Advanced Materials Research Vols. 512-515

Abstract: Mg_1.7 M_0.3 Ni (M = Mg, La, Nd and Ce) alloys were prepared by vacuum induction melting under the high purity helium atmosphere. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to study the phase structures of tested alloys, and their morphologies and hydrogen storage properties were intensively studied by pressure-composition -temperature (PCT) test. It was found that the Mg-M-Ni(M=Mg, La, Nd and Ce)alloys appeared multiphase structures, and as Nd substituting Mg the Mg-Nd-Ni obtained the optimal activation behavior, plateau characteristics, hydrogen cycling reversibility and kinetic properties.

Abstract: The assembly force in a proton exchange membrane fuel cell (PEMFC) stack affects the characteristics of the porosity and electrical conductivity. Generally, the stack is assembled at room temperature while it’s operated at about 80 °Cor even higher. As a result, the assembly pressure can’t keep constant due to thermal expansion. This paper focuses on the contact pressure between membrane electrode assembly (MEA) and bipolar plates in real operations. A three-dimensional finite element (FE) model for the assembly process is established with coupled thermal-mechanical effects. The discipline of contact pressure under thermal-mechanical effect is investigated. A single cell stack is fabricated in house for the analysis of contact pressures on gas diffusion layer at different temperatures. The results show that as the temperature increases, contact pressure increases due to thermal expansion. It indicates that the influence of thermal expansion due to temperature variation should be taken into consideration for the design of the stack assembly process.

Abstract: Kinetics of mesophilic biohydrogen production from ozone-pretreated palm oil mill effluent (POME) using C. butyricum and C. acetobutylicum co-culture was investigated. All experiments were setup in 0.5-L batch reactors under mesophilic condition (37°C), pH 6, and POME concentration of 5,000-30,000 mg COD L^-1. At the concentration of 15,000 mg COD L^-1, maximum hydrogen production yield for non-ozone pretreated POME and ozone pretreated POME were 318 and 122 mL g^-1 COD_removed, respectively. Acetic and butyric acids were dominant fermentation products in liquid phase. Ozone-pretreatment of POME showed no significant improvement on the hydrogen production by the co-culture.

Abstract: Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), power density and anode potential are used to characterize the mediator microbial fuel cell at different methylene blue (MB) concentrations. At lower MB concentration between 9.98×10-3 mmol/L and 1.66×10-1 mmol/L, the increased power density is enabled by using high mediator concentrations. Higher peak power density of 159.6 mw/m2 is observed compared with the peak power density of 36.0 mw/m2. But MB at too high concentration is disadvantageous to the perform of MFC. At the MB concentration of 2.50×10-1 mmol/L, the peak power output is just 128.4 mw/m2, which is lower than 159.6 mw/m2 at MB concentration of 1.66×10-1 mmol/L.

Abstract: Cr(VI) was reduced at a carbon felt cathode in an air-cathode dual-chamber microbial fuel cell (MFC). The reduction of Cr(VI) was proven to be strongly associated with the electrogenerated H2O2 at the cathode. At pH 3.0, only 27.3% of Cr(VI) was reduced after 12h in the nitrogen-bubbling-cathode MFC, while complete reduction of Cr(VI) was achieved after 6h in the air-bubbling-cathode MFC in which the reduction of oxygen to H₂O₂ was confirmed. The results showed that the efficient reduction of Cr(VI) could be achieved with an air-bubbling-cathode MFC.

Abstract: The experiment took a continuous stirred tank reactor as a reacting device, which based on molasses wastewater and brown sugar wastewater as the fermentation substrate. We studied the hydrogen production capacity with the two different substrates under the anaerobic fermentation. The results showed that the maximum hydrogen production yield were 0.99 L/d (molasses as the substrate) and 1.95L/d (brown sugar as the substrate), respectively, with the hydraulic retention time (HRT) of 6.2 h, temperature of (35 ± 1) °C and the reactor substrate concentration of 3000 mg COD/L. At the same time, the liquid end components were changed in a large scope. During the first 28 days, acetic acid and propionic acid were the main components, when molasses was replaced by brown sugar as the substrate, the percentages of propionic acid and butyrate acid decreased significantly from 25.7%, 15.4% to 11.8%, 9.47%, respectively. And the fermentation type was transformed from the mixed-acid-type fermentation to the more stable ethanol-type fermentation.

Abstract: In the field of architecture, “energy-saving building” has been mentioned as a strategy which is as important as the ones of our population, resources, environment and sustainable development. The design of the building wall materials in the building envelope is the key step of the wall insulation, which can be taken as the key technology in building energy efficiency. Tests, starting from the thermal characteristics of the building envelope and the raw materials, taking heat transfer coefficient as an important parameter, show that the polystyrene particulate composite silicate thermal insulation material can be designed to meet energy-saving requirements.

Abstract: Aluminum substitution in CuInSe₂ could have important implications for photovoltaic applications. To better understand the Al doping effects, we have performed density functional calculations on the CuInSe₂ chalcopyrite as well as on Al-doped derivative compounds with different concentrations using the generalized gradient approximation. The structural and electronic properties of the pure and Al-doped CuInSe₂ have been calculated. We find that the substitution of In by Al creates structural deformation, and the band gap of CuIn_1-xAl_xSe₂ broadens as Al content increases. These are further discussed with the analysis of lattice parameters, bond lengths and angles, and electronic structures changes.

Abstract: Al(OH)3 ultrafine powder was extracted from fly ash with the method of dispersing agent-carbonizating. Fly ash is activated by the method of sintering with limestone, so the inert mullite can be convert into C₁₂A₇ which can be dissolved in Na₂CO₃ liquor. The conversion of β-C₂S to γ-C₂S is accompanied by an increase in volume and results in the self-pulverization of the sintering feed, and the diameter of the self-pulverized powder is below 1μm. Na₂CO₃ liquor was used to leach Al₂O₃ in the form of NaAlO₂ from the self-pulverized powder. High performance dispersing agent is added in the carbonation process to control the crystal and aggregation of Al(OH)₃, and the ultrafine powder of Al(OH)₃ is prepared, which diameter is less than 0.4μm.

Abstract: In this study various factors of the new type low temperature zinc phosphating process were studid to the film-formed. This was perfected the phosphating process conditions, and caused the phosphate film performance to achieve the best.