• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.35-41
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• 2013

In this study, we investigated the effect of the number of passes through agrinder on the pore characteristics of nanofibrillated cellulose (NFC) mat. The beaten pulp suspension was used to make NFC suspension using a grinder. To evaluate the pore characteristics of a NFC mat, the surface morphology of the dried NFC mat was observed with FE-SEM and the specific surface area was analyzed with BET nitrogen gas adsorption. The structure of NFC mat was changed with the different number of passes and drying methods. The specific surface area of NFC mat increased with the increase in the number of passes. The 20-passed NFC mat had 20 times larger specific surface area ($141m^2/g$) compared to the 0-passed NFC mat. The specific surface area was strongly correlated with the average pore size in NFC mat. The average pore diameter in NFC mat was calculated from the gas sorption isotherms using BJH model. The value was 13 - 15 nm, indicating that the NFC mat had mesoporous structure.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.362-367
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• 1999

We intended to make the activated carbon fibers which could separate, remove and recover the volatile organic compounds of benzene, toluene, acetone and methanol. Changing activation temperature and time, large specific surface area and narrow pore distribution could be obtained. The activated carbon fibers have large adsorption capacity and selectivility for those organic compounds. We characterized the adsorption capability of the activated carbon fibers for benzene, toluene, acetone and methanol by BET specific surface area and pore size and micropore volume measurements. In the result of activation, the maximum value of BET specific surface area of the fibers was $1100\m^2$/g at $800^{\circ}C$ for 60 minutes and $K_2$O was reduced actively in this condition. Their average pore size was 5.8~5.9$\AA$. The activated carbon fibers prepared in this work had high adsorption rate to saturation and the selectibility for the above organic compounds. The adsorbed amount of acetone and methanol(diameter of$ 4.3\AA$ and $4.4\AA$ respectively) which are smaller than micropore diameter in size was 43~49%, which was larger value than benzene and toluene(in the same diameter as $5.9\AA$).

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.382-390
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• 2015

Poly(methyl methacrylate) (PMMA) supports and amine additives were investigated to adsorb $CO_2$. PMMA supports were fabricated by using different ratio of pore forming agents (porogen) to control the BET specific surface area, pore volume and distribution. Toluene and xylene are used for porogens. Supported amine sorbents were prepared by wet impregnation of tetraethylenepentamine (TEPA) on PMMA supports. So we could identify the effect of the pore structure of supports and the quantity of impregnated TEPA on the adsorption capacity. The increased amount of toluene as pore foaming agent resulted in the decreased average pore diameter and the increased BET surface area. Polymer supports with huge different pore distribution could be fabricated by controlling the ratio of porogen. After impregnation, the support with micropore structure is supposed the pore blocking and filling effect so that it has low $CO_2$ capacity and kinetics due to the difficulty of diffusing. Macropore structure indicates fast adsorption capacity and low influence of amine loading. In case of support with mesopore, it has high performance of adsorption capacity and kinetics. So high surface area and meso-/macro- pore structure is suitable for $CO_2$ capture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.210-215
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• 2002

This thesis is contents on the crystal grown by the solide phase method at $925^{\circ}C$ with orthorhombic structure that $LiMnO_{2}$ active material synthesised with precurse $Mn_{2}O_{3}$ and $LiOH.H_{2}O$ material to get three voltage level. The porosity analysis of the grown crystal in secondary batteries $LiMnO_{2}$ thin film is $1.323E+02\AA$ of the average pore diameter of powder particles and its structure to be taken the pore diameter was prepared. Adding voltage area to get properties of charge and discharge of which experiment result of $LiMnO_{2}$ thin film area 2.2V~4.3V, current and scan speed were 0.1mAh/g and $0.2mV/cm^{2}$ respectively, and properties of the charge and discharge to be got optimum experiment condition parameter and density rate of Li for analyze that unit discharge capacity with metal properties is 87mAh/g was 96.9[ppm] at 670.784[nm] wavelength, and density rate of Mn analyzed 837[ppm] at 257.610[nm]. It can be estimated the quality of thin film that wrong cell reject from the bottle of electrolyte. The results of SEM and XRD were the same that of original researchers.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1569-1579
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• 2021

This study aims to provide microstructural characterization for the matrix graphite which molten salt reactors (MSRs) use, and improve resistance to molten salt infiltration of the matrix graphite for fuel elements. Mesocarbon microbeads (MCMB) densified matrix graphite A3-3 (MDG) was prepared by a quasi-isostatic pressure process. After densification by MCMBs with average particle sizes of 2, 10, and 16 ㎛, the pore diameter of A3-3 decreased from 924 nm to 484 nm, 532 nm, and 778 nm, respectively. Through scanning electron microscopy, the cross-section energy spectrum and time-of-flight secondary ion mass spectrometry, resistance levels of the matrix graphite to molten salt infiltration were analyzed. The results demonstrate that adding a certain proportion of MCMB powders can improve the anti-infiltration ability of A3-3. Meanwhile, the closer the particle size of MCMB is to the pore diameter of A3-3, the smaller the average pore diameter of MDG and the greater the densification. As a matrix graphite of fuel elements in MSR was involved, the thermal and mechanical properties of matrix graphite MDG were also studied. When densified by the MCMB matrix graphite, MDGs can meet the molten salt anti-infiltration requirements for MSR operation.

