TiO2 nano-flakes with high activity obtained from phosphorus doped TiO2 nanoparticles by hydrothermal method

TiO₂ nano-wires (Ti-NWs) and nano-flakes (Ti-NFs) were obtained from phosphorus doped TiO₂ nanoparticles (Ti-P) by hydrothermal method and by subsequent heat treatment respectively. FE-SEM micrograph of the as prepared sample depicts well formed, entangled and randomly oriented nano-wires morphology, which changes to nano-flakes morphology after heat treatment. Structural characterization of the samples by X-ray diffraction shows anatase phase for both the samples. Absorption edge of the Ti-NWs sample shows blueshift where as the Ti-NFs sample exhibit redshift compared to precursor sample as evidenced by UV–Visible absorption spectra, which is due to change in morphology and crystallinity of the samples. XPS studies indicate the presence of titanium and oxygen species only. From the EPR measurements with in-situ visible light irradiation, the number of photogenerated charge carriers is found to be very high for nano-flakes sample. Methyleneblue degradation profiles depict very high activity of Ti-NFs sample compared to Ti-NWs and the precursor samples, which is due to the observed redshift in the absorption edge, change in morphology and high crystallinity of the sample which in turn increases the optical response and separation of photogenerated charge carriers as evidenced by the optical and EPR measurements respectively.     

White light emission based on both upconversion and thermal processes from Nd3+ doped yttrium silicate

In the present study, white light emission based on both upconversion and thermal processes from single-phase yttrium silicate nanopowder doped with Neodymium (III) (Nd³⁺) was investigated at both room pressure and vacuum (0.01 mbar) with a diode laser excitation of 808 nm. 1% Nd³⁺ doped (per mole) yttrium silicate (Y₂O₃:SiO₂) nanopowder was synthesized by using the sol-gel method and annealed at 1250 °C for 12 h to obtain the powder form. Emission for upconverted white light mainly due to the transitions of Nd³⁺ ions was obtained below ~ 5.79 W of the laser beam power at atmospheric pressure. For powers exceeding ~ 5.79 W, the powder emitted a thermal white light (WL) due to the photon avalanche mechanism together with thermal processes. The threshold power to obtain thermal white light with the transitions of Nd³⁺ ions was decreased to ~ 3.51 W at the vacuum condition. These processes were investigated in detail by studying the spectral differences of the rise and decay patterns at atmospheric pressure and vacuum conditions.     

Measurement of Consumed Energy Due to the Two-Phase Pressure Drop in a Pulsed Semi-Industrial Column: Effect of Geometry

This article deals with the evaluation of pressure drop and consumption of energy for a steady-state solvent extraction in a horizontal pulsed sieve-plate column, which are important for the design and optimization of the periodic-flow processes for industrial applications. In this study, the pressure drop and the position of loading points are investigated. Moreover, a mathematical evaluation on the energy consumption in the case of a pulsed flow is conducted, and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and plate-free area is investigated as well. The results of this study are helpful for optimization of column geometry targeted to higher performance and lower energy consumption.     

Microarray analysis of high light intensity stress on hydrogen production metabolism of Rhodobacter capsulatus

Biohydrogen obtained from purple non sulfur bacteria (PNSB) is an environmentally friendly alternative for hydrogen production. PNSB can be employed in large scale outdoor photobioreactors to produce hydrogen by photofermentation with sunlight as the light source. In external environmental conditions, however, bacteria can experience stress due to high light intensities, which can inhibit or slow down hydrogen production. Previous studies with other PNSB showed varying responses to light intensities (above 4000 lux), in some cases improving, and in others adversely affecting hydrogen production.In this study, Rhodobacter capsulatus, a PNSB species that produce hydrogen efficiently from dark fermenter effluents containing acetate, was used to investigate the effects of high light intensity stress on the hydrogen production metabolism at the gene expression level. A microarray analysis was carried out using a custom-design Affymetrix GeneChip TR_RCH2a520699F. R. capsulatus DSM1710 was grown under a cyclic illumination of 2000 and 7000 lux (12 h light/12 h dark) in a hydrogen production medium having 30 mM acetate and 2 mM glutamate, and was exposed to a high light intensity (10,000 lux) for 1 h in the middle of a light period. The results reveal that photosynthetic reaction center genes were down-regulated in order to protect the photosynthetic membrane from damage. On the other hand, the expression of nitrogenase and electron transport system genes were enhanced by high light intensity. These results show that a high light intensity stress drives R. capsulatus to direct gene expression towards hydrogen production, which supports the hypothesis that hydrogen production is a way for the disposal of excess reducing equivalents to maintain the internal redox balance.     

