• 환경위생공학
• /
• 제13권3호
• /
• pp.19-29
• /
• 1998

The calcination reactivity of limestone and physical property changes of calcined lime were investigated with a temperature($720~1000^{\circ}C$ under atmospheric gas($N_2$, $CO_2$) conditions. The mechanisms of mass transport in a lime matrix were represented by the evaporation and condensation (${\gamma}=1.7$) at $1000^{\circ}C$ and the volume diffusion (${\gamma}=2.7$) at $800^{\circ}C$, which was obtained by the specific surface area of calcined lime with sintering conditions. Also, the effect of physical property on the reactivity of sulfation reaction was determined by the changes of pore size with $lime-SO_2$ reaction in this work. The initial sulfation rate of calcined lime increased with increasing temperature, whereas the capture capacity of $SO_2$ exhibited a maximum value at $900^{\circ}C$. The pore volume of sulfated lime was decreased with increasing sulfation time, but the major pores shifted to the distribution of larger size at a temperature of $850{\;}~{\;}1000^{\circ}C$. The mean pore size of sulfated lime based on pore volume decreased gradually at $1000^{\circ}C$; however, it increased with sulfation time up to 40 min and rapidly decreased thereafter.

• 공업화학
• /
• 제4권1호
• /
• pp.113-124
• /
• 1993

Polyacrylonitrile계 섬유를 전구체로 하여 비등온 과정에 의한 활성화를 승온속도를 달리한 TGA(thermogravimetric analysis) 방법으로 연구하였다. 탄소섬유 -$H_2O$(30%)-$N_2$계 비등온 활성화 과정에서 유도된 속도식 $f=1-\exp(-a{\Delta}T)^b$는 실험값과 잘 일치하였다. 전환율에 따른 세공 용적은 pore volume model에 의한 이론값과 비교적 잘 일치하였고, 이때의 세공 구조는 승온속도, 활성화 온도와 내부 및 외부 전환율과의 복합적인 작용에 의하여 결정되었다.

• Bulletin of the Korean Chemical Society
• /
• 제31권6호
• /
• pp.1638-1642
• /
• 2010

Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol, carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption, respectively.

• 한국응용과학기술학회지
• /
• 제27권3호
• /
• pp.310-317
• /
• 2010

The electrochemical properties of electric double layer capacitor(EDLC) was studied by controlling pore size distribution and specific surface area of the activated carbon fiber(ACF). The mesoporous ACF, which was prepared by the iron exchange method, showed the tendency of increasing average pore size and decreasing total surface area. The mesoporous ACF (surface area = 2225 $m^2$/g, pore size=1.93 nm) showed increased mesopore(pore size=1~3nm) volume from 0.055 cc/g to 0.408 cc/g compared to its raw ACF. The charging capacity of the EDLC which uses the prepared mesoporous ACF also increased from 0.39 F/$cm^2$ to 0.55 F/$cm^2$. From these results, it can be known that the electrochemical properties of EDLC are mainly dependent on the specific surface area, but above the surface area 2200 $m^2$/g, it is the mesopore volume that affects the performance of the capacitor considerably. Because the increased mesopore volume results in a decreased ion mobility resistance, the charge capacitance is enhanced.

• Carbon letters
• /
• 제3권2호
• /
• pp.85-92
• /
• 2002

4D carbon fiber preforms were manufactured by weaving method and their carbon fiber volume fractions were 50% and 60%. In order to form carbon matrix on the preform, coal tar pitch was used for matrix precursor and high density carbon/carbon composites were obtained by high densification process. In this process, manufacture of high density composites was more effective according to pressure increasement. When densificating the preform of 60% fiber volume fraction with 900 bar, density of the composites reached at 1.90 $g/cm^3$ after three times processing. Degree of pressure in the densification process controls macro pore but it can not affect micro pore. During the carbonization process, micro pore of the preform were filled fully by once or twice densification processing. But micro pore were not filled easily in the repeating process. Therefore, over three times densification processing is the filling micro pore.

• 한국세라믹학회지
• /
• 제35권10호
• /
• pp.1085-1093
• /
• 1998

Amorphous alumina powder prepared by the fast calcination of aluminum trihydroxide(Al(OH)3 gibbsite) for 0.5 second at 580$^{\circ}C$ was investigated rehydration propeties. Phase composition crystal size and mor-phology surface area pore volume and pore size distribution of pesudo-boehmite and bayerite crystals changed with temperature time water/alumina ratio and particle size when amorphous alumina rehydrated with water. Phase compositions were examined with XRD and DTA and crystal sized morphologies were investigaed with SEM and TEM. Also rehydration properties of amorphous alumina were in-vestigated by measuring the surface area pore volume and pore size distribution.

