Amount Of H2 Research Articles

Rationally designed novel multifunctional poly(ionic liquid)s for ultra-selective valorization of Yiwu lignite to monocyclic aromatic compounds

The selective valorization of lignite into monocyclic aromatic compounds (MCACs) is extremely challenging due to its chemical inertness and geometrical complexity. The catalytic efficiency of lignite valorization into MCACs over solid acids is significantly reduced by the presence of H2O resulting in the leaching and deactivation of acid sites. Moreover, the precise fabrication of poly(ionic liquid)s (PILs) containing Brønsted-Lewis acidic sites, well-defined mesoporous channels, and hydrophobicity remains a considerable challenge. Herein, a novel hydrophobic mesoporous PILs with strong Brønsted-Lewis acid sites was successfully constructed by a synergistic regulation-induced copolymerization strategy for the first time. More exotically, the resultant multifunctional PILs was found to be ultra-efficient catalyst for the selective valorization of Yiwu lignite (YL) into MCACs with 23.5 wt.% yield, which is the highest yield reported for lignite catalytic valorization by precious metal-free catalysts under mild conditions. The co-catalysis mechanisms of YL valorization into MCACs over the multifunctional PILs are confirmed by characterization methods and the synergistic catalysis mechanisms are as follows: (1) hydrophobic micro-environment: the hydrophobic micro-environment created by hydrophobic block is favorable for preventing the leaching and deactivation of Brønsted-Lewis acid sites; (2) mesoporous confinement: the well-defined mesoporous channels strengthen the adsorption amount of H2 and increases the concentration of substrates; (3) synergistic catalytic active hydrogen transfer of Brønsted-Lewis acid sites: Brønsted-Lewis acid sites synergistically promote H2 heterolysis to the mobile H+ and immobile H−, and then the resulting mobile H+ transfers to oxygen atom in lignite to produce MCACs via C–O bond cleavage. This work not only sheds some light on developing the multifunctional solid acid catalysts, but also demonstrates an efficient catalyzing method to produce lignite-based MCACs by co-catalysis of Brønsted-Lewis acidic sites, mesoporous confinement, and hydrophobic micro-environment.

Boosting the H2 Production Efficiency via Photocatalytic Organic Reforming: The Role of Additional Hole Scavenging System

The simultaneous photocatalytic H2 evolution with environmental remediation over semiconducting metal oxides is a fascinating process for sustainable fuel production. However, most of the previously reported photocatalytic reforming showed nonstoichiometric amounts of the evolved H2 when organic substrates were used. To explain the reasons for this phenomenon, a careful analysis of the products and intermediates in gas and aqueous phases upon the photocatalytic hydrogen evolution from oxalic acid using Pt/TiO2 was performed. A quadrupole mass spectrometer (QMS) was used for the continuous flow monitoring of the evolved gases, while high performance ion chromatography (HPIC), isotopic labeling, and electron paramagnetic resonance (EPR) were employed to understand the reactions in the solution. The entire consumption of oxalic acid led to a ~30% lower H2 amount than theoretically expected. Due to the contribution of the photo-Kolbe reaction mechanism, a tiny amount of formic acid was produced then disappeared shortly after the complete consumption of oxalic acid. Nevertheless, a much lower concentration of formic acid was generated compared to the nonstoichiometric difference between the formed H2 and the consumed oxalic acid. Isotopic labeling measurements showed that the evolved H2, HD, and/or D2 matched those of the solvent; however, using D2O decreased the reaction rate. Interestingly, the presence of KI as an additional hole scavenger with oxalic acid had a considerable impact on the reaction mechanism, and thus the hydrogen yield, as indicated by the QMS and the EPR measurements. The added KI promoted H2 evolution to reach the theoretically predictable amount and inhibited the formation of intermediates without affecting the oxalic acid degradation rate. The proposed mechanism, by which KI boosts the photocatalytic performance, is of great importance in enhancing the overall energy efficiency for hydrogen production via photocatalytic organic reforming.

