal from water using tree fern as the sorbent.

PubMed

Ho, Yuh-Shan

2005-07-01

The sorption of lead from water onto an agricultural by-product, tree fern, was examined as a function of pH. The sorption processes were carried out using an agitated and baffled system. Pseudo-second-order kinetic analyses were performed to determine the rate constant of sorption, the equilibrium sorption capacity, and the initial sorption rate. Application of the pseudo-second-order kinetics model produced very high coefficients of determination. Results showed the efficiency of tree fern as a sorbent for lead. The optimum pH for lead removal was between 4 and 7, with pH 4.9 resulting in better lead removal. Ion exchange occurred in the initial reaction period. In addition, a relation between the change in the solution hydrogen ion concentration and equilibrium capacity was developed and is presented.

Effects of near-bottom water oxygen concentration on biogeochemical cycling of C, N and S in sediments of the Gulf of Gdansk (southern Baltic)

NASA Astrophysics Data System (ADS)

Lukawska-Matuszewska, Katarzyna; Kielczewska, Joanna

2016-04-01

Sediments from four sampling sites in the Gulf of Gdansk were sampled to test how different oxygen concentrations in near-bottom water affects biogeochemical cycling of C, N and S. Vertical distributions of content of organic carbon (OC), total nitrogen (TN) and total sulfur (TS) and number of sulfate-reducing bacteria (SRB) in sediments were determined. Pore water total alkalinity (TA), dissolved inorganic carbon (DIC), sulfate, hydrogen sulfide, ammonium and phosphate were analyzed and benthic fluxes of DIC, hydrogen sulfide and ammonium were calculated. Concentrations of OC and TN decreased and concentration of TS increased with sediment depth. Highest concentrations of OC, TN and TS were observed in silty clay sediments from hypoxic and anoxic sediments below the permanent halocline. Organic matter (OM) accumulation in sediments and oxygen deficiency in near-bottom water stimulate preservation of OC and burial of TS in this area. Concentrations of TA, DIC, hydrogen sulfide, ammonium and phosphate in pore water increased, while concentration of sulfate decreased with sediment depth. Hydrogen sulfide, ammonium and phosphate was a significant additional source of TA in pore water under hypoxic and anoxic conditions. Mineralization of OM at oxygen concentrations <2 ml l-1 occurred mainly via bacterial sulfate reduction. Diurnal hydrogen sulfide fluxes under hypoxic conditions ranged from 400 to 1240 μmol m-2 d-1. Ammonium fluxes were estimated on 534 - 924 μmol m-2 d-1. Corresponding fluxes measured under anoxic conditions were 266 μmol m-2 d-1 and 106 μmol m-2 d-1. Sediments under oxic conditions became a place of the intensive regeneration of carbon - DIC flux from sediment reached 2775 μmol m-2 day-1. Sediment-water DIC fluxes under hypoxic and anoxic conditions were much lower and ranged from 1015 to 1208 μmol m-2 d-1.

Heat Pre-Treatment of Beverages Wastewater on Hydrogen Production

NASA Astrophysics Data System (ADS)

Uyub, S. Z.; Mohd, N. S.; Ibrahim, S.

2017-06-01

At present, a large variety of alternative fuels have been investigated and hydrogen gas is considered as the possible solution for the future due to its unique characteristics. Through dark fermentation process, several factors were found to have significant impact on the hydrogen production either through process enhancement or inhibition and degradation rates or influencing parameters. This work was initiated to investigate the optimum conditions for heat pre-treatment and initial pH for the dark fermentative process under mesophilic condition using a central composite design and response surface methodology (RSM). Different heat treatment conditions and pH were performed on the seed sludge collected from the anaerobic digester of beverage wastewater treatment plant. Heat treatment of inoculum was optimized at different exposure times (30, 90, 120 min), temperatures (80, 90 and 100°C) and pH (4.5, 5.5, 6.5) in order to maximize the biohydrogen production and methanogens activity inhibition. It was found that the optimum heat pre-treatment condition and pH occurred at 100°C for 50 min and the pH of 6.00. At this optimum condition the hydrogen yield was 63.0476 ml H2/mol glucose (H2 Yield) and the COD removal efficiency was 90.87%. In conclusion, it can be hypothesized that different heat treatment conditions led to differences in the initial microbial communities (hydrogen producing bacteria) which resulted in the different hydrogen yields.

Editors' Choice—Field Trials Testing of Mixed Potential Electrochemical Hydrogen Safety Sensors at Commercial California Hydrogen Filling Stations

DOE PAGES

Brosha, Eric Lanich; Romero, Christopher Jesse; Poppe, Daniel; ...

2017-10-27

Hydrogen safety sensors must meet specific performance requirements, mandated by the U.S. Department of Energy, for hydrogen fueling station monitoring. Here, we describe the long-term performance of two zirconia-based mixed potential electrochemical hydrogen gas sensors, developed specifically with a high sensitivity to hydrogen, low cross-sensitivity, and fast response time. Over a two-year period, sensors with tin-doped indium oxide and strontium doped lanthanum chromite electrodes were deployed at two stations in four field trials tests conducted in Los Angeles. The sensors documented the existence of hydrogen plumes ranging in concentration from 100 to as high as 2700 ppm in the areamore » surrounding the dispenser, consistent with depressurization from 700 bar following vehicle refueling. As expected, the hydrogen concentration reported by the mixed potential sensors was influenced by wind direction. Baseline stability testing at a Chino, CA station showed no measureable baseline drift throughout 206 days of uninterrupted data acquisition. The high baseline stability, excellent correlation with logged fueling/depressurization events, and absence of false alarms suggest that the zirconia-based mixed potential sensor platform is a good candidate for protecting hydrogen infrastructure where frequent calibrations or sensor replacement to reduce the false alarm frequency have been shown to be cost prohibitive.« less

Editors' Choice—Field Trials Testing of Mixed Potential Electrochemical Hydrogen Safety Sensors at Commercial California Hydrogen Filling Stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brosha, Eric Lanich; Romero, Christopher Jesse; Poppe, Daniel

Hydrogen safety sensors must meet specific performance requirements, mandated by the U.S. Department of Energy, for hydrogen fueling station monitoring. Here, we describe the long-term performance of two zirconia-based mixed potential electrochemical hydrogen gas sensors, developed specifically with a high sensitivity to hydrogen, low cross-sensitivity, and fast response time. Over a two-year period, sensors with tin-doped indium oxide and strontium doped lanthanum chromite electrodes were deployed at two stations in four field trials tests conducted in Los Angeles. The sensors documented the existence of hydrogen plumes ranging in concentration from 100 to as high as 2700 ppm in the areamore » surrounding the dispenser, consistent with depressurization from 700 bar following vehicle refueling. As expected, the hydrogen concentration reported by the mixed potential sensors was influenced by wind direction. Baseline stability testing at a Chino, CA station showed no measureable baseline drift throughout 206 days of uninterrupted data acquisition. The high baseline stability, excellent correlation with logged fueling/depressurization events, and absence of false alarms suggest that the zirconia-based mixed potential sensor platform is a good candidate for protecting hydrogen infrastructure where frequent calibrations or sensor replacement to reduce the false alarm frequency have been shown to be cost prohibitive.« less

Catalyzed borohydrides for hydrogen storage

DOEpatents

Au, Ming [Augusta, GA

2012-02-28

A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

DOE Hydrogen Program: 2006 Annual Merit Review and Peer Evaluation Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milliken, J.

This report summarizes comments from the Peer Review Panel at the FY 2006 DOE Hydrogen Program Annual Merit Review, held on May 16-19, 2006, in Arlington, Virginia. The projects evaluated support the Department of Energy and President Bush's Hydrogen Initiative. The results of this merit review and peer evaluation are major inputs used by DOE to make funding decisions. Project areas include hydrogen production and delivery; hydrogen storage; fuel cells; technology validation; safety, codes and standards; education; and systems analysis.

DOE Hydrogen Program: 2005 Annual Merit Review and Peer Evaluation Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chalk, S. G.

This report summarizes comments from the Peer Review Panel at the FY 2005 DOE Hydrogen Program Annual Merit Review, held on May 23-26, 2005, in Arlington, Virginia. The projects evaluated support the Department of Energy and President Bush's Hydrogen Initiative. The results of this merit review and peer evaluation are major inputs used by DOE to make funding decisions. Project areas include hydrogen production and delivery; hydrogen storage; fuel cells; technology validation; safety, codes and standards; education; and systems analysis.

DOE Hydrogen Program: 2007 Annual Merit Review and Peer Evaluation Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milliken, J.

This report summarizes comments from the Peer Review Panel at the FY 2007 DOE Hydrogen Program Annual Merit Review, held on May 14-18, 2007, in Washington, D.C. The projects evaluated support the Department of Energy and President Bush's Hydrogen Initiative. The results of this merit review and peer evaluation are major inputs used by DOE to make funding decisions. Project areas include hydrogen production and delivery; hydrogen storage; fuel cells; technology validation; safety, codes and standards; education; and systems analysis.

A study of alternative designs for a system to concentrate carbon dioxide in a hydrogen-depolarized cell

NASA Technical Reports Server (NTRS)

1973-01-01

Experimental results are presented on alternative designs for a hydrogen depolarized cell to concentrate CO2 in spacecraft atmospheric control systems. Data cover technical problems, methods for solving these problems, and the suitability of such a cell for CO2 removal and control of atmospheric humidity during the flight mode.

Internal hydrogen-induced subcritical crack growth in austenitic stainless steels

NASA Astrophysics Data System (ADS)

Huang, J. H.; Altstetter, C. J.

1991-11-01

The effects of small amounts of dissolved hydrogen on crack propagation were determined for two austenitic stainless steel alloys, AISI 301 and 310S. In order to have a uniform distribution of hydrogen in the alloys, they were cathodically charged at high temperature in a molten salt electrolyte. Sustained load tests were performed on fatigue precracked specimens in air at 0 ‡C, 25 ‡C, and 50 ‡C with hydrogen contents up to 41 wt ppm. The electrical potential drop method with optical calibration was used to continuously monitor the crack position. Log crack velocity vs stress intensity curves had definite thresholds for subcritical crack growth (SCG), but stage II was not always clearly delineated. In the unstable austenitic steel, AISI 301, the threshold stress intensity decreased with increasing hydrogen content or increasing temperature, but beyond about 10 wt ppm, it became insensitive to hydrogen concentration. At higher concentrations, stage II became less distinct. In the stable stainless steel, subcritical crack growth was observed only for a specimen containing 41 wt ppm hydrogen. Fractographic features were correlated with stress intensity, hydrogen content, and temperature. The fracture mode changed with temperature and hydrogen content. For unstable austenitic steel, low temperature and high hydrogen content favored intergranular fracture while microvoid coalescence dominated at a low hydrogen content. The interpretation of these phenomena is based on the tendency for stress-induced phase transformation, the different hydrogen diffusivity and solubility in ferrite and austenite, and outgassing from the crack tip. After comparing the embrittlement due to internal hydrogen with that in external hydrogen, it is concluded that the critical hydrogen distribution for the onset of subcritical crack growth is reached at a location that is very near the crack tip.

Main factors causing intergranular and quasi-cleavage fractures at hydrogen-induced cracking in tempered martensitic steels

NASA Astrophysics Data System (ADS)

Kurokawa, Ami; Doshida, Tomoki; Hagihara, Yukito; Suzuki, Hiroshi; Takai, Kenichi

2018-05-01

Though intergranular (IG) and quasi-cleavage (QC) fractures have been widely recognized as typical fracture modes of the hydrogen-induced cracking in high-strength steels, the main factor has been unclarified yet. In the present study, the hydrogen content dependence on the main factor causing hydrogen-induced cracking has been examined through the fracture mode transition from QC to IG at the crack initiation site in the tempered martensitic steels. Two kinds of tempered martensitic steels were prepared to change the cohesive force due to the different precipitation states of Fe3C on the prior γ grain boundaries. A high amount of Si (H-Si) steel has a small amount of Fe3C on the prior austenite grain boundaries. Whereas, a low amount of Si (L-Si) steel has a large amount of Fe3C sheets on the grain boundaries. The fracture modes and initiations were observed using FE-SEM (Field Emission-Scanning Electron Microscope). The crack initiation sites of the H-Si steel were QC fracture at the notch tip under various hydrogen contents. While the crack initiation of the L-Si steel change from QC fracture at the notch tip to QC and IG fractures from approximately 10 µm ahead of the notch tip as increasing in hydrogen content. For L-Si steels, two possibilities are considered that the QC or IG fracture occurred firstly, or the QC and IG fractures occurred simultaneously. Furthermore, the principal stress and equivalent plastic strain distributions near the notch tip were calculated with FEM (Finite Element Method) analysis. The plastic strain was the maximum at the notch tip and the principle stress was the maximum at approximately 10 µm from the notch tip. The position of the initiation of QC and IG fracture observed using FE-SEM corresponds to the position of maximum strain and stress obtained with FEM, respectively. These findings indicate that the main factors causing hydrogen-induced cracking are different between QC and IG fractures.

The GA sulfur-iodine water-splitting process - A status report

NASA Astrophysics Data System (ADS)

Besenbruch, G. E.; Chiger, H. D.; McCorkle, K. H.; Norman, J. H.; Rode, J. S.; Schuster, J. R.; Trester, P. W.

The development of a sulfur-iodine thermal water splitting cycle is described. The process features a 50% thermal efficiency, plus all liquid and gas handling. Basic chemical investigations comprised the development of multitemperature and multistage sulfuric acid boost reactors, defining the phase behavior of the HI/I2/H2O/H3PO4 mixtures, and development of a decomposition process for hydrogen iodide in the liquid phase. Initial process engineering studies have led to a 47% efficiency, improvements of 2% projected, followed by coupling high-temperature solar concentrators to the splitting processes to reduce power requirements. Conceptual flowsheets developed from bench models are provided; materials investigations have concentrated on candidates which can withstand corrosive mixtures at temperatures up to 400 deg K, with Hastelloy C-276 exhibiting the best properties for containment and heat exchange to I2.

