In the present research, we prepared the activated carbon (AC) sorbents to remove gas-phase mercury. The mercury adsorption of virgin AC, chemically treated AC and fly ash was performed. Sulfur impregnated and sulfuric acid impregnated ACs were used as the chemically treated ACs. A simulated flue gas was made of SOx, NOx and mercury vapor in nitrogen balance. A reduced mercury adsorption capacity was obtained with the simulated gas as compared with that containing only mercury vapor in nitrogen. With the simulated gas, the sulfuric acid treated AC showed the highest performance, but it might have the problem of corrosion due to the emission of sulfuric acid. It was also found that the high sulfur impregnated AC also released a portion of sulfur at 140℃. Thus, it was concluded that the low sulfur impregnated AC was suitable for the treatment of flue gas in terms of stability and efficiency.
Microstructure plays an important role in controlling the fracture behaviour of carbon-carbon composites and hence their mechanical properties. In the present study effort was made to understand how the different interfaces (fiber/matrix interactions) influence the development of microstructure of the matrix as well as that of carbon fibers as the heat treatment temperature of the carbon-carbon composites is raised. Three different grades of PAN based carbon fibres were selected to offer different surface characteristics. It is observed that in case of high-strength carbon fiber based carbon-carbon composites, not only the matrix microstructure is different but the texture of carbon fiber changes from isotropic to anisotropic after HTT to 2600℃. However, in case of intermediate and high modulus carbon fiber based carbon-carbon composites, the carbon fiber texture remains nearly isotropic at 2600℃ because of relatively weak fiber-matrix interactions.
In this paper, impregnated activated carbon fiber (IACF) was manufactured to pitch-based activated carbon fibers (ACF) with potassium hydroxide (KOH) by using wet impregnation method to raise nitrogen oxides (NOx) adsorptivity. The properties of IACF were observed using EPMA, TGA and DSC and NOx adsorptivity was observed at high and low temperature. Before and after adsorption was analyzed using ToF-SIMS for examine surface characterization of adsorbed NOx. The results showed that the better adsorptivity appeared for increasing KOH ratio. So, NOx adsorptivity showed result that is proportional between KOH and the adsorbed amount. On the other hand, adsorbent that manufactured without washing was better NOx adsorptivity than adsorbent that manufactured with washing. The behavior of adsorption show that crossing time of NO and NO2 delayed for a rising adsorptivity. And NO ratio increased but NO2 ratio decreased according as KOH ratio increases. NOx was confirmed through surface analysis that remain in NO2- and NO3- form on IACF surface.
In the reaction of gas-solid phases, the microwave energy plays a role as a catalyst, because it causes friction between adjacent molecules and enables an unique characteristics of interior heating of the materials. When the dipole gases are adsorbed inside of the pore of carbon materials, the gases are decomposed by the microwave energy and reacted with the carbon atoms. Using this principle, we could make the activated carbon from coconut shell within 20 minute, and this residence time for activation is about 1/16 of rotary kiln. The BET surface area of activated carbon made by microwave is about 1,100m2/g similar to conventional method of rotary kiln. In this study, the power of microwave generator was 400~1000W, and the gas for activation was steam mainly.
Electrostatic spinnings were performed with the solutions of PAN/DMF to be nanofiber webs. The diameter of the fibers ranged from 200 nm to 1000 nm depending on the PAN concentration and on the applied DC voltage. The nanofibers were oxidatively stabilized and subsequently carbonized up to 1000℃ with carbonization yield of 40%. The bulk electric conductivity of the carbonized web increased form 6.8×10-3S/cm to 1.96 S/cm while the carbonizaton temperature increased from 700℃ to 1000℃.
The two-step surface modifications of activated carbon was carried out to improve the adsorption capacity of toxic heavy metal ions in liquid phase. Physical and chemical properties of the as-received activated carbon (AC) and two kinds of surface-modified activated carbons (1stAC and 2ndAC) were evaluated through the BET analysis, surface acidity, and oxides measurements. Specific surface area and pore volume did not significantly change, but surface oxide-group remarkably increased by the surface modification. Equilibrium and batch adsorptions of the various metals, such as Pb, Cd, and Cr, using AC, 1stAC, and 2ndAC were performed at initial pH 5. The adsorption capacity and rate of 2ndAC were higher than those of AC and 1stAC. The carboxylic/sodium carboxylate complex groups were developed from the two-step surface modification of activated carbon, which strongly affected the adsorption of metal ions.