Effects Of Preparation Parameters Research Articles

Effects of Preparation Parameters on Room Temperature Formation of Vanadium-Doped TiO2 Nanocrystalline Powder

Vanadium-doped titania (TiO2) nanocrystalline was obtained at room temperature by cohydrolysis of tetrabutyl titanate and vanadium (IV) oxyacetyl acetonate in large amount of water. The shape of crystal grains formed at room temperature is irregular, and their average size is <10 nm. X-ray diffractometer, high-resolution transmission electron microscope, ultraviolet (UV)/Vis spectrometer, energy dispersion spectroscopy, and X-ray photoelectron spectrometer were used to study the effects of vanadium amount, pH value, and water dosage on the crystallization behavior, optical properties, and photocatalytic activity of thus-obtained vanadium-doped TiO2. The results showed that enough acidity at least pH (pH=2) and excessive water at least water dosage r=120 are necessary to obtain crystallized vanadium-doped TiO2 at room temperature. Optical absorption results showed that the absorption edge of vanadium-doped TiO2 shifted to longer wavelength comparing with the counterpart without vanadium. Thus-prepared vanadium-doped TiO2 nanocrystallines can utilize visible light well. The photodegradation results revealed that thus-prepared vanadium-doped TiO2 nanocrystalline has photocatalytic activity under daylight irradiation.

Effect of Preparation Parameters of Sulfur Cathodes on Electrochemical Properties of Lithium Sulfur Battery

Effect of Preparation Parameters of Sulfur Cathodes on Electrochemical Properties of Lithium Sulfur Battery

Effect of preparation parameters on the properties of TiO 2 nanoparticles for dye sensitized solar cells

Nano-sized TiO 2 powders have been prepared by sol–gel method. Influences of the different preparation parameters on the TiO 2 nano-powder properties were investigated. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO 2 nanoparticles. Yield efficiency of the resulted nanoparticles was calculated and the reaction efficiency was estimated. Maximum efficiency of 98.9% was achieved at autoclaving temperature of 245 °C for time duration of 12 h. X-ray diffraction analyses show the presence of anatase structure at low and high autoclaving temperatures. Fraction of rutile phase is detected with increasing the calcination temperature and reach 40% at 850 °C. High resolution transmission electron microscopy (HRTEM) showed spherical nanoparticles of 8–9 nm at autoclaving temperature of 130 °C, while elongated nanoparticles of 14–18 nm in length and 9 nm in width were measured at autoclaving temperature of 245 °C. The solar cell performance was measured for various TiO 2 dye sensitized solar cells. Samples of high autoclaving temperature gave an improvement in the efficiency to be 8.5% while those of lower autoclaving temperature had an efficiency of 7.29%. An enhancement in both open circuit voltage ( V oc) and fill factor (FF) is obviously detected, where elongated nanoparticles are measured by HRTEM, which improved the electronic conductivity and consequently FF and V oc.

Effects of preparation parameters on the textural features of a granular zeolite/activated carbon composite material synthesized from elutrilithe and pitch

A granular composite material containing zeolite and activated carbon was prepared from elutrilithe and pitch powder. The process consisted of the following steps: pyrolysis of pre-shaped raw material, carbon dioxide activation, and subsequent hydrothermal transformation of aluminosilicate in alkaline solution. The resulting material exhibited hierarchical pore structure with high surface area and porosity as characterized by X-ray diffraction and nitrogen adsorption. The addition of pitch powder enhanced mechanical strength of the granular composite and adjusted zeolite-to-carbon ratio. Further, effects of preparation parameters on porosity of activated carbon and phase composition of zeolite were investigated. During carbon dioxide activation, porosity evolution resulted in the formation of new micropores in the carbon precursor and further enlarged original micropores; and the textural characteristics of activated carbon mainly depended on temperature and activation time. Zeolite with high crystallinity was obtained with appropriate alkalinity, temperature and hydrothermal synthesis time.

Sol-gel-derived lead-magnesium-niobium titanate thin films for ultrahigh-value capacitor applications

A Pb(Mg0.33Nb0.67)0.65Ti0.35O3 material system was synthesized by the sol-gel method; thin films were deposited via the spin-coating technique, and processed using the rapid thermal annealing. Effects of preparation parameters, such as annealing temperature and atmosphere, on the phase composition, microstructure and electrical properties were identified. Morphologically uniform and crack-free films were obtained. Among the obtained films, the highest k value was found to be 1425 for the 380 nm thick film that was annealed at 750 °C in O2 indicating the suitability of this material system for ultrahigh-value capacitor applications.