The GA sulfur-iodine water-splitting process - A status report

NASA Technical Reports Server (NTRS)

Besenbruch, G. E.; Chiger, H. D.; Mccorkle, K. H.; Norman, J. H.; Rode, J. S.; Schuster, J. R.; Trester, P. W.

1981-01-01

The development of a sulfur-iodine thermal water splitting cycle is described. The process features a 50% thermal efficiency, plus all liquid and gas handling. Basic chemical investigations comprised the development of multitemperature and multistage sulfuric acid boost reactors, defining the phase behavior of the HI/I2/H2O/H3PO4 mixtures, and development of a decomposition process for hydrogen iodide in the liquid phase. Initial process engineering studies have led to a 47% efficiency, improvements of 2% projected, followed by coupling high-temperature solar concentrators to the splitting processes to reduce power requirements. Conceptual flowsheets developed from bench models are provided; materials investigations have concentrated on candidates which can withstand corrosive mixtures at temperatures up to 400 deg K, with Hastelloy C-276 exhibiting the best properties for containment and heat exchange to I2.

Container and method for absorbing and reducing hydrogen concentration

DOEpatents

Wicks, George G.; Lee, Myung W.; Heung, Leung K.

2001-01-01

A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

Reactions of hydrogen with V-Cr-Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiStefano, J.R.; DeVan, J.H.; Chitwood, L.D.

In the absence of increases in oxygen concentration, additions of up to 400 ppm hydrogen to V-4 Cr-4 Ti did not result in significant embrittlement as determined by room temperature tensile tests. However, when hydrogen approached 700 ppm after exposure at 325 C, rapid embrittlement occurred. In this latter case, hydride formation is the presumed embrittlement cause. When oxygen was added during or prior to hydrogen exposure, synergistic effects led to significant embrittlement by 100 ppm hydrogen.

Electrochemical hydrogen sulfide biosensors.

PubMed

Xu, Tailin; Scafa, Nikki; Xu, Li-Ping; Zhou, Shufeng; Abdullah Al-Ghanem, Khalid; Mahboob, Shahid; Fugetsu, Bunshi; Zhang, Xueji

2016-02-21

The measurement of sulfide, especially hydrogen sulfide, has held the attention of the analytical community due to its unique physiological and pathophysiological roles in biological systems. Electrochemical detection offers a rapid, highly sensitive, affordable, simple, and real-time technique to measure hydrogen sulfide concentration, which has been a well-documented and reliable method. This review details up-to-date research on the electrochemical detection of hydrogen sulfide (ion selective electrodes, polarographic hydrogen sulfide sensors, etc.) in biological samples for potential therapeutic use.

Sequential hydrogen and methane coproduction from sugary wastewater treatment by "CSTRHyd-UASBMet" system

NASA Astrophysics Data System (ADS)

Hao, Ping

2017-10-01

Potentiality of sequential hydrogen bioproduction from sugary wastewater treatment was investigated using continuous stirred tank reactor (CSTR) for various substrate COD concentrations and HRTs. At optimum substrate concentration of 6 g COD/L, hydrogen could be efficiently produced from CSTR with the highest production rate of 3.00 (±0.04) L/L reactor d at HRT of 6 h. The up flow anaerobic sludge bed (UASB) reactor was used for continuous methane bioproduction from the effluents of hydrogen bioproduction. At optimal HRT 12 h, methane could be produced with a production rate of 2.27 (±0.08) L/L reactor d and the COD removal efficiency reached up to the maximum 82.3%.

Polarity control of h-BN nanoribbon edges by strain and edge termination.

PubMed

Yamanaka, Ayaka; Okada, Susumu

2017-03-29

We studied the polarity of h-BN nano-flakes in terms of their edge geometries, edge hydrogen termination, and uniaxial strain by evaluating their electrostatic potential using density functional theory. Our calculations have shown that the polarity of the nanoribbons is sensitive to their edge shape, edge termination, and uniaxial tensile strain. Polarity inversion of the ribbons can be induced by controlling the hydrogen concentration at the edges and the uniaxial tensile strain. The polarity inversion indicates that h-BN nanoribbons can exhibit non-polar properties at a particular edge hydrogen concentration and tensile strain, even though the nanoribbons essentially have polarity at the edge. We also found that the edge angle affects the polarity of nanoribbons with hydrogenated edges.

Immune enhancement of chemotherapeutants on lymphocystis disease virus (LDV) infected Paralichthys olivaceus.

PubMed

Harikrishnan, Ramasamy; Kim, Man-Chul; Kim, Ju-Sang; Balasundaram, Chellam; Heo, Moon-Soo

2010-11-01

In olive flounder, Paralichthys olivaceus infected with lymphocystis disease virus (LDV) bath treatment with formalin, hydrogen peroxide or Jenoclean at 50, 100, and 200 ppm daily 10 min for 60 days enhanced the innate immune response and disease resistance. Jenoclean enhanced the immune parameters at the lowest concentration of 50 ppm; on the other hand, hydrogen peroxide bath treatment enhanced the immunity level at 100 ppm, while formalin was effective only at 200 ppm. A low cumulative mortality and high relative percent survival was noted in Jenoclean treated group followed by formalin and hydrogen peroxide treated groups. In olive flounder at low concentrations of 50 ppm or 100 ppm hydrogen peroxide and Jenoclean effectively prevent LDV infection. Published by Elsevier Ltd.

Melatonin protects against clomiphene citrate-induced generation of hydrogen peroxide and morphological apoptotic changes in rat eggs.

PubMed

Tripathi, Anima; PremKumar, Karuppanan V; Pandey, Ashutosh N; Khatun, Sabana; Mishra, Surabhi Kirti; Shrivastav, Tulsidas G; Chaube, Shail K

2011-09-30

The present study was aimed to determine whether clomiphene citrate-induces generation of hydrogen peroxide in ovary, if so, whether melatonin could scavenge hydrogen peroxide and protect against clomiphene citrate-induced morphological apoptotic changes in rat eggs. For this purpose, forty five sexually immature female rats were given single intramuscular injection of 10 IU pregnant mare's serum gonadotropin for 48 h followed by single injections of 10 IU human chorionic gonadotropin and clomiphene citrate (10 mg/kg bw) with or without melatonin (20 mg/kg bw) for 16 h. The histology of ovary, ovulation rate, hydrogen peroxide concentration and catalase activity in ovary and morphological changes in ovulated eggs were analyzed. Co-administration of clomiphene citrate along with human chorionic gonadotropin significantly increased hydrogen peroxide concentration and inhibited catalase activity in ovary, inhibited ovulation rate and induced egg apoptosis. Supplementation of melatonin reduced hydrogen peroxide concentration and increased catalase activity in the ovary, delayed meiotic cell cycle progression in follicular oocytes as well as in ovulated eggs since extrusion of first polar body was still in progress even after ovulation and protected against clomiphene citrate-induced egg apoptosis. These results clearly suggest that the melatonin reduces oxidative stress by scavenging hydrogen peroxide produced in the ovary after clomiphene citrate treatment, slows down meiotic cell cycle progression in eggs and protects against clomiphene citrate-induced apoptosis in rat eggs. Copyright © 2011 Elsevier B.V. All rights reserved.

Effects of Plasma Hydrogenation on Trapping Properties of Dislocations in Heteroepitaxial InP/GaAs

NASA Technical Reports Server (NTRS)

Ringel, S. A.; Chatterjee, B.

1994-01-01

In previous work, we have demonstrated the effectiveness of a post-growth hydrogen plasma treatment for passivating the electrical activity of dislocations in metalorganic chemical vapor deposition (MOCVD) grown InP on GaAs substrates by a more than two order of magnitude reduction in deep level concentration and an improvement in reverse bias leakage current by a factor of approx. 20. These results make plasma hydrogenation an extremely promising technique for achieving high efficiency large area and light weight heteroepitaxial InP solar cells for space applications. In this work we investigate the carrier trapping process by dislocations in heteroepitaxial InP/GaAs and the role of hydrogen passivation on this process. It is shown that the charge trapping kinetics of dislocations after hydrogen passivation are significantly altered, approaching point defect-like behavior consistent with a transformation from a high concentration of dislocation-related defect bands within the InP bandgap to a low concentration of individual deep levels after hydrogen passivation. It is further shown that the "apparent" activation energies of dislocation related deep levels, before and after passivation, reduce by approx. 70 meV as DLTS fill pulse times are increased from 1 usec. to 1 msec. A model is proposed which explains these effects based on a reduction of Coulombic interaction between individual core sites along the dislocation cores by hydrogen incorporation. Knowledge of the trapping properties in these specific structures is important to develop optimum, low loss heteroepitaxial InP cells.

Device for sampling and enriching impurities in hydrogen comprising hydrogen-permeable membrane

DOEpatents

Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon D. H.; Kumar, Romesh

2017-01-31

Provided herein are methods and devices to enrich trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentration of impurities so as to allow the detection of the impurities using commonly-available detection methods.

BCA-kMC Hybrid Simulation for Hydrogen and Helium Implantation in Material under Plasma Irradiation

NASA Astrophysics Data System (ADS)

Kato, Shuichi; Ito, Atsushi; Sasao, Mamiko; Nakamura, Hiroaki; Wada, Motoi

2015-09-01

Ion implantation by plasma irradiation into materials achieves the very high concentration of impurity. The high concentration of impurity causes the deformation and the destruction of the material. This is the peculiar phenomena in the plasma-material interaction (PMI). The injection process of plasma particles are generally simulated by using the binary collision approximation (BCA) and the molecular dynamics (MD), while the diffusion of implanted atoms have been traditionally solved by the diffusion equation, in which the implanted atoms is replaced by the continuous concentration field. However, the diffusion equation has insufficient accuracy in the case of low concentration, and in the case of local high concentration such as the hydrogen blistering and the helium bubble. The above problem is overcome by kinetic Monte Carlo (kMC) which represents the diffusion of the implanted atoms as jumps on interstitial sites in a material. In this paper, we propose the new approach ``BCA-kMC hybrid simulation'' for the hydrogen and helium implantation under the plasma irradiation.

[Fatal outcome of an hydrogen sulfide poisoning].

PubMed

Querellou, E; Jaffrelot, M; Savary, D; Savry, C; Perfus, J-P

2005-10-01

We report a case of fatal outcome poisoning by massive exposure to hydrogen sulfide of a sewer worker. This rare event was associated with a moderate intoxication of two members of the rescue team. The death was due to asystole and massive lung oedema. Autopsy analysis showed diffuse necrotic lesions in lungs. Hydrogen sulfide is a direct and systemic poison, produced by organic matter decomposition. The direct toxicity mechanism is still unclear. The systemic toxicity is due to an acute toxicity by oxygen depletion at cellular level. It is highly diffusable and potentially very dangerous. At low concentration, rotten egg smell must trigger hydrogen sulfide suspicion since at higher concentration it is undetectable, making intoxication possible. In case of acute intoxication, there is an almost instantaneous cardiovascular failure and a rapid death. Hydrogen sulfide exposure requires prevention measures and more specifically the use of respiratory equipment for members of the rescue team.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xuefang; Hecht, Ethan S.; Christopher, David M.

Much effort has been made to model hydrogen releases from leaks during potential failures of hydrogen storage systems. A reduced-order jet model can be used to quickly characterize these flows, with low computational cost. Notional nozzle models are often used to avoid modeling the complex shock structures produced by the underexpanded jets by determining an “effective” source to produce the observed downstream trends. In our work, the mean hydrogen concentration fields were measured in a series of subsonic and underexpanded jets using a planar laser Rayleigh scattering system. Furthermore, we compared the experimental data to a reduced order jet modelmore » for subsonic flows and a notional nozzle model coupled to the jet model for underexpanded jets. The values of some key model parameters were determined by comparisons with the experimental data. Finally, the coupled model was also validated against hydrogen concentrations measurements for 100 and 200 bar hydrogen jets with the predictions agreeing well with data in the literature.« less

SFG study of the ethanol in an acidic medium--Pt(110) interface: effects of the alcohol concentration.

PubMed

Gomes, Janaina F; Busson, Bertrand; Tadjeddine, Abderrahmane

2006-03-23

Ethanol in an acidic solution-Pt(110) interface was studied by SFG spectroscopy (between 1820 and 2325 cm(-1)) to explore primarily the effects of the alcohol concentration. Stretching bands of H-Pt (ca. 1970 or 2050 cm(-1)) and CO (ca. 1980 and 2040 cm(-1)) species, produced by the ethanol oxidation, were detected during the adsorption and oxidation of 0-1 mol L(-1) ethanol in a 0.1 mol L(-1) HClO(4) solution on the electrode surface. Hydrogen and CO coadsorb stably on Pt(110) between 0.05 and 0.15 V in ethanol-containing solutions. In this potential range, the blue shift of the hydrogen resonance (ca. 80 cm(-1)) reveals a weakening of the hydrogen bonding between adsorbed hydrogen and water molecules in the double layer. After the hydrogen desorption (0.15 V), the formation of compact CO islands, depending on the ethanol concentration, lifts the Pt(110) surface reconstruction. In ethanol-free solution, the surface remains reconstructed. The lower-frequency CO band is assigned to the CO species adsorbed on (1 x 2) reconstructed Pt(110) domains, having smaller local coverages, while the higher-frequency CO band is attributed to the close-packed CO species adsorbed on (1 x 1) patches. The reaction pathway forming CO(2) is less favored with increasing ethanol concentration.

Genotoxic and chemopreventive assessment of Cynara scolymus L. aqueous extract in a human-derived liver cell line.

