Hydrogen Gas Concentration Research Articles

Study of a Method for Measuring Hydrogen Gas Concentration Using a Photon-counting Raman Lidar System

Study of a Method for Measuring Hydrogen Gas Concentration Using a Photon-counting Raman Lidar System

Improved selectivity and low concentration hydrogen gas sensor application of Pd sensitized heterojunction n-ZnO/p-NiO nanostructures

Heterojunction based gas sensor was fabricated by forming two semiconductor nanostructures interface i.e. n-type ZnO nanorods and p-type NiO nanoplates. These nanostructures were synthesized via chemical routes. Palladium (Pd) nanoparticles (NPs) were synthesized and sensitized on the surface of heterojunction sensor material to enhance the gas response. Sensor materials were characterized using XRD, TEM, FESEM, EDS, Elemental mapping, and XPS techniques for their physicochemical properties. The n-ZnO/p-NiO heterojunction sensors with and without Pd NPs sensitization were investigated for low hydrogen gas concentration 2–100 ppm. Pd NPs sensitized n-ZnO/p-NiO heterojunction sensor showed higher response of 72% towards 100 ppm hydrogen (H2) gas concentration at the operating temperature 225 °C, whereas 53% response was noted by p-NiO/n-ZnO heterojunction sensor for 100 ppm concentration at 237 °C operating temperature. Both the sensors were investigated for selectivity studies using methane (CH4), carbon monoxide (CO), nitrogen dioxide (NO2), carbon dioxide (CO2) and H2 gases. Higher selectivity was observed towards H2 gas for both the sensors. The gas responses of both sensors were investigated at various operating temperatures and concentrations. Transient response, repeatability, and stability were also confirmed for both sensors. The gas sensing mechanism for heterojunction sensors was elucidated.

Hydrogen production by the steam reforming of waste lubricating oil

ABSTRACTThe production of Hydrogen from the used lubricating oil through steam reforming is an effective and novel method of recovering the energetic content of waste lubricating oil (WLO). This work was geared towards utilising ASPEN Plus V8.8 to develop a predictive simulation for the production of Hydrogen from WLO via steam reforming. All aspects of factor sensitivity and interactions as regards the steam reforming of WLO was exhaustively studied. The simulation model was developed and run successfully without any errors. The sensitivity of the simulation to pressure, temperature and steam-to-oil ratio (STOR) from the simulation was first studied to help determine the optimal values of each factor. The optimal values for the process parameters are reforming temperature of 600°C, reforming pressure of 1 atm and STOR of 10 kg/kg. The synthesis gas obtained at optimal conditions has a Hydrogen gas content of 75%, Carbon dioxide content of 21%, carbon monoxide content of 3.7% and only trace quantities of methane. The factor interaction study of all chemical species in the product stream was summarily carried out and any combinatory effects of these factors were elucidated.

The Neutral Gas Properties of Extremely Isolated Early-type Galaxies III

Abstract We report on the neutral hydrogen gas content (21 cm emission) of eight extremely isolated early-type galaxies (IEGs) using the Green Bank Telescope. Emission is detected in seven of the eight objects. This paper is the third in a series that collectively present new H i observations for 20 IEGs. Among the 14 H i detections in our observations, eight exhibit a Gaussian-like H i line profile shape, four are double-peaked, one is triple-peaked, and another has a plateaued rectangular shape. Five additional IEGs observed in previous surveys were added to our analysis, bringing the total number of IEGs with H i observations to 25. Of these objects, emission is detected in 19 (76%). The 25 IEGs in our combined study have gas masses that are systematically larger than their luminosity-matched comparison galaxy counterparts. The IEGs presented here follow a trend of increasing gas-richness with bluer B − V colors. This correlation is also observed in a comparison sample drawn from the literature composed of loose group and field early-type galaxies. Two IEGs, KIG 164 and KIG 870, exhibit properties highly anomalous for spheroidal systems: luminous (M B = −20.5, −20.1) and blue (B − V = 0.47, 0.48), respectively, with substantial neutral gas, M H i = 4.1 and 5.5 × 109 M ☉. Other IEG systems may represent early-type galaxies continuing to assemble via quiescent H i accretion from the cosmic web or relaxed merged systems.

