Suitable Synthesis Conditions Research Articles

Preparation of Mn-Fe Binary Oxide for Arsenic Removal from Aqueous Solution

Adsorption removal of arsenic from contaminated drinking water was carried out by using Mn-Fe binary oxide adsorbent. Main phase of adsorbents was influenced by pH value of solution, and pH of 10 is the suitable synthesis condition to achieve the Mn-Fe binary oxide suspension adsorbents. Adsorbents with Mn/Fe mole ratio from 6/4 to 2/8 exhibits higher arsenite removal larger than 99.6%.

Shell-Derived Heterogeneous Base Catalyst for Transesterification of Palm Oil

In the present work, shell, which is available in abundance, low cost and non-toxicity, was used as a source of calcium for preparation of heterogeneous base catalysts. The catalyst was prepared by dissolution-precipitation method in which a calcined shell was mixed with Zn(NO3)2 and Al2O3 under acidic conditions, followed by calcination at 300-700 °C. ZSA-I was referred to as the catalyst attained under the suitable synthesis conditions. Physicochemical properties of ZSA-I were studied by using X-ray fluorescence spectroscopy (XRF), powder X-ray diffraction (XRD), thermogravimetric/ differential thermal analysis (TG/DTA) and CO2-pulse chemisorption analysis. ZSA-I gave the highest fatty acid methyl ester yield of 99 wt.% in the transesterification of palm oil with methanol and can be reused at least 5 times with a retention of the methyl ester yield higher than 96 wt.%.

Preparation of Carboxylic Acid from 3,3,3-Trifluoropropenylmagnesium Bromide

Propinic acid containing trifluoromethyl group was synthesized from 2-bromo-3,3,3-trifluoropropene,which was obtained via two steps:addition of 3,3,3-trifluoropropene and bromine followed by an elimination reaction.Then the reaction of magnesium,2-bromotrifluoropropene,different initiators and carbon dioxide in tetrahydrofuran produced 1-bromo-2-trifluoromethylpropionic,0.8 g of the product was obtained by extrated with 10% sodium carbonate solution.The purity of the product was 99.6% and the yield was 3.6%.Its structure was characterized by MS,IR,1H NMR and 13C NMR.The main by-products were 1,1-difluoropropadiene,2,3-bis(trifluoromethyl)-1,3-butadiene and their and cycloaddition products.The suitable synthesis conditions of the reactions were determined as follows:THF was used as reaction solvent,dibromoethane as the initiator,reaction temperature for preparing the Grignard reagent was 30 ℃,the Grignard reaction temperature was 0 ℃.

302 液中プラズマ蒸着法におけるダイヤモンドの最適生成条件の検討(機械材料・材料加工I)

302 液中プラズマ蒸着法におけるダイヤモンドの最適生成条件の検討(機械材料・材料加工I)

Effects of polymerization conditions on the properties of poly(furfuryl alcohol) composite membranes

AbstractPoly(furfuryl alcohol) (PFA) composite membranes were prepared by polymerization of furfuryl alcohol (FA) using sulfuric acid (H2SO4) as the catalyst and polysulfone ultrafiltration membrane as the substrate. The membrane samples were characterized by ATR‐IR, TGA, SEM, and gas permeation technique. The effects of synthesis conditions including the FA/H2SO4 molar ratio, polymerization temperature, and the type of solvent on the chemical structure, surface morphology, and gas permeation properties of PFA composite membranes were studied. Our results showed that the suitable synthesis conditions for the preparation of PFA composite membranes with smooth surfaces and uniform structure include (1) FA/H2SO4 molar ratios: 74‐300, (2) polymerization temperatures: 80–100°C, and (3) solvents: ethanol and acetone. The PFA composite membrane prepared with a FA/H2SO4 molar ratio of 250, a polymerization temperature of 80°C and ethanol as the solvent exhibited the highest H2/N2 ideal selectivity ( $ {\rm{\alpha }}_{{\rm{H}}_{\rm{2}} {\rm{/N}}_{\rm{2}} } = 24.9 $), and a H2 permeability of 206 Barrers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Hydrothermal synthesis of nanocrystalline zeolite Beta by acid-catalyzed hydrolysis of teraethylorthosilicate