Valorization of biomass as co-catalyst for simultaneous remediation and hydrogen production from sugar industry wastewater by catalytic wet air oxidation

In this study, the usage of biomass-based materials as co-catalysts was tested for simultaneous sugar industry wastewater treatment/hydrogen production by catalytic wet air oxidation and the final product distribution in gas and liquid effluents were investigated. For this purpose, biochar (BC) and graphene oxide-like biomass derivative (BGO) were synthesized from corncob and coupled with LaCoO3 (LC). LaCoO3-Biochar (LC/BC) catalyst was determined as the most compatible one with pure LC in terms of removal efficiencies which were approximately 100% for total saccharide (TSC), 90% of total organic carbon (TOC) and chemical oxygen demand (COD) removal, respectively. This shows that biochar is a promising alternative to replace metal catalysts. The catalyst reusability was examined and the fresh and used catalysts were characterized by SEM-EDX, XRD, and BET analyses. There were slight decreases in catalytic activities of all catalysts including LC which were associated with the chemical and morphological alterations supported by the characterization analyses as a result of formation of acidic intermediates some of which were identified as formic acid and acetic acid in the liquid effluent. The formation of CO2 was determined as proportional with TOC reduction but the behaviour for H2 production was the opposite as a result of total oxidation in which the final products are CO2 and H2O. Although the amount of H2 produced was relatively lower for the selected catalyst LC/BC with higher treatment performance, the produced H2/initial sucrose ratio equal to 0.109 was considered as promising.

The role of tungsten chemical state and boron on ammonia formation using N2–H2 radiofrequency discharges

This work aims at investigating the role of tungsten and boron surfaces on ammonia production with N2–H2 radiofrequency plasmas at 3 Pa. The experiments combine the analysis of the reaction products and surface chemical environment using mass spectrometry and x-ray photoelectron spectroscopy (XPS). We show that NH3 is formed upon discharges of N2 or H2 after having exposed a tungsten (W) foil to H2 or N2, respectively. A higher amount of ammonia is formed for the N2-then-H2 case, which we explain by the larger number of Eley–Rideal reaction channels for the formation of NH x (s) and the lower surface diffusion barrier for adsorbed hydrogen, calculated using the density functional theory (DFT). As a result, H(s) combines with N(s) or NH x (s) through Langmuir–Hinshelwood at a faster rate than N(s) combines with another N(s). The amount of NH3 formed with N2–H2 discharges after conditioning the tungsten foil with H2, N2 or O2 was also investigated. We observed that this pre-conditioning plays no major role on the amount of NH3 detected with the residual gas analyser, albeit a small decrease was observed after H2 contamination. With DFT, the adsorption energies of H on WO3 and W are found to be similar, while the adsorption of N on WO3 is significantly weaker. The similar NH3 concentrations obtained with a clean and oxidized tungsten surface thus suggest that the adsorption of N does not limit the formation rate of ammonia. The production of NH3 on boron was evaluated as well. The boron surface reduced the amount of detected ammonia almost by half. On the one side, a significant amount of H2 was removed from the surface during the Ar cleaning that followed, which suggests a strong retention of hydrogen. On the other side, the XPS data reveals that nitrogen forms strong bonds with boron and impurities on the surface, regardless on whether hydrogen is previously present on the surface or in the plasma volume. The presence of hydrogen in the plasma volume, simultaneously with nitrogen or after nitrogen exposure, is nevertheless necessary for the formation of NH(s) and NH2(s). No NH3(s) was however detected with XPS. The increased retention of both hydrogen and nitrogen on the boron surface may thus hinder the formation of NH3.