A hydrogen gas concentration measurement method using the Raman lidar system

The Raman lidar system is a hydrogen gas detecting technique capable of detecting the local hydrogen gas concentration and range in air remotely, because hydrogen gas has a very strong Raman effect. Therefore, hydrogen Raman cells have been widely used for laser wavelength conversion. This paper discusses a method for measuring hydrogen gas concentration using the Raman lidar system. Hydrogen gas combustion is affected by the volume percent of local hydrogen gas concentration in air, and for safety, accurate measurement is important. When hydrogen gas leaks into the air, the local composition of the air is changed. However, the Raman Effect is affected by the number of molecules. Therefore, it is impossible to measure the volume percent concentration of hydrogen gas when using one of the Raman signals of the hydrogen gas or nitrogen gas. To measure the volume percent concentration of hydrogen gas using the Raman lidar system, the equation between the concentrations of hydrogen gas in volumetric concentration units was derived using the ratio of the Raman signal from hydrogen and nitrogen gas. To verify the equation, hydrogen gas concentration measuring experiments were carried out using the Raman lidar system. The results confirmed the Raman lidar system was able to measure the volume percent concentration of hydrogen gas from 0 to 30 Vol.% at a distance of up to 30 m.

Sensitivity of ferromagnetic resonance in PdCo alloyed films to hydrogen gas

In this work we study the ferromagnetic resonance (FMR) response of CoxPd1-x alloy samples with varying compositions (x = 0.65, 0.39, 0.24 and 0.14). We find significant differences in the FMR response of the samples to the presence of hydrogen gas in the samples’ environment. Without any special processing, the films with x = 0.39 and 0.24 demonstrated behaviour which is promising for application in hydrogen gas sensing. Using FMR in the alloy thin films, we were able to measure hydrogen gas concentration in a very broad range - from 0.05% to 100%.

Gas Sensing and Structural Properties of a Nano-structure MoO3-based Hydrogen Sensor

In this research, thin films of molybdenum trioxide were deposited on a glass substrate using Doctor Blade method. Ammonium Heptamolbudate tetrahydrate (NH4)6Mo7O24 powder is considered as a precursor to this study. Growth of the samples in three main directions of (020), (040) and (060) showed the formation of a layered structure and also the formation of α-phase of molybdenum oxide. In addition, scanning electron microscope imaging of the samples showed flat micro-capsule like structure. Furthermore, gas sensing properties of the fabricated structure were studied in expose to different concentrations of hydrogen gas. The highest and lowest sensitivities were reported about 16 and 91%, for 100 and 1000 ppm of hydrogen gas, respectively, which shows more sensitivity compare to previous studies. Moreover, the fabricated sensor exhibits good stability as well as repeatability for H2 gas detection.

Safety of inhaled hydrogen gas in healthy mice.

The purpose of this work was to determine the safety of inhaled hydrogen gas in healthy animals. Female mice were exposed to medical air with or without hydrogen gas (concentration 2.4%) for 72 hours (n = 25 mice/group). Mice underwent a standardized and validated neurobehavioral examination, SmithKline Beecham, Harwell, Imperial College, Royal London Hospital, Phenotype Assessment (SHIRPA) protocol, prior to and following the exposure period. Blood was withdrawn for serologic evaluation and all major organ tissues were evaluated histologically. The average hydrogen concentration within the chamber was 2.27%. Following exposure, there was no significant change in body weight in either group. Similarly, there was no significant change in the total SHIRPA score, although hydrogen-treated mice exhibited significantly lower spontaneous locomotor activity (P < 0.0001) in a subset of the test; all other aspects of the mouse neurologic exam were normal in hydrogen-treated animals. Brain histopathology was also normal in all mice, as was the histology of all other major organs. There were no significant differences in complete blood count, serum chemistry, or arterial blood gases between control and hydrogen-treated mice (P > 0.05 for all). Hydrogen gas did not appear to cause significant adverse effects when administered to healthy mice for 72 hours, with the possible exception of decreased spontaneous locomotor activity. The study was approved by the Institutional Animal Care and Use Committee at Boston Children’s Hospital, USA (approved number 18-01-3536) on January 25, 2018.

