Papers by Keyword: Molar Ratio

Abstract: The substitution of Mg/Al hydrotalcite catalyst over the glucose-isomerase is expected to decrease the space-time and reduce the energy consumption of glucose isomerization into fructose. The quality of the Mg/Al hydrotalcite catalyst is determined during the synthesis process. The synthesis has been carried out in the various Mg/Al molar ratio and precipitation times and observed the catalytic activity in the isomerization. Response Surface Methodology (RSM) is used to analyze statistically the optimum condition of the synthesis process. The Mg/Al molar ratio was 1:1 to 4:1 with a precipitation time of 720-1080 min. The characterization of the Mg/Al hydrotalcite catalyst includes the functional groups of the constituent compounds by FTIR, the crystallinity and particle size by (XRD), and the surface area of the catalyst by BET. The RSM results show the optimum condition of the Mg/Al molar ratio and precipitation time to produce the highest mass catalyst product of Mg/Al hydrotalcite catalyst (3,38 g) is 3.34:1 and 984.85 min. The highest degree of crystallinity obtained is 28.70% with the particle size is 10.19 Å. The highest yield and selectivity of the isomerization process are 56.95% and 91.89%, respectively. By the RSM analytical method, the Mg/Al molar ratio and the precipitation time used in this catalyst synthesis do not give a significant effect on the catalytic activity of the isomerization.

Abstract: This study focused on the production of bioactive pure cordierite ceramic and the evaluation of its bioactivity by immersing it in simulated bodily fluid (SBF) and coating it on CP-Ti utilizing the dip coating Procedure. Cordierite is created by chemical coprecipitation, which involves combining Cordierite gel with a water-based sol-gel composed of Alumina Al2O3, magnesium oxide MgO, and silicon oxide SiO2. They used a hydraulic press to form cordierite into a cylindrical shape with a pressure of 4 bar and a holding time of 30 minutes at this pressure. Firing presses reach temperatures of 1250 C^o and have a holding time of 2 hours. A Field Emission Scanning Electron Microscope (FESEM) was used to examine the microstructure, which revealed a homogenous distribution of the compounds with negligible porosities. The phase transitions that cur during the sintering Process is studied using X-ray diffraction (XRD). The structural investigation of specimens revealed the formation of the cordierite phase at 1250 C^o, as well as the development of cristobalite, spinel, protoestatite, and corundum with cordierite phase. The dip coating Procedure was utilized to cover commercial pure titanium (CP-Ti) samples with cordierite powder. CP and Tafel exploration tests show that coated CP-Ti has superior passivation than uncoated Substrate. By comparing the findings of uncoated and coated CP-Ti, this paper concludes that the cordierite system acts as a good passivation layer.

Abstract: In the current paper, fundamental aspects of heavy oil and wax deposition problems are defined. Wax or in another term is cloud point occur when the oil starts to precipitate. When it’s started to precipitate, it can cause major problem to industry of oil and gas. In this study, ZnO nanoparticles were chosen to study the effect of varying molar ratio from 1:1, 1:2, 1:3 to the morphology and size of the nanoparticle. The structures and properties were recognized with energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) methods. EDX and FE-SEM is to study the morphology of ZnO structure while XRD is to determine the purity and size of the nanoparticle. From the study, 1:1 ratio has the smallest size of nanoparticle with 10.37 nm while 1:2 and 1:3 give the size of 12.3 nm and 16.37 nm respectively. As the molar ratio is increases, the size of nanoparticle become bigger. The influenced of ZnO nanoparticles on rheological behaviour of model oils and the wax content is reported. From the study, the addition of ZnO nanoparticle reduced the rheology behaviour of crude oil by varying nanoparticle sizes, temperature and shear rate. ZnO nanoparticle can reduce the deposition of wax up to 50% with influenced of smaller nanoparticle size. Effect of size of nanoparticle highly impact the viscosity and wax content. This prove that, by introducing nanoparticle into crude oil, wax content can be reduced thus decrease the chance for crude to precipitate.

Abstract: Tobermorite is the main mineral which provides to aerated concrete mechanical properties. It is produces during hydrothermal conditions by reacting silicon and calcium oxides. Within this research was evaluated tobermorite formation using high temperature combustion fly ash and quartz sand, as the siliceous raw materials. As a binder was used lime. Emphasis was also placed on the molar ratio of C/S, which is crucial for the formation of tobermorite and was given 0.73 and 1.00. Hydrothermal synthesis was carried out in a laboratory autoclave at temperatures of 170 and 190 °C.

Abstract: In this paper, nanosized La_0.85Na_0.15MnO₃ (LNMO) has been synthesized via sol-gel method by involving two major steps, first the complexation of citric acid (CA) with metal ions (MI) and second the polyesterification between CA and ethylene glycol (EG). The effect of molar ratio CA:MI varying from 2-4 on structure, microstructure and electrical transport properties of LNMO have been investigated by constant the amount of EG. All samples show single perovskite phase with hexagonal structure and space group R3c after sintering at 800°C for 10h. Sample of molar ratio 2.5 is observed to possess smallest grain sizes which yield high resistivity value compared with others, is suggested to originate from the increase of tunneling barriers (grain boundaries). The large low field magnetoresistance (LFMR) of about ~ -16% at 0.1T and low temperature confirmed the important role of grain boundaries in the nanosized LNMO.