Electric Double-Layer Capacitors from Activated Carbon Derived from Black Liquor

Black liquor derived from a hardwood tree was activated by potassium hydroxide, and the performance as electric double-layer capacitors in a non-aqueous electrolyte of activated carbons with high surface area was presented in this work. The effects of preparation parameters on the char yield, Brunauer−Emmett−Teller (BET) surface area, pore structure, and capacitance of the resulting products were investigated. The results show that the char yield and capacitance decrease with the increase of the carbonization temperature (600−900 °C). Nitrogen adsorption isotherms of activated carbons indicate that they were mainly micropores. The BET surface area increases slowly with the increase of the activation temperature, reaching the maximum value of 3089.2 m2 g−1 at 900 °C, 3 times larger than a commercial activated carbon from charcoal (943.5 m2 g−1). Capacitance is found to be approximately proportional to the BET surface area, and the maximum capacitance of 41.4 F g−1 was developed. In addition, the results ob...

Effect of preparation parameters on Co-Mo/B2O3/Al2O3 catalysts prepared by a post-treatment using citric acid as a chelating agent

Effect of preparation parameters on Co-Mo/B2O3/Al2O3 catalysts prepared by a post-treatment using citric acid as a chelating agent

Effects of preparative parameters on the structure and performance of Ca–La metal oxide catalysts for oil transesterification

The effects of preparative parameters on the surface basicity, composition, and transesterification activities of several Ca–La metal oxide catalysts were investigated. Four different preparation methods: ammonia–ethanol–carbon dioxide precipitation, physical mixing, impregnation, and co-precipitation, were studied. It was found that the ammonia–ethanol–carbon dioxide precipitation method resulted in the highest BET specific surface area, base strength and base site concentration. Moreover, catalyst surface composition and basicity are a function of calcination temperature, precipitants, pH, and molar ratio of Ca to La in precursor solution, and storage conditions. XRD, XPS, basicity and BET tests revealed that catalyst structure and dispersion of Ca species strongly influenced the catalyst activity. High surface concentration of Ca species, strong base strength and high concentration of base sites, and high specific surface area are characteristics of an active transesterification catalyst.

Preparation of Co-Al mixed oxide-supported gold catalysts and their catalytic activity for N 2O decomposition

Au/Co-Al catalysts were prepared by using the ion-exchange and coprecipitation methods, and their activities for the catalytic decomposition of N 2O were tested. BET, XRD, and H 2-TPR techniques were used to characterize the catalysts. The results show that the activity of Au/Co-Al catalyst prepared by using ion-exchange method is higher than that using coprecipitation method. For the catalysts prepared by ion-exchange method, the effects of preparation parameters, such as Au loading, pretreatment of HAuCl 4 solution, and calcination temperature, upon N 2O conversion were investigated. The optimal preparation parameters of Au/Co-Al catalysts are 1.1% of Au loading, HAuCl 4 solution adjusted to pH 9, and 300°C of calcination temperature. It is indicated that the addition of Na species in Co-Al mixed oxide promoted the reduction of Co 3+ to Co 2+ and enhanced the catalytic activity for N 2O decomposition.

Heat denatured/aggregated albumin-based biomaterial: effects of preparation parameters on biodegradability and mechanical properties

Albumin-based biomaterials prepared using heat-aggregation or cross-linking agents have been used in various biomedical applications such as solder materials for laser-assisted tissue welding, anti-bacterial coatings and drug carriers. In this study, solid albumin-based materials were prepared via heat aggregation of albumin solution. The study aimed to determine the influences of the preparation parameters such as albumin concentration in solution, solution pH and temperature, on the mechanical properties as well as the biodegradation rate of heat-aggregated albumin-based materials. The results demonstrated that the materials prepared from the albumin solution with the pH of 8.5 had the highest mechanical strength. Augmenting the albumin concentration in solution led to an increase in mechanical strength, and the materials prepared from the solution with isoelectric albumin pH (pH 4.8) possessed the lowest biodegradation rate and those prepared at pH 12 showed the highest biodegradation rate.

The Effects of Preparation Parameters on the Up-Conversion Properties of NaYF4:Yb3+, Er3+ Nanopowders by a Solvothermal Method

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Preparation of lactic acid bacteria-enclosing alginate beads in emulsion system: effect of preparation parameters on bead characteristics

The immobilization of plant growth-promoting bacteria in biodegradable polymeric supports is effective in providing them with a suitable microenvironment for increased survival, compared to free bacteria, in agricultural land. In this study, we optimized the preparation parameters for bacteria-enclosing calcium alginate gel beads with a view to large-scale production. An emulsion system was used and the optimization was based on alginate bead recovery and entrapment efficiency of viable bacteria. Lactic acid bacteria were used as a plant growth-promoting bacteria. The optimized conditions were as follows: the concentration of calcium chloride in the aqueous phases was 1.1% (w/v), the volume ratio of alginate solution to total aqueous phases was 0.93, and the agitation time was 0.5–1.0 h. The mean diameter of the beads could be controlled (approximately from 100 to 300 μm) by varying the agitation rate.