The Study on Permissible Value of Hydrogen Gas Concentration in Purge Gas of FCV

The Study on Permissible Value of Hydrogen Gas Concentration in Purge Gas of FCV

Pyrolysis of chlorine contaminated municipal plastic waste: In-situ upgrading of pyrolysis oils by Ni/ZSM-5, Ni/SAPO-11, red mud and Ca(OH)2 containing catalysts

This work is focussing to the thermo-catalytic batch pyrolysis of contaminated real municipal plastic waste using different catalyst mixtures in their different ratios: Ni/ZSM-5, red mud, Ca(OH)2 and Ni/SAPO-11, red mud, Ca(OH)2. The effect of the catalysts to the pyrolysis oil properties and the in-situ upgrading (especially the storage, transportation and corrosion stability) of pyrolysis oil was investigated. High concentration of Ni/ZSM-5 and Ni/SAPO-11 zeolites in catalyst mixtures can increase the yield of gases and pyrolysis oil, the concentration of aromatics or the hydrogen content in gases; however the presence of red mud in higher content can further increase the hydrogen concentration. ZSM-5 based catalysts showed higher efficiency in aromatization reactions. An accelerated aging test at 80 °C till 1 week was performed to investigate the storage and transportation stability of pyrolysis oils. Only slight increase was found in the density and viscosity, on the other hand there was a bit greater increase using SAPO-11 based catalysts than ZSM-5. The change in the olefin content was followed via bromine number and FTIR spectra of pyrolysis oil, which resulted ∼3% and ∼4% decreasing using Ni/ZSM-5 and Ni/SAPO-11 containing catalyst mixtures. Regarding acidic components, they significantly increased by aging time, while the high red mud and/or Ca(OH)2 in catalyst mixtures had notable benefit, because they can drastically decrease the concentration of chlorinated compounds, which led to less weight loss during corrosion test using copper plate till 60 days at 20 °C.

Fermentable Sugar Ingestion, Gas Production, and Gastrointestinal and Central Nervous System Symptoms in Patients With Functional Disorders

Functional gastrointestinal disorders (FGID) are defined by broad phenotypic descriptions and exclusion of recognizable disease. FGIDs cause multi-organ symptoms and abnormal results in a wide range of laboratory tests, indicating broad mechanisms of pathogenesis. Many patients with FGID develop symptoms following ingestion of fermentable sugars; we investigated the associations between symptoms and intestinal gas production following sugar provocation tests to elucidate mechanisms of FGID. We performed fructose and lactose breath tests in 2042 patients with a diagnosis of FGID (based on Rome III criteria), referred to a gastroenterology practice from January 2008 through December 2011. Medical and diet histories were collected from all subjects. Breath samples were collected before and each hour after, for 5 hours, subjects ingested fructose (35 g) and lactose (50 g) dissolved in 300 mL water. Hydrogen and methane gas concentrations were measured and GI and non-GI symptoms were registered for 5 hours following sugar ingestion. Symptom and gas time profiles were compared, treelet transforms were used to derive data-related symptom clusters, and the symptom severity of the clusters were analyzed for their association with breath gas characteristics. We identified 11 GI and central nervous system (CNS) symptom profiles and hydrogen and methane breath concentrations that changed significantly with time following sugar ingestion. Treelet transform analysis identified 2 distinct clusters, based on GI and CNS symptoms. The severity scores for the GI and CNS symptoms correlated following ingestion of sugars (all, P<.0001). However, only the GI symptoms associated with hydrogen and methane gas production (all, P < .0001). In an analysis of breath test results from more than 2000 patients with FGIDs, we identified clusters of GI and CNS symptoms in response to fructose of lactose ingestion. The association between specific symptoms and breath gas concentrations indicate distinct mechanisms of FGID pathogenesis, such as changes in the microbiome or mechanical and chemical sensitization. ClinicalTrials.gov ID: NCT02085889.

