Papers by Keyword: BET Surface Area

Abstract: The aim of this research is to identify the crystal structure, surface area, and magnetic properties of The Mn_0.25Fe_2.75O₄-rGO (reduced Graphene Oxide) nanocomposites (NCs). The synthesis of Mn_0.25Fe_2.75O₄-rGO nanocomposites used the co-precipitation method. The rGO was obtained from the chemical reduction of GO by hydrazine hydrate as the reduction agent. The ratio between Mn_0.25Fe_2.75O₄ nanoparticles and rGO was 1:1 that ultrasonicated at 200 Hz for an hour. The IR spectra of NCs from the FTIR instrument showed that the absorption band around 580 cm^-1 and 1622 cm^-1 corresponds to the stretching mode of Fe-O and C=C respectively. According to X-Ray Diffraction (XRD) pattern analysis, peak of Mn_0.25Fe_2.75O₄ was detected on 2θ at 30.1°, 35.5°, 53.5°, 57.1°, 62.7° and the peak of rGO phases was amorphous that detected on 2θ between 17º and 30º. The XRD pattern analysis and FTIR spectra have proved the completion of NC’s synthesis. The crystallite size was between 10.3 nm by Scherer's formula. The Specific Surface Area showed that the surface area of the nanocomposites was 100.61 m²/g and the Molecular cross-sectional area was 0.162 nm² by BET Theory. The Magnetic properties show that the NCs were Superparamagnetic material that has a saturation magnetization of 9.34 emu/g. The material has many potentials to be explored by the researcher around the world.

Abstract: The preparation of carbon materials from low-cost agricultural residues is presented in this work. Carbon products were prepared from carbonized cassava tuber (cassava tuber char, CTC) using a chemical activation assisted sonochemical process incorporating KOH as an activating agent. The physical properties such as proximate analysis, ultimate analysis and FTIR spectra of raw material were studied using cassava tuber collected from farmland in the Kanchanaburi Province. The structure of the precursor material played a significant role in influencing the quality and properties of the as-prepared carbon. It was found that the specific surface area of carbon products was improved through chemical activation assisted sonochemical process at 80 °C for 4 hours. The influence of KOH impregnation ratios on the specific surface area of the prepared carbon was also investigated in the activation step. Moreover, the properties of cassava tuber-carbon material were characterized by SEM, FTIR, XRD, and multipoint BET analysis. Finally, the application of cassava tuber carbon material as a carbon support for ZnO photocatalyst was investigated by a simple technique.

Abstract: Rubber-seed shell was selected as the precursor for the preparation of activated carbon by chemical activation with KOH as an activating agent. Impregnation-Activation Method and Carbonization-Impregnation-Activation Method were investigated with different concentration of KOH solution. Rubber-seed shell activated carbons were characterized by using scanning electron microscope, fourier transform infared spectroscopy and nitrogen adsorption isotherms. The results present that the first method which impregnation of precursor in 2%wt. KOH solution with the ratio of 300 g/l for 24 hrs before thermal activation at 700°C for 2 hrs under 2 cm³/min of nitrogen flow, was satisfied to prepare the Rubber-seed shell activated carbon. Products with maximum BET surface area, average pore diameter and volume ratio of micropores to mesopores were equal to 429 m²/g, 2.09 nm and 4.19, respectively.

Abstract: Four samples of covalent organic framework-1 (COF-1) assigned as S1 to S4 were prepared by varying the initial mass of 1,4-benzene diboronic acid (BDBA) used and heating condition. The samples were physically characterized using Brunauer–Emmett–Teller (BET) surface area analysis and FESEM analysis. The BET surface area value showed an increasing trend with increasing mass of BDBA used. The highest achievable BET surface area is recorded by COF-1 (S3) with a value of 107.9 m²/g. The low surface area obtained is likely due to the distribution of particles with large pore sizes. This is confirmed by the Field Emission Scanning Electron Microscopy (FESEM) images which correlate well with the surface area obtained. The presence of dendrites phase within the COF-1 structure also indicates incomplete formation of a crystalline structure, hence contributed to the low surface area achieved. It was also found that the use of ramping heating did not significantly influence the formation of COF-1 crystalline structure which promotes the surface area.