Direct utilization of CO2 via methanol synthesis for natural gas fields with high CO2 concentration

CO2-rich natural gas fields are left abandoned because of the large amount of energy required for the complete separation of CO2 and the relatively low CH4 content. To utilize such natural gas, this study investigated the direct transformation of CO2 via reforming and methanol synthesis. An acid gas removal unit was used to remove H2S and release sweet gas, including a mixture of CO2 and CH4. Two different amine absorbents were considered to compare the effects of CO2 concentration in the sweet gas—methyldiethanolamine (MDEA) and a mixture of MDEA and diethanolamine (DEA). Sweet gas was fed into the reforming process, where syngas was produced via dry reforming. Because dry reforming produced syngas with a small amount of H2, steam supplementation through a high-pressure steam generator was considered to promote steam reforming by recycling the water produced by the reverse water-gas-shift reaction or by feeding additional water. Syngas was fed into the methanol synthesis process, and the recycled cases showed higher methanol production rates than the open-loop cases despite the decreased local conversion of CO. Techno-economic analysis was performed to determine the optimal configuration to maximize profitability; the Case II-5-R (a mixture of MDEA and diethanolamine (DEA), steam supplementation of 1500 kgmole/h, recycle loop) was selected as the optimal case with a payback period of 4.24 years and return on investment of 0.173 y−1. The techno-economic analysis proved that the proposed strategy can promote further development of natural gas fields with high CO2 concentrations.

Hydrogen Production from Alteration of Chicxulub Crater Impact Breccias: Potential Energy Source for a Subsurface Microbial Ecosystem.

A sulfate-reducing population of thermophiles grew in porous, permeable niches within glass-bearing impact breccias of the Chicxulub impact crater. The microbial community grew in an impact-generated hydrothermal system that vented on the seafloor several hundred meters beneath the sea surface. Potential electron donors for that metabolism are hydrocarbons, although a strong C-isotope signature of that source does not exist. Model calculations explored here suggest that alteration of glass within the impact breccias may have produced H2 in sufficient quantities for population growth as the hydrothermal system cooled through thermophilic temperatures, although it is sensitive to the oxidation state of iron in the melt rock prior to hydrothermal alteration and the secondary mineral assemblage. At high water-to-rock ratios and temperatures below 45°C, H2 yields are insufficient to maintain a population of hydrogenotrophic sulfate-reducing bacteria, but yields double with a higher proportion of ferrous iron between 45 and 65°C. The most reduced rocks (i.e., highest proportion of ferrous iron) that are allowed to form andradite, which is observed in core samples, produce copious amounts of H2 in the temperature window for thermophiles and hyperthermophiles. Mixtures of melt rock and carbonate, which is observed in breccia matrices, produce somewhat less H2, and the onset of massive H2 production is shifted to higher temperatures (i.e., lower W/R).

Effect of Localized Temperature Difference on Hydrogen Fermentation

In a lab-scale bioreactor system, (20 L of effective volume in our study) controlling a constant temperature inside bioreactor with a total volume 25 L is a simple process, whereas it is a complicated process in the actual full-scale system. There might exist a localized temperature difference inside the reactor, affecting bioenergy yield. In the present work, the temperature at the middle layer of bioreactor was controlled at 35 °C, while the temperature at top and bottom of bioreactor was controlled at 35 ± 0.1, ±1.5, ±3.0, and ±5.0 °C. The H2 yield of 1.50 mol H2/mol hexoseadded was achieved at ±0.1 and ±1.5 °C, while it dropped to 1.27 and 0.98 mol H2/mol hexoseadded at ±3.0 and ±5.0 °C, respectively, with an increased lactate production. Then, the reactor with automatic agitation speed control was operated. The agitation speed was 10 rpm (for 22 h) under small temperature difference (<±1.5 °C), while it increased to 100 rpm (for 2 h) when the temperature difference between top and bottom of reactor became larger than ±1.5 °C. Such an operation strategy helped to save 28% of energy requirement for agitation while producing a similar amount of H2. This work contributes to facilitating the upscaling of the dark fermentation process, where appropriate agitation speed can be controlled based on the temperature difference inside the reactor.