Thermophilic Biohydrogen Fermentation of Kitchen Waste

Batch tests were conducted to obtain optimal feedstock concentration and cultivation temperature for efficient biohydrogen production via mixed anaerobic cultures with various kitchen waste concentrations of 10–80 g chemical oxygen demand (COD)/L and cultivation temperatures of 35–55 °C. The experimental results indicate that to produce biohydrogen from kitchen waste, thermophilic cultivation temperature is more favorable than mesophilic cultivation temperature in giving high hydrogen yield, maximum hydrogen production rate and hydrogen gas content. Temperatures 50 and 55 °C gave same levels of fermentation efficiency in hydrogen yield, maximum hydrogen production rate and hydrogen gas content with values of 70 mL/g CODadded, 80 mL/L-h and 50%, respectively. These parameter values were 5–10 folds of those at 35–45 °C. However, before the industry application, it is suggested to further investigate a continuously-feeding mode and pilot-scale operations to collect the data for full-scale design and operation.

Beyond Chemical Bonding Interaction: An Insight into the Growth Process of 1D ZnO on Few‐Layer Graphene for Excellent Photocatalytic and Room Temperature Gas Sensing Applications

AbstractA facile chemical synthesis approach is reported for simultaneous reduction of graphene oxide (GO) and chemically planted 1D ZnO Nanorods (NRs) on the few‐layer graphene (FLG) through chemical bonding interaction. The chemically bonded 1D ZnO – few layer graphene nanostructures are investigated by high resolution scanning transmission electron microscopy, photoelectron spectroscopy, X‐ray diffraction and photoluminescence studies. This multifunctional nanostructure efficiently boosts the photocatalytic activity by photodegradation of industrial pollutants within 5 minutes under natural sunlight irradiation and also senses the very low concentration (10 ppm) of hydrogen gas at room temperature with very high sensing response. The emerging photocatalytic performance and the room temperature gas sensing characteristics of 1D ZnO – few layer graphene is attributed to the presence of C–Zn chemical bonds, which plays an essential role in the interfacial charge transfer process between the graphene layers and 1D ZnO NRs. The strong chemical bonding interaction and interfacial charge transfer effects have been experimentally elucidated from the ionization value and work function characteristics of the synthesized hybrid nanostructure. This work demonstrates the simple way of preparing hybrid nanostructure with exposed crystal facets, which could provide an exposure for developing multifunctional nanomaterials towards sensing and removal of hazardous pollutants from our environment.

Improvement of the Measuring Accuracy of the Raman Lidar for Remote Detection of the Hydrogen Gas

Hydrogen gas detection technique is very important because it is very flammable and explosive. A Raman lidar system is one of the techniques for the detection of hydrogen gas remotely. The signal to noise ratio of the Raman lidar is not high, because Raman scattering signals by the hydrogen gas are very weak and its signals include the background noise signals such as the pumping laser, laser-induced fluorescents signals, and ambient light. This paper discusses the improvement of the accuracy of the Raman lidar system for measuring hydrogen gas by eliminating the background noise signals. To verify the accuracy improvement effects, experiments of measuring the hydrogen gas concentration are carried out. As the results of the experiment, The coefficient of the determination(R2) of the calibrated Raman signal of the hydrogen gas distribution by using the background noise signals was improved from 0.9985 to 0.9995 and the mean of the measuring error rates are decreased from 0.9794 to 0.7179, which is an improvement of about 27%.

