• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.195-204
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• 2002

Mineralogy and the exposed surface area are two of the most important factors controlling dissolution and weathering rates of soils. The mixture of inorganic and organic materials of various size distributions and structures that constitute soils makes the calculation of weathering rates difficult. The surface area of soil minerals plays an important role in most of programs for calculating the weathering rates and critical loads. The Brunauer-Emmett-Teller (BET) measurement is recommended for the measurement of specific surface area. However, BET values measured without organic matter removal are in fact those far all the N2-adsorbed surface areas, including the surfaces covered and aggregated with organisms. Surfaces occupied by organisms are assumed to be more reactive to weathering by organic activities. Therefore, the BET surface area difference before and after organic removal depicts the area occupied by organisms. The present study shows that the BET values after organic matter removal using $H_2$O$_2$ are larger than those without removal by 1.68~4.87 $m^2$/g. This implies that BET measurement without organic removal excludes the reactive area occupied by organisms and that the area occupied by organisms in soils is much larger than expected. It is suggested that specific surface area measurement for calculating weathering rates of mineral soils should be made before and after organic matter removal. The results of a column experiment are presented to demonstrate the potential retarding influence that this organic matter may have on mineral dissolution and weathering.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.787-795
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• 2012

The purpose of this study is to synthesize transition metal doped mesoporous silica catalyst and to characterize its surface in an attempt to decomposition of $N_2O$. Transition metal used to surface modification were Ru, Pd, Cu and Fe concentration was adjusted to 0.05 M. The prepared mesoporous silica catalysts were characterized by X-ray diffraction, BET surface area, BJH pore size, Scanning Electron Microscopy and X-ray fluorescence. The results of XRD for mesoporous silica catalysts showed typical the hexagonal pore system. BET results showed the mesoporous silica catalysts to have a surface area of 537~973 $m^2/g$ and pore size of 2~4 nm. The well-dispersed particle of mesoporous silica catalysts were observed by SEM, the presence and quantity of transition metal loading to mesoporous surface were detected by XRF. The $N_2O$ decomposition efficiency on mesoporous silica catalysts were as follow: Ru>Pd>Cu>Fe. The results suggest that transition metal doped mesoporous silica is effective catalyst for decomposition of $N_2O$.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.569-573
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• 2013

In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of $CO_2$ as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and $925^{\circ}C$), activation time (15, 30, 45 and 60 minutes) and $CO_2$ flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and $CCl_4$ onto ACF was investigated and both were found to correlate with surface area.

• Journal of Environmental Science International
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• v.19 no.6
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• pp.681-687
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• 2010

Mesoporous silica was prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide (CTMABr) as a surfactant. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of mesoporous silica were determined by XRD, SEM, TEM and BET. Also, surface potential of mesoporous silica was measured using zeta potential. $N_2$ adsorption isotherm characteristics, including the specific surface area ($S_{BET}$), total pore volume $V_T$), and average pore diameter ($D_{BJH}$), were determined by BET. As a result, SBET of $100m^2/g{\sim}1500m^2/g$ was determined from the $N_2$ adsorption isotherm. Also, the average pore diameter was 2 nm∼4 nm. Mesoporous silica's surface potential of minus charge was determined from zeta potential.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.673-679
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• 2008

In this study, Mesoporous silica were prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide(CTMABr) as a template. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of Mesoporous silica were determined by XRD, SEM, and BET. N$_2$ adsorption isotherm characteristics, including the specific surface area(S$_{BET}$), total pore volume(V$_T$), and average pore diameter(D$_{BJH}$), were determined by BET. Also, the adsorption character of Pb(II) and Cd(II) ion on Mesoporous silica were measured using ICP. As a result, a SBET of 100$\sim$1,500 m$^2$/g was determined from the N$_2$ adsorption isotherm. Also, the average pore diameter of 2$\sim$4 nm. The adsorption of Pb ion and Cd ion on Mesoporous silica become different depending on the pH of solution. The adsorption amount of Mesoporus silica had higher than that of silicagel.

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.252-256
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• 2010

The study was done to change the morphology and pore size of SBA-15 silica, and the characteristics of SBA-15 silica were investigated with TG-DSC, XRD, SEM, TEM and N2 adsorption-desorption under changing aging conditions. SBA-15 silica having a 2D-hexagonal structure was synthesized and confirmed by SEM and TEM. The structure of mesoporus silica SBA-15 showed a pore having regularly formed hexagonal structure and a passage having a cylindrical shape. This result is in good agreement with the pore forming in XRD and cylindrical shape of the structure in $N_2$ adsorption-desorption isotherm. SBA-15 silica showed a large BET surface area of $603-698\;m^2/g$, a pore volume of $0.673-0.926\;cm^3/g$, a large pore diameter of 5.62-7.42 nm, and a thick pore wall of 3.31-4.37 nm. This result shows that as the aging temperature increases, the BET surface area, pore volume, and pore diameter increase but the pore wall thickness decreases. The BET surface areas in SM-2 and SM-3 are as large as $698\;m^2/g$. However, SM-2 has a large surface area and forms a thick pore wall, when the aging temperature is $100^{\circ}C$ and is synthesized into stable mesoporous SBA-15 silica.

