• Geomechanics and Engineering
• /
• 제17권2호
• /
• pp.157-164
• /
• 2019

The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.

• 한국세라믹학회지
• /
• 제37권7호
• /
• pp.638-644
• /
• 2000

The sintering behaviors of the glass-alumina composites for low firing temperature were investigated as functiions of the volume fraction of alumina powder and the particle size with respect to porosity and pore shape. As the volume fraction of alumina powder was increased or the particle size of it was decreased, the sintering temperature of open pore-closing was raised. When the volume fractions of alumina which had 2.19$\mu\textrm{m}$ median diameter were increased with 20, 30, 40, and 50%, the sintering temperatures of open pore-closing were 425, 450, 475, and 500$^{\circ}C$. And when the median particle size of alumina was diminished from 2.19$\mu\textrm{m}$ to 0.38$\mu\textrm{m}$, the sintering temperature of open pore-closing was increased from 450$^{\circ}C$ to 475$^{\circ}C$. Especially, the sintering temperature, which showed maximum density, was corresponded with the stage of open pore-closing and after achieving maximum density over heating resulted in dedensification of specimen, so called, over-firing behavior.

• 한국재료학회지
• /
• 제20권5호
• /
• pp.252-256
• /
• 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.

• 한국의류학회지
• /
• 제21권1호
• /
• pp.206-216
• /
• 1997

The purpose of this study was to determine the pore size distributions (PSDs) of polyester woven fabrics by using liquid extraction method. Three types of PSDs-percent PSD, PSD per unit area of sample and PSD per unit weight of sample-were evaluated. Plain, twill and satin polyester fabrics with various fabric counts were used as specimens. Results showed that the interyarn PSDs reflected the fabric characteristics such as the fabric count and the weave type and the intrayarn PSDs reflected the thread characteristics such as the number of fibers, the fiber diameter, the thread diameter and the thread twist. Of three types of PSDs, the PSD per unit area of sample best reflect fabric and thread characteritics. As the fabric count decreased, rc increased and interyarn pore volume increased. The PSDs were skewed to the small pore sizes and the pore volumes decreased in the order of plain> twill> satin. As the number of fibers, the fiber diameter and the thread twist decreased, the intrayarn pore volumes were increased.

• 한국세라믹학회지
• /
• 제55권1호
• /
• pp.74-79
• /
• 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 those of bentonite and zeolite. It was effective to add white cement as well as a retarding agent to control the setting time of the ceramic paint. As the amount of added porous materials increases, the specific surface area and total pore volume of ceramic paint increase, but the average pore diameter decreases. The addition of porous materials having a high specific area and a large pore volume improves the moisture absorptive and desorptive performance of the ceramic paint. Therefore, in this experiment, the moisture absorptive and desorptive properties were best when active clay was added. Also, as the added amount of porous materials increases, the moisture absorptive and desorptive properties improve. In this experiment, when 70 mass% of active clay was added to ceramic paint, the hygroscopicity was highest at about $80g/m^2$.

• Carbon letters
• /
• 제11권3호
• /
• pp.224-234
• /
• 2010

Four activated carbons were produced by two-stage process as followings; semi-carbonization of indigenous biomass waste, i.e. cotton stalks, followed by chemical activation with KOH under various activation temperatures and chemical ratios of KOH to semi-carbonized cotton stalks (CCS). The surface area, total pore volume and average pore diameter were evaluated by $N_2$-adsorption at 77 K. The surface morphology and oxygen functional groups were determined by SEM and FTIR, respectively. Batch equilibrium and kinetic studies were carried out by using a basic dye, methylene blue as a probe molecule to evaluate the adsorption capacity and mechanism over the produced carbons. The obtained activated carbon (CCS-1K800) exhibited highly microporous structure with high surface area of 950 $m^2/g$, total pore volume of 0.423 $cm^3/g$ and average pore diameter of 17.8 ${\AA}$. The isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 222 mg/g for CCS-1K800. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The pseudo-second-order model fitted better for kinetic removal of MB dye. The results indicate that such laboratory carbons could be employed as low cost alternative to commercial carbons in wastewater treatment.