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.45-50
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• 2005

Titania gel formations were prepared by sol-gel method using titanium(IV) chloride $(TiCl_4)$, and its characteristics were analyzed by varying the $epoxide/TiCl_4$ ratio and the amount of water In the end, titania $(TiO_2)$ aerogel were prepared using supercritical drying process. VOCs such as benzene, toluene, and m-xylene (BTX) were oxidized using prepared titania aerogel and commercially available $TiO_2$, and its performance was compared. The surface area, pore volume, and average pore diameter of 1,2-epoxybutane are significantly smaller than the propylene oxide. And the titania aerogels with 6 moi of epoxides have high surface areas, pore volumes, and average pore diameters. As a result of photo-oxidation, conversion of benzene was reached about $70\%$, and other reactants were reached about $60\%$ similarly. The conversion of BTX was increased as inlet concentration decreased. The reactivity of titania calcined at $600^{\circ}C$ was greater than $400^{\circ}C$ and $800^{\circ}C$. Water is required as a reactants for the oxidation of VOCs, and the continuous consumption of hydroxyl radicals required replenishments to maintain catalyst activity. The activity ratio increased with increasing reaction time when enough amount of water was present in the reactor.

• Membrane and Water Treatment
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• v.1 no.2
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• pp.121-137
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• 2010

This work presents inexpensive inorganic precursor formulations to yield submicron range symmetric ceramic microfiltration (MF) membranes whose average pore sizes were between 0.1 and $0.4{\mu}m$. Incidentally, the sintering temperature used in this work was about 800 to $950^{\circ}C$ instead of higher sintering temperatures ($1100^{\circ}C$) that are usually deployed for membrane fabrication. Thermogravimetric (TGA) and X-Ray diffraction (XRD) analysis were carried out to evaluate the effect of temperature on various phase transformations during sintering process. The effect of sintering temperature on structural integrity of the membrane as well as pore size distribution and average pore size were evaluated using scanning electron microscopy (SEM) analysis. The average pore sizes of the membranes were increased from 0.185 to $0.332{\mu}m$ with an increase in sintering temperature from 800 to $950^{\circ}C$. However, a subsequent reduction in membrane porosity (from 34.4 to 19.6%) was observed for these membranes. Permeation experiments with both water and air were carried out to evaluate various membrane morphological parameters such as hydraulic pore diameter, hydraulic permeability, air permeance and effective porosity. Later, the membrane prepared with a sintering temperature of $950^{\circ}C$ was tested for the treatment of synthetic oily waste water to verify its real time applicability. The membrane exhibited 98.8% oil rejection efficiency and $5.36{\times}10^{-6}\;m^3/m^2.s$ permeate flux after 60 minutes of experimental run at 68.95 kPa trans-membrane pressure and 250 mg/L oil concentration. Based on retail and bulk prices of the inorganic precursors, the membrane cost was estimated to be $220 /$m^2$ and $1.53 /$m^2$, respectively.

• Korean Journal of Materials Research
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• v.28 no.1
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• pp.62-67
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• 2018

Active clay, bentonite and zeolite were used as porous materials for humidity controlling ceramic boards. The specific area and the pore volume of active clay were higher than bentonite and zeolite. The flexible strength of the gypsum board decreased with an increasing amount of porous material, and the flexible strength was lowest when active clay with a higher specific surface area than others porous materials was added. The specific surface area and total pore volume of ceramic boards containing porous material were highest at $102.25m^2/g$, $0.142cm^3/g$, respectively, when the active clay was added. In addition, as the amount of added porous materials increased, the specific surface area and total pore volume of the ceramic board increased, but the average pore diameter decreased. The addition of s porous materials with a high specific area and a large pore volume improved the moisture absorptive and desorptive performance of the ceramic board. Therefore, in this experiment, the moisture absorptive and desorptive properties were the best when active clay was added. Furthermore, as the amount of added porous materials increased, the moisture absorptive and desorptive properties improved. When 70 mass% of active clay was added to ${\alpha}$-type gypsum, the hygroscopicity was the highest, about $300g/m^2$, in this experiment.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1495-1496
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• 2011

Anodic aluminum oxide (AAO) nanotemplates for nano electronic device applications have been attracting increasing interest because of ease of fabrication, low cost process, and possible fabrication in large area. The size and density of the nanostructured materials can be controlled by changing the pore diameter and the pole density of AAO nanotemplate. In this paper, AAO nanotemplate was fabricated by second anodization method. In addition, effects of electrolyte and anodization voltate on the microstructure of porous alumina films were investigated. Vertically well aligned pores had the average pore sizes of 15-70 nm and the length of approximately 40 ${\mu}m$.

• Journal of Powder Materials
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• v.12 no.3
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• pp.220-224
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• 2005

Boehmite (AlOOH) powder with uniform pore size and high specific surface area were synthesized via sol-gel method using metal salts, $Al_2(SO_4)_3$ and $NaAlO_2$. During these synthetic process, the effects of the aging time were investigated to determine the optimal synthetic conditions of boehmite. X-ray diffraction, BET, Raman/IR, and scanning electron microscopy techniques were used for the characterization of the powder. Boehmite gel synthesized at the first stage of the experimental procedure transformed to crystalline boehmite phase after aging for 6 hours. The specific surface area of the crystalline boehmite showed a maximum value, $350m^2/g$, at aging time of 72 hours. The pore size of the boehmite increased with increasing aging time and the boehmite with average pore diameter of 3.6 nm was obtained at aging time of 96 hours.