• Geomechanics and Engineering
• /
• 제2권3호
• /
• pp.191-202
• /
• 2010

The porosity (including the specific surface area and pore volume-diameter distribution) of montmorillonitic soft rock (MSR) was studied experimentally with an electrochemical treatment, based on which the change in porosity was further analyzed from the perspective of its electrokinetic potential (${\zeta}$ potential) and the isoelectric point of the electric double layer on the surface of the soft rock particles. The variation between the ${\zeta}$ potential and porosity was summarized, and used to demonstrate that the properties of softening, degradation in water, swelling, and disintegration of MSR can be modified by electrochemical treatment. The following conclusions were drawn. The specific surface area and total pore volume decreased, whereas the average pore diameter increased after electrochemical modification. The reduction in the specific surface area indicates a reduction in the dispersibility and swelling-shrinking of the clay minerals. After modification, the ${\zeta}$ potential of the soft rock was positive in the anodic zone, there was no isoelectric point, and the rock had lost its properties of softening, degradation in water, swelling, and disintegration. The ${\zeta}$ potential increased in the intermediate and cathodic zones, the isoelectric point was reduced or unchanged, and the rock properties are reduced. When the ${\zeta}$ potential is increased, the specific surface area and the total pore volume were reduced according to the negative exponent law, and the average pore diameter increased according to the exponent law.

• 한국응용과학기술학회지
• /
• 제31권3호
• /
• pp.408-415
• /
• 2014

In order to prepare high-quality activated carbons (ACs), coal tar pitch (CTP), and mixtures of CTP and petroleum pitch (PP) were activated with KOH. The ACs prepared by activation of CTP in the range of $700{\sim}1000^{\circ}C$ for 1~5 h had very porous textures with large specific surface areas of $2470{\sim}3081m^2/g$. The optimal activation conditions of CTP were determined as CTP/KOH ratio of 1:4, activation temperature of $900^{\circ}C$, and activation time of 3 h. The obtained AC showed the highest micro-pore volume, and pretty high specific surface area and meso-pore volume. The micro-pore volumes and specific areas of activated mixtures of CTP and PP were similar to each other but the meso-pore volume could be increased. In order to change the degree of crystallinity of precursors before KOH activation process, the CTPs were carbonized in the range of $500{\sim}900^{\circ}C$. As the carbonization temperature increased, the specific surface area and pore volume of the activated ACs with the same activation conditions for CTP decreased dramatically. It was demonstrated that the increased pore size distribution of AC electrodes in the range of 1 to 2 nm plays an important role in the performance of electric double-layer capacitor.

• 한국환경농학회지
• /
• 제25권4호
• /
• pp.316-322
• /
• 2006

본 연구는 도곡 광산의 광미 중 Cd, Cu, Pb, Zn의 용출 특성을 탐색하기 위해 수행하였으며, 환경에 영향을 미칠 수 있는 수용성과 0.1 M HCl 용출물을 대상으로 Batch 시험과 Column 시험을 실시하였다. Batch 시험에서 수용성 중금속은 Cd 2.31 mg/kg, Cu 129.38 mg/kg, Pb 17.17 mg/kg, Zn 287.53 mg/kg이었으며, 0.1H HCl 추출물은 Cd mg/kg, Cu mg/kg, Pb mg/kg, Zn mg/kg이었다. 수용성 중금속의 초기 용출농도는 Zn > Cu > Pb > Cd의 순이었으며, 수용성 중금속의 용출속도상수는 Pb > Cu > Cd > Zn의 순이었다. 0.1M HCl 추출물의 초기 용출농도는 Zn > Cu > Pb > Cd의 순이었으며, 용출속도상수는 Pb > Cd > Zn > Cu의 순이었다. 중금속의 용출속도는 주로 추출액과 광미의 물리적 화학적 특성에 따라 달라질 수 있으며, 이러한 결정 요소에 의하여 본 시험에서는 Pb의 용출속도가 가장 높은 것으로 조사되었다. Column시험에서 수용성 중금속은 Cd과 Cu, Zn의 경우 2 pore volume에서 의사평형에 도달하였으나, Pb의 경우 10 pore volume에서 의사 평형에 도달하였다. 0.1 M HCl을 column에 통과시켰을 때 Cd, Cu, Zn은 1 pore volume에서 용출농도의 최대점을 나타냈으나, Pb은 5 pore volume에서 최대점을 나타내었으며, 이동속도는 Cd > Zn > Cu > Pb의 순으로 조사되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.998-1003
• /
• 2008

It has been recognized unsaturated soil behaviour playing an important role in geomechanics. Up to now, only a few experimental data are available for the technical difficulties related to both volume changes and suction measurements. In this study, the volume changes of unsaturated compacted silty soil were monitored with proximeter (i.e. non-contactable transducer) during various triaxial compression tests, which gave a realistic estimation in the volume changes of unsaturated soil sample. Various triaxial compression tests for unsaturated soil under different drainage conditions are carried out. The behaviour of the pore pressure, namely, the pore-air pressure and the pore-water pressure, and matric suction during the shearing tests are investigated. The experimental results have revealed that the mechanical behaviour of unsaturated soil can be significantly affected by the matric suction.