Hydrogen Production Ability Research Articles

Reclassification of non-type strain Clostridium pasteurianum NRRL B-598 as Clostridium beijerinckii NRRL B-598

The complete genome sequence of non-type strain Clostridium pasteurianum NRRL B-598 was introduced last year; it is an oxygen tolerant, spore-forming, mesophilic heterofermentative bacterium with high hydrogen production and acetone-butanol fermentation ability. The basic genome statistics have shown its similarity to C. beijerinckii rather than the C. pasteurianum species. Here, we present a comparative analysis of the strain with several other complete clostridial genome sequences. Besides a 16S rRNA gene sequence comparison, digital DNA–DNA hybridization (dDDH) and phylogenomic analysis confirmed an inaccuracy of the taxonomic status of strain Clostridium pasteurianum NRRL B-598. Therefore, we suggest its reclassification to be Clostridium beijerinckii NRRL B-598. This is a specific strain and is not identical to other C. beijerinckii strains. This misclassification explains its unexpected behavior, different from other C. pasteurianum strains; it also permits better understanding of the bacterium for a future genetic manipulation that might increase its biofuel production potential.

Full visible-light absorption of TiO2 nanotubes induced by anionic S22− doping and their greatly enhanced photocatalytic hydrogen production abilities

TiO2, as a benchmark photocatalyst for hydrogen production through water splitting, has a relatively large band gap (3.2eV for anatase and 3.0eV for rutile) requiring UV light (290–400nm) for electronic excitations from the valence band to the conduction band, hence utilizing only a small part of the solar spectrum. The construction of new electronic band gap, especially in the visible region (400–800nm), is of great importance for improving TiO2 optical and photocatalytic properties. In this work, though it is deem metastable and can induce a broad visible-light adsorption in previous literatures, anionic S22− has been successfully introduced into TiO2 nanotubes, which is different from the previous works about S-doped TiO2 that contain only cationic S4+ and S6+. Resultantly, the S22− doped TiO2 nanotubes exhibit a full visible-light absorption (from 400 to 800nm) and a greatly enhanced photocatalytic H2-production rate under visible-light irradiation (9610μmolh−1g−1, about 13.7 and 37 times of other cationic and anion S-doped TiO2 nanoparticles, respectively, almost highest in all the results reported previously in literatures of TiO2 doped with non-metal elements).

The enhanced photocatalytic activity of g-C3N4-LaFeO3 for the water reduction reaction through a mediator free Z-scheme mechanism

A g-C3N4/LaFeO3 solid–solid interface showing enhanced hydrogen production ability under visible-light irradiation through a mediator free Z-Scheme mechanism.

Effect of carbon sources on the aggregation of photo fermentative bacteria induced by L-cysteine for enhancing hydrogen production.

Poor flocculation of photo fermentative bacteria resulting in continuous biomass washout from photobioreactor is a critical challenge to achieve rapid and stable hydrogen production. In this work, the aggregation of Rhodopseudomonas faecalis RLD-53 was successfully developed in a photobioreactor and the effects of different carbon sources on hydrogen production and aggregation ability were investigated. Extracellular polymeric substances (EPS) production by R. faecalis RLD-53 cultivated using different carbon sources were stimulated by addition of L-cysteine. The absolute ζ potentials of R. faecalis RLD-53 were considerably decreased with addition of L-cysteine, and aggregation barriers based on DLVO dropped to 15-43% of that in control groups. Thus, R. faecalis RLD-53 flocculated effectively, and aggregation abilities of strain RLD-53 cultivated with acetate, propionate, lactate and malate reached 29.35, 32.34, 26.07 and 24.86%, respectively. In the continuous test, hydrogen-producing activity was also promoted and reached 2.45mol H2/mol lactate, 3.87mol H2/mol propionate and 5.10mol H2/mol malate, respectively. Therefore, the aggregation of R. faecalis RLD-53 induced by L-cysteine is independent on the substrate types, which ensures the wide application of this technology to enhance hydrogen recovery from wastewater dominated by different organic substrates.