Bifunctional catalyst based on molecular structure: Spherical mesoporous TiO2 and gCN for photocatalysis

Here, we designed a molecular structure fabrication route based on spherical mesoporous TiO2 and exfoliated graphitic carbon nitride (mTiO2_ex-gCN) by combining hard templating and hydrothermal methods. The mTiO2_ex-gCN boosted two photocatalytic processes: hydrogen evolution under simulated solar illumination and degradation of Rhodamine B (RhB) with the assistance of UV–vis and visible light irradiations. RhB degradation under UV–vis light was 2.94 and 1.39 times higher than ex-gCN and mTiO2, respectively. Additionally, dye degradation under visible light was enhanced by a 1.22 factor in respect to ex-gCN. However, a more spectacular performance was detected in the process of photocatalytic hydrogen evolution – the efficiency of the catalyst yielded a 70 times higher amount of H2 in respect to ex-gCN. It is proposed that enhanced photocatalytic activity is due to synergy provided by individual counterparts, which tuned energy band gap, improved specific surface area, and enhanced ability to suppress the charge carrier recombination.

In-Operando Measurement of Hydrogen Crossover in Proton Exchange Membrane Electrolysis Cells at Differential Pressures

Low temperature water electrolysis (LTE) using proton exchange membrane electrolysis cells (PEMECs) is a promising approach for producing green H2 that can use electricity from renewable sources. In practice, H2 is stored and dispensed at high pressures. To alleviate efficiency losses associated with pressurizing the product hydrogen, PEMECs can be operated at high differential pressures, e.g., >30bar on the cathode side. However, high differential pressure operation can result in undesirable H2 crossover to the anode (O2) side. This not only reduces the Faradaic efficiency of the cell, but also can result in flammability hazards. H2 crossover in PEMECs is a function of both materials properties such as membrane thickness, water uptake, and permeability, and operating conditions such as temperature, differential pressure, and current density. Example data are shown in Figure 1. While thinner membranes are susceptible to higher H2 crossover rates, they are a desirable material to use because they can result in significantly improved cell performance and lower material and production costs. To mitigate safety concerns related to H2 crossover, gas recombination catalyst (GRC) layers can be introduced into the membrane electrode assembly. The GRCs will react the crossover H2 with O2 to produce water, thereby minimizing the amount of H2 entering the O2 stream. In this talk we will present data from in-operando crossover measurements of PEMECs employing a variety of membrane materials, both with and without GRCs. The experiments are complimented by modeling results that allow further insights into the processes at hand. Multiple temperatures, differential pressures, and current densities are studied. The results will investigate the tradeoff between performance and capturable H2 production that occurs when thinner membranes are used, and how this effect responds to differential pressure operation. Figure 1

Large Eddy Simulation of rich ammonia/hydrogen/air combustion in a gas turbine burner

Ammonia and hydrogen are promoted as potential energy carriers for centralized energy restitution. This article investigates ammonia/hydrogen/air premixed turbulent combustion, using Large-Eddy Simulations, in an academic atmospheric gas turbine swirled burner. A one-dimensional flame analysis demonstrates the existence of a trade-off in NOX and NH3 emissions for ammonia/hydrogen blends, and the possibility to obtain 1D flame propagation characteristics close to that of a lean methane flame by adjusting the amount of H2. Large-Eddy Simulations of the PRECCINSTA burner exhibit stable combustion, while the optimized trade-off equivalence ratio is pinpointed at φ=1.46 for XH2Fuel=0.46. Corresponding emissions are XNOX≈XNH3≈300 ppmv. Large amounts of hydrogen are found in the exhaust gases, inducing a low combustion efficiency. The flame structure, combustion dynamics, influence of kinetics modelling and mesh resolution are discussed. This work paves the way for future studies, in the perspective of applications to industrial systems.