• 한국환경과학회지
• /
• 제24권11호
• /
• pp.1463-1471
• /
• 2015

The surface modified activated carbons (SMACs) were prepared with various $P_2O_5$ concentrations using two activated carbons (ACs: waste citrus peel-based activated carbon and coconut-based activated carbon). The characteristics and adsorptivity of bisphenol A (one of phenolic endocrine disrupting chemicals) were compared between ACs and SMACs. The contents of C, H and N of SMACs were similar to those of ACs, but the content of $P_2O_5$ for the former increased greatly than for the latter, due to the impregnation of $P_2O_5$ into the pores. The specific surface area, total pore volume, average pore diameter and iodine adsorptivity for the former decreased due to the impregnation of $P_2O_5$ into the pores, compared to those for the latter. The adsorptivity of bisphenol A for the former were higher than that for the latter, although specific surface area, total pore volume, average pore diameter and iodine adsorptivity for the former were lower than those for the latter.

• 한국환경보건학회지
• /
• 제29권1호
• /
• pp.34-42
• /
• 2003

The objective of this study is to investigate the waste recycling possibility, practicability, economic efficiency and acid gas sorbent use of the hard-shelled mussel. This study is to investigate the hydration/calcination reaction and fixed bed reactor. The physical-chemical characteristics of the hard-shelled mussel were analyzed by ICP SEM-EDX, BET and pore volume. Thus, the results could be summarized as follows; Hard-shelled mussel can be used as iron-manufacture and chemical sorbents considering more than 53.7% of the mussel is lime content. The SO$_2$removal efficiency of the hard-shelled mussel after calcined hydration increased thirty times as a result of the higher pore size, specific surface area and pore volume. Also, the CaO content, pore volume, pore size distribution and specific surface area greatly influenced the SO$_2$ and NOx removal reactivity. The optimum particle diameter average of hard-shelled mussel was $\pm$100 mesh, which was applied to the sorbent on the medium/small scale waste incinerator and flue gas desulfurization processes.

• 대한환경공학회지
• /
• 제30권9호
• /
• pp.900-906
• /
• 2008

활성탄을 제조하기 위하여 원료물질로서 음식물쓰레기를 이용하였다. 음식물쓰레기를 염화아연으로 약품활성화 하였다. 실험은 서로 다른 약품첨가비율(활성화제/음식물쓰레기), 활성화 온도, 그리고 활성화시간을 변수로 하여 수행하였다. 활성화물의 특성을 나타내기 위하여 요오드가와 메틸렌블루 가, BET 표면적, 세공 용적, 미세공 비율, 세공 직경, 수율 그리고 주사전자현미경 관찰을 수행하였다. 로터리 킬른 반응로를 이용하여 염화아연 함침비 1.0배인 시료를 500$^{\circ}C$에서 60분 동안 활성화하여 제조한 활성화물의 요오드가는 480 mg/g, 메틸렌블루 가는 95 mL/g, BET 표면적은 410 m$^2$/g, 세공 용적은 0.248 cm$^3$/g, 그리고 평균세공직경은 2.43 nm로 나타났다. 제조한 활성탄의 총 표면적중 미세공 면적 비율은 70.7%, 총 세공 용적 중 미세공 용적 비율은 53.2%를 나타냈다.

• Macromolecular Research
• /
• 제13권2호
• /
• pp.107-113
• /
• 2005

We developed an algorithm to simulate the generation of virtual nanowebs using the Monte Carlo method. To evaluate the pore size of the simulated multi-layered nanoweb, an estimation algorithm was developed using a ghost particle having zero volume and mass. The penetration time of the ghost particle through the virtual nanoweb was dependent on the pore size. By using iterative ghost particle penetrations, we obtained reliable data for the evaluation of the pore size and distribution of the virtual nanowebs. The penetration time increased with increasing number of layers and area ratio, whereas it decreased with increasing fiber diameter. Dimensional analysis showed that the penetration time can be expressed as a function of the fiber diameter, area ratio and number of layers.