Abstract: The effects of hydrochloric acid (HCL) modification of the surface area, morphology and physico-chemical properties of Sayong kaolinite clay was investigated in this study. Sayong kaolinite clay was refluxed with different concentration of HCL (1M, 5M and 10M) at 100 °C for 4 hours and followed by calcination at 500 °C at 1 hour. The samples of untreated and treated clay were characterized by different analytical equipment such as BET Surface Area Analyzer, X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), Thermogravimetric Analyzer (TGA) and Field Emission Scanning Electron Microscopy (FESEM). The acid treatment increased the surface area of the Sayong kaolinite clay almost three times from 24.46 m²/g to the maximum value which is 64.04 m²/g once treated with 5M HCL. The increasing of the surface area is due to the formation of amorphous silica phase and removal of the octahedral Al³⁺ cations and other impurities (such as Mg²⁺, K⁺, Ca⁺ etc.) when the acid strength is increasing as reported in XRF analysis. FTIR study shows the change of the peak intensity of several types of structural OH groups that presently in the untreated and acid treated samples. TGA-DTA profiles shows that acid treatment increased the amount of physisorbed water as the acid concentration is increased. There are three of endothermic peaks was observed in the untreated sample which centered at 49 °C, 275 °C and 520 °C. However, when the clay samples treated with acid, it has increased the physisorbed water and decreased the structural and coordinated water which caused the change in the endothermic curves in the treated sample.

Abstract: A series of laboratory experiments on the change characteristic of BET surface area and pore size of alkaline residue(Huaian) under different temperatures were carried, the experimental procedure and results are described and analyzed in this study. The BET surface area of alkaline residue decrease obviously with temperature increasing, and the decresing tendency is slowly after 600°C. The experiment resluts show that 600°C is a threshold of alkaline residue BET surface area change. Pore size slowly increases with temperature rising. In the experimental study, alkaline residue surface morphology is researched by SEM under different temperature, SEM images showed that alkaline residue is porous polymeric aggregate in natural conditon, there is an improtant influence of thermal treatment on alkaline residue surface morphology. The porous aggregate is more compact, and its pore gradually increses with temperature rising.

Abstract: The silica-alumina-pillared rectorite materials (SiAl-REC) were developed a novel method, which combined several techniques such as ion-exchange, intercalation and surfactant modification. The morphology, composite structure and pore properties of such composite materials, were investigated by X-ray powder diffraction (XRD), Fourier-transform infra-red (FTIR) spectra, as well as Nitrogen Adsorption-Desorption Isotherms. The layer structure of the prepared materials retained and their pore structures were found to be slit-shaped pores located between plate-like particles. The prepared SiAl-REC materials had a BJH pore volume of 0.65cm³ g-1, a remarkably high BET specific surface area940m² g^-1 and a narrow pore size distribution in the mesoporous region 4.3 nm after thermal treatment at 600 °C.

Abstract: Activated carbon（AC）were prepared from lignin by chemical activation with sodium hydroxide（NaOH）. The influence of activation temperature，activation time and impregnation ration on the BET surface areas were investigated. Based on the central composite design (CCD) and response surface methodology(RSM)，the optimized technological parameters were as follows: temperature 751°C， time 57min and impregnation ration 2.06, BET surface areas was up to 1437.20 m2/g.The adequacy of the model equation for predicting the optimum response values was verified effectively by the validation.

Abstract: Al-pillared montmorillonites (Al-MMT) were synthesized from naturally occurring sodium montmorillonite through exchange of interlamellar ions with hydroxyalumina polycations. Furthermore, Powder X-ray diffraction (XRD), Fourier transformation infra-red spectra (FTIR), Thermogravimetric analysis (TG), and differential scanning calorimetry (DSC) were applied in order to study the themal stability, hydrothermal stability and synthesis mechanisms of pillared materials. The Al-MMT are thermally stable and hydrothermal stability up to700°C. X-ray diffractograms of Al-MMT calcined at 700 0C show a sharp and intense d001 peak, corresponding to a basal spacing of 1.66nm. Until calcinations at 8000C, the pillared clays generally retain their structural ordering as evidenced by a broad basal (001) peak, which is an indication that the layer structure lost some long-range ordering. In a 100% steam flow under atmospheric pressure at 7000C, the characteristic d001 spacing of Al-MMT decreases from 1.83nm to 1.71nm, intensity of basal peak reduced by58%. However, after hydrothermal at 8000C, the basal (001) peak is not observed, indicating a complete structural collapse. Synthesis mechanisms for Al-MMT are established. Some of tetrahedral silicons or aluminums inverse towards gallery to react with pillaring agents and yield Alp-O-AlsⅣ or Alp-O-Sis bridges which would firmly fix the pillars to the host clay.

Abstract: . Al-pillared rectorites (Al-REC) were synthesized from natural calcium rectorite through the exchange of inter-lamellar ions with hydroxyalumina polycations. Furthermore, the morphology, composite structure and pore properties of such composite materials were investigated by Powder X-ray Diffraction (XRD), Fourier Transformation Infra-red Spectra (FTIR) and Nitrogen Adsorption-Desorption Isotherms. The products retain their layered structure and their pore structures are a slit-shaped pore between plate-like particles. The resultant products possess BJH pore volume as large as 0.04cm3g-1, high BET specific surface area of over 100m2g-1, narrow pore size distribution in the mesopore region of 7-9nm after thermal treatment at 300 °C.