(Keynote) Towards Robust Li-Mediated Electrosynthesis of Ammonia at High Rate and Faradaic Efficiency

Synthesis of ammonia will most likely rely on the Haber-Bosch technologies for a reasonable period of time, but will now use increasing amounts of H2 derived from water electrolysis to substantially decrease the CO2 footprint. The next stage of the technological evolution of NH3 production will build upon electrochemical systems combining the nitrogen reduction and hydrogen oxidation half-reactions. The preference of H2 as a source of electrons and protons over water is dictated by the very high sensitivity to even very low concentrations of H2O of the current most efficient (and arguably the only) approach to convert N2 to NH3 electrochemically, viz. via a lithium redox mediated process.The presentation will discuss possible strategies towards further improvements in the sustainable NH3 synthesis from N2 and H2 in aprotic electrolyte solutions and will present latest developments in the field from our group. Notwithstanding the hydrogen oxidation reaction is the most studied and best understood electrocatalytic process in aqueous electrolytes, it presents a broad host of challenges when attempted in organic media. This will be demonstrated through the comparison of the H2 oxidation kinetics in various tetrahydrofuran-based electrolytes for different nanoparticulate metal catalysts. In the domain of the nitrogen reduction reaction, the development of stable high-performance Li-mediated systems through the design of a genuinely stable proton shuttle and optimised electrolytes will be presented. Implementation of these strategies enables robust ammonia electrosynthesis on a timescale of days with the yield rates of ca 200 nmol s-1 cm-2 (per cathode surface area) and with a faradaic efficiency for the N2 reduction to NH3 of 99 ± 2 %. In conclusion, a perspective on possible future directions that are likely to further advance the presented technologies and the overall concept of the Ammonia Economy for the future energy will be discussed.

A Novel Porous Ti-Squarate as Efficient Photocatalyst in the Overall Water Splitting Reaction under Simulated Sunlight Irradiation.

A new porous titanium(IV) squarate metal-organic framework (MOF), denoted as IEF-11, having a never reported titanium secondary building unit, is successfully synthesized and fully characterized. IEF-11 not only exhibits a permanent porosity but also an outstanding chemical stability. Further, as a consequence of combining the photoactive Ti(IV) and the electroactive squarate, IEF-11 presents relevant optoelectronic properties, applied here to the photocatalytic overall water splitting reaction. Remarkably, IEF-11 as a photocatalyst is able to produce record H2 amounts for MOF-based materials under simulated sunlight (up to 672 µmol gcatalyst in 22 h) without any activity loss during at least 10 d.

Production of Hydrogen by Purple Non-Sulfur Bacteria Rhodopseudomonas yavorovii IMV B-7620