Nanocrystalline zeolite Beta was synthesized via the acid-catalyzed hydrolysis of teraethylorthosilicate (TEOS) under static hydrothermal conditions. Various parameters, such as pH value for hydrolyzing TEOS, SiO 2/Al 2O 3 ratio, template content, crystallization temperature and time, were investigated to obtain the suitable synthesis conditions. The produced samples were characterized by XRD, SEM, TEM, IR, ICP, surface areas, pore volumes and pore distributions. Compared with the traditional base-catalyzed hydrolysis of TEOS, the silicate precursors created by the acid-catalyzed hydrolysis of TEOS are proved to be favorable to the formation of nanocrystalline zeolite Beta.

Silicalite-1 membrane on millimeter-sized HZSM-5 zeolite extrudates: Controllable synthesis and catalytic behavior in toluene disproportionation

Silicalite-1 membrane was synthesized onto the millimeter-sized HZSM-5 zeolite extrudates by a hydrothermal method. The key step of the synthesis is to pretreat the rough external surface of extrudates with the cationic poly-flocculent poly-dimethyldiallylammonium chloride followed with the adsorption of silicalite-1 seeds. The seed size, and the concentrations of the seed and PAC were adjusted to get the suitable synthesis conditions. The resulting HZSM-5/silicalite-1 composite catalysts were characterized by SEM, XRD and N 2 adsorption. Catalytic performances were measured in the disproportionation of toluene with a pressured fixed-bed reactor. HZSM-5/silicalite-1 core/shell composites are proved to be successfully and controllably synthesized, giving much higher selectivity for para-xylene than the thermodynamic equilibrium value. The selectivity for para-xylene is enhanced by passivating acid sites of the external surface of HZSM-5 by the non-acidic silicalite-1 membrane, as well as the shape-selective diffusion of para-xylene inside silicalite-1 pores, and the conversion of toluene is decreased due to the additional diffusion resistance from the silicalite-1 membrane. The extent of these changes depends on the density and thickness of the membrane.

Study of growth, optical and morphological properties of Zn(O;OH)S thin films synthesized by CBD method

In this work, we investigated thin films of Zn(O;OH)S as substitute of thin films of CdS, which are conventionally used as buffer layer in chalcopyrite based solar cells. Thin films of Zn(O;OH)S were deposited by chemical bath deposition (CBD) method using a chemical bath containing thiourea, zinc acetate, sodium citrate and ammonium. Soda-lime glass and soda-lime glass covered with thin films of CuGaSe2 (CGS) were used as substrates in the deposition of thin films of Zn(O;OH)S. The Avrami equation was used to study the growth rate of thin film of Zn(O,OH)S on both substrates. The influence of the substrate kind and time of synthesis on the growth rate, optical and morphological properties of the as-grown thin films of Zn(O,OH)S have been carried out through spectrophotometry and atomic force microscopy (AFM) techniques. Finally, we found suitable conditions for synthesis of thin films Zn(O,OH)S to be used as buffer layer in CGS based solar cells.

Effect of the synthesis initiation mode on the structure and properties of sulfadiazine molecularly imprinted polymers

AbstractIn the presence of imprinting molecules of sulfadiazine, two kinds of molecularly imprinted polymers (MIPs) were synthesized by photoinitiated and thermally initiated polymerizations, respectively. The combination of sulfadiazine and α‐methyl acrylic acid and their composite ratio were studied by differential UV absorption spectrometry. The results show that a combined effect between the functional monomer and the imprinting molecule occurred in the solution. The structure and properties of these synthetic polymers were researched and compared with IR spectroscopy, transmission electron microscopy, and a balanced combination of static experiments. The polymer materials synthesized in these two ways had the same molecular structure, but their morphology was different. Furthermore, through the adsorption isotherm, Scatchard analysis, and evaluation of the imprinting efficiency, we determined that the lower temperature was a more suitable synthesis condition for the polymerization of the MIPs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

