Maximum Amount Of Hydrogen Research Articles

Biohydrogen Production from Waste Black Cumin (Nigella Sativa) Extract Liquid.

Hydrogen creates water during combustion. Therefore, it is expected to be the most promising environmentally friendly energy alternative in the coming years. This study used extract liquid obtained from the waste nigella sativa generated by the black cumin oil industry. The performance of biological hydrogen manufacturing via dark fermentation was investigated in the fluidized bed reactor (FBR) and completely stirred tank reactor (CSTR) under the operation conditions of pH 5.0, 4.0, and 6.0 and a hydraulic retention time (HRT) of 36 and 24 h. The performance of hydrogen manufacturing was determined to be good under an organic loading ratio (OLR) of 6.66 g.nigella sativa extract/L and pH 4.0. According to these conditions, the maximum amount of hydrogen in CSTR and FBR was found to be 20.8 and 7.6 mL H2/day, respectively. The operating process of the reactors displayed that a reduction in HRT augmented biohydrogen manufacturing. The work that used mixed culture found that the dominant microbial population at pH 4.0 involved Hydrogenimonas thermophila, Sulfurospirillum carboxydovorans, Sulfurospirillum cavolei, Sulfurospirillum alkalitolerans, and Thiofractor thiocaminus. No research on waste black cumin extract was found in biohydrogen studies, and it was determined that this substrate source is applicable for biological hydrogen manufacturing.

Biohydrogen production from chewing gum manufacturing residue in a two-step process of dark fermentation and photofermentation

Abstract Two-step hybrid system of microbiological hydrogen production with the diluted solid wastes from chewing gum production as a substrate was studied. As the first step, dark fermentation with the digested sludge at different concentrations of waste was performed. The effluent originating from the dark process was subsequently applied in photofermentation with Rhodobacter sphaeroides bacteria. In the first step, the degradation of sweetening substances as well as Talha gum remaining in waste was observed. Hydrogen, carbon dioxide and liquid metabolites (Volatile Fatty Acids - VFAs) were the main products. The maximum hydrogen production in dark fermentation (0.36 L/Lmedium) was observed at concentration of 67 g waste/L. Effluents from the first step, containing mainly xylitol, butyric, acetic, lactic and propionic acids, served as the source of organic carbon for photofermentation. The maximum amount of hydrogen at this step reached 0.80 L H2/L of diluted (1:8) effluent. The presence of significant concentration of ammonium ions (∼480 mg/L) in non-diluted effluent completely ceased the hydrogen formation by nitrogenase, therefore reduction in the amount of NH4+ ions in the medium was necessary. This was realized by the dilution of effluent from dark fermentation. The total amount of hydrogen produced in sequential dark and photo-fermentation process under the optimized reaction conditions reached the volume of ∼6.7 L H2/L of non-diluted waste.

Evaluation of hydrogen production by Clostridium strains on beet molasses

Clostridium acetobutylicum DSM 792, C. acetobutylicum DSM 1731 and two newly isolated bacteria defined as the members of genus Clostridium – based on the 16S rRNA analysis and biochemical traits – were characterized with regard to their hydrogen production in media containing increasing beet molasses concentrations. The highest hydrogen yield was observed for C. acetobutylicum DSM 792 with a yield of 2.8 mol H2 mol−1 hexose in medium including 60 g L−1 molasses. This bacterium also produced the maximum amount of hydrogen (5908.8 mL L−1) at the same molasses concentration. A slightly lower hydrogen yield was measured for C. acetobutylicum DSM 1731 (2.5 mol H2 mol−1 hexose) when grown on 40 g L−1 molasses. The new isolates Clostridium roseum C and Clostridium saccharoperbutylacetonicum PF produced hydrogen with yields of 2.0 mol H2 mol−1 hexose at 40 and 60 g L−1 molasses and 2.1 mol H2 mol−1 hexose at 40 g L−1 molasses, respectively.