PubMed

da Silva, Regiane Pereira; Jacociunas, Laura Vicedo; de Carli, Raíne Fogliati; de Abreu, Bianca Regina Ribas; Lehmann, Mauricio; da Silva, Juliana; Ferraz, Alexandre de Barros Falcão; Dihl, Rafael Rodrigues

2017-10-01

Cynara scolymus L., popularly known as artichoke, is consumed as food and used as tea infusions for pharmacological purposes to treat liver dysfunctions and other conditions. Scientific data on the safety and protective effect of artichoke in human-derived liver cells is missing. This study investigated the genotoxic and modulatory effect of a liophilized extract suspended in water of C. scolymus L. leaves. Four extract concentrations (0.62, 1.25, 2.5 and 5.0 mg/mL) were evaluated using the comet assay on human hepatocyte cultures, HepG2 cells. Genotoxicity was assessed after two treatment periods, 1 and 24 h. Antigenotoxicity was evaluated against oxidative lesions induced by hydrogen peroxide in pre-, simultaneous and post-treatment protocols. Artichoke leaves aqueous extract induced genotoxic effects in HepG2 cells after 1- and 24-h treatments. In turn, extract concentrations of 0.62, 1.25 and 2.5 mg/mL, exhibited a protective effect in pretreatment, compared to hydrogen peroxide alone. However, in simultaneous and post-treatment protocols, only the lowest concentration reduced the frequency of DNA damage induced by hydrogen peroxide. In addition, in the simultaneous treatment protocol, the highest artichoke extract concentration increased hydrogen peroxide genotoxicity. It can be concluded that artichoke is genotoxic, in vitro, to HepG2 cells, but can also modulate hydrogen peroxide DNA damage.

Divacancy-hydrogen complexes in dislocation-free high-purity germanium. [Annealing, Hall effect, steady-state concentration energy dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haller, E.E.; Hubbard, G.S.; Hansen, W.L.

1976-09-01

A defect center with a single acceptor level at E/sub v/ + 0.08 eV appears in H/sub 2/-grown dislocation-free high-purity germanium. Its concentration changes reversibly upon annealing up to 650 K. By means of Hall-effect and conductivity measurements over a large temperature range the temperature dependence of the steady-state concentration between 450 and 720 K as well as the transients following changes in temperature were determined. The observed acceptor level is attributed to the divacancy-hydrogen complex V/sub 2/H. The complex reacts with hydrogen, dissolved in the Ge lattice or stored in traps, according to V/sub 2/H + H reversible V/submore » 2/H/sub 2/. An energy level associated with the divacancy-dihydrogen complex was not observed. These results are in good agreement with the idea that hydrogen in germanium forms a ''very deep donor'' (i.e., the energy level lies inside the valence band).« less

Solar hydrogen production with cerium oxides thermochemical cycle

NASA Astrophysics Data System (ADS)

Binotti, Marco; Di Marcoberardino, Gioele; Biassoni, Mauro; Manzolini, Giampaolo

2017-06-01

This paper discusses the hydrogen production using a solar driven thermochemical cycle. The thermochemical cycle is based on nonstoichiometric cerium oxides redox and the solar concentration system is a solar dish. Detailed optical and redox models were developed to optimize the hydrogen production performance as function of several design parameters (i.e. concentration ratio, reactor pressures and temperatures) The efficiency of the considered technology is compared against two commercially available technologies namely PV + electrolyzer and Dish Stirling + electrolyzer. Results show that solar-to-fuel efficiency of 21.2% can be achieved at design condition assuming a concentration ratio around 5000, reduction and oxidation temperatures of 1500°C and 1275 °C. When moving to annual performance, the annual yield of the considered approach can be as high as 16.7% which is about 43% higher than the best competitive technology. The higher performance implies that higher installation costs around 40% can be accepted for the innovative concept to achieve the same cost of hydrogen.

Hydrogen peroxide inhibits iodide uptake and iodine organification in cultured porcine thyroid follicles.

PubMed

Fukayama, H; Murakami, S; Nasu, M; Sugawara, M

1991-01-01

We investigated the effect of hydrogen peroxide on the process of thyroid hormone formation in a physiologic culture system of porcine thyroid follicles that we recently established. Porcine thyroid follicles cultured in medium containing 1 mU/mL TSH were exposed to 0 to 500 microM hydrogen peroxide in the presence of 0.1 microCi carrier-free Na125 and sodium iodide for 2 h. Iodide uptake and iodine organification were measured in this incubation system. The kinetics of iodide uptake were used to explain the action of hydrogen peroxide. In addition, cAMP content and Na+,K(+)-ATPase activity (an enzyme necessary for iodide uptake) were measured to investigate the mechanism of hydrogen peroxide action. Hydrogen peroxide at concentrations of 100, 200, and 500 microM inhibited iodide uptake in a dose-dependent manner. Iodide organification was inhibited only when the concentration of hydrogen peroxide was greater than 200 microM. The kinetics of iodide uptake indicated that hydrogen peroxide was a noncompetitive inhibitor with iodide. Inhibition of iodide uptake and iodine organification by hydrogen peroxide were not mediated by alteration of cAMP content of Na+,K(+)-ATPase activity, since exposure to even 500 microM hydrogen peroxide did not change these parameters in the follicle when compared with those of control samples. Our results suggest that the iodide transport system in the thyroid follicle is inhibited at 200 microM hydrogen peroxide or greater.

Impact of furan derivatives and phenolic compounds on hydrogen production from organic fraction of municipal solid waste using co-culture of Enterobacter aerogenes and E. coli.

PubMed

Sharma, Preeti; Melkania, Uma

2017-09-01

In the present study, the effect of furan derivatives (furfural and 5-hydroxymethylfurfural) and phenolic compounds (vanillin and syringaldehyde) on hydrogen production from organic fraction of municipal solid waste (OFMSW) was investigated using co-culture of facultative anaerobes Enterobacter aerogenes and E. coli. The inhibitors were applied in the concentration ranges of 0.25, 0.5, 1, 2 and 5g/L each. Inhibition coefficients of phenolic compounds were higher than those of furan derivatives and vanillin exhibited maximum inhibition coefficients correspondingly lowest hydrogen yield among all inhibitors. Furfural and 5-hydroxymethylfurfural addition resulted in an average decrease of 26.99% and 37.16% in hydrogen yield respectively, while vanillin and syringaldehyde resulted in 49.40% and 42.26% average decrease in hydrogen yield respectively. Further analysis revealed that Furfural and 5-hydroxymethylfurfural were completely degraded up to concentrations of 1g/L, while vanillin and syringaldehyde were degraded completely up to the concentration of 0.5g/L. Volatile fatty acid generation decreased with inhibitors addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Laser peening for reducing hydrogen embrittlement

DOEpatents

Hackel, Lloyd A.; Zaleski, Tania M.; Chen, Hao-Lin; Hill, Michael R.; Liu, Kevin K.

2010-05-25

A laser peening process for the densification of metal surfaces and sub-layers and for changing surface chemical activities provides retardation of the up-take and penetration of atoms and molecules, particularly Hydrogen, which improves the lifetime of such laser peened metals. Penetration of hydrogen into metals initiates an embrittlement that leaves the material susceptible to cracking.

Ground operations demonstration unit for liquid hydrogen initial test results

NASA Astrophysics Data System (ADS)

Notardonato, W. U.; Johnson, W. L.; Swanger, A. M.; Tomsik, T.

2015-12-01

NASA operations for handling cryogens in ground support equipment have not changed substantially in 50 years, despite major technology advances in the field of cryogenics. NASA loses approximately 50% of the hydrogen purchased because of a continuous heat leak into ground and flight vessels, transient chill down of warm cryogenic equipment, liquid bleeds, and vent losses. NASA Kennedy Space Center (KSC) needs to develop energy-efficient cryogenic ground systems to minimize propellant losses, simplify operations, and reduce cost associated with hydrogen usage. The GODU LH2 project has designed, assembled, and started testing of a prototype storage and distribution system for liquid hydrogen that represents an advanced end-to-end cryogenic propellant system for a ground launch complex. The project has multiple objectives including zero loss storage and transfer, liquefaction of gaseous hydrogen, and densification of liquid hydrogen. The system is unique because it uses an integrated refrigeration and storage system (IRAS) to control the state of the fluid. This paper will present and discuss the results of the initial phase of testing of the GODU LH2 system.

Ground Operations Demonstration Unit for Liquid Hydrogen Initial Test Results

NASA Technical Reports Server (NTRS)

Notardonato, W. U.; Johnson, W. L.; Swanger, A. M.; Tomsik, T.

2015-01-01

NASA operations for handling cryogens in ground support equipment have not changed substantially in 50 years, despite major technology advances in the field of cryogenics. NASA loses approximately 50% of the hydrogen purchased because of a continuous heat leak into ground and flight vessels, transient chill down of warm cryogenic equipment, liquid bleeds, and vent losses. NASA Kennedy Space Center (KSC) needs to develop energy-efficient cryogenic ground systems to minimize propellant losses, simplify operations, and reduce cost associated with hydrogen usage. The GODU LH2 project has designed, assembled, and started testing of a prototype storage and distribution system for liquid hydrogen that represents an advanced end-to-end cryogenic propellant system for a ground launch complex. The project has multiple objectives including zero loss storage and transfer, liquefaction of gaseous hydrogen, and densification of liquid hydrogen. The system is unique because it uses an integrated refrigeration and storage system (IRAS) to control the state of the fluid. This paper will present and discuss the results of the initial phase of testing of the GODU LH2 system.

Constitutive and damage material modeling in a high pressure hydrogen environment

NASA Technical Reports Server (NTRS)

Russell, D. A.; Fritzemeier, L. G.

1991-01-01

Numerous components in reusable space propulsion systems such as the SSME are exposed to high pressure gaseous hydrogen environments. Flow areas and passages in the fuel turbopump, fuel and oxidizer preburners, main combustion chamber, and injector assembly contain high pressure hydrogen either high in purity or as hydrogen rich steam. Accurate constitutive and damage material models applicable to high pressure hydrogen environments are therefore needed for engine design and analysis. Existing constitutive and cyclic crack initiation models were evaluated only for conditions of oxidizing environments. The main objective is to evaluate these models for applicability to high pressure hydrogen environments.

Immersing lungs in hydrogen-rich saline attenuates lung ischaemia-reperfusion injury.

PubMed

Takahashi, Mamoru; Chen-Yoshikawa, Toyofumi F; Saito, Masao; Tanaka, Satona; Miyamoto, Ei; Ohata, Keiji; Kondo, Takeshi; Motoyama, Hideki; Hijiya, Kyoko; Aoyama, Akihiro; Date, Hiroshi

2017-03-01

Anti-oxidant effects of hydrogen have been reported in studies examining ischaemia-reperfusion injury (IRI). In this study, we evaluated the therapeutic efficacy of immersing lungs in hydrogen-rich saline on lung IRI. Lewis rats were divided into three groups: (i) sham, (ii) normal saline and (iii) hydrogen-rich saline. In the first experiment, the left thoracic cavity was filled with either normal saline or hydrogen-rich saline for 1 h. Then, we measured the hydrogen concentration in the left lung using a sensor gas chromatograph ( N = 3 per group). In the second experiment, lung IRI was induced by occlusion of the left pulmonary hilum for 1 h, followed by reperfusion for 3 h. During the ischaemic period, the left thoracic cavity was filled with either normal saline or hydrogen-rich saline. After reperfusion, we assessed lung function, histological changes and cytokine production ( N = 5-7 per group). Immersing lungs in hydrogen-rich saline resulted in an elevated hydrogen concentration in the lung (6.9 ± 2.9 μmol/1 g lung). After IRI, pulmonary function (pulmonary compliance and oxygenation levels) was significantly higher in the hydrogen-rich saline group than in the normal saline group ( P  < 0.05). Similarly, pro-inflammatory cytokine levels (interleukin-1β and interleukin-6) in the left lung were significantly lower in the hydrogen-rich saline group than in the normal saline group ( P  < 0.05). Immersing lungs in hydrogen-rich saline delivered hydrogen into the lung and consequently attenuated lung IRI. Hydrogen-rich solution appears to be a promising approach to managing lung IRI. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

NASA Astrophysics Data System (ADS)

Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez; Gyergyek, Tomaz; Stockel, Jan; Varju, Jozef; Panek, Radomir; Balat-Pichelin, Marianne

2014-06-01

Initial stages of Inconel 625 superalloy (Ni60Cr30Mo10Ni4Nb1) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr2O4 compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al2O3 crystals.

Full-scale demonstration of in situ cometabolic biodegradation of trichloroethylene in groundwater 2. Comprehensive analysis of field data using reactive transport modeling

NASA Astrophysics Data System (ADS)

Gandhi, Rahul K.; Hopkins, Gary D.; Goltz, Mark N.; Gorelick, Steven M.; McCarty, Perry L.