CuGaS2-ZnS p-n nanoheterostructures: a promising visible light photo-catalyst for water-splitting hydrogen production.

In this work, novel CuGaS2-ZnS p-n type semiconductor nanoheterostructures were synthesized by a solution route, and demonstrated experimentally to be a very promising visible light active photo-catalyst for water-splitting hydrogen production. The construction of CuGaS2-ZnS heterostructures follows a multi-step strategy, employing Cu1.94S nanocrystals first as catalytic assistants for the hetero-growth of ZnS on their surfaces, and then as sacrificial seeds for the formation of CuGaS2. Excitingly, attributed to the efficient charge separation introduced by the p-n heterojunctions, the hydrogen production ability of the CuGaS2-ZnS nanoheterostructures under visible light irradiation is 15 times higher than that of the CuGaS2 component, and comparable to that of the CdS nanophase which is currently regarded as one of the most active visible photo-catalysts for hydrogen generation.

Bio-hydrogen Production from Beer Wastewater in an Internal Circulation (IC) Reactor

An internal circulation (IC) using hydrogen-producing anaerobic granular sludge as seed sludge and beer wastewater as substrate was employed to evaluate the effect of hydrogen production and the performance of reactor. Running at the temperature of 35±1 °C, the pH value of influent controlled is 5.5 and organic loading rate (OLR) from 30 kg COD/(m3●d) to 42 kg COD/(m3●d), the IC reactor presents a high hydrogen production ability as the hydrogen production rate (HPR) maximized at 6.0-6.83 m3/(m3●d). Hydrogen volume content was estimated to be 42-46% of the total biogas and the biogas was free of methane throughout the study. COD removal efficiency could reach 20-30% and the dissolved fermentation products were predominated by ethanol with the concentration of 900-950 mg/L, which accounts for 45%- 56% of the total liquid products. These values may imply that the IC reactor is a kind of feasible fermentative hydrogen production equipment.

Surface plasmon resonance enhanced light absorption of Au decorated composition-tuned ZnO/ZnxCd1−xSeyTe1−y core/shell nanowires for efficient H2 production

Efficient solar-to-hydrogen photoelectrodes need harvest sunlight to capacity and improve the separation efficiency of charge carriers for chemical reactions in water. Herein, we demonstrate the merits of type-II heterostructures with component controllable quaternary shells (ZnxCd1−xSeyTe1−y) and the surface plasmon resonance of Au nanoparticles to satisfy photocatalytic requirements. Our ZnO/ZnxCd1−xSeyTe1−y/Au nanostructures display a broad absorption edge from UV to NIR (Near Infrared) and high charge separation efficiency. The finite element method simulation and UV-vis-NIR diffuse reflectance spectroscopy confirm the enhanced absorption of visible light. Furthermore, these ZnO/ZnxCd1−xSeyTe1−y/Au heterostructures show remarkable hydrogen-production ability from water, suggesting a type of photocatalytic paradigm for H2 production.

Bio-Hydrogen Production through Anaerobic Microorganism Fermentation from Molasses Wastewater in a Continuous Stirred Tank Reactor

In order to treat the beet sugar factory wastewater and produce hydrogen, a low pH, ethanol-type fermentation process had happened in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L in this experiment. The results showed that after inoculation with activated sludge and operation at organic loading rate (OLR) of 9 kgCOD/m3·d, hydraulic retention time (HRT) of 8h, influent pH value of 6.5 and temperature of 35°C for 30 days, the CSTR achieved stable ethanol-type fermentation. During this period of stable operation, the reactor showed a stable COD removal efficiency of 19.2% and hydrogen production rate of 0.1L/gMLSS·d. Effluent pH ranged from 4.0 to 4.5. The total amount of ethanol and acetic acid was 1384 mg/L, accounted for 81% of the total liquid products, which can be attributed to ethanol-type fermentation. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.

