Papers by Keyword: Reaction Time

Abstract: Lithium-ion batteries are the preferred choice for electric vehicles (EVs) due to their high energy density, low self-discharge, thermal stability, and long cycle life. Morphology of materials is essential in assessing the effectiveness of lithium-ion battery cathodes. One effective way to evaluate cathode quality is by examining its precursor (NMC-811) morphology using SEM. Samples were taken every 20 minutes over 2 hours, revealing that longer reaction times improve the homogeneity and semi-spherical shape of the NMC-811 precursor, with increased particle density and a reduced average diameter. NMC-811 was synthesized by a calcination process at temperatures of 450°C, 600°C, and 700°C, and sintering temperatures of 800°C and 900°C. SEM analysis revealed that higher calcination temperatures resulted in a more homogeneous particle structure, with variations in holding time having minimal impact on particle shape.

Abstract: In this research, a homemade autoclave reactor was used for preparing iron oxide nanoparticles by hydrothermal technique at different reaction times by using ferric chloride, ferrous sulfate, and ammonium hydroxide as raw materials. The XRD characterization showed that the nanoparticles of the samples have high crystallinity with the crystal phase of magnetite, furthermore, the crystal phase of hematite appears clearly as the reaction time increased. The SEM results showed when the time of reaction increased the average particle size increased too from 28.1 to 49.2 nm. That means the reaction time is an effective parameter for the nanoparticle's growth, The EDX spectrum verified the confirmation of iron oxide nanoparticles by the appearance of Iron and Oxygen peaks. The FT-IR results showed that all samples have an absorption peak at about 578 cm^-1 corresponding to the Fe-O bond stretching modes of the in magnetite and the peak of hematite appeared as the reaction time increased above 2 hours which was confirmed with XRD results. Finally, the reaction time is a powerful tool for controlling in size and phase of nanoparticle preparation. Keywords: Hydrothermal, Iron Oxide, Reaction time, magnetite, and hematite.

Abstract: In this research, iron oxide nanoparticles were prepared by a new hydrothermal pyrolysis technique at different reaction times. X-ray diffractometer (XRD) characterization showed that the nanoparticles have high crystallinity with a combination of two crystal phases maghemite and magnetite, as the reaction time increase the ratio of magnetite phase to maghemite phase increased. The morphological properties of the samples showed an increase in the particle size from 58 to 108 nm due to the single domain–multidomain transition as showed by scanning electron microscope (SEM). Electron Dispersive X-ray (EDX) spectra showed only peaks of oxygen and iron that verified the formation of iron oxide nanoparticles. The Fourier transform infrared spectroscopy (FT-IR) showed that the absorption peaks at about 578 cm^-1 and 630 cm^-1 correspond to the stretching modes of the Fe-O in magnetite, as the reaction time increased the peak around 630 cm^-1 decreased due to the magnetite phase only. Finally, all the results showed the formation of iron oxide nanoparticles by this new technique that merges spray pyrolysis and hydrothermal techniques with many advantages such as spraying successive parameters in a short time, high-speed, good homogeneity, and pure material with small particle size.

Abstract: In the recent time, there is increasing research in the area of alternative fuels as the exhausts of presently used petroleum-based fuels have been identified to have negative effects on the environment. Fuels produced from plant oils and animal fats have the tendencies of replacing petro fuels since they are renewable in nature. One of these renewable fuels is biodiesel. However, the homogenous catalyst used in biodiesel production has some drawbacks such as difficulty in separation from the fuel, soap formation and corrosiveness of the product mixture. In this work, the use of heterogeneous catalyst sourced from local raw materials (kaolin and eggshell) for the production of biodiesel from oil of desert date seed has been investigated. The kaolin obtained from Alkaleri Mining Site, Bauchi, was calcined in an oven at 800 °C for 3 h. The calcined kaolin was then chemically activated. Also, the eggshell-based catalyst was produced from raw eggshells after washing, drying, grinding, sieving using 0.3 mm sieve size and calcining at 900 °C for 3 h. Furthermore, the oil content of the desert date seed, which was acquired from a local market in Bauchi, was extracted via solvent extraction in a laboratory with a yield of 42%. Then, the biodiesel was subsequently prepared by mixing the oil, methanol and catalyst in a flat bottom flask and heating the mixture for a specified period. The catalyst concentration, methanol to oil ratio and time of reaction were subsequently varied to obtain the best yield. The results obtained revealed that an optimum yield of 29% could be obtained at methanol to oil ratio of 6:1 and a reaction time of 60 min using 1.5 g of eggshell-based catalyst while an optimum yield of 22% was obtained with 0.6 g for kaolin-based catalyst at a reaction time of 60 min and methanol to oil ratio of 4:1. It is recommended that further work should be carried out to improve on the yield of the biodiesel obtained using the heterogeneous catalysts.