The Effect of Preparation Parameters of MCM-41 Supported Pt/Ni Catalysts and their Hydrogenation Properties

A series of Pt50Ni50 supported on MCM-41 catalysts were prepared via wet co-impregnation of the metal salts H2PtCl6 and NiSO4·6H2O. The metal salts were reduced using NaBH4 and catalytic activities of the catalysts were investigated for the hydrogenation of benzene to cyclohexane. The effect of various reduction conditions such as reduction temperature, NaBH4 concentration and the medium in which reduction was carried out was investigated. Results show that optimum catalytic activity occurs when catalysts are synthesized at 273 K using 0.3 M of NaBH4 in a medium of ethanol. The variation in reduction rate with reduction conditions influenced the metal particle morphology which effected catalytic activity. Further comparison of the reactivity of Pt50Ni50 with that of the respective monometallic catalysts synthesized at optimum conditions, show that the Pt50Ni50 exhibited superior reactivity. Surface properties of the catalysts were characterized using H2-TPR, H2-adsorprtion and H2-TPD analyzes. Studies on the morphology of the metal particles and composition were obtained via TEM and SEM equipped with elemental analysis.

Photoelectrocatalytic COD determination method using highly ordered TiO 2 nanotube array

This work focuses on the experimental studies of a photoelectrocatalytic method for COD determination in a thin-cell reactor based on a highly effective TiO 2 nanotube array electrode. The effect of preparation parameters on the photoelectrocatalytic performance of TiO 2 nanotube array electrodes including the electrolyte, anodic potential, anodic time, solution pH, calcination temperature and time was examined. The TiO 2 nanotube array electrode prepared in preparation parameters at 1% HF electrolyte solution, anodic potential 20 V, anodic time 5 min, calcination temperature 450 °C with highly photoelectrocatalytic performance was chosen as the working electrode. When it is used in a thin-cell photoeletrocatalytic reactor for COD determination, it requires about 1–5 min to complete the oxidation of organics without further titration, much faster than the standard K 2Cr 2O 7 method (2–4 h). It consumes very limited harmless and inexpensive supporting electrolyte, free from secondary pollution. A wide dynamic working range of 0–850 mg/L can be achieved by this method, much wider than any other photoeletrocatalytic methods using TiO 2 nanoparticles or nanofilms in the reported literature. The effects of the water components were studied to propose the TiO 2 nanotube array method. Real sample analyses were also carried out and the COD value of real samples determined by this method agreed well with the standard dichromate method, and it shows good accuracy, stability and reproducibility.

Synergistic effect of TiO2 and iron oxide supported on fluorocarbon films. Part 1: Effect of preparation parameters on photocatalytic degradation of organic pollutant at neutral pH

Iron oxide and TiO2 were immobilized on modified polyvinyl fluoride films in a sequential process. Synergic effects of iron oxide and TiO2 on the polymer film were observed during the heterogeneous degradation of hydroquinone (HQ) in the presence of H2O2 at pH close to neutrality and under simulated solar irradiation. Within the degradation period, little iron leaching (<0.5mg/L) was observed.The surface of commercial polyvinyl fluoride (PVF) film was modified by TiO2 under light inducing oxygen group (C–OH, CO, COOH) formation on the film surface. During this treatment, TiO2 nanoparticles simultaneously bind to the film, leading to PVFf–TiO2. The possible mechanistic pathway for the TiO2 deposition and the nature of the polymer–TiO2 interaction are discussed. Furthermore PVF and PVFf–TiO2 were immersed in an aqueous solution for the deposition of iron oxide layer by hydrolysis of FeCl3, leading to PVF–Fe oxide and to PVFf–TiO2–Fe oxide respectively.HQ degradation and mineralization mediated by PVFf–TiO2, PVF–Fe oxide and PVFf–TiO2–Fe oxide were investigated under different conditions. Remarkable synergistic effects were observed for PVFf–TiO2–Fe oxide possibly due to Fe(II) regeneration, accelerated by electron transfer from TiO2 to the iron oxide under light.