Hydrogen production by microorganisms is studied by using different sources of carbon for their cultivation. Purple non-sulfur bacteria are capable of producing molecular hydrogen phototrophically with the simultaneous accumulation of biomass on organic substrates that may be waste from various industries. That fact makes the study of this group of microorganisms very much promising. The aim. The determination of the ability of purple non-sulfur bacteria Rhodopseudomonas yavorovii IMV B-7620 to produce hydrogen consuming different organic substrates and their effects on the main metabolic indicators of culture growth. Methods. Bacteria were grown in 100 mL glass jars in liquid modified ATCC No. 1449 medium for 14 days at temperature +27...+30ºC and at constant light (200 lux). Biomass accumulation and hydrogen production in the cultivation medium were determined using sodium acetate (12 and 36 mM), malate (12 and 36 mM), succinate (36 mM), glucose (36 mM), starch (36 mM), sodium citrate (36, 60, 90 mM). Biomass was determined turbidimetrically, the composition of the gas phase was determined using a gas chromatograph LHM-8-MD, redox potential and pH were estimated potentiometrically. The volume of gas synthesized was measured on a syringe scale. Determination of the content of organic acids in the culture liquid was analyzed by high performance liquid chromatography. Results. The utilization of organic compounds (malate, glucose, starch, sodium citrate) by R. yavorovii IMV B-7620 is accompanied by hydrogen synthesis. Under the growth with sodium acetate, bacteria produce small amounts of succinate. The malate metabolism results in the production of small amounts of fumarate on the 7th day of cultivation and isocitrate on the 10th day of cultivation. On the 14th day of cultivation, the cultural liquid contains a small amount of succinate. On the 14th day of cultivation, R. yavorovii IMV B-7620 produces 7.64±0.04% of hydrogen in the medium with malate (36 mM). However, the maximum concentration of hydrogen in the gas phase (21.26±0.08%) was gained on the 14th day of cultivation in the medium with sodium citrate. The maximum concentration of H2 in the gas phase during the growth in the medium with sodium citrate (60 mM) and NH4+ was 27.83±5.46% on the 7th day of cultivation and 35.69±0.40% with increasing concentration of sodium citrate up to 90 mM on the 10th day of cultivation. The total volume of hydrogen was 25.54±0.49 mL of H2 during the growth of R. yavorovii IMV B-7620 in the medium with 90 mM sodium citrate and NH4+. That is 1.5 times more than the amount of H2 produced during the growth of bacteria in the medium with 60 mM sodium citrate with the addition of NH4+. Conclusion. Purple non-sulfur bacteria R. yavorovii IMV B-7620 synthesize hydrogen during photofermentation of organic compounds. Bacteria were isolated from the water of Yavoriv Lake (Lviv region, Ukraine) formed as a result of flooding of the sulfur quarry. Bacteria consume sodium citrate, malate, glucose, starch and emit hydrogen. The total volume of hydrogen during the growth of R. yavorovii IMV B-7620 in the medium with 90 mM sodium citrate and NH4+ is 25.54±0.49 mL H2.

Hydrogen generation from serpentinization of iron-rich olivine on Mars, icy moons, and other planetary bodies

Serpentinization of olivine-rich ultramafic rocks is increasingly recognized to have been widespread in the solar system throughout its history. This process has gained particular attention among planetary scientists because it generates molecular hydrogen (H2) and methane (CH4), compounds that can supply metabolic energy to biological communities and contribute to greenhouse warming of planetary atmospheres. While serpentinization of olivine has been the subject of numerous experimental and theoretical studies over the years, this work has focused almost exclusively on the magnesium-rich olivine that is characteristic of the terrestrial mantle. In contrast, very few studies have examined serpentinization of the more iron-enriched olivine compositions that may be more common in other rocky planetary bodies in the solar system. Accordingly, a series of thermodynamic models were constructed to investigate secondary mineral formation and H2 generation during serpentinization of olivine as a function of Fe content and temperature. The results show that serpentinization of Fe-rich olivine is capable of generating substantially greater amounts of H2 per mole than is observed for serpentinization of Mg-rich olivine, by a factor of two to ten depending on temperature and olivine composition. For all olivine compositions, H2 is generated from ferric Fe incorporated into both magnetite and serpentine at higher temperatures; however, it is derived exclusively from precipitation of serpentine at lower temperatures as brucite replaces magnetite in the equilibrium secondary mineral assemblage. Serpentine and brucite formed during serpentinization are predicted to become increasingly enriched in Fe with greater Fe content of the original olivine, although the serpentine has proportionally lower Fe contents than the olivine while brucite has somewhat higher Fe contents. Between 10% and 40% of the Fe partitioned into serpentine occurs in the ferric state (FeIII), which accounts for a substantial fraction of H2 production for most conditions. In addition, the maximum temperature at which olivine undergoes serpentinization decreases with increasing Fe content of the olivine, so that Fe-enriched olivine can remain stable to lower temperatures when compared with more Mg-rich olivine compositions. Overall, the results indicate that serpentinization on other planetary bodies may have a substantially greater capacity to supply H2 to support biological communities and enhance atmospheric greenhouse warming than analogous processes on Earth.

Effects of Diesel-Biodiesel-Ethanol Fuel Blend on a Passive Mode of Selective Catalytic Reduction to Reduce NO x Emission from Real Diesel Engine Exhaust Gas.