2002-04-01

We present an analysis of an extensively monitored full-scale field demonstration of in situ treatment of trichloroethylene (TCE) contamination by aerobic cometabolic biodegradation. The demonstration was conducted at Edwards Air Force Base in southern California. There are two TCE-contaminated aquifers at the site, separated from one another by a clay aquitard. The treatment system consisted of two recirculating wells located 10 m apart. Each well was screened in both of the contaminated aquifers. Toluene, oxygen, and hydrogen peroxide were added to the water in both wells. At one well, water was pumped from the upper aquifer to the lower aquifer. In the other well, pumping was from the lower to the upper aquifer. This resulted in a ``conveyor belt'' flow system with recirculation between the two aquifers. The treatment system was successfully operated for a 410 day period. We explore how well a finite element reactive transport model can describe the key processes in an engineered field system. Our model simulates TCE, toluene, oxygen, hydrogen peroxide, and microbial growth/death. Simulated processes include advective-dispersive transport, biodegradation, the inhibitory effect of hydrogen peroxide on biomass growth, and oxygen degassing. Several parameter values were fixed to laboratory values or values from previous modeling studies. The remaining six parameter values were obtained by calibrating the model to 7213 TCE concentration data and 6997 dissolved oxygen concentration data collected during the demonstration using a simulation-regression procedure. In this complex flow field involving reactive transport, TCE and dissolved oxygen concentration histories are matched very well by the calibrated model. Both simulated and observed toluene concentrations display similar high-frequency oscillations due to pulsed toluene injection approximately one half hour during each 8 hour period. Simulation results indicate that over the course of the demonstration, 6.9 kg of TCE was degraded and that in the upper aquifer a region 40 m wide extending 25 m down gradient of the treatment system was cleaned up to less than 100 μg L-1 from initial concentrations of approximately 700 μg L-1. A smaller region was cleaned up to less than 30 μg L-1. Simulations indicate that the cleaned up area in the upper aquifer would continue to expand for as long as treatment was continued.

Demonstration of the Catalytic Decomposition of Hydrogen Peroxide.

ERIC Educational Resources Information Center

Conklin, Alfred R. Jr.; Kessinger, Angela

1996-01-01

Describes a demonstration known as Elephant's Toothpaste in which the decomposition of hydrogen peroxide is catalyzed by iodide. Oxygen is released and soap bubbles are produced. The foam produced is measured, and results show a good relationship between the amount of foam and the concentration of the hydrogen peroxide. (DDR)

9 CFR 113.408 - Avian mycoplasma antigen.

Code of Federal Regulations, 2012 CFR

2012-01-01

... completed product from each serial shall be tested for density, preservative content, homogeneity, hydrogen... sedimented at 1,000×g in a refrigerated centrifuge at 20 °C for 90 minutes. If the packed cell volume of the... when necessary to evaluate a granular appearing antigen. (d) Hydrogen ion concentration. The hydrogen...

9 CFR 113.408 - Avian mycoplasma antigen.

Code of Federal Regulations, 2013 CFR

2013-01-01

... completed product from each serial shall be tested for density, preservative content, homogeneity, hydrogen... sedimented at 1,000×g in a refrigerated centrifuge at 20 °C for 90 minutes. If the packed cell volume of the... when necessary to evaluate a granular appearing antigen. (d) Hydrogen ion concentration. The hydrogen...

9 CFR 113.408 - Avian mycoplasma antigen.

Code of Federal Regulations, 2010 CFR

2010-01-01

... completed product from each serial shall be tested for density, preservative content, homogeneity, hydrogen... sedimented at 1,000×g in a refrigerated centrifuge at 20 °C for 90 minutes. If the packed cell volume of the... when necessary to evaluate a granular appearing antigen. (d) Hydrogen ion concentration. The hydrogen...

Nanobiocatalytic Degradation of Acid Orange 7

NASA Astrophysics Data System (ADS)

Hastings, Jason

The catalytic properties of various metal nanoparticles have led to their use in environmental remediation applications. However, these remediation strategies are limited by their ability to deliver catalytic nanoparticles and a suitable electron donor to large treatment zones. Clostridium pasteurianum BC1 cells, loaded with bio-Pd nanoparticles, were used to effectively catalyze the reductive degradation and removal of Acid Orange 7 (AO7), a model azo compound. Hydrogen produced fermentatively by the C. pasteurianum BC1 acted as the electron donor for the process. Pd-free bacterial cultures or control experiments conducted with heat-killed cells showed limited reduction of AO7. Experiments also showed that the in situ biological production of H2 by C. pasteurianum BC1 was essential for the degradation of AO7, which suggests a novel process where the in situ microbial production of hydrogen is directly coupled to the catalytic bio-Pd mediated reduction of AO7. The differences in initial degradation rate for experiments conducted using catalyst concentrations of 1ppm Pd and 5ppm Pd and an azo dye concentration of 100ppm AO7 was 0.39 /hr and 1.94 /hr respectively, demonstrating the importance of higher concentrations of active Pd(0). The degradation of AO7 was quick as demonstrated by complete reductive degradation of 50ppm AO7 in 2 hours in experiments conducted using a catalyst concentration of 5ppm Pd. Dye degradation products were analyzed via Gas Chromatograph-Mass Spectrometer (GCMS), High Performance Liquid Chromatography (HPLC), UltraViolet-Visible spectrophotometer (UV-Vis) and Matrix-Assisted Laser Desorption/Ionization (MALDI) spectrometry. The presence of 1-amino 2-naphthol, one of the hypothesized degradation products, was confirmed using mass spectrometry.

Use of Tissue Metabolite Analysis and Enzyme Kinetics To Discriminate between Alternate Pathways for Hydrogen Sulfide Metabolism.

PubMed

Augustyn, Kristie D Cox; Jackson, Michael R; Jorns, Marilyn Schuman

2017-02-21

Hydrogen sulfide (H 2 S) is an endogenously synthesized signaling molecule that is enzymatically metabolized in mitochondria. The metabolism of H 2 S maintains optimal concentrations of the gasotransmitter and produces sulfane sulfur (S 0 )-containing metabolites that may be functionally important in signaling. Sulfide:quinone oxidoreductase (SQOR) catalyzes the initial two-electron oxidation of H 2 S to S 0 using coenzyme Q as the electron acceptor in a reaction that requires a third substrate to act as the acceptor of S 0 . We discovered that sulfite is a highly efficient acceptor and proposed that sulfite is the physiological acceptor in a reaction that produces thiosulfate, a known metabolic intermediate. This model has been challenged by others who assume that the intracellular concentration of sulfite is very low, a scenario postulated to favor reaction of SQOR with a considerably poorer acceptor, glutathione. In this study, we measured the intracellular concentration of sulfite and other metabolites in mammalian tissues. The values observed for sulfite in rat liver (9.2 μM) and heart (38 μM) are orders of magnitude higher than previously assumed. We discovered that the apparent kinetics of oxidation of H 2 S by SQOR with glutathione as the S 0 acceptor reflect contributions from other SQOR-catalyzed reactions, including a novel glutathione:CoQ reductase reaction. We used observed metabolite levels and steady-state kinetic parameters to simulate rates of oxidation of H 2 S by SQOR at physiological concentrations of different S 0 acceptors. The results show that the reaction with sulfite as the S 0 acceptor is a major pathway in liver and heart and provide insight into the potential dynamics of H 2 S metabolism.

High-yield hydrogen production from biomass by in vitro metabolic engineering: Mixed sugars coutilization and kinetic modeling.

PubMed

Rollin, Joseph A; Martin del Campo, Julia; Myung, Suwan; Sun, Fangfang; You, Chun; Bakovic, Allison; Castro, Roberto; Chandrayan, Sanjeev K; Wu, Chang-Hao; Adams, Michael W W; Senger, Ryan S; Zhang, Y-H Percival

2015-04-21

The use of hydrogen (H2) as a fuel offers enhanced energy conversion efficiency and tremendous potential to decrease greenhouse gas emissions, but producing it in a distributed, carbon-neutral, low-cost manner requires new technologies. Herein we demonstrate the complete conversion of glucose and xylose from plant biomass to H2 and CO2 based on an in vitro synthetic enzymatic pathway. Glucose and xylose were simultaneously converted to H2 with a yield of two H2 per carbon, the maximum possible yield. Parameters of a nonlinear kinetic model were fitted with experimental data using a genetic algorithm, and a global sensitivity analysis was used to identify the enzymes that have the greatest impact on reaction rate and yield. After optimizing enzyme loadings using this model, volumetric H2 productivity was increased 3-fold to 32 mmol H2⋅L(-1)⋅h(-1). The productivity was further enhanced to 54 mmol H2⋅L(-1)⋅h(-1) by increasing reaction temperature, substrate, and enzyme concentrations--an increase of 67-fold compared with the initial studies using this method. The production of hydrogen from locally produced biomass is a promising means to achieve global green energy production.

Mixed-culture H2 fermentation performance and the relation between microbial community composition and hydraulic retention times for a fixed bed reactor fed with galactose/glucose mixtures.

PubMed

Anburajan, Parthiban; Park, Jong-Hun; Sivagurunathan, Periyasamy; Pugazhendhi, Arivalagan; Kumar, Gopalakrishnan; Choi, Chang-Su; Kim, Sang-Hyoun

2017-09-01

This study examined the mesophilic continuous biohydrogen fermentation from galactose and glucose mixture with an initial substrate concentration of 15 g/L (galactose 12 g/L and glucose 3 g/L) as a resembling carbon source of pretreated red algal hydrolyzate. A fixed bed reactor was fed with the sugar mixture at various hydraulic retention times (HRTs) ranging 12 to 1.5 h. The maximum hydrogen production rate of 52.6 L/L-d was found at 2 h HRT, while the maximum hydrogen yield of 2.3±0.1 mol/mol hexose added, was achieved at 3 h HRT. Microbial communities and species distribution were analyzed via quantitative polymerase chain reaction (qPCR) and the dominant bacterial population was found as Clostridia followed by Lactobacillus sp. Packing material retained higher 16S rRNA gene copy numbers of total bacteria and Clostridium butyricum fraction compared to fermentation liquor. The finding of the study has demonstrated that H 2 production from galactose and glucose mixture could be a viable approach for hydrogen production. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Traction–separation relationships for hydrogen induced grain boundary embrittlement in nickel via molecular dynamics simulations

DOE PAGES

Barrows, Wesley; Dingreville, Rémi; Spearot, Douglas

2015-10-19

A statistical approach combined with molecular dynamics simulations is used to study the influence of hydrogen on intergranular decohesion. This methodology is applied to a Ni Σ3(112)[11¯0] symmetric tilt grain boundary. Hydrogenated grain boundaries with different H concentrations are constructed using an energy minimization technique with initial H atom positions guided by Monte Carlo simulation results. Decohesion behavior is assessed through extraction of a traction–separation relationship during steady-state crack propagation in a statistically meaningful approach, building upon prior work employing atomistic cohesive zone volume elements (CZVEs). A sensitivity analysis is performed on the numerical approach used to extract the traction–separationmore » relationships, clarifying the role of CZVE size, threshold parameters necessary to differentiate elastic and decohesion responses, and the numerical averaging technique. Results show that increasing H coverage at the Ni Σ3(112)[11¯0] grain boundary asymmetrically influences the crack tip velocity during propagation, leads to a general decrease in the work of separation required for crack propagation, and provides a reduction in the peak stress in the extracted traction–separation relationship. Furthermore the present framework offers a meaningful vehicle to pass atomistically derived interfacial behavior to higher length scale formulations for intergranular fracture.« less

Measurement techniques investigated for detection of hydrogen chloride gas in ambient air

NASA Technical Reports Server (NTRS)

Gregory, G. L.

1976-01-01

Nine basic techniques are discussed, ranging from concentration (parts per million) to dosage only (parts per million-seconds) measurement techniques. Data for each technique include lower detection limit, response time, instrument status, and in some cases, specificity. Several techniques discussed can detect ambient hydrogen chloride concentrations below 1 part per million with a response time of seconds.

Dual-Anode Nickel/Hydrogen Cell

NASA Technical Reports Server (NTRS)

Gahn, Randall F.; Ryan, Timothy P.

1994-01-01

Use of two hydrogen anodes in nickel/hydrogen cell reduces ohmic and concentration polarizations contributing to internal resistance, yielding cell with improved discharging performance compared to single-anode cell. Dual-anode concept incorporated into nickel/hydrogen cells of individual pressure-vessel type (for use aboard spacecraft) and common pressure-vessel type, for use on Earth to store electrical energy from photovoltaic sources, "uninterruptible" power supplies of computer and telephone systems, electric vehicles, and load leveling on power lines. Also applicable to silver/hydrogen and other metal/gas batteries.

Hall effect spintronics for gas detection

NASA Astrophysics Data System (ADS)

Gerber, A.; Kopnov, G.; Karpovski, M.

2017-10-01

We present the concept of magnetic gas detection by the extraordinary Hall effect. The technique is compatible with the existing conductometric gas detection technologies and allows the simultaneous measurement of two independent parameters: resistivity and magnetization affected by the target gas. Feasibility of the approach is demonstrated by detecting low concentration hydrogen using thin CoPd films as the sensor material. The Hall effect sensitivity of the optimized samples exceeds 240% per 104 ppm at hydrogen concentrations below 0.5% in the hydrogen/nitrogen atmosphere, which is more than two orders of magnitude higher than the sensitivity of the conductance detection.

Batch methods for enriching trace impurities in hydrogen gas for their further analysis

DOEpatents

Ahmed, Shabbir; Lee, Sheldon H.D.; Kumar, Romesh; Papdias, Dionissios D.

2014-07-15

Provided herein are batch methods and devices for enriching trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentrating impurities using hydrogen transport membranes wherein the time period for concentrating the sample is calculated on the basis of optimized membrane characteristics, comprising its thickness and permeance, with optimization of temperature, and wherein the enrichment of trace impurities is proportional to the pressure ratio P.sub.hi/P.sub.lo and the volume ratio V.sub.1/V.sub.2, with following detection of the impurities using commonly-available detection methods.

Effect of species, life stage, and water temperature on the toxicity of hydrogen peroxide to fish

USGS Publications Warehouse

Rach, J.J.; Schreier, Theresa M.; Howe, G.E.; Redman, S.D.