Hydrogen gas production from distillery wastewater by dark fermentation

The influence of concentration of distillery wastewaters, concentration of inoculum and pH value on hydrogen generation in batch dark fermentation process was studied. Anaerobic digested sludge from municipal purification unit was applied as the source of bacteria mixture. The best specific yield was obtained in system containing 10% v/v of inoculum and 20% v/v of the waste (S0/X0 = 2.8), whereas the maximum amount of hydrogen and the highest rate of reaction was achieved in system containing 25% v/v inoculum and 40% v/v of waste (S0/X0 = 2.2). The content of generated hydrogen in biogas was always higher than 62%. Maximum amount of generated hydrogen was 1 l H2/l medium and the rate was 0.12 l/l/h. Liquid metabolites of hydrogen generation process were mainly acetic and butyric acids. Ethanol and propionic acid were in traces. The ratio of HBu/HAc in medium influenced the yield of generated hydrogen.

Tricyclometalated Iridium Complexes as Highly Stable Photosensitizers for Light‐Induced Hydrogen Evolution

The development of an efficient and stable artificial photosensitizer for visible-light-driven hydrogen production is highly desirable. Herein, a new series of charge-neutral, heteroleptic tricyclometalated iridium(III) complexes, [Ir(thpy)2(bt)] (1-4; thpy = 2,2'-thienylpyridine, bt = 2-phenylbenzothiazole and its derivatives), were systematically synthesized and their structural, photophysical, and electrochemical properties were established. Three solid-state structures were studied by X-ray crystallographic analysis. This design offers the unique opportunity to drive the metal-to-ligand charge-transfer (MLCT) band to longer wavelengths for these iridium complexes. We describe new molecular platforms that are based on these neutral iridium complexes for the production of hydrogen through visible-light-induced photocatalysis over an extended period of time in the presence of [Co(bpy)3](2+) and triethanolamine (TEOA). The maximum amount of hydrogen was obtained under constant irradiation over 72 h and the system could regenerate its activity upon the addition of cobalt-based catalysts when hydrogen evolution ceased. Our results demonstrated that the dissociation of the [Co(bpy)3](2+) catalyst contributed to the loss of catalytic activity and limited the long-term catalytic performance of the systems. The properties of the neutral complexes are compared in detail to those of two known non-neutral bpy-type complexes, [Ir(thpy)2(dtb-bpy)](+) (5) and [Ir(ppy)2(dtb-bpy)](+) (6; ppy = 2-phenylpyridine, dtb-bpy = 4,4'-di-tert-butyl-2,2'-dipyridyl). This work is expected to contribute toward the development of long-lasting solar hydrogen-production systems.

Hydrogen zoning in zinc-bearing staurolite from a high-P, low-T diasporite (Samos, Greece): A combined EMP-SIMS-FIB-FTIR study

Li-rich zincostaurolite occurs as millimeter-long crystals at the marble footwall of a meta-karst-bauxite on eastern Samos. The Samos rocks have been metamorphosed during an early Alpine high- P , low- T metamorphism (M1) followed by a late Alpine greenschist-grade overprint (M2). Textures and mineral chemistry indicate that staurolite formed from gahnite, cookeite, and pyrophyllite during the early M1 stage. Staurolite crystals show growth zoning with cores enriched in Zn. Concentrations of Fe, Mg, Co, and, to a minor extent, Li increase toward the rims. Hydrogen concentrations were analyzed by SIMS. They are significantly higher in cores (up to 5.97 atoms H per 48 O) compared to rims (3.9 to 4.5 atoms H) and clearly negatively correlated with Al. Synchroton-light polarized FTIR spectra on oriented FIB-prepared foils show the same zonation effect, the absolute hydrogen concentrations being systematically lower by about 25%. The discrepancy is caused by sub-micrometer scale hydrogen loss at the crystal surface during FIB-thinning. This staurolite is unique as from the three available hydrogen sites the H3 site has the highest occupation ever observed, whereas the H2 site is not occupied. This is probably due to the high Li content. The zonation in hydrogen is interpreted as reflecting the two-stage growth. M1-staurolite that formed a low T of about 400–450 °C and high P of >1.5 GPa incorporated nearly the maximum amount of hydrogen allowed by the staurolite structure (6 H pfu) and was subsequently overgrown and marginally replaced during the M2 stage by less hydrous, Fe-Co richer staurolite. Hydrogen zoning in staurolite is facilitated by the sensitivity of its structure to changing P-T conditions. Water in staurolite is maximized at high P and low T . Cores of staurolite from Samos represent the most hydrous staurolite compositions reported to date.