Sonochemical synthesis of PANI-BiVO4-GO semiconductor nanocomposite highly efficient visible-light photocatalytic performance

Abstract

Polyaniline/Bismuth Vanadate/Graphene Oxide (PANI-BiVO₄-GO) or BGPA composite was prepared by sonochemical deposition of bismuth vanadate-graphene oxide (BiVO₄) nanoparticles on the surface of polyaniline (PANI). The best photocatalytic degradation performance was obtained by 5wt% BGPA composites for MB, RhB, and SO dyes, which is approximately 4 times higher than that of 1% BGPA. Meanwhile, the photocatalytic stability of BiVO₄ was significantly improved by introducing PANI into the PANI-BiVO₄-GO composite. The dramatic promotion of the photocatalytic degradation performance and the photocatalytic stability can be attributed to the formation of a heterojunction free electron between PANI and BiVO₄-GO. The existence of those extra free electrons can dramatically enhance the efficiency of the photogenerated electrons, which accelerate the transfer of photogenerated holes from BiVO₄-GO to PANI, and therefore inhibit the self-oxidation of BiVO₄.     

Influence of doped platinum nanoparticles on photocatalytic performance of CuO–SiO2 for degradation of Acridine orange dye

Preparation of cupric oxide-silicon dioxide nanoparticles was carried out using a sol-gel method. Cupric oxide-silicon dioxide nanoparticles were decorated by different weight percent of platinum (0.5, 1.0, 3.0 and 5.0 wt %) using method of photoassisted deposition. XRD remarks revealed that XRD patterns for all samples are composed of cupric oxide. Therefore, silicon dioxide is amorphous and decoration of cupric oxide-silicon dioxide nanoparticles by platinum has no effect on the formed phase. Also, due to low percent of platinum there are no peaks for platinum oxide or platinum. Cupric oxide has bandgap energy absorb in visible region but has high e-h recombination rate. Decoration of cupric oxide-silicon dioxide nanoparticles by platinum was decreased bandgap energy from 2.38 to 1.91 eV and also decrease rate of e-h recombination rate. The photocatalytic activity of platinum decorated cupric oxide-silicon dioxide nanoparticles was measured under visible light for Acridine orange dye degradation. 100% of Acridine orange dye can be degraded using 3.0 wt % of platinum decorated cupric oxide-silicon dioxide photocatalyst, 1.2 g/L dose of platinum decorated cupric oxide-silicon dioxide photocatalyst and 30 min reaction time. 3.0 wt % of platinum decorated cupric oxide-silicon dioxide photocatalyst has photocatalytic stability for five times.     

新型“U”型板溶气气浮装置浓缩生化污泥的应用

介绍新型"U"型板溶气气浮装置以及"U"型板的工作原理,重点分析"U"型板溶气气浮对生化污泥的浓缩效果。在不同的污泥负荷、溶气回流比、PAC以及PAM加药量的情况下,进行气浮中试试验,寻找最佳的试验工况。试验结果表明,当污泥负荷为57 kg/(m^2·h)、溶气回流比为35%、PAC加药量为30 mg/L、PAM加药量为8 mg/L时,气浮出泥的污泥含固率能稳定在5.55%左右,"U"型板溶气气浮对生化污泥的浓缩效果很好。这对实际生产中气浮工艺取代二沉池以及重力浓缩池提供了现实可行的指导意义。     

Fabrication of multi-filler thermoset-based composite bipolar plates for PEMFCs applications: Molding defects and properties characterizations

The bipolar plate (BP) material should possess contradictory properties. They should also manufacture from low-cost methods and materials. In the current investigation, thermoset-based composite materials reinforced with conductive fillers, and the compression molding process is implemented. In addition to fabricating the bipolar plates (BPs) with and without the flowing channels, alleviating the defects during the molding process is performed. The channels are perfectly formed on the plates with the designed depth of 0.65 mm and 0.5 mm of width. In the meanwhile, we alleviate different molding defects, which spoil the surface appearance and part properties. Regarding the physical properties, the water contact angle is measured to be around 85°. The through-plane electrical conductivity of molded plates showed high values up to 38 S/cm, and the interfacial contact resistance measured to be 18–24 mΩ cm². The mean value of the flexural strength of the produced samples was equal to 47 MPa, which is almost twice the DOE target (>25 MPa).     

极薄、超宽规格装甲板压力淬火工艺数值模拟优化

利用数值模拟的方法对极薄、超宽规格装甲板淬火过程的畸变进行了模拟研究,并对脉冲式压力淬火的控制参数进行了优化。通过对比不同冷却条件装甲板的变形量,确定了脉冲式压力淬火的脉冲压力和周期。结果表明,脉冲约束的模拟条件下,装甲板在厚度Z方向上的最终变形量为1.7 mm,不仅小于2 mm的标准要求,而且可以实现装甲板的小淬火畸变前提下满足其表面无压痕、划痕等其他损伤的实际生产需求。