The effects of ethanol on combustion and emission were investigated on a single-cylinder unmodified diesel engine. The ethanol content of 10–50 vol % was chosen to blend with diesel and biodiesel fuels. Selective catalytic reduction (SCR) of nitrogen oxides (NOx) in the passive mode was also studied under real engine conditions. Silver/alumina (Ag/Al2O3) was selected as the active catalyst, and H2 (3000–10000 ppm) was added to assist the ethanol-SCR. The low cetane number of ethanol resulted in longer ignition delay. The diesel–biodiesel–ethanol fuel blends caused an increase in fuel consumption due to their low calorific value. The brake thermal efficiency of the engine fuelled with relatively low ethanol fraction blends was higher than that of diesel fuel. Unburned hydrocarbons (HC) and carbon monoxide (CO) increased, while NOx decreased with ethanol quantity. The higher ethanol quantity led to increases in the HC/NOx ratio which directly affected the performance of NOx-SCR. Addition of H2 considerably improved the activity of Ag/Al2O3 for NOx reduction. The proper amount of H2 added to promote the ethanol-SCR depended strongly on the temperature of the exhaust where a high fraction of H2 was required at a low exhaust temperature. The maximum NOx conversion of 74% was obtained at a low engine load (25% of maximum load), an ethanol content of 50 vol %, and H2 addition of 10000 ppm.

Protective Effect of Molecular Hydrogen Following Different Routes of Administration on D-Galactose-Induced Aging Mice.

BackgroundMolecular hydrogen (H2) has been recognized as an effective antioxidant with no or little side effects. While it is known that oxidative stress is closely associated with aging, the beneficial effect of H2 on oxidative stress-related aging is still unclear. In this study, a mouse model of D-galactose-induced aging was employed to investigate the protective effects of H2.MethodsThe mice were administrated of H2 via different routes (4% H2 inhalation, H2-rich water drinking, and H2-rich saline injection), the aging-related biomarkers in plasma and the oxidative stress in different tissues were measured.ResultsThe results showed that H2 improved aging-related biomarkers, ie, total antioxidant capacity, advanced glycation end products, tumor necrosis factor-α, free fatty acids, and alanine aminotransferase in plasma. Furthermore, H2 alleviated oxidative stress in the liver, brain, and heart by reducing the levels of lipid peroxidation and malondialdehyde and increasing the activity of superoxide dismutase. In addition, it seems that 4% H2 inhalation was the most effective regarding the amount of H2 taken up and in reducing the markers of oxidative stress in some of the tissues; however, the other routes of administration resulted in the same efficacy in most indicators.ConclusionH2 can prevent oxidative stress in D-galactose-induced aging mice when administered by different routes.

Stray Gassing of Oil in HV Transformers

Currently produced insulating oils tend to generate gases at relatively low temperatures (90–200 °C). This phenomenon, defined by CIGRE as stray gassing (SG), can hinder the diagnostics of oil-filled electrical equipment based on the DGA method, because high amounts of hydrogen H2 and saturated hydrocarbons can sometimes occur in service without an actual fault. The aim and contribution of this article is to present how to distinguish such cases from electrical partial discharges or hot spots in paper, which may be risky for the safe operation of equipment and demand further investigation. Very high levels of H2 and high levels of C2H6 are observed recently in some families of HV transformers in Poland. This article presents DGA results of oil samples taken from these transformers together with results of laboratory tests of stray gassing of these oils performed according to CIGRE procedure. By using Duval Pentagon 2 it is possible to compare stray gassing patterns in the laboratory and in real transformers and evaluate the temperature range of possible defects. Stray gassing/overheating of oil in transformers, within this temperature range and whatever the possible other causes, is not a concern for their safe operation, according to observations published by CIGRE.