Fabrication, characterization and hydrogen gas sensing performance of nanostructured V2O5 thin films prepared by plasma focus method

Nanocrystalline V2O5 thin films were deposited on glass substrates at room temperature using a low energy (1.3 kJ) plasma focus device. The argon:oxygen gas mixture (in 7:3 ratio) was utilized as a working gas and metallic vanadium was used as the anode tip material. The V2O5 thin films were synthesized with different number of shots (10, 20 and 30 shots), at 0° angular position with respect to the anode axis and at same axial position from the tip of anode (10 cm). The structural properties and phase composition of the thin films were studied by means of X-ray diffraction (XRD) and Raman scattering analysis. The results obtained from scanning electron microscopy (SEM), and atomic force microscopy (AFM) analyzes revealed that the size of nanoparticles/agglomerates and surface roughness of V2O5 thin films strongly depend on number of shots. The variation in the gas response of the V2O5 thin films for 1000 ppm concentration of hydrogen gas at different operating temperatures (150–350 °C) revealed an optimal operating temperature of 275 °C. Moreover, among all the V2O5 thin films studied, the sample deposited with ten shots showed the maximum gas response to various H2 concentrations at optimal operating temperature.

Non-steady characteristics of dispersion and ignitability for high-pressurized hydrogen jet discharged from a pinhole

Hydrogen gas concentrations and jet velocities were measured downstream by a high response speed flame ionization detector and PIV (Particle Image Velocimetry) in order to investigate the characteristics of dispersion and ignitability for 40–82 MPa high-pressurized hydrogen jet discharged from a nozzle with 0.2 mm diameter. The light emitted from both OH radical and water vapor species yielded from hydrogen combustion, ignited by an electric spark, were recorded by two high speed cameras. From the results, the empirical formula concerning the relationships for time-averaged concentrations, concentration fluctuations and ignition probability were obtained to suggest that they would be independent of hydrogen discharge pressure.

Real-time hydrogen mud logging during the Wenchuan earthquake fault scientific drilling project (WFSD), holes 2 and 3 in SW China

We present hydrogen gas concentration data for drilling mud extracted during the Wenchuan Earthquake Fault Scientific Drilling (WFSD; holes 2 and 3), measured on-line during drilling in SW China. Hydrogen influx into the well at depth is largely dependent on lithology and fracture density. In hole WFSD-2, the average background concentration of hydrogen is lower in granitic rocks than in sedimentary formations. More than five major hydrogen influxes were detected while drilling through the sedimentary formations, and two hydrogen-rich zones were detected in the granite (1240–1243 m and 1383.5–1405 m depth). In hole WFSD-3, mud extracted from a tectonic breccia contains high hydrogen concentrations at depths of 600–1000 m depth, and relatively low concentrations below 1000 m depth. In both holes, we observe a lack of hydrogen in the center of the fault zone and high concentrations of hydrogen in fractured zones. Hydrogen concentration in both holes displays significant vertical heterogeneity, and is positively correlated with fracture density. Hydrogen was likely sourced from interaction between water and fresh silicate minerals surfaces that were exposed during faulting, from the mantle, and from faulting events. Fracture zones provide the main channels for the migration of hydrogen gas. The variations in background hydrogen concentrations relate to changes in porosity and permeability. The two hydrogen-rich zones (642.36–676.22 m, and 1383.5–1405 m) were likely caused by earthquake activity or far-field triggering during WFSD-2 drilling. The results of this study provide gas data that can be used to model fault activity. It is important to consider the relationship between hydrogen gas and the seismic cycle, and to use such data to identify seismic precursors.

