Papers by Keyword: Surface Area

Abstract: Facing the current inefficiency of boron extraction from boron concentrate, this paper used mechanical activation as a pretreatment method to improve the extraction of B₂O₃ from boron concentrate, and researched the influences of milling conditions, including the ball-sample mass ratio, the diameter of milling ball, and filling ratio of chamber, on the B₂O₃ activity. The changes in the properties of the milled products were investigated to analyze the mechanism of activation. These three milling conditions all affected the B₂O₃ activity more or less, as evidenced by the changes of B₂O₃ activity with these milling factors. Under optimized milling conditions, the B₂O₃ activity could be enhanced from 67.52% of the non-activated boron concentrate to 85.01%. The results also showed that the specific surface area increased and the crystal structure was damaged, which accelerated the reaction between the alkaline leaching solution and boron concentrate samples and enhanced the B₂O₃ activity of the samples.

Abstract: In this paper are presented both the fill factor of 0.75 and an efficiency approaching 14.64 % of solar cell, which were achieved, despite the non-optimized process. A new Cu-based additive of pastes were applied for formation of front contact on silicon solar cells. Front contact were screen-printed using commercial silver paste containing the CuXX additive prepared at laboratory. It is the world's first copper based paste appropriate for high-temperature production processes of front contact of the solar cell.

Abstract: In the current study, various morphologies of zinc oxide (ZnO) including nanorods, nanoflowers, nanosheets/flakes, nanospherical particles, nanohexagonal sheets, and nanoneedles have been prepared by using single step and two-step hydrothermal processes with optimized parameters such as growth temperature, growth time and compositions of both the seed and growth solutions. Fluorine doped tin oxide (FTO) coated glass was used as the substrate. The prepared morphologies were characterized with the help of scanning electron microscopy (SEM) and the purity of nanostructures was confirmed by elemental analysis (EDX). These nanostructures were used as photo-anode material to fabricate the DSSC using a dye (Rhodamine B) for enhancing the range of solar spectrum that is to be adsorbed. Finally the fabricated solar cells were characterized in terms of their efficiency, gauged by their fill factor. Among different morphologies investigated as photo anode materials; nanosheets/flakes were found to be showing maximum efficiency, with fill factor values around 0.5 due to their larger surface area, better porosity and enhanced capability of light trapping and scattering.

Abstract: BaCeO₃ has attracted great interest in research worldwide, whether doped with other elements on the site A and / or B of perovskite ABO₃ or not, thus enabling its use in different applications. However, the properties exhibited by perovskite depend on partial or total replacement at the site, as well as the applied synthesis method. In this work we studied crystal structure, crystallographic parameters, morphology and textural properties of BaPrO₃ perovskite synthesized by EDTA-Citrate complexation process. The adopted methodology makes it possible to obtain powders with orthorhombic crystal structure ( a=6.07 Å; b=6.3 Å e c=8.7 Å) and crystallite size of approximately 100 nm. That perovskite has dense and irregular agglomerates with surface area and pore volume of about 2.37 m² g^-1 and 0.7x10^-8m³g^-1, respectively. Finally, the methodology has demonstrated effectiveness in achieving crystalline phase with similar characteristics and properties obtained by different methods.

Abstract: The effect of microwave-heating on the morphology and surface area of NaX zeolite was studied. The characteristics of NaX zeolite, which has a porous structure, make NaX zeolite applicable as a catalyst. Generally, the process of NaX zeolite formation with an FAU-type structure, either naturally or synthetically, requires quite a long time. Therefore, in this research the effect of microwave heating on the produced sample was investigated using XRD, SEM, and BET surface area measurement. The heating time parameter was varied to determine the optimal conditions for the synthesis of NaX zeolite. The results indicated that microwave-heating is capable of accelerating the crystallization process and reduce the agglomeration of NaX zeolite, as shown by the XRD and SEM results. Based on the SEM result, the particle size distributions of the samples microwave-heated for 1, 3, and 5 minutes, were 350.5, 262.5, and 243.9 nm respectively. In addition, prolonging the microwave-heating time made the surface area of the samples become larger. The specific surface area of the samples microwave-heated for 1, 3, and 5 minutes, 55.9, 153.5, and 204.1 m2/g respectively.