Abstract: Incorporation of carbon nanomaterials (CNMs) into polymer such as Polyacrylonitrile (PAN) fibres allow electric current to pass through easily. Therefore in this study, bulk quantities of CNMs are synthesised using Chemical Vapor Deposition (CVD) method by manipulating the reaction time and catalyst ratio. Polypropylene wastes are used as the carbon precursor and ferrocene as metal catalyst in the CVD experiment. Addition of 1 wt% synthesised-CNMs into electrospun PAN fibres successfully increased the electrical conductivity by 50%. Addition of CNMs improved the crystallinity of electrospun-PAN/CNMs fibres as proven by XRD analysis. Electrospun PAN/CNMs-A fibres show larger diameter than the diameter of electrospun PAN/CNMs-B. Large bead formations contained densely-packed CNMs-A within the structure of electrospun PAN/CNMs-A fibres hindered their effectiveness to conduct the electricity. On the contrary, PAN/CNMs-B shows remarkable improvement in electrical conductivity when loosely-packed CNMs-B are added to the PAN fibres.

Abstract: This paper discusses the effect of reaction time and temperature of silver-copper nanoparticles prepared by a polyol method. In this study, silver-copper nanoparticles were synthesized through the green approach of polyol method using ethylene glycol (EG) as green solvent and reductant, and polyoxyethylene-(80)-sorbitan monooleate (Tween 80) as a nontoxic stabilizer. The phase and morphology of silver-copper nanoparticles were characterized by X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM). The results XRD confirmed silver and copper nanoparticles to be phase-pure crystalline silver and copper with face-centered cubic (fcc) structure on the basis of XRD analyses. FESEM analysis confirmed the existence of Ag and Cu nanoparticles.

Abstract: In this paper, synthesis and fluorescence performance of graphene oxide have been primarily studied. Fistly, graphene oxide with remarkable fluorescence performance was prepared by modified hummer’s method. Secondly, changing the reaction time, the structure and size of graphene oxide were analyzed using X-ray diffraction (XRD) and Malvern Zeta-Size Analyzer, and the effects of different reaction conditions on the XRD patterns of graphene oxide were discussed. Finally, the fluorescence performance of graphene oxide solution were analyzed using fluorescence spectrometer.

Abstract: Road accident is one of the top ten causes of deaths around the world. Malaysia is not an exception as in the year 2007 there were 6282 road traffic fatalities and 21363 non-fatal road traffic injuries. Research on hazard perception skill of drivers in recent years shows that the driving skill is a mian factor of accident causation and accident prevention. A video-based hazard perception test and questionnaires were used to study the effect of experience, type of hazards, and type of driving settings to the hazard perception skill of Malaysian drivers. The findings of the study shows that in general experienced drivers have better hazard perception than novice drivers, and experience in road accident contributes toward the development of hazard perception more significantly among novice drivers. The study also shows that both driver groups have slowest perception on hazards caused by vulnerable road users. Drivers also perceive hazards faster in rural areas compared to residential and city areas.

Abstract: Using FGD gypsum as raw material, calcium sulfate whisker was prepared by hydrothermal synthesis method. Through testing the aspect ratio of calcium sulfate whisker, the effect of reaction temperature, reaction time, desulfurization gypsum slurry concentration and pH value on the growth of calcium sulfate whisker were deeply researched. The optimum conditions for the preparation were that the reaction temperature was 150 °C, reaction time was 270min, the slurry concentration was 10% and the slurry pH value was 6.

Abstract: CuO/γ-Al₂O₃ catalyst was used to deal with the waste leachate in CWAO technology of, and the SEM and TEM characterization showed: active component in the surface of the carrier distribution is uniform; In CWAO process, six factors, based on the COD_Cr removal rate and turbidity removal rate, the biggest impact factor is reaction temperature, and the influence factors of the top three were reaction temperature, catalyst dosage and reaction time. The influence factors of those in the bottom three are influent water pH, oxygen partial pressure, stirring intensity, and three factors of influence on the strength is close. Optimizing operation process, in order: reaction temperature of 200 °C, catalyst dosage of 1.5 g, oxygen partial pressure of 2.0 MPa, stirring intensity 800 rpm, influent water pH of 7.0, the reaction time of 70 min.