Semi-analytic galaxies – I. Synthesis of environmental and star-forming regulation mechanisms

We present results from the semi-analytic model of galaxy formation SAG applied on the MultiDark simulation MDPL2. SAG features an updated supernova (SN) feedback scheme and a robust modelling of the environmental effects on satellite galaxies. This incorporates a gradual starvation of the hot gas halo driven by the action of ram pressure stripping (RPS), that can affect the cold gas disc, and tidal stripping (TS), which can act on all baryonic components. Galaxy orbits of orphan satellites are integrated providing adequate positions and velocities for the estimation of RPS and TS. The star formation history and stellar mass assembly of galaxies are sensitive to the redshift dependence implemented in the SN feedback model. We discuss a variant of our model that allows to reconcile the predicted star formation rate density at $z \gtrsim 3$ with the observed one, at the expense of an excess in the faint end of the stellar mass function at $z=2$. The fractions of passive galaxies as a function of stellar mass, halo mass and the halo-centric distances are consistent with observational measurements. The model also reproduces the evolution of the main sequence of star forming central and satellite galaxies. The similarity between them is a result of the gradual starvation of the hot gas halo suffered by satellites, in which RPS plays a dominant role. RPS of the cold gas does not affect the fraction of quenched satellites but it contributes to reach the right atomic hydrogen gas content for more massive satellites ($M_{\star}\gtrsim 10^{10}\,{\rm M}_{\odot}$).

In vivo quantification of hydrogen gas concentration in bone marrow surrounding magnesium fracture fixation hardware using an electrochemical hydrogen gas sensor

Magnesium (Mg) medical devices are currently being marketed for orthopedic applications and have a complex degradation process which includes the evolution of hydrogen gas (H2). The effect of H2 exposure on relevant cell types has not been studied; and the concentration surrounding degrading Mg devices has not been quantified to enable such mechanistic studies. A simple and effective method to measure the concentration of H2 in varying microenvironments surrounding Mg implants is the first step to understanding the biological impact of H2 on these cells. Here, the in vivo measurement of H2 surrounding fracture fixation devices implanted in vivo is demonstrated. An electrochemical H2 microsensor detected increased levels of H2 at three anatomical sites with a response time of about 30 s. The sensor showed the H2 concentration in the bone marrow at 1 week post-implantation (1460 ± 320 µM) to be much higher than measured in the subcutaneous tissue (550 ± 210 µM) and at the skin surface (120 ± 50 µM). Additionally, the H2 concentrations measured in the bone marrow exceeded the concentration in a H2 saturated water solution (∼800 µM). These results suggest that H2 emanating from Mg implants in bone during degradation pass through the bone marrow and become at least partially trapped because of slow permeation through the bone. This study is the first to identify H2 concentrations in the bone marrow environment and will enable in vitro experiments to be executed at clinically relevant H2 concentrations to explore possible biological effects of H2 exposure. Statement of SignificanceAn electrochemical H2 sensor was used to monitor the degradation of a Mg fracture fixation system in a lapine ulna fracture model. Interestingly, the H2 concentration in the bone marrow is 82% higher than H2 saturated water solution. This suggests H2 generated in situ is trapped in the bone marrow and bone is less permeable than the surrounding tissues. The detectable H2 at the rabbit skin also demonstrates a H2 sensor’s ability to monitor the degradation process under thin layers of tissue. H2 sensing shows promise as a tool for monitoring the degradation of Mg alloy in vivo and creating in vitro test beds to more mechanistically evaluate the effects of varying H2 concentrations on cell types relevant to osteogenesis.

Hydrogen gas production from food wastes by electrohydrolysis using a statical design approach

Hydrogen gas production was investigated by electrohydrolysis of food waste due to its high organic content. Different voltages generated by DC power supply were applied to food waste in order to produce hydrogen gas. Effects of the DC voltage, reaction time and initial solid content on cumulative hydrogen gas production, hydrogen gas content in the gas phase and total organic carbon (TOC) removal were investigated by using a Box-Behnken statistical experiment design approach. The most suitable voltage/reaction time/solid content values resulting in the highest hydrogen gas content (99%), the highest cumulative hydrogen gas formation (7000 mL) and total organic carbon removal (33%) were determined as 5 V/75 h/20%. The results indicated that food wastes constitute a good source for H2 gas production by electrohydrolysis. Hydrogen gas produced by electrohydrolysis of food waste can be directly used in fuel cells due to its high putrity.