Multicolour photochromic behaviour of silver nanoparticles in titanium dioxide matrix

AbstractWe implemented photocatalytic technique of preparation of composite material consisting of silver nanoparticles embedded in nanoporous titanium dioxide matrix which has an unique property of multicolour photochromic behaviour. We report on the effect of preparation parameters on optical and photochromic properties of the material. In particular we investigate the role of the concentration of TiO2 nanoparticles in the ethanol solution used to produce the films for Ag deposition. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Monolithic Pt/Ce 0.8Zr 0.2O 2/cordierite catalysts for low temperature water gas shift reaction in the real reformate

Monolithic catalysts were prepared by washcoating Ce 0.8Zr 0.2O 2 slurries and then impregnating platinum or rhenium onto cordierite substrates, and characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), inductively coupled plasma (ICP), temperature-programmed-reduction (TPR) and temperature-programmed deposition of CO (CO-TPD) techniques. The effects of preparation parameters on the catalytic performance for water gas shift (WGS) reaction were investigated in details, including different Ce 0.8Zr 0.2O 2 powder as washcoat, coat loadings, metal loadings, Pt/Re weight ratio and impregnation sequences. In addition, pyrophoricity (exposure to oxygen stream) and long-term stability were carried out over monolithic catalysts with the optimized composition. The results showed that Ce 0.8Zr 0.2O 2 prepared by microemulsion methods was the preferred washcoat, and that 50 wt% Ce 0.8Zr 0.2O 2 coat loading and 0.68 wt% Pt loading were required to reduce CO content to ca. 1%. The optimal catalytic performance was achieved over 0.11 wt% Re/0.34 wt% Pt/50 wt% Ce 0.8Zr 0.2O 2–M/cordierite catalyst. Pyrophoricity tests indicated that no obvious activity loss was observed over 0.11 wt% Re/0.34 wt% Pt/50 wt% Ce 0.8Zr 0.2O 2–M/cordierite catalyst after three exposures to oxygen; while 17% of the initial activity was lost over industrial B206 after one exposure. Monolithic 0.11 wt% Re/0.34 wt% Pt/50 wt% Ce 0.8Zr 0.2O 2–M/cordierite catalyst exhibited good stability during 80 h on-stream test.

Effect of preparative parameters on the characteristic of poly(vinylidene fluoride)-based microporous layer for proton exchange membrane fuel cells

The effect of preparative parameters on the characteristic of PVDF-based microporous layers (MPL) for proton exchange membrane (PEM) fuel cell was investigated. Physical properties of MPL involving electrical resistance, gas permeability and microstructure were examined. The results show that the characteristics of MPL were affected by preparative parameters, such as PVDF concentration, type of electrically conductive filler and its loading, PVDF/electrically conductive filler ratio, as well as type of PVDF solvent. The PEM fuel cell performance test demonstrates that the obtained MPL has a great potential and interest for further study and development.

Preferential oxidation of CO in hydrogen stream over nano-gold catalysts prepared by photodeposition method

A series of gold catalysts supported on TiO 2 were prepared by photodeposition method. The effects of preparation parameters, such as power of UV light, irradiation time, and initial gold concentration, on the characteristics of the catalysts were studied. The catalysts were characterized by inductively coupled plasma-mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, and high-resolution transmission electron microscopy. The catalytic activity of the catalyst for preferential oxidation of CO in hydrogen stream (PROX) was measured in a fixed-bed plug-flow reactor. The reactant gas containing 1.33% CO, 1.33% O 2, 65.33% H 2 and He for balance was fed into the reactor with a space velocity of 30,000 ml/g h. The lower power source lamp can deposit small gold particles on the support, which in turn was responsible for the enhanced catalytic activity. The photodeposition method facilitates to prepare gold particles as small as 1.5 nm on the support. These catalysts were very active and selective in PROX reaction. However, the small gold particles were not stable as long as the reaction temperature was > 50 ∘ C .

Barium titanate ceramic inks for continuous ink-jet printing synthesized by mechanical mixing and sol-gel methods

Ink-jet printing of ceramic thick films is one of low cost on-site ceramic pattern fabrication methods. It is necessary to investigate the rheological behaviour of ceramic inks and drying behaviour of droplets. Two kinds of BaTiO 3 ceramic inks were prepared by mechanical mixing and sol-gel methods, respectively. The effect of preparation parameters, such as quantity of polyacrylic acid(PAA) and solid content, on physicochemical and rheologic properties of the ceramic inks was investigated. The results show that they satisfy the requirements of continuous ink-jet printing. The appearances of printed dots and single printed layers were observed by SEM. The SEM images indicate that dots printed with mixing method ink are in ring shape, and dots printed with sol-gel method ink are in pancake shape, so the printed layer surface with the latter ink is smoother. The causes of these phenomena were discussed.