Hydrogen production conditions from food waste by dark fermentation with Clostridium beijerinckii KCTC 1785

The optimum conditions for biological hydrogen production from food waste by Clostridium beijerinckii KCTC 1875 were investigated. The optimum initial pH and fermentation temperature were 7.0 and 40°C, respectively. When the pH of fermentation was controlled to 5.5, a maximum amount of hydrogen could be obtained. Under these conditions, about 2,737 mL of hydrogen was produced from 50 g COD/L of food waste for 24 h, and the hydrogen content in the biogas was 38%. Hydrogen production rate and yield were about 108 mL/L·h and 128 mL/g CODdegraded, respectively. High concentrations of acetic (< 5,000 mg/L) or butyric acid (< 3,000 mg/L) significantly inhibited hydrogen production.

Utilization of gamma-ray irradiation for hydrogen production from water

A technique has been proposed to promote hydrogen production from water by increasing the energy deposition in water through the conversion of γ-ray to low-energy electrons, which is achieved by putting solid materials into water. Simulation studies by the MCNP code indicate that the average deposited energy in water can be increased by optimizing geometry of the materials. In the present experiments using Al2O3 particles of various average diameters, the maximum amount of hydrogen produced is 3.48 μmol/cm3 for the water containing Al2O3 particles of 3 μm diameter, which is more than two order of magnitude larger of the H2 produced in water-only configuration.

TiNi-YNi alloys. Interaction with hydrogen

Phase equilibria in the Ti-Ni-Y system at the TiNi-YNi section are studied using physical and chemical methods (metallography, radiography, differential thermal and electron microprobe analyses). Data on hydrogen sorption and desorption by ternary system Y-Ni alloys are obtained. It is shown that the TiNi-YNi section is quasibinary eutectic with the coordinates 990 °C and ∼40 at.% Y. The solubility of Y and Ti in TiNi and YNi mononickelides is approximately + + . Based on sorption data, two hydrides may exist in the alloys with 30 to 40 at.% Y, which are thermally stable at 800 °C and over a range of 300 to 600 °C. It is revealed that the maximum amount of hydrogen at 0.1 MPa is absorbed by binary the YNi, YNi2, and YNi5 phases at room temperature.

Transition-metal-doping-enhanced hydrogen storage in boron nitride systems

The authors perform spin-polarized density functional theory simulations on the 3d transition metal (TM) series (Sc to Fe) doped system borazine (B3N3H6). The Sc and Ti bind most strongly to borazine but Cr and Mn do not bind at all. With increasing hydrogen content the bound hydrogen species becomes molecular. The maximum amount of hydrogen that can be stored is 4H2 per TM atom for Sc, Ti, and V dopants (∼6wt% bound hydrogen). The binding energy of hydrogen in these systems is of the order of −0.3to−0.7eV∕H2, desirable for practical hydrogen storage applications. The optimum dopant is titanium.

Nitrous oxide pneumoperitoneum revisited

Nitrous oxide has been effectively banned from use in therapeutic laparoscopy because of fear of combustion. These fears rest on two case reports, a misunderstanding of the physical chemistry of nitrous oxide, and lack of information on the presence of flammable colonic gases in the pneumoperitoneum mixture. This study aims to identify the presence and quantify the amount of hydrogen and methane found in the peritoneal cavity during laparoscopic GI procedures, and then to compare the gas concentrations detected with known limits of combustion. Gas standards with known concentrations of hydrogen and methane were placed in polypropylene syringes and analyzed on a mass spectrometer after 1, 2, 3, and 4 h. This established the rate at which these gases would be leached through a polypropylene syringe--the amount of gas lost during transport from the patient to the laboratory. Twenty gas samples were drawn, randomly, 30 min to 2 h following the start of laparoscopic gastrointestinal procedures. The samples were analyzed for hydrogen and methane within 30 min of their aspiration from the abdominal cavity. An inconsequential amount of methane was lost from the polypropylene syringe in 4 h. After 1 h, one-half the hydrogen had leached from the polypropylene syringe. Hydrogen was detected in the pneumoperitoneum of four patients at a concentration ranging from 0.016 to 0.075%. No methane was detected in any sample. For combustion to occur in a nitrous oxide environment, hydrogen or methane must occupy 5.5% of the gas volume. The maximum amount of hydrogen we detected was less than 1/50 of the combustion threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of nitrogen source on hydrogen generation by a photosynthetic bacterium

Axenic culture of photosynthetic purple sulphur bacterium, isolated from a paper mill effluent, grew best with ammonium chloride as nitrogen source. Cells grown with N2 or ammonium chloride produced hydrogen with initial lag periods of 24 and 48 h, respectively. The maximum amount of hydrogen was evolved by cells grown with N2 and with malate as electron donor.