1997-01-01

Hydrogen peroxide is a drug of low regulatory priority status that is effective in treating fish and fish eggs infected by fungi. However, only limited information is available to guide fish culturists in administering hydrogen peroxide to diseased fish. Laboratory tests were conducted to determine (1) the sensitivity of brown trout Salmo trutta, lake trout Salvelinus namaycush, fathead minnow Pimephales promelas, walleye Stizostedion vitreum, channel catfish Ictalurus punctatus, and bluegill Lepomis, machrochirus to hydrogen peroxide treatments; (2) the sensitivity of various life stages of rainbow trout Oncorhynchus mykiss to hydrogen peroxide treatments; and (3) the effect of water temperature on the acute toxicity of hydrogen peroxide to three fish species. Fish were exposed to hydrogen peroxide concentrations ranging from 100 to 5,000 mu L/L (ppm) for 15-min or 45-min treatments every other day for four consecutive treatments to determine the sensitivity of various species and life stages of fish. Except for walleye, most species of fish tested (less than or equal to 2 g) tolerated hydrogen peroxide of 1,000 mu L/L or greater. Walleyes were sensitive to hydrogen peroxide concentrations as low as 100 mu L/L. A correlation was found between the toxicity of hydrogen peroxide and the life stages of rainbow trout; larger fish were more sensitive. Generally, the toxicity of hydrogen peroxide increased for all species as water temperature increased. The results of these experiments demonstrate that it is important to consider the effects of species, life stage, and water temperature when conducting hydrogen peroxide treatments.

Adsorption, hydrogenation and dehydrogenation of C2H on a CoCu bimetallic layer

NASA Astrophysics Data System (ADS)

Wu, Donghai; Yuan, Jinyun; Yang, Baocheng; Chen, Houyang

2018-05-01

In this paper, adsorption, hydrogenation and dehydrogenation of C2H on a single atomic layer of bimetallic CoCu were investigated using first-principles calculations. The CoCu bimetallic layer is formed by Cu replacement of partial Co atoms on the top layer of a Co(111) surface. Our adsorption and reaction results showed those sites, which have stronger adsorption energy of C2H, possess higher reactivity. The bimetallic layer possesses higher reactivity than either of the pure monometallic layer. A mechanism of higher reactivity of the bimetallic layer is proposed and identified, i.e. in the bimetallic catalyst, the catalytic performance of one component is promoted by the second component, and in our work, the catalytic performance of Co atoms in the bimetallic layer are improved by introducing Cu atoms, lowing the activation barrier of the reaction of C2H. The bimetallic layer could tune adsorption and reaction of C2H by modulating the ratio of Co and Cu. Results of adsorption energies and adsorption configurations reveal that C2H prefers to be adsorbed in parallel on both the pure Co metallic and CoCu bimetallic layers, and Co atoms in subsurface which support the metallic or bimetallic layer have little effect on C2H adsorption. For hydrogenation reactions, the products greatly depend on the concentration and initial positions of hydrogen atoms, and the C2H hydrogenation forming acetylene is more favorable than forming vinylidene in both thermodynamics and kinetics. This study would provide fundamental guidance for hydrocarbon reactions on Co-based and/or Cu-based bimetallic surface chemistry and for development of new bimetallic catalysts.

Hybrid vehicle system studies and optimized hydrogen engine design

NASA Astrophysics Data System (ADS)

Smith, J. R.; Aceves, S.

1995-04-01

We have done system studies of series hydrogen hybrid automobiles that approach the PNGV design goal of 34 km/liter (80 mpg), for 384 km (240 mi) and 608 km (380 mi) ranges. Our results indicate that such a vehicle appears feasible using an optimized hydrogen engine. We have evaluated the impact of various on-board storage options on fuel economy. Experiments in an available engine at the Sandia CRF demonstrated NO(x) emissions of 10 to 20 ppM at an equivalence ratio of 0.4, rising to about 500 ppm at 0.5 equivalence ratio using neat hydrogen. Hybrid simulation studies indicate that exhaust NO(x) concentrations must be less than 180 ppM to meet the 0.2 g/mile ULEV or Federal Tier II emissions regulations. LLNL has designed and fabricated a first generation optimized hydrogen engine head for use on an existing Onan engine. This head features 15:1 compression ratio, dual ignition, water cooling, two valves and open quiescent combustion chamber to minimize heat transfer losses. Initial testing shows promise of achieving an indicated efficiency of nearly 50% and emissions of less than 100 ppM NO(x). Hydrocarbons and CO are to be measured, but are expected to be very low since their only source is engine lubricating oil. A successful friction reduction program on the Onan engine should result in a brake thermal efficiency of about 42% compared to today's gasoline engines of 32%. Based on system studies requirements, the next generation engine will be about 2 liter displacement and is projected to achieve 46% brake thermal efficiency with outputs of 15 kW for cruise and 40 kW for hill climb.

Kinetic D/H fractionation during hydration and dehydration of silicate glasses, melts and nominally anhydrous minerals

NASA Astrophysics Data System (ADS)

Roskosz, M.; Deloule, E.; Ingrin, J.; Depecker, C.; Laporte, D.; Merkel, S.; Remusat, L.; Leroux, H.

2018-07-01

The distribution of hydrogen isotopes during diffusion-driven aqueous processes in silicate glasses, melts and crystals was investigated. Hydration/dehydration experiments were performed on silica glasses at 1000 °C and 1 bar total pressure. Dehydration triggered by decompression-driven bubble nucleation and growth was performed on rhyolitic melts at 800 °C and a few hundred MPa. Hydrogen extraction from a nominally anhydrous mineral (grossular) single crystal was carried out at 800 °C and ambient pressure. After these three series of experiments, pronounced water (sensu lato) concentration profiles were observed in all recovered samples. In the grossular single-crystal, a large spatial variation in H isotopes (δD variation > 550‰) was measured across the sample. This isotopic distribution correlates with the hydrogen extraction profile. The fit to the data suggests an extreme decoupling between hydrogen and deuterium diffusion coefficients (DH and DD respectively), akin to the decoupling expected in a dilute ideal gas (DH/DD ≈ 1.41). Conversely, no measurable spatially- and time-resolved isotopic variations were measured in silicate glasses and melts. This contrasted behavior of hydrogen isotopes likely stands in the different water speciation and solution mechanisms in the three different materials. Glasses and melts contain essentially hydroxyl and molecular water groups but the mobile species is molecular water in both cases. Protonated defects make up most of the water accommodated in grossular and other nominally anhydrous minerals (NAM). These defects are also the mobile species that diffuse against polarons. These results are crucial to accurately model the degassing behavior of terrestrial and lunar magmas and to derive the initial D/H of water trapped in fluid inclusions commonly analyzed in mantle NAMs, which suffered complex geological histories.

Topological defect clustering and plastic deformation mechanisms in functionalized graphene

NASA Astrophysics Data System (ADS)

Nunes, Ricardo; Araujo, Joice; Chacham, Helio

2011-03-01

We present ab initio results suggesting that strain plays a central role in the clustering of topological defects in strained and functionalized graphene models. We apply strain onto the topological-defect graphene networks from our previous work, and obtain topological-defect clustering patterns which are in excellent agreement with recent observations in samples of reduced graphene oxide. In our models, the graphene layer, containing an initial concentration of isolated topological defects, is covered by hydrogen or hydroxyl groups. Our results also suggest a rich variety of plastic deformation mechanism in functionalized graphene systems. We acknowledge support from the Brazilian agencies: CNPq, Fapemig, and INCT-Materiais de Carbono.

[Gas chromatography with a Pulsed discharge helium ionization detector for measurement of molecular hydrogen(H2) in the atmosphere].

PubMed

Luan, Tian; Fang, Shuang-xi; Zhou, Ling-xi; Wang, Hong-yang; Zhang, Gen

2015-01-01

A high precision GC system with a pulsed discharge helium ionization detector was set up based on the commercial Agilent 7890A gas chromatography. The gas is identified by retention time and the concentration is calculated through the peak height. Detection limit of the system is about 1 x 10(-9) (mole fraction, the same as below). The standard deviation of 140 continuous injections with a standard cylinder( concentration is roughly 600 x 10(-9)) is better than 0.3 x 10(-9). Between 409.30 x 10(-9) and 867.74 x 10(-9) molecular hydrogen mole fractions and peak height have good linear response. By using two standards to quantify the air sample, the precision meets the background molecular hydrogen compatibility goal within the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) program. Atmospheric molecular hydrogen concentration at Guangzhou urban area was preliminarily measured by this method from January to November 2013. The results show that the atmospheric molecular hydrogen mole fraction varies from 450 x 10(-9) to 700 x 10(-9) during the observation period, with the lowest value at 14:00 (Beijing time, the same as below) and the peak value at 20:00. The seasonal variation of atmospheric hydrogen at Guangzhou area was similar with that of the same latitude stations in northern hemisphere.

Hydrogen halide cleaning of powder metallurgy nickel-20 chromium-3 thoria.

NASA Technical Reports Server (NTRS)

Herbell, T. P.

1972-01-01

The Cr2O3 content of powder metallurgy nickel-20 chromium-3 thoria was reduced with atmospheres consisting of hydrogen plus hydrogen chloride (HCl) or hydrogen bromide (HBr). The nonthoria oxygen content or 'oxygen excess' was reduced from an initial amount of greater than 50,000 ppm to less than 100 ppm. Low temperatures were effective, but lowest oxygen levels were achieved with the highest cleaning temperature of 1200 C.

Reactive Oxygen Species are Ubiquitous along Subsurface Redox Gradients

NASA Astrophysics Data System (ADS)

Nico, P. S.; Yuan, X.; Davis, J. A.; Dwivedi, D.; Williams, K. H.; Bhattacharyya, A.; Fox, P. M.

2016-12-01

Reactive oxygen species (hydroxyl radical, superoxide, hydrogen peroxide, etc.) are known to be important intermediates in many biological and earth system processes. They have been particularly well studied in the realms of atmospheric chemistry and aquatic photochemistry. However, recently there is increasing evidence that they are also present in impactful quantities in dark systems as a result of both biotic and abiotic reactions. Herein we will present a complementary suite of laboratory and field studies examining the presence and production of hydrogen peroxide under relevant subsurface conditions. The laboratory work examines the redox cycling between reduced organic matter, molecular oxygen, and Fe which results in not only the production of hydrogen peroxide and oxidation of organic functional groups but also the maintenance of steady-state concentration of Fe(II) under fully oxygenated aqueous conditions. The field studies involve three distinct locations, namely a shallow subsurface aquifer, a hyporheic zone redox gradient across a river meander, and a hillside shale seep. In all cases detectable quantities (tens of nanomolar) of hydrogen peroxide were measured. In general, concentrations peak under transitional redox conditions where there is the simultaneous presence of reduced Fe, organic matter, and at least trace dissolved oxygen. Many, but not all, of the observed dynamics in hydrogen peroxide production can be reproduced by a simple kinetic model representing the reactions between Fe, organic matter, and molecular oxygen, but many questions remain regarding the role of microorganisms and other redox active chemical species in determining the detected hydrogen peroxide concentrations. The consistent detection of hydrogen peroxide at these disparate locations supports the hypothesis that hydrogen peroxide, and by extension, the entire suite of reactive oxygen species are ubiquitous along subsurface redox gradients.

The presence of isolated hydrogen donors in heavily carbon-doped GaAs

NASA Astrophysics Data System (ADS)

Fushimi, Hiroshi; Wada, Kazumi

1994-12-01

The deactivation mechanism of carbon acceptors in GaAs has systematically been studied by measuring the annealing behavior and depth profiles of the carrier concentration. It is found that hydrogen impurities dominate carbon deactivation. Their deactivation undergoes two different ways: Hydrogen donors isolated from carbon acceptors compensate carbon and hydrogen impurities neutralize the carbon by forming neutral carbon-hydrogen complexes. The compensating hydrogen donors diffuse out extremely fast at relatively low temperatures. This is, to the best of our knowledge, the first report on the presence of isolated hydrogen donors in heavily carbon-doped GaAs. The dissociation of carbon-hydrogen complexes is much slower than reported. The mechanism is discussed in terms of a hydrogen retrapping effect by carbon.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Xiaofei; Borole, Abhijeet P.; Pavlostathis, Spyros G.

In this study, furanic and phenolic compounds are problematic byproducts resulting from the decomposition of lignocellulosic biomass during biofuel production. This study assessed the capacity of a microbial electrolysis cell (MEC) to produce hydrogen gas (H 2) using a mixture of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as the sole carbon and energy source in the bioanode. The rate and extent of biotransformation of the five compounds, efficiency of H 2 production, as well as the anode microbial community structure were investigated. The five compoundsmore » were completely transformed within 7-day batch runs and their biotransformation rate increased with increasing initial concentration. At an initial concentration of 1,200 mg/L (8.7 mM) of the mixture of the five compounds, their biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode coulombic efficiency was 44-69%, which is comparable to wastewater-fed MECs. The H 2 yield varied from 0.26 to 0.42 g H 2-COD/g COD removed in the anode, and the bioanode volume-normalized H 2 production rate was 0.07-0.1 L/L-d. The major identified fermentation products that did not transform further were catechol and phenol. Acetate was the direct substrate for exoelectrogenesis. Current and H 2 production were inhibited at an initial substrate concentration of 1,200 mg/L, resulting in acetate accumulation at a much higher level than that measured in other batch runs conducted with a lower initial concentration of the five compounds. The anode microbial community consisted of exoelectrogens, putative degraders of the five compounds, and syntrophic partners of exoelectrogens. The H 2 production route demonstrated in this study has proven to be an alternative to the currently used process of reforming natural gas to supply H 2 needed to upgrade bio-oils to stable hydrocarbon fuels.« less

The development of hydrogen sensor technology at NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Neudeck, Philip G.; Jefferson, G. D.; Madzsar, G. C.; Liu, C. C.; Wu, Q. H.

1993-01-01

The detection of hydrogen leaks in aerospace applications, especially those involving hydrogen fuel propulsion systems, is of extreme importance for reasons of reliability, safety, and economy. Motivated by leaks occurring in liquid hydrogen lines supplying the main engine of the Space Shuttle, NASA Lewis has initiated a program to develop point-contact hydrogen sensors which address the needs of aerospace applications. Several different approaches are being explored. They include the fabrication of PdAg Schottky diode structures, the characterization of PdCr as a hydrogen sensitive alloy, and the use of SiC as a semiconductor for hydrogen sensors. This paper discusses the motivation behind and present status of each of the major components of the NASA LeRC hydrogen sensor program.

