Papers by Keyword: Surface Area

Abstract: This study presents the preliminary characterization of commercial calcium oxide (CaO) and aluminum oxide (Al₂O₃) catalysts intended for application in the catalytic upgrading of biomass-derived bio-oil. The catalysts were characterized using Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, Thermo gravimetric Analysis (TGA), and X-ray Diffraction (XRD). SEM images revealed that both catalysts exhibit irregular, rough-surfaced particles with visible fractures and mesostructured textures conducive to catalytic activity. BET results indicated a specific surface area of 50.301 m²/g for CaO and 129.442 m²/g for Al₂O₃, with corresponding pore diameters of 2.64 nm and 2.647 nm, respectively, confirming their mesoporosity. TGA of CaO showed substantial weight loss associated with moisture, hydroxide, and carbonate decomposition, indicating the need for pre-calcination to restore active oxide phases. In contrast, Al₂O₃ exhibited minor mass loss mainly due to dehydration and dehydroxylation of surface-bound species. XRD analysis confirmed the presence of crystalline γ-Al₂O₃ and highly crystalline CaO with characteristic diffraction planes for their respective phases. These findings demonstrate that both commercial catalysts possess favorable physicochemical properties particularly high surface area, thermal stability, and mesoporous structure that make them promising candidates for vapor-phase upgrading in biomass pyrolysis systems.

Abstract: An effective powder consumption is indispensable for enlarging the diameter and thickness of SiC crystals. We employed three types of filling designs for SiC source powder with different distances between the surface of the seed and the source powder. To maintain the shape of the designs, the SiC source powder was heat-treated in an Ar atmosphere at 680 torr within a temperature range of 1500 to 1600°C. The SiC source powder consumption and contribution to growth in well-structured layouts increased due to the increase in the surface area of SiC source powder, despite its lower initial powder filling. The numerical simulation showed that the well-structured layouts with a higher surface area of SiC source powder have a higher partial pressure of Si and SiC₂ gases (supersaturation of these gas phases) near the seed region compared to the without well-structured layouts. The computed tomography (CT) analysis of the cross-section of SiC source powder after the growth run clearly showed that the source powder was previously sublimated at the region of the crucible wall, and recrystallization at the surface region of the source powder physically retarded the pathway of SiC source gases to the region of the SiC seed crystal. The newly designed well-structured layouts of the source powder have an economical advantage in achieving effective powder consumption during crystal growth.

Abstract: In this study, the activation of natural diatomite was done with alkaline solution. The diatomite powder was sieved and purified prior to activation at room temperature (Alk-DA RT) and 85 °C (Alk-DA 85 °C). The effect of activation time of Alk-DA 85 °C samples was observed for 1 h, 2 h and 5 h. At temperature interval from room temperature to 530 °C, the weight loss for all of Alk-DA are less than R-DA. The reduction of particle aggregation was found in Alk-DA at both RT and 85 °C as shown in SEM images, indicating the activation by NaOH that effectively breaks down the bulky structure. The formation of silanol group (Si-OH) were obtained on the surface of Alk-DA. However, BET result revealed there is no increment of surface area and porosity in case of RT. In addition, Alk-DA 85 °C samples at 1 h and 2 h provided the spongy surfaces with obvious improvement of surface area, and reduction in porosity and pore size. In contrast, Alk-DA 85 °C 5 h showed more cluster of particle aggregation. Moreover, it can be observed that Alk-DA 85 °C 1 h is the most interesting for further study since it potentially provides high gas adsorption but only requires a shorter activation time.

Abstract: Lignin, one of the interesting carbon sources which underutilized, gives great interest in transforming into value-added material, specifically as a solid acid catalyst. In this study, lignin undergoes heat treatment at temperatures 400–600 °C for 1 and 2 h, followed by sulfonation on a 1:10 (carbon-to-acid, g/mL) ratio in a reflux setup at 150 °C for 15 h to produce lignin carbon acid catalysts. The characterization of the catalysts was performed by the elemental analyzer, N₂ adsorption-desorption, Fourier transform infrared (FTIR), and acid density calculation. The effects of lignin carbon preparations on the catalyst's physiochemical properties as well as the effectiveness of sulfonation were evaluated. The selected catalyst was tested in levulinic acid esterification at selected fixed conditions; 1:10 molar ratio of levulinic acid-to-ethanol, 10 wt.% of catalyst loading, for 3 h of reaction at 80 °C and 200 rpm in a batch reaction system. At higher heat treatment temperatures and time of carbon preparation, the surface area of the catalysts was recorded to increase resulting in the acid density reduction. For the catalytic activity, 62.36 mol% (Batch 1) and 61.64 mol% (Batch 2) of ethyl levulinate yield were obtained over LCS-400-1 with a good acid density of 0.0223 mmol/m² and a surface area of 43.28 m²/g. The results of this study show that the conditions for carbon preparation significantly influence the catalyst's physical and chemical characteristics.

