• Journal of environmental and Sanitary engineering
• /
• v.13 no.3
• /
• 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.

• Applied Chemistry for Engineering
• /
• v.4 no.1
• /
• pp.113-124
• /
• 1993

Thermogravimetric analysis of copolymer of acrylonitrile(95%) and methyl acrylate(5%) have been carried out to investigate the activation under $H_2O$(30%) -$N_2$atmosphere at various heating rates. The kinetic equation [$f=1-\exp(-a{\Delta}T)^b$] which was derived on the basis of the nonisothermal activation process of carbon fiber in the $H_2O$(30%)-$N_2$system showed good agreement with experimetal results. The pore volume upon conversion was in good agreement with the model of theoretical pore volume. The pore structures of the activated carbon fiber were influenced by the heating rate, activation temperature and internal-external conversions.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.6
• /
• 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.

• Journal of the Korean Applied Science and Technology
• /
• v.27 no.3
• /
• 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
• /
• v.3 no.2
• /
• 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.

• Journal of the Korean Ceramic Society
• /
• v.35 no.10
• /
• 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
• /
• v.2 no.3
• /
• 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.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.3
• /
• 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.

• Korean Journal of Environmental Agriculture
• /
• v.25 no.4
• /
• pp.316-322
• /
• 2006

Objective of this research was to assess the release characteristics of metals from the mine tailing to base the prediction of metal load potential from tailing to soils. Water-soluble concentrations of Cd, Cu, Pb and Zn released from mine tailing after 2 hrs were 2.31, 129.38, 17.17, and 287.53 mg/kg, respectively, as compared to 1.6, 128, 108, and 142 mg/kg that were extractable by 0.1 M HCl. Kinetics of metal releases followed the power function model significantly indicating that more of water soluble fractions of those metals released at the initial short time, followed by a slow increase. Concentrations of metals released from tailing by water and 0.1 M HCl were in the orders of Zn > Cu > Pb > Cd. The breakthrough curve from the column experiment showed that concentrations of Cd, Cu, and Zn reached at highest after one pore volume, but that of Pb reached highest after five pore volumes when 0.1 M HCl was used as eluent. The release rate of Cd from mine tailing was the fastest but Pb was the slowest. The cumulative mass of metal released by 0.1 M HCl was in the order of Zn > Cu > Pb > Cd after nine pore volume elution.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• 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.