Safety Issues with Hydrogen as a Vehicle Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadwallader, Lee Charles; Herring, James Stephen

1999-10-01

This report is an initial effort to identify and evaluate safety issues associated with the use of hydrogen as a vehicle fuel in automobiles. Several forms of hydrogen have been considered: gas, liquid, slush, and hydrides. The safety issues have been discussed, beginning with properties of hydrogen and the phenomenology of hydrogen combustion. Safety-related operating experiences with hydrogen vehicles have been summarized to identify concerns that must be addressed in future design activities and to support probabilistic risk assessment. Also, applicable codes, standards, and regulations pertaining to hydrogen usage and refueling have been identified and are briefly discussed. This reportmore » serves as a safety foundation for any future hydrogen safety work, such as a safety analysis or a probabilistic risk assessment.« less

Safety Issues with Hydrogen as a Vehicle Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. C. Cadwallader; J. S. Herring

1999-09-01

This report is an initial effort to identify and evaluate safety issues associated with the use of hydrogen as a vehicle fuel in automobiles. Several forms of hydrogen have been considered: gas, liquid, slush, and hydrides. The safety issues have been discussed, beginning with properties of hydrogen and the phenomenology of hydrogen combustion. Safety-related operating experiences with hydrogen vehicles have been summarized to identify concerns that must be addressed in future design activities and to support probabilistic risk assessment. Also, applicable codes, standards, and regulations pertaining to hydrogen usage and refueling have been identified and are briefly discussed. This reportmore » serves as a safety foundation for any future hydrogen safety work, such as a safety analysis or a probabilistic risk assessment.« less

Deep levels due to hydrogen in ZnO single crystals

NASA Astrophysics Data System (ADS)

Parmar, Narendra; Weber, Marc; Lynn, Kelvin

2009-05-01

Hydrogen impurities and oxygen vacancies are involved in the ˜0.7 eV shift of the optical absorption edge of ZnO. Deuterium causes a smaller shift. Titanium metal is used to bind hydrogen as it diffuses out of ZnO. Positron annihilation spectroscopy coupled with other techniques point to the presence of oxygen vacancies. Removing hydrogen followed by annealing in oxygen reduces the carrier concentration.

Hydrogen peroxide on the surface of Europa

USGS Publications Warehouse

Carlson, R.W.; Anderson, M.S.; Johnson, R.E.; Smythe, W.D.; Hendrix, A.R.; Barth, C.A.; Soderblom, L.A.; Hansen, G.B.; McCord, T.B.; Dalton, J.B.; Clark, R.N.; Shirley, J.H.; Ocampo, A.C.; Matson, D.L.

1999-01-01

Spatially resolved infrared and ultraviolet wavelength spectra of Europa's leading, anti-jovian quadrant observed from the Galileo spacecraft show absorption features resulting from hydrogen peroxide. Comparisons with laboratory measurements indicate surface hydrogen peroxide concentrations of about 0.13 percent, by number, relative to water ice. The inferred abundance is consistent with radiolytic production of hydrogen peroxide by intense energetic particle bombardment and demonstrates that Europa's surface chemistry is dominated by radiolysis.

Hydrogen peroxide on the surface of Europa.

PubMed

Carlson, R W; Anderson, M S; Johnson, R E; Smythe, W D; Hendrix, A R; Barth, C A; Soderblom, L A; Hansen, G B; McCord, T B; Dalton, J B; Clark, R N; Shirley, J H; Ocampo, A C; Matson, D L

1999-03-26

Spatially resolved infrared and ultraviolet wavelength spectra of Europa's leading, anti-jovian quadrant observed from the Galileo spacecraft show absorption features resulting from hydrogen peroxide. Comparisons with laboratory measurements indicate surface hydrogen peroxide concentrations of about 0.13 percent, by number, relative to water ice. The inferred abundance is consistent with radiolytic production of hydrogen peroxide by intense energetic particle bombardment and demonstrates that Europa's surface chemistry is dominated by radiolysis.

Hydrogen or formate: Alternative key players in methanogenic degradation.

PubMed

Schink, Bernhard; Montag, Dominik; Keller, Anja; Müller, Nicolai

2017-06-01

Hydrogen and formate are important electron carriers in methanogenic degradation in anoxic environments such as sediments, sewage sludge digestors and biogas reactors. Especially in the terminal steps of methanogenesis, they determine the energy budgets of secondary (syntrophically) fermenting bacteria and their methanogenic partners. The literature provides considerable data on hydrogen pool sizes in such habitats, but little data exist for formate concentrations due to technical difficulties in formate determination at low concentration. Recent evidence from biochemical and molecular biological studies indicates that several secondary fermenters can use both hydrogen and formate for electron release, and may do so even simultaneously. Numerous strictly anaerobic bacteria contain enzymes which equilibrate hydrogen and formate pools to energetically equal values, and recent measurements in sewage digestors and biogas reactors indicate that - beyond occasional fluctuations - the pool sizes of hydrogen and formate are indeed energetically nearly equivalent. Nonetheless, a thermophilic archaeon from a submarine hydrothermal vent, Thermococcus onnurineus, can obtain ATP from the conversion of formate to hydrogen plus bicarbonate at 80°C, indicating that at least in this extreme environment the pools of formate and hydrogen are likely to be sufficiently different to support such an unusual type of energy conservation. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Hydrogen production from formic acid in pH-stat fed-batch operation for direct supply to fuel cell.

PubMed

Shin, Jong-Hwan; Yoon, Jong Hyun; Lee, Seung Hoon; Park, Tai Hyun

2010-01-01

Enterobacter asburiae SNU-1 harvested after cultivation was used as a whole cell biocatalyst, for the production of hydrogen. Formic acid was efficiently converted to hydrogen using the harvested cells with an initial hydrogen production rate and total hydrogen production of 491 ml/l/h and 6668 ml/l, respectively, when 1 g/l of whole cell enzyme was used. Moreover, new pH-stat fed-batch operation was conducted, and total hydrogen production was 1.4 times higher than that of batch operation. For practical application, bio-hydrogen produced from formic acid using harvested cells was directly applied to PEMFC for power generation.

Mobile measurement of methane and hydrogen sulfide at natural gas production site fence lines in the Texas Barnett Shale.

PubMed

Eapi, Gautam R; Sabnis, Madhu S; Sattler, Melanie L

2014-08-01

Production of natural gas from shale formations is bringing drilling and production operations to regions of the United States that have seen little or no similar activity in the past, which has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the four core counties of the Barnett Shale (Denton, Johnson, Tarrant, and Wise). A mobile measurement survey was conducted in the vicinity of 4788 wells near 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the four-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 cavity ring-down spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving on roads on the exterior of the lease sites. Over 150 hr of data were collected from March to July 2012. During two sets of drive-by measurements, it was found that 66 sites (16.5%) had methane concentrations > 3 parts per million (ppm) just beyond the fence line. Thirty-two lease sites (8.0%) had hydrogen sulfide concentrations > 4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. Measured concentrations generally did not correlate well with site characteristics (natural gas production volume, number of wells, or condensate production). t tests showed that for two counties, methane concentrations for dry sites were higher than those for wet sites. Follow-up study is recommended to provide more information at sites identified with high levels of methane and hydrogen sulfide. Implications: Information regarding air emissions from shale gas production is important given the recent increase in number of wells in various regions in the United States. Methane, the primary natural gas constituent, is a greenhouse gas; hydrogen sulfide, which can be present in gas condensate, is an odor-causing compound. This study surveyed wells representing one-third of the natural gas production volume in the Texas Barnett Shale and identified the percent of sites that warrant further study due to their fence line methane and hydrogen sulfide concentrations.

Effect of oxide films on hydrogen permeability of candidate Stirling heater head tube alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuon, S R; Misencik, J A

1981-01-01

High pressure hydrogen has been selected as the working fluid for the developmental automotive Stirling engine. Containment of the working fluid during operation of the engine at high temperatures and at high hydrogen gas pressures is essential for the acceptance of the Stirling engine as an alternative to the internal combustion engine. Most commercial alloys are extremely permeable to pure hydrogen at high temperatures. A program was undertaken at NASA Lewis Research Center (LeRC) to reduce hydrogen permeability in the Stirling engine heater head tubes by doping the hydrogen working fluid with CO or CO/sub 2/. Small additions of thesemore » gases were shown to form an oxide on the inside tube wall and thus reduce hydrogen permeability. A study of the effects of dopant concentration, alloy composition, and effects of surface oxides on hydrogen permeability in candidate heater head tube alloys is summarized. Results showed that hydrogen permeability was similar for iron-base alloys (N-155, A286, IN800, 19-9DL, and Nitronic 40), cobalt-base alloys (HS-188) and nickel-base alloys (IN718). In general, the permeability of the alloys decreased with increasing concentration of CO or CO/sub 2/ dopant, with increasing oxide thickness, and decreasing oxide porosity. At high levels of dopants, highly permeable liquid oxides formed on those alloys with greater than 50% Fe content. Furthermore, highly reactive minor alloying elements (Ti, Al, Nb, and La) had a strong influence on reducing hydrogen permeability.« less

Possible Role of Hydrogen in the Earth Core

NASA Astrophysics Data System (ADS)

Takahashi, E.; Imai, T.

2011-12-01

Possible role of hydrogen in the Earth core has been discussed by Stevenson (1977) and demonstrated experimentally by Fukai (1984), Okuchi (1997) and others. Planetary theory proposes a possibility of hydrogen incorporation in Earth's magma ocean from ambient solar nebula gas (Ikoma & Genda 2005, Genda & Ikoma 2008). More recently, migration of snow line during planet formation was examined (Min et al., 2010; Oka et al, 2011) and it was proposed that the Earth building material originally contained abundant water as ice and hydrous minerals. Therefore, it is very important to investigate the fate of water in the planet building process and clarify the role of hydrogen in the planetary core. Using SPring-8 synchrotron (NaCl capsule, LiAlH4 as hydrogen source), we determined the melting curve of FeH up to 20 GPa under hydrogen saturated conditions (Sakamaki, Takahashi et al, 2009). Observed melting point is below 1300C and has a very small dT/dP slope. By extrapolating the melting curve using Lindeman's law, we proposed that hydrogen could lower the melting temperature of the Earth core by more than 1500K than current estimate. Here we report our new experiments using SPring-8 synchrotron (single crystal diamond capsule, water as hydrogen source). Hydrogen concentration and melting temperature of FeHx that coexists with hydrous mantle minerals were determined at 15-20GPa and 1000-1600C. We show that 1) hydrogen concentration in FeHx at 1000C, coexisting with hydrous-B and ringwoodite is approximately X=0.6. 2) Upon heating, hydrous-B decomposes and hydrogen strongly partitions into FeHx (X=0.8~1.0) than ringwoodite. 3) FeHx that coexists with ringwoodite melts between ~1300C (solidus) and ~1600C (liquidus). Combined our new experiments with those by Sakamaki et al (2009) and Shibazaki et al (2009), partitioning of hydrogen between proto-core and primitive mantle is discussed. We propose that >90% of water in the source material may have entered the Earth core. Given large hydrogen concentration in the Earth core, temperature of the outermost core could be as low as that of lower mantle adiabat. Presence of the light element-rich layer at the top 300km layer of the outer core (Helffrich & Kaneshima, 2010) may be easily understood if there is no temperature gap between the core and the lower mantle.

Refractive Secondary Solar Concentrator Being Designed and Developed

NASA Technical Reports Server (NTRS)

Macosko, Robert P.; Donovan, Richard M.

1998-01-01

As the need for achieving super high temperatures (2000 K and above) in solar heat receivers has developed so has the need for secondary concentrators. These concentrators refocus the already highly concentrated solar energy provided by a primary solar collector, thereby significantly reducing the light entrance aperture of the heat receiver and the resulting infrared radiation heat loss from the receiver cavity. Although a significant amount of research and development has been done on nonimaging hollow reflective concentrators, there has been no other research or development to date on solid, single crystal, refractive concentrators that can operate at temperatures above 2000 K. The NASA Lewis Research Center recently initiated the development of single-crystal, optically clear, refractive secondary concentrators that, combined with a flux extractor, offer a number of significant advantages over the more conventional, hollow, reflective concentrators at elevated temperatures. Such concentrators could potentially provide higher throughput (efficiency), require no special cooling device, block heat receiver material boiloff from the receiver cavity, provide for flux tailoring in the cavity via the extractor, and potentially reduce infrared heat loss via an infrared block coating.The many technical challenges of designing and fabricating high-temperature refractive secondary concentrators and flux extractors include identifying optical materials that can survive the environment (high-temperature, vacuum and/or hydrogen atmosphere), developing coatings for enhanced optical and thermal performance, and developing crystal joining techniques and hardware that can survive launch loads.

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Brien, Christopher J.; Foiles, Stephen M.