High surface area graphite as alternative support for proton exchange membrane fuel cell catalysts

The suitability of a high surface area graphite (HSAG) as proton exchange membrane fuel cell (PEMFC) catalyst support has been evaluated and compared with that of the most popular carbon black: the Vulcan XC72. It has been observed that Pt is arranged on the graphite surface resulting in different structures which depend on the catalysts synthesis conditions. The influence that the metal particle size and the metal-support interaction exert on the catalysts degradation rate is analyzed. Temperature programmed oxidation (TPO) under oxygen containing streams has been shown to be a useful method to assess the resistance of PEMFC catalysts to carbon corrosion. The synthesized Pt/HSAG catalysts have been evaluated in single cell tests in the cathode catalytic layer. The obtained results show that HSAG can be a promising alternative to the traditionally used Vulcan XC72 carbon black when suitable catalysts synthesis conditions are used.

Blue Light Emission from Stress-Activated CaYAl3O7 : Eu

We have revealed that phosphor emits blue light under the application of mechanical stress, called mechanoluminescence (ML). The influences of sintering temperature on photoluminescence (PL) and ML were investigated in order to gain suitable synthesis conditions. The results revealed that the sample sintered at shows strong PL and ML intensities, while further heating induces quenching of PL and ML. The ML and PL spectra are similar, which indicates that ML is emitted from the same center of ions as PL. This blue ML emission can be observed by the naked eye when the sample sintered at is compressed. Furthermore, the ML intensity of proportionally increased with the increase of mechanical load.

Observer design for a class of Lipschitz time-delay systems

This paper deals with observers design of non-linear time-delay systems. We investigate in particular, a useful technique based on the use of the Differential MeanValue Theorem (DMVT) and the Lyapunov-Krasovskii functionals to give a very suitable sufficient synthesis condition to assure exponential convergence. The obtained condition is formulated in terms of matrix inequality which becomes linear whenever an unknown scalar is chosen a priori. On the other hand, we introduce a simple and relevant transformation to show how to extend the obtained results to a particular class of continuous but non-differentiable systems. To show performances of the proposed approach and the large class of systems that may be concerned, numerical examples are provided.

Synthesis and Characterization of Alkyl Methacrylate-based Microgels by Experimental Design Method

In this work, alkyl methacrylate-based microgels were synthesized by an experimental design method, and their sebum absorption characteristics were investigated. The results of fractional factorial experimentation indicated that the cross-linking agent content, solvent content, and stirring speed were the main parameters in the synthesis of the microgels. The suitable synthesis conditions were determined by the response surface design method. Through a study of the monomer and solvent effects, it was confirmed that the microgel shows the highest sebum absorption ratio when t-butyl methacrylate is used as a monomer or when acetone is used as a solvent. The optimal microgel synthesis conditions for cosmetic application were determined, and the resulting microgel had a mean particle size of 4.7 µm and a sebum absorption ratio of 435%.

Carbon molecular sieves from palm shell: Effect of the benzene deposition times on gas separation properties

In the present work, an effort has been made to develop suitable process conditions for synthesis of carbon molecular sieve (CMS) from a locally available palm shell of Tenera type. The process involves three stages; carbonization, physical activation with steam, and carbon deposition by using benzene cracking technique. The highest micropore volume of activated carbon was obtained at 53.2% burn-off, which is then used as a precursor for CMS production. In order to narrow down the pore mouth size to a required size, benzene was cracked at 800 °C for 15–60 min. The characterization of the samples was assessed by physical adsorption of N 2 at 77 K. The adsorption kinetic of CO 2, CH 4, O 2 and N 2 were measured at room temperature in order to determine the sample behavior as CMS.