Effect of short-time hydrothermal pretreatment of kitchen waste on biohydrogen production: Fluorescence spectroscopy coupled with parallel factor analysis

The enhancement of bio-hydrogen production from kitchen waste by a short-time hydrothermal pretreatment at different temperatures (i.e., 90°C, 120°C, 150°C and 200°C) was evaluated. The effects of temperature for the short-time hydrothermal pretreatment on kitchen waste protein conversion and dissolved organic matter characteristics were investigated in this study. A maximum bio-hydrogen yield of 81.27mL/g VS was acquired at 200°C by the short-time hydrothermal pretreatment during the anaerobic fermentative hydrogen production. Analysis of the dissolved organic matter composition showed that the protein-like peak dominated and that three fluorescent components were separated using fluorescence excitation–emission matrix spectra coupled with the parallel factor model. The maximum fluorescence intensities of protein-like components decomposed through the parallel factor analysis has a significant correlation with the raw protein concentration, showed by further correlation analysis. This directly impacted the hydrogen production ability.

Continuous Hydrogen Production in a Novel Photo-Bioreactor with High Light Conversion Efficiency

A novel disk photo-bioreactor was employed to produce hydrogen continuously by Rhodopseudomonas faecalis RLD-53. The ability of hydrogen production was investigated in different feeding times and HRTs. The maximum total hydrogen yield in the photo-bioreactor reached 2.68 mol H2/mol acetate at 48h HRT and 4d feeding time. Experimental results indicated that feeding times and HRTs are two key factors determined biomass in the photo-bioreactor and hydrogen production capacity. Moreover, the photo-fermentation hydrogen production is strongly dependent on light energy supply, the light conversion efficiency of the novel photo-bioreactor was 1.6%, it is higher than that that of most of reported photobioreactors. Therefore, these results demonstrated that the disk photo-bioreactor was a useful and efficient reactor in entire continuous hydrogen production.

Effect of Substrate Concentration on Hydrogen Production from Fermentation of Sugar Wastewater

The biological hydrogen production by the sugar wastewater is an effective way to achieve the reclamation. In this paper, the effect of substrate concentration on the hydrogen production is discussed through employing the self-made continuous flow anaerobic fermentation hydrogen production reactor, taking the sludge in urban sewage treatment plant as the inoculated sludge and the simulated sugar wastewater as the substrate. The experimental results show that the best hydrogen production effect can be obtained when the temperature is (37±1) °C, HRT is 7h, the water alkalinity is around 530mg/L and the substrate concentration is 5000mg/L, namely the organic load is 60kgCOD/(m3·d). The volumes of gas production and hydrogen production both reach the maximum. The average values are respectively 36.2L/d and 21.8L/d. The obtained hydrogen production rate is 0.93kgCOD/(m3·d). During the whole process, the proportion of volatile acid composition remains stable, which is the butyric acid-type fermentation. When the concentration of COD is increased to 6000-8000mg/L, the ability of hydrogen production of system will be significantly dropped due to the increase of pH of system. The hydrogen production performance can be restored through artificially and timely lowering the water alkalinity. However, the hydrogen production rate will be decreased compared to the previous situation.

Characteristics of hydrogen production by an aciduric transposon-mutagenized strain of Pantoea agglomerans BH18

Based on the generation of Pantoea agglomerans BH18 library using Tn7 transposon system, mutant screens were conducted for improvement the ability of hydrogen production of this strain. These mutants were used to test for ability of hydrogen production in the initial pH of 5.0. In contrast to wild type strain BH18, a transposon mutant, named as strain TB108, was screened for high hydrogen-producing capability and acid tolerance in the initial pH of 5.0. The factors required for hydrogen production of the aciduric transposon-mutagenized strain TB108 were determined. The mutant strain TB108 similar as wild type strain BH18 was able to produce hydrogen over a wide range of salt concentration from 0.4% to 6%. Under the marine conditions with the initial pH of 5.0 and glucose concentration of 10 g/L, the total hydrogen production of the mutant TB108 was (1.36 ± 0.04) mol H2/mol glucose (mean ± S.E.), increasing by 55% compared with wild type. In addition, the mutant strain TB108 could produce hydrogen using many carbon sources such as fructose, glucose, sucrose, sorbitol and so on. This result demonstrated that the mutant strain with high acid tolerance is beneficial for improvement of hydrogen production.