Low-mobility twin grain boundaries dominate the microstructure of grain boundary-engineered materials and are critical to understanding their plastic deformation behaviour. The presence of solutes, such as hydrogen, has a profound effect on the thermodynamic stability of the grain boundaries. This work examines the case of a Σ3 grain boundary at inclinations from 0° ≤ Φ ≤ 90°. The angle Φ corresponds to the rotation of the Σ3 (1 1 1) < 1 1 0 > (coherent) into the Σ3 (1 1 2) < 1 1 0 > (lateral) twin boundary. To this end, atomistic models of inclined grain boundaries, utilisingmore » empirical potentials, are used to elucidate the finite-temperature boundary structure while grand canonical Monte Carlo models are applied to determine the degree of hydrogen segregation. In order to understand the boundary structure and segregation behaviour of hydrogen, the structural unit description of inclined twin grain boundaries is found to provide insight into explaining the observed variation of excess enthalpy and excess hydrogen concentration on inclination angle, but the explanatory power is limited by how the enthalpy of segregation is affected by hydrogen concentration. At higher concentrations, the grain boundaries undergo a defaceting transition. In order to develop a more complete mesoscale model of the interfacial behaviour, an analytical model of boundary energy and hydrogen segregation that relies on modelling the boundary as arrays of discrete 1/3 < 1 1 1 > disconnections is constructed. Lastly, the complex interaction of boundary reconstruction and concentration-dependent segregation behaviour exhibited by inclined twin grain boundaries limits the range of applicability of such an analytical model and illustrates the fundamental limitations for a structural unit model description of segregation in lower stacking fault energy materials.« less

46 CFR 148.330 - Zinc ashes; zinc dross; zinc residues; zinc skimmings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... by the vessel's flag state administration for use in hydrogen atmospheres; and (iii) Has nonsparking fans. (2) Combustible gas detectors capable of measuring hydrogen concentrations of 0 to 4.1 percent by... hydrogen in the space above the cargo exceeds 1 percent by volume, the ventilation system must be run until...

Assessing microbial competition in a hydrogen-based membrane biofilm reactor (MBfR) using multidimensional modeling.

PubMed

Martin, Kelly J; Picioreanu, Cristian; Nerenberg, Robert

2015-09-01

The membrane biofilm reactor (MBfR) is a novel technology that safely delivers hydrogen to the base of a denitrifying biofilm via gas-supplying membranes. While hydrogen is an effective electron donor for denitrifying bacteria (DNB), it also supports sulfate-reducing bacteria (SRB) and methanogens (MET), which consume hydrogen and create undesirable by-products. SRB and MET are only competitive for hydrogen when local nitrate concentrations are low, therefore SRB and MET primarily grow near the base of the biofilm. In an MBfR, hydrogen concentrations are greatest at the base of the biofilm, making SRB and MET more likely to proliferate in an MBfR system than a conventional biofilm reactor. Modeling results showed that because of this, control of the hydrogen concentration via the intramembrane pressure was a key tool for limiting SRB and MET development. Another means is biofilm management, which supported both sloughing and erosive detachment. For the conditions simulated, maintaining thinner biofilms promoted higher denitrification fluxes and limited the presence of SRB and MET. The 2-d modeling showed that periodic biofilm sloughing helped control slow-growing SRB and MET. Moreover, the rough (non-flat) membrane assembly in the 2-d model provided a special niche for SRB and MET that was not represented in the 1-d model. This study compared 1-d and 2-d biofilm model applicability for simulating competition in counter-diffusional biofilms. Although more computationally expensive, the 2-d model captured important mechanisms unseen in the 1-d model. © 2015 Wiley Periodicals, Inc.

Individual and co-operative roles of lactic acid and hydrogen peroxide in the killing activity of enteric strain Lactobacillus johnsonii NCC933 and vaginal strain Lactobacillus gasseri KS120.1 against enteric, uropathogenic and vaginosis-associated pathogens.

PubMed

Atassi, Fabrice; Servin, Alain L

2010-03-01

The mechanism underlying the killing activity of Lactobacillus strains against bacterial pathogens appears to be multifactorial. Here, we investigate the respective contributions of hydrogen peroxide and lactic acid in killing bacterial pathogens associated with the human vagina, urinary tract or intestine by two hydrogen peroxide-producing strains. In co-culture, the human intestinal strain Lactobacillus johnsonii NCC933 and human vaginal strain Lactobacillus gasseri KS120.1 strains killed enteric Salmonella enterica serovar Typhimurium SL1344, vaginal Gardnerella vaginalis DSM 4944 and urinary tract Escherichia coli CFT073 pathogens. The cell-free culture supernatants (CFCSs) produced the same reduction in SL1344, DSM 4944 and CFT073 viability, whereas isolated bacteria had no effect. The killing activity of CFCSs was heat-stable. In the presence of Dulbecco's modified Eagle's minimum essential medium inhibiting the lactic acid-dependent killing activity, CFCSs were less effective at killing of the pathogens. Catalase-treated CFCSs displayed a strong decreased activity. Tested alone, hydrogen peroxide triggered a concentration-dependent killing activity against all three pathogens. Lactic acid alone developed a killing activity only at concentrations higher than that present in CFCSs. In the presence of lactic acid at a concentration present in Lactobacillus CFCSs, hydrogen peroxide displayed enhanced killing activity. Collectively, these results demonstrate that for hydrogen peroxide-producing Lactobacillus strains, the main metabolites of Lactobacillus, lactic acid and hydrogen peroxide, act co-operatively to kill enteric, vaginosis-associated and uropathogenic pathogens.

Hydrogenation of citral into its derivatives using heterogeneous catalyst

NASA Astrophysics Data System (ADS)

Sudiyarmanto, Hidayati, Luthfiana Nurul; Kristiani, Anis; Aulia, Fauzan

2017-11-01

Citral as known as a monoterpene can be found in plants and citrus fruits. The hydrogenation of citral into its derivatives become interesting area for scientist. This compound and its derivatives can be used for many application in pharmaceuticals and food areas. The development of heterogeneous catalysts become an important aspect in catalytic hydrogenation citral process. Nickel supported catalysts are well known as hydrogenation catalyst. These heterogeneous catalysts were tested their catalytic activity in hydrogenation of citral. The effect of various operation conditions, in term of feed concentration, catalyst loading, temperature, and reaction time were also studied. The liquid products produced were analyzed by using Gas Chromatography-Mass Spectroscopy (GC-MS). The result of catalytic activity tests showed nickel skeletal catalyst exhibits best catalytic activity in hydrogenation of citral. The optimum of operation condition was achieved in citral concentration 0.1 M with nickel skeletal catalyst loading of 10% (w/w) at 80 °C and 20 bar for 2 hours produced the highest conversion as of 64.20% and the dominant product resulted was citronellal as of 56.48%.

Hydrogen absorption by thin Pd/Nb films deposited on glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reisfeld, G.; Jisrawi, N.M.; Ruckman, M.W.

Hydrogen absorption by 200{endash}2000-A-thick Pd-capped Nb films, between 5 and 110{degree}C, was studied by simultaneous four-probe resistivity and volumetric measurements. The resistivity as a function of hydrogen concentration was measured while charging the films with hydrogen, and was used to compute the change in hydrogen concentration in the film, during the reaction with oxygen. For the thinnest films (200 A thick), the hydrogen charging and discharging curves indicate that a first-order gas-liquid-like phase transition with a {ital T}{sub {ital c}} of 70{endash}75{degree}C takes place. The H-Nb phase diagram for the 200-A film looks like the H/bulk Nb {alpha}-{alpha}{prime} phase diagrammore » which has a higher {ital T}{sub {ital c}} (173{degree}C). We attribute the substantial modifications of the film{close_quote}s phase diagram to the clamping of the Nb film at its interfaces with glass and Pd and to the nanostructure of the films. {copyright} {ital 1996 The American Physical Society.}« less

First-principles study of hydrogen adsorption in metal-doped COF-10

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Miaomiao; Sun Qiang; Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284

2010-10-21

Covalent organic frameworks (COFs), due to their low-density, high-porosity, and high-stability, have promising applications in gas storage. In this study we have explored the potential of COFs doped with Li and Ca metal atoms for storing hydrogen under ambient thermodynamic conditions. Using density functional theory we have performed detailed calculations of the sites Li and Ca atoms occupy in COF-10 and their interaction with hydrogen molecules. The binding energy of Li atom on COF-10 substrate is found to be about 1.0 eV and each Li atom can adsorb up to three H{sub 2} molecules. However, at high concentration, Li atomsmore » cluster and, consequently, their hydrogen storage capacity is reduced due to steric hindrance between H{sub 2} molecules. On the other hand, due to charge transfer from Li to the substrate, O sites provide additional enhancement for hydrogen adsorption. With increasing concentration of doped metal atoms, the COF-10 substrate provides an additional platform for storing hydrogen. Similar conclusions are reached for Ca doped COF-10.« less

Ion Beam Analysis of the Thermal Stability of Hydrogenated Diamond-Like Carbon Thin Films on Si Substrate

NASA Astrophysics Data System (ADS)

Nandasiri, M. I.; Moore, A.; Garratt, E.; Wickey, K. J.; AlFaify, S.; Gao, X.; Kayani, A.; Ingram, D.

2009-03-01

Unbalanced magnetron sputtering deposition of C-H films has been performed with various levels of negative substrate bias and with a fixed flow rate of hydrogen. Argon was used as a sputtering gas and formed the majority of the gas in the plasma. The effect of hydrogenation on the final concentration of trapped elements and their thermal stability with respect to hydrogen content is studied using ion beam analysis (IBA) techniques. The elemental concentrations of the films were measured in the films deposited on silicon substrates with a 2.5 MeV of H+ beam, which is used to perform Rutherford Backscattering Spectrometry (RBS) and Non-Rutherford Backscattering spectrometry (NRBS) and with 16 MeV of O5+ beam, used to perform Elastic Recoil Detection Analysis (ERDA). Effect of bias on the thermal stability of trapped hydrogen in the films has been studied. As the films were heated in-situ in vacuum using a non-gassy button heater, hydrogen was found to be decreasing around 400° C.

Numerical Investigation of the Hydrogen Jet Flammable Envelope Extent with Account for Unsteady Phenomena

NASA Astrophysics Data System (ADS)

Chernyavsky, Boris; Benard, Pierre

2010-11-01

An important aspect of safety analysis in hydrogen applications is determination of the extent of flammable gas envelope in case of hydrogen jet release. Experimental investigations had shown significant disagreements between the extent of average flammable envelope predicted by steady-state numerical methods, and the region observed to support ignition, with proposed cause being non-steady jet phenomena resulting in significant variations of instantaneous gas concentration and velocity fields in the jet. In order to investigate the influence of these transient phenomena, a numerical investigation of hydrogen jet at low Mach number had been performed using unsteady Large Eddy Simulation. Instantaneous hydrogen concentration and velocity fields were monitored to determine instantaneous flammable envelope. The evolution of the instantaneous fields, including the development of the turbulence structures carrying hydrogen, their extent and frequency, and their relation with averaged fields had been characterized. Simulation had shown significant variability of the flammable envelope, with jet flapping causing shedding of large scale rich and lean gas pockets from the main jet core, which persist for significant times and substantially alter the extent of flammability envelope.

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

PubMed

Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

2016-02-01

In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

High Concentrations of Hydrogen-bearing Volatiles at the Base of Poleward-facing slopes in the Moon's Large Southern Permanently Shadowed Regions.

NASA Astrophysics Data System (ADS)

McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Livengood, T. A.; Litvak, M. L.; Sanin, A. B.; Starr, R. D.

2016-12-01

In this paper we review evidence that indicates that high concentrations of hydrogen-bearing volatiles are biased towards the base of poleward-facing slopes (PFS) in the Moon's large southern permanently shadowed regions (PSR). Results are derived from a correlated study of Lunar Reconnaissance Orbiter instrument maps of: epithermal neutron leakage flux observed by the Lunar Exploration Neutron Detector (LEND), topography derived from the Lunar Observing Laser Altimeter (LOLA) and surface thermal maps derived from the Diviner radiometer. Maximum concentrations of hydrogen-volatiles, likely as water ice, are observed in the Cabeus crater's PSR, 0.62 wght% water-equivalent-hydrogen. Detailed studies show that the occurrence of hydrogen-volatiles at the base of the (PFS) are correlated with the locations of low PSR temperatures of Cabeus, Haworth, Shoemaker and Faustini. LEND observations show no consistent correlation to smaller impact craters and the lowest temperatures within the PSR's. It is not presently known if the high volatile concentrations are due to downslope migration or thermal stability in the PFS breaks in slope. 15-km Full-width at Half-Maximum (FWHM) is shown to be an upper-bounds condition for the LEND collimated sensor's spatial resolution, derived from a cross-sectional profile, through the permanently shadowed region at Cabeus'. LEND's high-resolution spatial response is further illustrated in a 220-km long profile cut through the co-aligned permanently shadowed regions and partially-illuminated ridges of Haworth, Shoemaker, Faustini and Amundsen craters.

Quality-assured measurements of animal building emissions: particulate matter concentrations.

PubMed

Heber, Albert J; Lim, Teng-Teeh; Ni, Ji-Qin; Tao, Pei-Chun; Schmidt, Amy M; Koziel, Jacek A; Hoff, Steven J; Jacobson, Larry D; Zhang, Yuanhui; Baughman, Gerald B

2006-12-01

Federally funded, multistate field studies were initiated in 2002 to measure emissions of particulate matter (PM) < 10 microm (PM10) and total suspended particulate (TSP), ammonia, hydrogen sulfide, carbon dioxide, methane, nonmethane hydrocarbons, and odor from swine and poultry production buildings in the United States. This paper describes the use of a continuous PM analyzer based on the tapered element oscillating microbalance (TEOM). In these studies, the TEOM was used to measure PM emissions at identical locations in paired barns. Measuring PM concentrations in swine and poultry barns, compared with measuring PM in ambient air, required more frequent maintenance of the TEOM. External screens were used to prevent rapid plugging of the insect screen in the PM10 preseparator inlet. Minute means of mass concentrations exhibited a sinusoidal pattern that followed the variation of relative humidity, indicating that mass concentration measurements were affected by water vapor condensation onto and evaporation of moisture from the TEOM filter. Filter loading increased the humidity effect, most likely because of increased water vapor adsorption capacity of added PM. In a single layer barn study, collocated TEOMs, equipped with TSP and PM10 inlets, corresponded well when placed near the inlets of exhaust fans in a layer barn. Initial data showed that average daily mean concentrations of TSP, PM10, and PM2.5 concentrations at a layer barn were 1440 +/- 182 microg/m3 (n = 2), 553 +/- 79 microg/m3 (n = 4), and 33 +/- 75 microg/m3 (n = 1), respectively. The daily mean TSP concentration (n = 1) of a swine barn sprinkled with soybean oil was 67% lower than an untreated swine barn, which had a daily mean TSP concentration of 1143 +/- 619 microg/m3. The daily mean ambient TSP concentration (n = 1) near the swine barns was 25 +/- 8 microg/m3. Concentrations of PM inside the swine barns were correlated to pig activity.