The Synthesis and Properties of High Pure δ Layered Sodium Disilicate

Abstract δ layered sodium disilicate (δ-Na2Si2O5) is a single layer silicate and has good properties as detergent builder. However, it is difficult to synthesize high pure δ-Na2Si2O5. In this paper, a feasible and simple technology was found by decreasing Na content in liquid sodium silicate (water glass). The crystalline time was short and no seed needed. The suitable synthesis conditions were Si/Na = 1.05–1.10, calcining at 720 °C for 5 minutes. The synthesis conditions are of industrial value. XRD and 29Si NMR data proved that synthesized samples were δ-Na2Si2O5 without impure phase. High pure δ-Na2Si2O5 exhibited good ions binding ability and reached 312 to 338 mg CaCO3/g.

Effect of Aging Time on Crystalline Structure Evolution of TiO2 Nanoparticles

It has been well realized that anatase TiO2 transforms to a more thermodynamically stable rutile phase by heat treatment at moderately high temperature, typically higher than 600 °C. However, by using suitable synthesis condition the anatast-to-rutitle phase transformation can occur at much lower temperature. In this present work, phase transformation during aging of TiO2 sol at room temperature was investigated. The sol was prepared based on hydrolysis and condensation of tetrabutyl orthotitanate precursor in the presence of small amount of water and hydrochloric acid. During aging time span of 50 days, the sol was sampled every 10 days for crystal structure and size analysis. It was found that aging time had a pronounced effect on anatase-to-rutile phase transformation accompanied by crystallite growth. Complete phase transformation was observed within 40 days of aging.

Electrodeposition of hard magnetic films and microstructures

Electrochemical deposition of materials with hard magnetic properties in the as-deposited state is essential for the efficient integration of micro-magnetic components into MEMS devices. Here we discuss the growth process and the microstructure-magnetic properties correlation for two Co-rich alloys, Co–Ni–P and Co–Pt. Under suitable synthesis conditions, these materials exhibit perpendicular anisotropy and hard magnetic properties in the as-deposited state; in addition, such properties are maintained up to several micrometer film thickness through close control of the film microstructure. In the case of Co–Ni–P films we achieved a saturation magnetization of 1.21 T (963 emu/cm 3), perpendicular coercivity up to 188 kA/m (2.36 kOe) at a thickness of 10 μm, and energy products up to 4.2 kJ/m 3. Co-rich Co–Pt films were grown on several substrates – Cr, Cu(0 0 1), Cu(1 1 1), and Ru(0 0 0 1) – in order to control magnetic anisotropy and achieve optimum hard magnetic properties. Cu(1 1 1) contributes to stabilize the hexagonal hcp phase at high current density yielding excellent hard magnetic properties, although only in films thicker than 100 nm; saturation magnetization in these films was about 1.04 T (828 emu/cm 3). Perpendicular coercivities up to 485.6 kA/m (6.1 kOe) were obtained in 1 μm thick film deposited at 50 mA/cm 2. Ru(0 0 0 1) seed layers provide an appropriate interface structure to further facilitate the epitaxial growth of hcp films, yielding hard magnetic properties and perpendicular coercivity with a squareness ∼1 in films as thin as 10 nm. The hard magnetic properties were only marginally compromised at large film thickness. Deposition at higher current density (50 mA/cm 2) favored markedly improved hard magnetic properties. The Co–Pt films on Ru exhibited perpendicular anisotropy with anisotropy constant up to 1.2 MJ/m 3. The electrodeposition process was further extended to fill lithographically patterned hole arrays (850 nm diameter, center-to-center distance 2550 nm and about 700 nm thick resist), yielding arrays of micron-sized hard magnetic cylinders with perpendicular coercivity of 361 kA/m (4.54 kOe) and high squareness.