Evaluating Colombian Clostridium spp. strains’ hydrogen production using glycerol as substrate

Background: The ability for hydrogen production of 13 native strains of Clostridium spp. strains isolated from Colombian soil was evaluated using glycerol substrate. Glycerol to hydrogen conversion was investigated using a batch fermentation reactor and industrial glycerol source (50 g.l -1 , pH 7.00). Results: The results were quantified regarding acids, hydrogen, biomass and solvent production. The selected strain gave good hydrogen over production output at 14.4 mmol H 2 .l -1 , productivity 0.3167 mg H 2 .h -1 l - 1 culture mediumand yield 0.1962 mol H 2 .mol -1 glycerol. A further fermentation assay a 4.0 liter batch reactor let to being 0.26 mg.l -1 .h -1 after 18 hrs of fermentation. Logistic model, Luedeking-Piret model and Luedeking-Piret modified models were used for modeling changes in cell growth, hydrogen production and substrate consumption (Correlation coefficients R 2 = 0.95 for biomass substrate, R 2 = 0.77 hydrogen production). Conclusions: Our results indicate that hydrogen production through glycerol bioconversion by native strains is possible.

Modified glycine-nitrate process(MGNP)로 합성한 BaCo1-x-yFexZryO3-δ산소투과도 및 수소생산성

A dense mixed ionic and electronic conducting ceramic membrane is one of the most promising materials because it can be used for separation of oxygen from the mixture gas. The ABO3 perovskite structure shows high chemical stability at high temperatures under reduction and oxidation atmospheres. BaCo1-x-yFexZryO3-δ (BCFZ) was well-known material as high mechanical strength, low thermal conductivity and stability in the high valence state. Glycine Nitrate Process (GNP) is rapid and effective method for powder synthesis using glycine as a fuel and show higher product crystallinity compared to solid state reaction and citrate-EDTA method. BCFZ was fabricated by modified glycine nitrate process. In order to control the burn-up reaction, NH4NO3 was used as extra nitrate. According to X-Ray Diffraction (XRD) results, BCFZ was single phase regardless of Zr dopants from y=0.1 to 0.3 on B sites. The green compacts were sintered at 1200°C for 2 hours. Oxygen permeability, methane partial oxidation rate and hydrogen production ability of the membranes were characterized by using Micro Gas Chromatography (Micro GC) under various condition. The high oxygen permeation flux of BCFZ 1-451 was about 1 ml?cm-2s-1. Using the humidified Argon gas, BCFZ 1-433 produced hydrogen about 1 ml?cm-2s-1.

Glycerol assimilation and production of 1,3-propanediol by Citrobacter amalonaticus Y19

Citrobacter amalonaticus Y19 (Y19) was isolated because of its ability for carbon monoxide-dependent hydrogen production (water-gas shift reaction). This paper reports the assimilation of glycerol and the production of 1,3-propanediol (1,3-PDO) by Y19. Genome sequencing revealed that Y19 contained the genes for the utilization of glycerol and 1,2-propanediol (pdu operon) along with those for the synthesis of coenzyme B12 (cob operon). On the other hand, it did not possess the genes for the fermentative metabolism of glycerol of Klebsiella pneumoniae, which consists of both the oxidative (dhaD and dhaK) and reductive (dhaB and dhaT) pathways. In shake-flask cultivation under aerobic conditions, Y19 could grow well with glycerol as the sole carbon source and produced 1,3-PDO. The level of 1,3-PDO production was improved when vitamin B12 was added to the culture medium under aerobic conditions. Under anaerobic conditions, cell growth and 1,3-PDO production on glycerol was also possible, but only when an exogenous electron acceptor, such as nitrate or fumarate, was added. This is the first report of the glycerol metabolism and 1,3-PDO production by C. amalonaticus Y19.

Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2Catalyst Wrapped by High Concentrated TiO2Particles

This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2photocatalyst coated with a high concentration of TiO2particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2particles (>4~5 mol). The synthesized core@shell-structured CuS@TiO2particles absorbed a long wavelength (a short band gap) above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2strongly withdraws the excited electrons from the valence band in TiO2because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

Fermentative hydrogen production from beet sugar factory wastewater treatment in a continuous stirred tank reactor using anaerobic mixed consortia

A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12 kgCOD·m−3·d−1, HRT of 8h, and temperature of 35°C for 28 days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18 kgCOD·m−3·d−1 on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493 mg·L−1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1–4.5, −250-(−290) mV, and 230–260 mgCaCO3·L−1. The specific hydrogen production rate of anaerobic activated sludge was 0.1 L·gMLVSS−1·d−1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.

The Separation Identification and Culture Optimization of Hydrogen Production X9 Bacteria

A high efficiency simultaneous cellulose degradation and hydrogen production strain X9 was obtained from the screening of the 125 strains of fermentative hydrogen production bacteria which were isolated from a continuous stirred-tank hydrogen production bioreactor (CSTR) with LM-1 and microcrystalline cellulose (MCC) medium and improved Hungered technique in this study. X9 was confirmed a new category by analyzing the results of biochemical and physiological test, shape character, 16S rDNA sequencing and phylogenetic, and then analysis characteristics of growth, culture parameters, the effects of components of medium on growth and ability of hydrogen production, the optimum technological parameters have been determined from orthogonal experiment and single factor test. Finally, X9 achieved maximum specific hydrogen yield of 4.9mmol/g with MCC under the optimal conditions.

Solvothermal synthesis of high hydrogen permeable Pd/Ag alloy particles and their hydrogen transport properties

Pd76Ag24 nanoparticles with high purity and a face-centered cubic structure were prepared using a solvothermal method. The lattice parameter of the Pd77Ag23 nanopowders (space group 225Fm3m) was calculated to be a = 3.9382 A. The primary particle size was calculated to be 7.7 nm from the X-ray line width using the Scherrer formula, and the interplanar distances was estimated to be 2.272 and 2.000 A based on indexing on the (111) and (200) plane, respectively. These values are slightly larger than those of pure Pd and smaller than Ag in the (111) plane. The linear relationship of the hydrogen permeation flux with the square root of the hydrogen partial pressure gradient across a 0.26-mm-thick Pd/Ag-YSZ cermet membrane confirmed the major hydrogen transport through the Pd/Ag phase of cermet membranes. The Pd/Ag-YSZ cermet membranes showed significantly higher hydrogen permeation flux than the Pd-YSZ cermet membrane, even though the activation energy for the Pd/Ag alloy cermet membranes showed slightly higher values than that of the Pd cermet membranes. The hydrogen–oxygen dual flux through Pd/Ag-YSZ cermet membranes was confirmed by the maximum hydrogen production by combining the ability of hydrogen production from water with the function of hydrogen separation on composite membranes

Improvement of hydrogen production by transposon-mutagenized strain of Pantoea agglomerans BH18

Pantoea agglomerans BH18, isolated from mangrove sludge, could produce hydrogen under marine culture condition. To improve the hydrogen-producing capacity of this strain, we constructed a stable transposon-mutagenized library of P. agglomerans BH18. A Tn7-based transposon was randomly inserted into genomic DNA of P. agglomerans BH18. Mutants were identified by kanamycin resistance and amplification of the inserted transposon sequences. A transposon mutant, named as strain TB212, was screened for the highest hydrogen production ability. The total volume of hydrogen gas evolved by this mutant strain TB212 was 60% higher than that of the wild type. The mutant strain TB212 was able to produce hydrogen over a wide range of initial pH from 5.0 to 10.0, with an optimum initial pH of 7.0, and hydrogen production was 2.52 ± 0.02 mol H2/mol glucose (mean ± S.E.) under marine culture condition. The mutant strain TB212 could produce hydrogen at the salt concentration from 3 to 6%. It was concluded that the transposon-mutagenized library may be a useful tool for investigation of high efficiency hydrogen-producing bacteria.