• Journal of Environmental Health Sciences
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• v.19 no.4
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• pp.25-32
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• 1993

Granular activated carbon is commonly used in fixed-bed adsorbers to remove organic chemicals. In this experiment organic chemical solutions were prepared by adding the reagent grade organic chemical to distilled water. Isotherm adsorption tests of volatile organic chemicals were conducted using bottle-point technique and column test. Organic chemicals after passing through the column were extracted with hexane and analyzed with gas chromatography (Hewlett-Packard 5890) to check the adsorption capacity and breakthrough curve. The result were as follows: 1. The BET surface area of coconut activated carbon was 658~1,010 m$^2$/g where as coconut shell carbon was 6.6 m$^2$/g. Coconut activated carbon increased the BET surface area and adsorption capacity in bottle-point isotherm. 2. The adsorption capacity of coconut activated carbon for trichloroethylene (TCE) was reduced in the presence of humic substance. 3. A decrease in particle size of activated carbon resulted in higher adsorption capacity and lower intraparticle diffusion coefficient. It is reflected not only as a decrease in Freudlich adsorption capacity value (K) but also as an increase in Freudlich exponenent value (1/n).

• Analytical Science and Technology
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• v.13 no.2
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• pp.194-199
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• 2000

The study on the adsorption, the surface properties and the antibacterial effects of the Ni-treated PAN based activated carbon fibers was carried out. In the adsorption study on the Ni-treated PAN based ACFs, Type I isotherms for N1-N3 and Type II-Type III isotherms for N4-N6 were obtained, respectively. Futhermore, their adsorbed volumes slowly were decreased with the increase in the mole concentration of Ni on the treated PAN based ACFs. From the BET equation, the specific surface areas of the Ni-treated PAN based ACFs were in the range of $692.58-895.24m^2/g$. The micropore volumes obtained from ${\alpha}_s$-method using common-t value were $0.19-0.56cm^3/g$. The surfaces of PAN based ACFs partially blocked by metal after the treatment were observed from the SEM micrographs. Finally, from the antibacterial effects using Shake flask method against E. coli, the percentage of the effects was 92.5-100% and the antibacterial effect was increased with the increase in mole concentration of Ni treated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.588-595
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• 2020

This study examined the catalytic property of Ni-catalyst used in the gas purifying process to manufacture inert gases of N2 and Ar with high-purity over 9N for semiconductor industrial applications. Two types of Ni-catalysts with a cylindrical shape (C1) and churros shape structure (C2) were compared for the assessment. Optical microscopy and FESEM were used to analyze the shape and microstructure of the Ni-catalyst. EDS, XRD, and micro-Raman characterization were performed to examine the composition and properties. BET and Pulse Titration analyses were conducted to check the surface area and catalytic property of the Ni-catalyst. From the composition analysis results, C1 contained a relatively large amount of graphite as an impurity, and C2 contained higher Ni contents than C1. From specific surface area analysis, the specific surface area of C2 was approximately 1.69 times larger than that of C1. From catalytic property analysis, outstanding performance in O₂ and CO impurity removal was observed at room temperature. Therefore, C2, having low-impurity and large specific surface area, is a suitable catalyst for the high-purity inert gas process in the semiconductor industry because of its outstanding performance in O₂ and CO impurity removal at room temperature.

• Polymer(Korea)
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• v.26 no.4
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• pp.445-451
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• 2002

In this work, the adsorption characteristics and mechanical interfacial properties of treated silicas by silane coupling agents, such as, ${\gamma}$-methacryloxy propyl trimethoxy silane (MPS), ${\gamma}$-glycidoxy propyl trimethoxy silane (GPS), and ${\gamma}$-mercapto propyl trimethoxy silane (MCPS), were investigated. The equilibrium spreading pressure ($pi_e$), surface free energy ($gamma_s$ s/), and specific surface area ($S_{BET}$) were studied by the BET method with $N_2$/77 K adsorption. The developments of nonpolar functional groups of the silica surfaces treated by silane coupling agents led to the increase in the $S_{BET}$, $pi_e$, and $gamma_s$, resulting in the improved tearing energy ($G_{mc}$)of the silica/rubber composites. The composites treated by MPS showed the superior mechanical interfacial properties in these systems. These results explained by changing of crystalline size, dispersion, agglomerate, and surface functional group of silica/rubber composites.