Preparation of intercalation compounds of carbon fibers through electrolysis using phosphoric acid electrolyte and their exfoliation

Preparation of intercalation compounds using H 3 PO 4 electrolyte solution in mesophase-pitch-based carbon fibers successfully carried out by electrolysis in less than 10 mol/dm 3 of its electrolyte solution. Structural changes with preparation of intercalation compounds of carbon fibers were confirmed by a peak appeared around 2 θ =8° observed after electrolysis, which corresponds to an interlayer spacing of about 0.9 nm through XRD pattern (anticathode: Cu Kα). This new peak was reasonably supposed to be due to the intercalation into interspacing of carbon layers. Suitable synthesis condition of the intercalation compounds was determined to be the concentration of electrolyte of 5 mol/dm 3 at the electrolysis. It was also confirmed by morphology changes through SEM, that is carbon fibers, which treated low electrolyte concentration synthesized the intercalation compounds easily, and then it revealed markedly morphology changes such as fibrils. It could become exfoliation as well as them treated by other acid treatment through rapid heat-treatment. The formation of graphite oxide was suggested when the kind of intercalate was analyzed with elementary and TPD analysis.

Amelogenin control over apatite crystal growth is affected by the pH and degree of ionic saturation

To study the mechanisms which promote the interactions of amelogenin proteins with the forming mineral to establish suitable conditions for the biomimetic synthesis of enamel in vitro. Saturated calcium phosphate solutions were used in conjunction with recombinant amelogenin proteins to induce mineral formation on glass-ceramics substrates containing oriented fluoroapatite crystals (FAP). The height of mineral layers formed on these substrates within 24 h was measured by atomic force microscopy (AFM). The effect of protein concentration, pH and degree of saturation (DS) on the growth of apatite mineral was evaluated. Mineralization experiments were performed at 0, 0.4 and 1.6 mg/ml amelogenin concentrations. Mineralization solutions were used at pH values of 6.5, 7.4, 8.0 and 8.8 and DS of calcium and phosphate between 9 and 13. Height and morphology of mineralized layer formed on glass-ceramic substrates as determined from AFM measurements. Homogeneous nucleation and crystal growth of thin layers on the FAP were observed, when calcium and phosphate ions were added. The height of these layers grown on (001) planes of FAP was strongly dependent on the protein concentration and pH. At concentrations of 0 and 0.4 mg/ml crystal grew 5-15 nm on the FAP, while they grew approximately to 200 nm at 1.6 mg/ml. The enhanced crystal growth was observed only at pH 6.5, 7.4 and 8.0, while layers only 20 nm thick were obtained at pH 8.8. An increase in DS resulted in uncontrolled growth of calcium phosphate mineral covering large areas of the substrate. Protein concentration, pH and the saturation of the mineralizing solution need to be considered carefully to provide suitable conditions for amelogenin-guided growth of apatite crystals.

Synthesis of carbon molecular sieves by benzene pyrolysis over microporous carbon materials

In the present work, an effort has been made to develop suitable process conditions for synthesis of carbon molecular sieves (CMS) from the locally available bituminous and walnut shell char (CH, CW). The process involves modifying a carbon support having a majority of micropores with an effective pore size of about 4–25 Å. The sieves are contacted with different concentration of a volatile carbon-containing organic compound. The char was crushed, milled and agglomerated with starch and pitch as the binders, and then carbonized in nitrogen atmosphere at 650–750 °C for about 60 min. In order to narrow down the pore mouth size, benzene was cracked at 650–800 °C, for 10–60 min to facilitate the deposition of coke on the carbon support. All the products were characterized by analysis of pore size distribution, volume of pores, surface area and adsorption data. The best carbon molecular sieve was obtained for feed benzene entrance in N 2 of 3.5 × 10 −4 g/ml, cracking time of 30 min and pyrolysis temperature of 800 °C. These carbon molecular sieves are suitable for gas separations. Their performance was judged by the kinetic separation of Ar–O 2 mixture. Besides their application to gas separation, these CMS materials are receiving increased attention as catalysts.