Abstract: The optimized surface morphology of electrospun magnesium oxide (MgO) nanofibers can be achieved based on the parameters set during the fabrication of nanofibers. However, not all materials used during the electrospinning process can be synthesized together as it depends on the application’s needs. This research aims to study the factors that influence the surface area of the MgO nanofibers due to material preparations and electrospinning parameters. The research is based on data obtained from the previous research and was analyzed to evaluate the effect on MgO nanofibers that synthesized with different materials. Based on the data analysis using Brunauer-Emmert-Teller (BET), the surface area for carbon sorbent is higher than organic sorbent. The surface area for carbon sorbent of nitrogen could be achieved up to 324.5 m²/g compared to only 104.8 m²/g using organic sorbent for magnesium oxalate dihydrate (MO). The studies show that the use of nitrogen as a carbon sorbent in the fabrication of electrospun MgO nanofibers may produce a good quality of nanofibers.

Abstract: Globally, the adverse environmental impact of waste plastics is of increasing concern. Most plastics are naturally non-degradable, thus imposes serious environmental threats, especially, to marine life. Upcycling such waste into valuable contents is an effective approach to managing waste plastics. In this study, graphene is synthesized from waste polystyrene (PS) by thermal decomposition at different temperatures (500, 600, 700, 800, 900 and 1000 °C) for two hours reaction time in a stainless steel autoclave. The synthesized materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-disperse X-ray analysis (EDS) and surface area by using Brunauer–Emmett–Teller (BET). The yield of the product materials was investigated and optimized against the temperature. The synthesized graphene is considered a promising material for many applications, especially in environmental applications.

Abstract: Natural clays, engineered Ag-nanoparticles (NP), TiO₂-NP, and exhausted coffee grounds were used to synthesize a nanocomposite 7NC using a Vertisol soil through a single-step by thermal method, to build a nanomaterial to degrade or filtrate pollutants from soils, water or air. The surface characteristics and the porosity of the composite were studied through nitrogen gas adsorption at liquid nitrogen temperature and application of the Brunauer–Emmett–Teller (BET) equation and the results indicated that the microporous composites ranged a surface area of 17.36 m² g^-1. X-ray diffraction showed crystalline structure and crystalline phase of the nanocomposites. HR-TEM-STEM results demonstrated that TiO₂-NP surrounded Ag-NP, and both were impregnated on natural soil nanoparticles. Oxidation states of the Ag-NP and TiO₂-NP were analyzed by X-ray photoelectron spectroscopy (XPS) The energy gap of nanocomposite 7NC was determined using the Kubelka-Munck model from Ultraviolet–visible diffuse reflectance (UV–Visible DRS) spectra. The photocatalytic activity of these nanocomposites was evaluated, and the results indicated that nanocomposite with Vertisol-soil-NP (7NC) degraded the harmful organic compound methylene blue (MB) while the antimicrobial activity and resistance against Escherichia coli and Staphylococcus aureus and the zone of inhibition (ZOI) also were analyzed. The nanocomposites Ag-NP/TiO₂-NP/natural-soil-NP/exhausted coffee-ground showed its for the development of an efficient material for environmental remediation with photocatalytic and antimicrobial activity.

Abstract: Limestone is one of the most ancient construction materials that exist, however it has become obsolete over the last decades, being replaced by industrial materials like cement. It must be considered that not only the construction lime can be used in works, but the limestone industry can provide other products like high purity lies The research about the surface area of high purity lime has verified that it exists an improvement in the adhesion and workability features of the material in comparison with construction lime, besides to be a more economical solution than masonry cement. It is proposed in this document the use of high purity lime in construction works to achieve the benefits previously mentioned. Various samples with different percentages of high purity limes were tested in the laboratory, analysing the surface area changes between them, considering its use for construction purposes and its performance.

Abstract: The advantages of palm kernel shell (PKS) as a renewable and sustainable material for activated carbon production have been explored for various applications such as water treatment, pollutant, pesticide, and heavy metal adsorption. However, the full promises of this material for energy storage devices have not been duly studied. In this research, PKS is physically activated and the effect of particle size on the physical characteristics of the activated char was investigated. Pellet (3 mm), granules (0.4 mm), and powder (0.0075 mm) are the sizes considered in the experiment. The surface morphology, surface area, porosity and functional group at different sized was analyzed. Finally, a suitable particle size was recommended for the electrode material of supercapacitor based on the physical characteristics of the activated carbon.

Abstract: The hydrophilic-hydrophobic surface area of alumina powder (Al₂O₃) oxidized at different temperatures was determined on the base of adsorption of water and butane vapor at 25°C. In the order to study the influence of thermal oxidation upon hydrophilic/hydrophobic character of the surface, samples of Al₂O₃ were characterized using granulometry, SEM and BET surface area measurement. SEM results showed that the thermal treatment does not affect the morphology of the Alunima. However, the increase of treatment temperature from 250 to 900°C results in changing of the hydrophilic-hydrophobic balance of Al₂O₃ surface.