Corrosion studies of a stainless steel structure for the ITER aqueous lithium salt blanket concept

The aqueous lithium salt blanket (ALSB) employs water, with a dissolved lithium compound, as both the coolant and tritium breeding medium. The ALSB concept is one of three blanket options currently being examined for breeding tritium in the International Thermonuclear Experimental Reactor (ITER). To provide data and recommendations for materials and chemistry selection relevant to application of the ALSB in ITER, corrosion studies have been initiated, focusing on type 316 stainless steel in lithium hydroxide and lithium nitrate solutions. This paper presents the preliminary results of these corrosion studies. The results to date, while preliminary, suggest that even at 90°C, a blanket utilizing 10% LiOH (the current lithium salt of choice for ITER ALSB applications) will not cause catastrophic failure of 316 stainless steel by either stress corrosion cracking or localized corrosion; that the general corrosion rate will not exceed about 40 μm/y and transport of material will certainly be much less than this value since most of the corrosion product will be included in the strong adherent surface film; and that, although hydrogen may be evolved due to electrolysis, the maximum amount of hydrogen is small compared to that expected to be produced by radiolysis. These observations are predicated on the assumption that the blanket will be completely deaerated, and that the corrosion potential of the alloy will be similar to that observed in the laboratory.

Photodecomposition of H 2S by silver doped cadmium sulfide and mixed sulfides with ZnS

Photogeneration of hydrogen by splitting water is a subject of high priority in solar energy related research. Another important area where hydrogen can be generated from cheap and readily available material is the photodecomposition of H 2S which is being produced in large quantities as a by-product in the coal and petroleum industries. In this paper we report the photochemical splitting of H 2S by CdS, CdS/Ag s, Cd x Zn x /Ag + loaded with platinum. The maximum amount of hydrogen was obtained in the case of CdS and Cd x Zn x S/Ag + with 20% of Pt (wt %) on to the semiconductor particle. A higher concentration of Pt than 2% has shown a decrease in the hydrogen evolution rate. The optimum quantities of Pt. Ag 2S and ZnS for optimum production of H 2 are 2%, 10,000 ppm and 20 mol%, respectively. A mechanism of the reaction is presented and discussed. The process of splitting H 2S may find an application in environmental pollution control for industry where H 2S and sulfides are formed as waste product pollutants.

The Effect of Reduced Intake-Air Pressure and of Hydrogen on the Performance of a Solid Injection Oil Engine

Summary(a)Introductory.—The paper deals with experiments carried out in the engineering laboratories of the University of Manchester on a Crossley solid-injection oil engine in which small quantities of hydrogen or coal gas were introduced along with the air supply to the engine.(b)Range of Investigation.—Three series of trials were run with hydrogen, each at a different load, namely, 53·4, 39·4, and; 24·4 b.h.p. The maximum amount of hydrogen used was slightly more than 3 per cent. by volume of the air supply, corresponding, at the lightest load, to some 14 per cent, by weight of the oil fuel supply.Three corresponding series of trials were run using coal gas in place of hydrogen, the maximum volume of gas employed being 5 per cent. of the air supply. At the lightest load this corresponds to approximately 2·4 times the weight of fuel oil used.(c)Conclusions.—Such quantities of hydrogen or coal gas can be used satisfactorily in the type of engine considered. No trouble was experienced due to pre-ignition or other causes, and the engine appeared to run more sweetly when gas was being used.When running at constant load and speed, the admission of small quantities of gas appears to cause combustion to take place at a slower rate, giving a lower maximum pressure and more burning down the expansion stroke. The thermal efficiency is in consequence slightly reduced, while the heat-losses to exhaust are increased.