Papers by Keyword: BET

Abstract: Utilization of agriculture waste has been an issue around the world. In this study, the natural cellulose was extracted from pineapple leaf. Under the optimal pretreatment conditions of 25 g/L, 368 K and 6 h, the ratio of obtained cellulose was above 85 wt%. The structure of obtained cellulose at different stage was confirmed by XRD results. Origin cellulose (OC) and pretreated cellulose (PC) belong to be cellulose I, while regenerated cellulose possessed cellulose II structure, attributed to the dissolution of ionic liquid which destroyed the hydrogen bonds between the cellulose molecules. On the other hand, the structure could be explained by the morphology analysis of OC, PC and RC. The porous network structure of RC led to the reduction of ordered crystalline region and the decrease of crystallinity (CrI), which was proved by BET results. However, the dissolution was testified to be a physical process through FTIR analysis, the existence of characteristic absorption peaks of cellulose. The thermal stability was decreased through pretreatment, dissolution processes, corresponding to the decrease of CrI. The disordered amorphous region of RC decides convenient for production and broad applications.

Abstract: Cobalt modified rectorite (Co@R) was prepared from sodium saturated rectorite (Na-R) with a two-step method of microwave-assisted ion-exchange and in-situ hydrolysis. The morphology, composite structure and pore properties of Co@R were observed with scanning electron microscopy (SEM), small angle X-ray Diffraction (XRD) and nitrogen adsorption-desorption isotherm. The adsorption ability and catalytic behavior of Co@R were studied with methyl blue (MB) as probe contaminant. The interstratified layered Na-R was stripped fully and the resultant material remained the layered structure with a slit-shaped pore between the layers of lamellar particles. The interlayer spacing d₀₀₁ of rectorite was increased successfully from 2.23 nm up to 2.72 nm. The Co@R has a BJH pore volume of 0.091 cm³ g^-1 resulting from the macropores and BET specific surface area of 28.5 m² g^-1. A set of test has shown that Co@R possesses the potential to become a good adsorbent and catalyst for activating peroxymonosulfate (PMS), removing organic pollutants efficiently.

Abstract: Aluminum and iron copillared rectorite (Al/Fe-R) was prepared from sodium saturated rectorite (Na-R) by ultrasonic-assisted pillaring with hydroxyalumina and hydroxyiron polycations. The morphology, composite structure, pore properties and light response characteristics of composite material were observed with scanning electron microscopy (SEM), small angle X-ray Diffraction (XRD), nitrogen adsorption-desorption isotherm and UVvis diffuse reflectance spectrum. The fabricated material retained the layered structure with a slit-shaped pore between the layers of lamellar particles. The interlayer spacing d₀₀₁ was increased successfully from 2.23 nm up to 2.98 nm. The resultant product has a high BET specific surface area of 165 m² g^-1 and good visible light response. The Al/Fe-R shows the potential to become a good adsorbent and catalyst.

Abstract: The objective of this work is to utilize a low-grade synthetic rutile to produce high-grade titania nanoparticles. Due to the nature of the precursor, the hydrothermal method needs modification in order to accommodate the precursors and chemical reagents. The product will be characterized with the XRD (crystallite size and crystallinity), EDXRF (chemical composition), SEM (Morphology), N₂ adsorption-desorption (Surface Area) and UV-Vis-NIR. Results revealed a crystallite size of less than 20 nm, a surface area of 186.8 m²/g, a morphology that is a combination of agglomeration and particles, and an optical band gap of 3.23 eV. It is concluded that synthetic rutile is a viable precursor to produce high quality titania nanoparticles.

Abstract: Carbon nanotubes have many applications and therefore widely produced. However, it is limited due to the high production cost. In this paper, by preparing the CNTs using the Thermal Chemical Vapor Deposition method, CNTs were synthesized with a low cost method since palm oil is used as the precursor which is a biodegradable and cheap source. The aerosol or spray pyrolysis method is used for single stage and double stage TCVD method. Then, the samples were both collected at deposition temperature of 750°C and were characterized using Brunauer, Emmett and Teller (BET) method. Since CNTs are said to have high surface area therefore BET method is used to prove this fact. Results showed that by using double stage TCVD method, more CNTs were synthesized compared to single stage TCVD method which produced more impurities namely amorphous carbon. CNTs also have higher surface area compared to amorphous carbon. To support this result, the images of the CNTs produced by same method but different parameters were characterized with field emission scanning electron microscope (FE-SEM) and the raman spectra was determined by the raman spectroscopy characterization.