'On-line' analyses of simulated solar wind implantations of terrestrial analogs of lunar materials

NASA Technical Reports Server (NTRS)

Blanford, G. E.; Bergesen, P.; Moeller, W.; Maurette, M.; Monart, B.

1986-01-01

In connection with the establishment of a lunar base, it would be necessary to provide water, and the feasibility to obtain water from solar wind (SW) implanted lunar soils has been considered. In this context, a project involving the examination of materials under conditions of simulated SW irradiation has been initiated. A description is presented of initial results on oligoclase, ilmenite, and simulated lunar glass (SLG). Attention is given to the reaction chamber, the target materials, the saturation concentrations, aspects of water release, depth profiles, thermal release, effects from helium-3 preimplants, mechanisms of possible water release related to direct emission and thermal release, and lunar soil components enriched in trapped SW hydrogen. It is found that ilmenite stores about twice as much deuterium as the other target materials. However, it is unknown whether the small enrichment factor will be sufficient to make the material a potential source of lunar water.

Comparative study of UV/TiO2, UV/ZnO and photo-Fenton processes for the organic reactive dye degradation in aqueous solution.

PubMed

Peternel, Igor T; Koprivanac, Natalija; Bozić, Ana M Loncarić; Kusić, Hrvoje M

2007-09-05

In this study advanced oxidation processes (AOPs), UV/TiO(2), UV/ZnO and photo-Fenton, were applied in order to degrade C.I. Reactive Red 45 (RR45) dye in aqueous solution. The effects of key operating parameters, such as initial pH, catalyst and hydrogen peroxide dosage as well as the effect of initial dye concentration on decolorization and mineralization extents were studied. Primary objective was to determine the optimal conditions for each of the processes. The influence of added zeolite on the process efficiency was also studied. UV/vis spectrophotometric and total organic carbon (TOC) measurements were performed for determination of decolorization and mineralization extents. It has been found that photo-Fenton process was the most efficient with 74.2% TOC removal and complete color removal achieved after a 1h treatment.

Hydrogen peroxide poisoning.

PubMed

Watt, Barbara E; Proudfoot, Alex T; Vale, J Allister

2004-01-01

Hydrogen peroxide is an oxidising agent that is used in a number of household products, including general-purpose disinfectants, chlorine-free bleaches, fabric stain removers, contact lens disinfectants and hair dyes, and it is a component of some tooth whitening products. In industry, the principal use of hydrogen peroxide is as a bleaching agent in the manufacture of paper and pulp. Hydrogen peroxide has been employed medicinally for wound irrigation and for the sterilisation of ophthalmic and endoscopic instruments. Hydrogen peroxide causes toxicity via three main mechanisms: corrosive damage, oxygen gas formation and lipid peroxidation. Concentrated hydrogen peroxide is caustic and exposure may result in local tissue damage. Ingestion of concentrated (>35%) hydrogen peroxide can also result in the generation of substantial volumes of oxygen. Where the amount of oxygen evolved exceeds its maximum solubility in blood, venous or arterial gas embolism may occur. The mechanism of CNS damage is thought to be arterial gas embolisation with subsequent brain infarction. Rapid generation of oxygen in closed body cavities can also cause mechanical distension and there is potential for the rupture of the hollow viscus secondary to oxygen liberation. In addition, intravascular foaming following absorption can seriously impede right ventricular output and produce complete loss of cardiac output. Hydrogen peroxide can also exert a direct cytotoxic effect via lipid peroxidation. Ingestion of hydrogen peroxide may cause irritation of the gastrointestinal tract with nausea, vomiting, haematemesis and foaming at the mouth; the foam may obstruct the respiratory tract or result in pulmonary aspiration. Painful gastric distension and belching may be caused by the liberation of large volumes of oxygen in the stomach. Blistering of the mucosae and oropharyngeal burns are common following ingestion of concentrated solutions, and laryngospasm and haemorrhagic gastritis have been reported. Sinus tachycardia, lethargy, confusion, coma, convulsions, stridor, sub-epiglottic narrowing, apnoea, cyanosis and cardiorespiratory arrest may ensue within minutes of ingestion. Oxygen gas embolism may produce multiple cerebral infarctions. Although most inhalational exposures cause little more than coughing and transient dyspnoea, inhalation of highly concentrated solutions of hydrogen peroxide can cause severe irritation and inflammation of mucous membranes, with coughing and dyspnoea. Shock, coma and convulsions may ensue and pulmonary oedema may occur up to 24-72 hours post exposure. Severe toxicity has resulted from the use of hydrogen peroxide solutions to irrigate wounds within closed body cavities or under pressure as oxygen gas embolism has resulted. Inflammation, blistering and severe skin damage may follow dermal contact. Ocular exposure to 3% solutions may cause immediate stinging, irritation, lacrimation and blurred vision, but severe injury is unlikely. Exposure to more concentrated hydrogen peroxide solutions (>10%) may result in ulceration or perforation of the cornea. Gut decontamination is not indicated following ingestion, due to the rapid decomposition of hydrogen peroxide by catalase to oxygen and water. If gastric distension is painful, a gastric tube should be passed to release gas. Early aggressive airway management is critical in patients who have ingested concentrated hydrogen peroxide, as respiratory failure and arrest appear to be the proximate cause of death. Endoscopy should be considered if there is persistent vomiting, haematemesis, significant oral burns, severe abdominal pain, dysphagia or stridor. Corticosteroids in high dosage have been recommended if laryngeal and pulmonary oedema supervene, but their value is unproven. Endotracheal intubation, or rarely, tracheostomy may be required for life-threatening laryngeal oedema. Contaminated skin should be washed with copious amounts of water. Skin lesions should be treated as thermal burns; surgery may be required for deep burns. In the case of eye exposure, the affected eye(s) shod eye(s) should be irrigated immediately and thoroughly with water or 0.9% saline for at least 10-15 minutes. Instillation of a local anaesthetic may reduce discomfort and assist more thorough decontamination.

Photooxidative removal of the herbicide Acid Blue 9 in the presence of hydrogen peroxide: modeling of the reaction for evaluation of electrical energy per order (E EO).

PubMed

Khataee, Ali R; Khataee, Hamid R

2008-09-01

The present work deals with photooxidative removal of the herbicide, Acid Blue 9 (AB9), in water in the presence of hydrogen peroxide (H2O2) under UV light illumination (30 W). The influence of the basic operational parameters such as amount of H2O2, irradiation time and initial concentration of AB9 on the photodegradation efficiency of the herbicide was investigated. The degradation rate of AB9 was not appreciably high when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The photooxidative removal of the herbicide was found to follow pseudo-first-order kinetic, and hence the figure-of-merit electrical energy per order (E Eo) was considered appropriate for estimating the electrical energy efficiency. A mathematical relation between the apparent reaction rate constant and H2O2 used was applied for prediction of the electricity consumption in the photooxidative removal of AB9. The results indicated that this kinetic model, based on the initial rates of degradation, provided good prediction of the E Eo values for a variety of conditions. The results also indicated that the UV/H2O2 process was appropriate as the effective treatment method for removal of AB9 from the contaminated wastewater.

Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry

PubMed Central

2013-01-01

The dopaminergic neurons of the nigrostriatal dopamine (DA) projection from the substantia nigra to the dorsal striatum become dysfunctional and slowly degenerate in Parkinson’s disease, a neurodegenerative disorder that afflicts more than one million Americans. There is no specific known cause for idiopathic Parkinson’s disease; however, multiple lines of evidence implicate oxidative stress as an underlying factor in both the initiation and progression of the disease. This involves the enhanced generation of reactive oxygen species, including hydrogen peroxide (H2O2), whose role in complex biological processes is not well understood. Using fast-scan cyclic voltammetry at bare carbon-fiber microelectrodes, we have simultaneously monitored and quantified H2O2 and DA fluctuations in intact striatal tissue under basal conditions and in response to the initiation of oxidative stress. Furthermore, we have assessed the effect of acute increases in local H2O2 concentration on both electrically evoked DA release and basal DA levels. Increases in endogenous H2O2 in the dorsal striatum attenuated electrically evoked DA release, and also decreased basal DA levels in this brain region. These novel results will help to disambiguate the chemical mechanisms underlying the progression of neurodegenerative disease states, such as Parkinson’s disease, that involve oxidative stress. PMID:23556461

Distribution and variability of precipitation chemistry in the conterminous United States, January through December 1983

USGS Publications Warehouse

Rinella, J.F.; Miller, T.L.

1988-01-01

Analysis of atmospheric precipitation samples, collected during the 1983 calendar year from 109 National Trends Network sites in the United States, are presented in this report. The sites were grouped into six geographical regions based on the chemical composition of the samples. Precipitation chemistry in these regions was influenced by proximity to (1) oceans, (2) major industrial and fossil-fuel consuming areas, and (3) major agricultural and livestock areas. Frequency distributions of ionic composition, determined on 10 chemical constituents and on precipitation quantities for each site, showed wide variations in chemical concentrations and precipitation quantities from site to site. Of the 109 sites, 55 had data coverage for the year sufficient to characterize precipitation quality patterns on a nationwide basis. Except for ammonium and calcium, both of which showed largest concentrations in the agricultural midwest and plains states, the largest concentrations and loads generally were in areas that include the heavily industrialized population center of the eastern United States. Except for hydrogen, all chemical ions are inversely related to the quantity of precipitation depth. Precipitation quantities generally account for less than 30% of chemical variation in precipitation samples. However, precipitation quantities account for 30 to 65% of the variations of calcium concentrations in precipitation. In regions where precipitation has a large ionic proportion of hydrogen-ion equivalents, much of the hydrogen-ion concentration could be balanced by sulfate equivalents and partly balanced by nitrite-plus-nitrate equivalents. In the regions where hydrogen-ion equivalents in precipitation were smaller, ammonion-and calcium-ion equivalents were necessary, along with the hydrogen-ion equivalents, to balance the sulfate plus nitrite-plus-nitrate equivalent. (USGS)

Experimental investigation and computational modeling of hot filament diamond chemical vapor deposition

NASA Astrophysics Data System (ADS)

Zumbach, Volker; Schäfer, Jörg; Tobai, Jens; Ridder, Michael; Dreier, Thomas; Schaich, Thomas; Wolfrum, Jürgen; Ruf, Bernhard; Behrendt, Frank; Deutschman, Olaf; Warnatz, Jürgen

1997-10-01

A joint investigation has been undertaken of the gas-phase chemistry taking place in a hot-filament chemical vapor-deposition (HFCVD) process for diamond synthesis on silica surfaces by a detailed comparison of numerical modeling and experimental results. Molecular beam sampling using quadrupole mass spectroscopy and resonance-enhanced multiphoton ionization time of flight mass spectroscopy (REMPI-TOF-MS) has been used to determine absolute concentrations of stable hydrocarbons and radicals. Resulting species of a CH4/H2, a CH4/D2 (both 0.5%/99.5%) and a C2H2/H2 (0.25%/99.75%) feedgas mixture were investigated for varying filament and substrate temperatures. Spatially resolved temperature profiles at various substrate temperatures, obtained from coherent anti-Stokes Raman spectroscopy (CARS) of hydrogen, are used as input parameters for the numerical code to reproduce hydrogen atom, methyl radical, methane, acetylene, and ethylene concentration profiles in the boundary layer of the substrate. In addition, the concentration of vibrationally excited hydrogen is determined by CARS. Results reveal only qualitative agreement between measured data and simulations, concerning concentrations of stable species and radicals probed near the surface, on filament and substrate temperature dependence, respectively. Hydrogen and deuterium experiments show similar behaviour for all species. In the case of CH4 as feedgas the model describes measured concentration profiles of CH3, CH4, and C2H2 qualitatively well. Large differences between model and experiment occur for hydrogen atoms (factor of 2) and C2H4 (factor of 3). For acetylene as feedgas the model is not able to give any predictions because no conversion of C2H2 is seen in the model in contrast to the experiment.

Ionization correction factors for H II regions in blue compact dwarf galaxies

NASA Astrophysics Data System (ADS)

Holovatyi, V. V.; Melekh, B. Ya.

2002-08-01

Energy distributions in the spectra of the ionizing nuclei of H II regions beyond λ <= 91.2 nm were calculated. A grid of photoionization models of 270 H II regions was constructed. The free parameters of the model grid are the hydrogen density nH in the nebular gas, filling factor, energy Lc-spectrum of ionizing nuclei, and metallicity. The chemical composition from the studies of Izotov et al. were used for model grid initialization. The integral linear spectra calculated for the photoionization models were used to determine the concentration ne, temperatures Te of electrons, and ionic concentrations n(A+i)/n(H+) by the nebular gas diagnostic method. The averaged relative ionic abundances n(A+i)/n(H+) thus calculated were used to determine new expressions for ionization correction factors which we recommend for the determination of abundances in the H II regions of blue compact dwarf galaxies.

Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borysow, Jacek, E-mail: jborysow@mtu.edu; Rosso, Leonardo del; Celli, Milva

2014-04-28

We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines weremore » narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.« less

Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

PubMed

Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

2014-04-28

We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

NASA Astrophysics Data System (ADS)

Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

2014-04-01

We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.