Analysis of Biohydrogen Production Potential from Organic Wastes Generated in Korea

Objectives : To mitigate greenhouse gas (GHG) emissions, our country is trying to replace fossil fuel to hydrogen (H2). H2 has higher energy yield (122 MJ/kg) than other energy sources (natural gas, coal, etc.), and is considered a clean fuel that produces only water upon combustion. The water electrolysis using renewable energy is one of the green-H2 producing methods, but its unstable characteristics depending on weather condition impede its practical application. Therefore, to establish green-H2 society, the use of waste and biomass is essential to fulfil the demand.Methods : In this study, we estimated the biohydrogen potential of organic solid wastes: food waste, livestock manure, and sewage sludge, which are the main feedstock of domestic biogas plant. For the H2 generation process, dark fermentation (DF) and steam biogas reforming (SBR) were considered.Results and Discussion : The potential amount of H2 through DF and SBR was 44,000 ton/y and 675,000 ton/y, respectively. The GHG reducing potential was estimated to be 5 million tons CO2-eq/year, but it can be lowered down to 2 million tons CO2-eq/year, considering the energy consumption during H2 generation process. Among the energy potential of produced H2, 7% and 60% is required for H2 production in DF and SBR, respectively.Conclusion The expected biohydrogen production was 718,000 ton/y which can account for about 14% of the domestic H2 production target in 2040 (526 million tons). The main source was livestock manure (86%), and minor fraction was from food waste (10%), and sewage sludge (4%). The GHG reducing potential was estimated to be 2 million tons CO2-eq/year, considering the energy consumption during H2 generation process.

Clostridium chrysemydis sp. nov., isolated from the faecal material of a painted turtle.

A strict anaerobic, Gram-stain-positive rod-shaped bacterium, designated PTT, was isolated from the faecal material of a painted turtle (Chrysemys picta). Based on a comparative 16S rRNA gene sequence analysis, the isolate was assigned to Clostridium sensu stricto with the highest sequence similarities to Clostridium moniliforme (97.4 %), Clostridium sardiniense (97.2 %) and the misclassified organism Eubacterium multiforme (97.1 %). The predominant cellular fatty acids of strain PTT were C14 : 0, C16 : 0 and an unidentified product with an equivalent chain length of 14.969. The G+C content determined from the genome was 28.8 mol%. The fermentation end products from glucose were acetate and butyrate with no alcohols detected and trace amounts of CO2 and H2 also detected; no respiratory quinones were detected. Based on biochemical, phylogenetic, genotypic and chemotaxonomic criteria, the isolate represents a novel species of the genus Clostridium for which the name Clostridium chrysemydis sp. nov. is proposed. The type strain is strain PTT (=CCUG 74180T=ATCC TSD-219T).

Hydrogen Production via Activated Waste Aluminum Cans and Its Potential for Methanation

The production of hydrogen via aluminum waste can powder (AWCP) prepared via disintegration and mechanochemical activation using metals was explored. AWCP and its composites were reacted in 1 M NaOH to produce hydrogen at standard temperature (25 °C) condition. Ternary AWCP (3% Sn–3% Mg) composite produced the highest amount of H2 (660 mL/0.5 g in 660 s) in terms of weight percentage of AWCP used as compared to the best binary AWCP (3% Sn) with 680 mL of H2 produced in 240 s. The activation metals contributed microgalvanic activity in AWCP, which in result yielded higher hydrolysis of AWCP. The undoped AWCP, binary, and ternary composites were tested for batch methanation at 220 °C using CO2 gas and Ni based catalyst. H2 produced from aluminum–water reaction was successfully used to produce CH4 via continuous methanation process. However, not all the H2 produced participated in the reaction. This was mainly due to the role of gas hourly space velocity and the performance of the catalyst. Undoped AWCP performed better than binary and ternary composite despite higher amount H2 produced due to the gas hourly space velocity. The potential of AWCP as a raw material for H2 production and simultaneous methanation has led to a promising solution of producing clean, sustainable, and economical energy for the future.