Abstract: Activated carbon is produced from high cellulose containing biomass such as filter paper (FP), bamboo waste and palm empty fruit bunches (EFB) by dehydrating agent, concentrated sulfuric acid (H₂SO₄). At room temperature, treatment of H₂SO₄ is removed all the water molecules in the biomass and leaving only porous carbon without emitting any gaseous by-products. After activation by carbon dioxide (CO₂), Brunauer-Emmett-Teller (BET) and X-ray Diffractometer (XRD) analysis showed the bamboo activated carbon (BAC) has good properties with higher surface area (862.76 m²/g), micropore area (463.62 m²/g) and some crystalline (graphite) phase formation. Acid treatment of biomass has shown high carbon content for FP (85.30%), bamboo (77.72%) and EFB (76.55%), and yield obtained was 47.85 wt.% (FP), 62.4 wt.% (bamboo) and 55.4 wt.% (EFB) by using dehydration method.

Abstract: The synthesis of alkylpolyglucosides involves condensation of decanol with dextrose in the presence of mesoporous silica sol-gel as a catalyst. In this study, mesoporous silica was produced using sol-gel technique by converting tetraethyl orthosilicate (TEOS) into silica. The mesoporous silica was characterized using BET surface area measurement and X-ray Photoelectron Spectroscopy surface analysis. The specific BET surface area was 794m²/g. From the XPS analysis, the Si2p binding energy is 103.7 eV while the O1s binding energy is 532.8eV indicating the formation of Si-O-Si bond which attributed to SiO₂. Mesoporous silica has been found efficient to be solid catalyst for synthesis alkylpolyglucosides and easy to be separated. The reaction was carried out 8 hours at 110°C-120°C under vacuum condition. The mass determination of alkylpoluglucosides has been achieved by ESI LC-MS/MS (ToF) positive-mode giving a mass peak at m/z = 343.21 corresponding to [M+⁺ of alkylmonoglucoside peak at retention time 11.0 min.

Abstract: The aim of the present research work is to examine the influence of mineral composition and grain size distribution on the properties of limestone and dolomite mineral fillers used in Hungarian road construction. Since these properties fundamentally define the features of asphalt pavements, our research goals were assigned accordingly. Different fractions of two mineral fillers (limestone from Alsózsolca and dolomite from Pilisvörösvár) were compared. We have observed deviations in the grain size distribution of some fractions of fillers that were free of contaminations. While limestone consists of a great amount of fines and a relatively small amount of coarse grains, in case of dolomite it is the opposite, that is, small amount of fines and greater amount of coarse grains. The decrease of the grain size of fractions resulted in a slight increase of specific surface area of fillers. We have observed that by the decrease of the grain size of fillers, the hydrophilic coefficient has also decreased. The increasing presence of fines however, resulted in the decrease of the hydrophilic coefficient.

Abstract: The corrosion products formed on carbon steel exposed to seawater were studied. Morphology, composition, structure and porosity of the rust were analysed by different methods: OM, SEM, FTIR, XRD and BET. The results indicate that the inner and outer rust layers formed on carbon steel in seawater are different in morphology, composition and structure. With increasing of exposure periods, the rust layers become more and more compact, which exhibit a high resistance to corrosion.

Abstract: In this work the Authors are dealing with the utilization of mineral fillers used in the Hungarian road construction. Six different types of mineral fillers – andesites, basalt, dolomite and limestone – were tested. In the purpose of the applicability of mineral aggregates in road construction XRD, BET specific surface test, as well as SEM tests were made and hydrophilic coefficient of fillers were also determined. The results of the XRD, BET specific surface test, SEM and hydrophilic coefficient tests show that all of the examined fillers are suitable for asphalt-technological applications, particularly limestone filler (Alsózsolca) and dolomite filler (Pilisvörösvár).