Abstract: This paper presents the results of an experimental investigation on molar ratios of MgO/ MgCl₂ affecting the hardness of magnesia grinding wheels, which is one of the most important properties. Magnesite grinding blocks of different ratios of MgO/MgCl₂ were prepared. The surface Rockwell hardness of which was tested under the same curing conditions. By an integrated assessment of the experimental studies of hardness and component, it is recognized that the molar ratios of MgO/MgCl₂ can significantly affect the properties of magnesia grinding wheels. With the increase of MgO/MgCl₂ molar ratio, hardness of the specimens increases. Scanning electron microscopy (SEM) studies on grinding blocks of different ratios indicated that micro needle shaped crystal structure of phase 5 are mainly responsible for hardness development. Finally the optimal recipe was selected in consideration of the characteristics of the silicon mechanical chemical grinding (MCG), which was verified to be effective by the following grinding experiment.

Abstract: Layered double hydroxide (LDH) hybrid materials of Zn-Al-layered double hydroxide-3,4-dichlorophenoxy acetate acidnanocomposites (ZADs) were prepared by direct self-assembly method. The pH of the solution was adjusted to 7.5 using 2M NaOH. Various Zn2+ to Al3+ molar ratios, R ranging from 1 to 6 were used with a fixed concentration of 3,4-D at 0.3 M. The Powder X-ray diffraction (PXRD) patterns showed the formation of well-ordered nanocomposite with the expansion of basal spacing from 8.9 Å in the Zinc-Aluminium-Layered Double Hydroxide (ZAL) to 18.7 - 22.1 Å in the resulting nanocomposites. The Fourier transform infrared (FTIR)spectra for the nanocomposites showed features for both ZAL and ZAD, showing the successful intercalation of the organic moiety into the LDH interlayer. The percentage loading of 3,4-dichlorophenoxy acetati acid(3,4-D) in LDH was found to be increased from 34.7-48.1 % (w/w), as the mole fraction of Al decreased from 0.44-0.15. This study shows that the mole fraction of zinc ion was replaced by aluminium ion in the LDH plays an important role in controlling the physic-chemical properties of the resulting material.

Abstract: Synthesis of cadmium sulfide (CdS) nanoparticles has been performed through the simple and rapid microwave-assisted polyol method, using cadmium chloride and thioacetamide as the cadmium and sulfur sources respectively. Attempts were made to control the size and crystallinity of the CdS nanoparticles by controlling microwave irradiation time and the initial molar ratio of the cadmium and sulfur sources. The structure of nanoparticles characterized by X-ray diffraction (XRD) was hexagonal. No peaks corresponding to impurities were detected, indicating the high purity of the product. The size of the prepared samples was calculated by Debye–Scherrer formula according to XRD spectra. The morphology of particles was observed in the transmission electron microscopy (TEM) images was spherical. The average size of nanoparticles was also estimated from these images. The optical absorption of CdS nanoparticles studied by UV-Visible spectroscopy showed a blue shift from bulk CdS due to quantum confinement. The size of nanoparticles was calculated by Brus formula according to UV-Visible spectrum and compared to XRD and TEM results.

Abstract: The use of Potassium-phosphate baths for the alloy deposition of Nickel–Molybdenum is recently proved equally good as Sodium-citrate baths. The coatings so obtained from Potassium-phosphate baths were examined for atomic weight percentage of Molybdenum. The variation in weight percentage of Molybdenum was obtained by varying different plating parameters like - molar ratio, current density range, and potential range. The observed co-deposited Molybdenum Atomic percentage variation in alloy was investigated for grain size, porosity in structure and surface roughness. The results revel that Molybdenum Atomic percentage in the Nickel–Molybdenum alloy has effect on porosity and surface roughness. It was also found that root mean square value of surface roughness was not only affected by the Molybdenum Atomic percentage but also by potential at relaxation time (TOFF) potential.

Abstract: ZnO as a semiconductor with wide direct band gap (3.37 eV) and high exciton binding energy of 60 meV. It has attracted in several applications such as solar cells, field emission, sensor, etc. In this study, different ZnO complex structures were prepared by precipitation method at different molar ratio. Zinc nitrate as zinc source, potassium hydroxide as precipitating agent and sodium dodecly sulphate as surfactant were used to synthesis the ZnO. The effect of different molar ratio on the morphology and size of final product have been investigated. The final products were characterized by X-ray diffraction (XRD) with Cu Kα radiation, field emission scanning electron microscopy (FESEM) with an attached energy dispersive x-ray spectroscopy (EDS) and photoluminescence spectrofluorophotometer (PL). From XRD patterns, all synthesized ZnO shows good crystallinity. Different morphologies of synthesized ZnO were obtained from FESEM including flower composed flakes, flower composed radial rods and single straight rods while the EDS result demonstrates elements Zn and O obtained in the product. A very strong UV emission at ~390 nm observed in PL spectra indicated that the ZnO are of high crystal quality.