Abstract: Para-wood residue was impregnated in 40% wt. of H₃PO₄ solution for 24 h before carbonization under different temperatures and times. The response surface methodology (RSM) based on Box-Behnken was applied to optimize the operating conditions in producing activated carbon with high specific surface area. The effects of three variables; impregnation ratio, carbonising temperature and time on the specific surface of activated carbons were investigated. The proposed model was almost in accordance with the experimental case with correlation efficient and of 0.9653 and 0.9029, respectively. The optimal conditions were found to be 6%wt. of impregnation ratio and carbonization at 400°C for 67.27 min. The predicted surface area of produced activated carbon under these optimal conditions determined by RSM was 1069.30 m²/g. Experimental validation at these conditions was observed of 978.95 m²/g which closely agreed with the predicted value. This obtained activated carbon structure composed of mesopores and micropores with the average pore diameter of 21.71°A. This study indicated the RSM based on Box-Behnken design was the effectively method to optimize the operating condition and maximize the specific surface area of produced activated carbons.

Abstract: A nanoporous copper (NPC) sample with well-ordered porosity of 20 nm was fabricated by an electrochemical dealloying single-phase Cu0.4Mn0.6 with an external potential of-0.5 V (MSE). The electrochemical mechanism of the dealloying process on the Cu-Mn surface was studied by a liner sweep voltammetry experiment, and an optimized applied voltage for the Cu-Mn system was recommended. The properties of the monolithic NPC, including morphology, chemical composition, surface area and wettability were systematically characterized. The specific surface area around 11.86 m2/g of the as-dealloyed NPC was measured by BET-nitrogen method. The micro/nanoscale bi-continuous 3D porous structures of NPC not only increase the surface area, but also improve the wettability of NPC surface since the increase in surface roughness.

Abstract: Effect of glucose loading on the synthesis mesoporous carbon had been studied using hard template method where mesoporous silica SBA-15 was used as a template. To obtain a large pore of mesoporous carbon sample, a large pore of silica template was used. A series of mesoporous carbon sample was synthesized by loading different amounts of glucose (2.5g, 5.0g and 10.0g) as a carbon precursor to ensure that the template was fully impregnated with precursor. After treatment process, the surface area of carbon samples were measured with Brunauer-Emmett-Teller (BET) analysis and it shows that higher amount of glucose gives higher surface area due to the large pore of the template used. The samples then were tested with cyclic voltammetry technique at different scan rates (10, 20, 30 and 50 mVs^-1) in 6M KOH electrolyte. It reveals that higher surface area samples show a higher specific capacitance with 119 F/g at slow scan rate 10 mVs^-1.

Abstract: Iron oxide (α-Fe2O3) as adsorbent was no longer new in CO2 adsorption studies. However, its contributions in the industry still in limited wherein lack of convincing results of quantifying of adsorbed CO2. This work presents an analysis for α-Fe2O3 was prepared by simple mixing method with identified the adsorption capacity that applied in CO2 capture. The synthesized α-Fe2O3 from different concentrations of precursor were analyzed using XRD, N2 adsorption-desorption isotherms with BET and BJH method, TEM, FTIR, CO2 adsorption at 298 K, CO2-TPD and TGA-DTG. It was noted that 2M concentration of precursor (s2M) with highest crystallite peaks shows highest surface area among all samples which indicative of well generated pores. The different concentration of precursor was found generated more porosity rather than particle size according to TEM micrograph. The sphere shape crystallite particle with high surface area (50.5 m2/g) and porosity were desirable properties in CO2 adsorption. Consequently, physically adsorbed CO2 with adsorption at 298 K was highest with adsorption capacity of at 17.0 mgCO2/gadsorbent. Finally, chemically adsorbed CO2 was successfully identified from CO2–TPD analysis with adsorption capacity of 0.19 mgCO2/gadsorbent and 1.31 mgCO2/gadsorbent at maximum desorption temperature of 375 °C and 749 °C respectively.

Abstract: Currently, the major concern in production of biodiesel is to find a new catalyst which can produce high quality of biodiesel at lower costs. In this study, titania supported CaO catalyst was prepared by a so-gel method. The characterization of catalyst was done using Brunauer-Emmett-Teller (BET) model method to characterize the surface area of the catalyst. Further, the ability of the catalyst for transterification reaction of waste cooking oil (WCO) with methanol was also assessed. The effect of calcination temperature on the catalyst to the transesterification reaction was examined to investigate the relation between catalyst calcination temperature and percentage yield (% yield) of biodiesel production.