간행물
Carbon Letters KCI 등재 Carbon letters
- 발행기관 한국탄소학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1976-4251 (Print)2233-4998 (Online)
- 수록기간 2000 ~ 2024
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
Vol.4 No.1 (2003년 3월) 7건
1.
2003.03
구독 인증기관 무료, 개인회원 유료
Recently, the control of pore-characteristics of nano-porous materials has been studied extensively because of their unique applications, which includes size-selective separation, gas adsorption/storage, heterogeneous catalysis, etc. The most widely adopted techniques for controlling pore characteristics include the utilization of pillar effect by metal oxide and of templates such as zeolites. More recently, coordination polymers constructed by transition metal ions and bridging organic ligands have afforded new types of nano-porous materials, porous metal-organic framework(porous MOF), with high degree and uniformity of porosity. The pore characteristics of these porous MOFs can be designed by controlling the coordination number and geometry of selected metal, e.g transition metal and rare-earth metal, and the size, rigidity, and coordination site of ligand. The synthesis of porous MOF by the assembly of metal ions with di-, tri-, and poly-topic N-bound organic linkers such as 4,4'-bipyridine(BPY) or multidentate linkers such as carboxylates, which allow for the formation of more rigid frameworks due to their ability to aggregate metal ions into M-O-C cluster, have been reported. Other porous MOF from co-ligand system or the ligand with both C-O and C-N type linkage can afford to control the shape and size of pores. Furthermore, for the rigidity and thermal stability of porous MOF, ring-type ligand such as porphyrin derivatives and ligands with ability of secondary bonding such as hydrogen and ionic bonding have been studied.
4,000원
2.
2003.03
구독 인증기관 무료, 개인회원 유료
The structural studies of amorphous isotropic carbon prepared from pyrolysis of phenol formaldehyde resin have been carried out using X-ray diffraction. X-ray diffraction from as prepared sample at 1000℃ and a sample treated at 1900℃ revealed that both are amorphous even though there are small differences in short range order. It is found that both are graphite like carbon (GLC) with predominantly sp2 hybridization. Small angle X-ray scattering results show that as prepared sample mainly consists of thin two dimensional platelets of graphitic carbon whereas they grow in thickness to become three dimensional materials of nano dimensions.
3,000원
3.
2003.03
구독 인증기관 무료, 개인회원 유료
Based on the previous results of the equilibrium and batch adsorptions, the removal efficiency of the two-step surface-modified activated carbon (2ndAC) for heavy metal ions such as Pb, Cd, and Cr in fixed column was evaluated by comparing with that of the as-received activated carbon (AC) and the first surface-modified activated carbon (1stAC). The order of metal removal efficiency was found as 2ndAC 〉 1stAC 》 AC, and the efficiency of the 2ndAC maintained over 98% from the each metal solution. Increase of the removal efficiency by the second surface modification was contributed to maintain favorable pH condition of bulk solution during adsorption process. The removal of the heavy metals on the 2ndAC was selective with Pb being removed in preference to Cr and Cd in multicomponent solutions and slightly influenced by phenol as the organic material.
4,000원
4.
2003.03
구독 인증기관 무료, 개인회원 유료
In this work, the effect of anodic oxidation treatment on Cr(VI) ion adsorption behaviors of activated carbon fibers (ACFs) was investigated. The aqueous solutions of 10 wt% H3PO4 and NH4OH were used for acidic and basic electrolytes, respectively. Surface characteristics and textural properties of ACFs were determined by XPS and N2 adsorption at 77 K. The heavy metal adsorption of ACFs was conducted by ICP. As a result, the adsorption amount of the anodized ACFs was improved in order of B-ACFs 〉 A-ACFs 〉 pristine-ACFs. In case of the anodized treated ACFs, the specific surface area was decreased due to the pore blocking or pore destroying by acidic electrolyte. However, the anodic oxidation led to an increase of the Cr(VI) adsorption, which can be attributed to an increase of oxygen-containing functional groups, such as, carboxylic, lactonic, and phenolic groups. It was clearly found that the Cr(VI) adsorption was largely influenced by the surface functional groups, in spite of the reduced specific surface area of the ACFs.
3,000원
5.
2003.03
구독 인증기관 무료, 개인회원 유료
In this study, densified 4D carbon/carbon composites were made from carbon fiber and coal tar pitch through the process of pressure impregnation and carbonization and then followed by carbonization and graphitization. To improve the oxidative resistance of the prepared carbon/carbon composites, the surface of carbon/carbon composites was coated on SiC by the pack cementation method. The SiC coated layer was created by depending on the constitution of pack powder, and reaction time of pack-cementation. The morpology of crystalline and texture of these SiC coated carbon/carbon composites were investigated by XRD, SEM/EDS observation. So the coating mechanism of pack-cementation process was proposed. The oxidative res istance were observed through the air oxidation test, and then the optimal condition of pack cementation was found by them. Besides, the oxidative mechanism of SiC formed was proposed through the observation of SiC coated surface, which was undergone by oxidation test.
4,000원
6.
2003.03
구독 인증기관 무료, 개인회원 유료
The specific adsorption behaviors of activated carbons (ACs) treated with 30 wt% H3PO4 or NaOH were investigated in the removals of NO or NH3. The acid and base values were determined by Boehm's titration method. And, the surface properties of ACs were studied by FT-IR and XPS analyses. Also, N2/77K adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET and t-plot methods, respectively. From the adsorption tests of NO and NH3, it was revealed in the case of acidic treatment on ACs that the NH3 removal was more effective due to the increase of acidic functional groups in carbon surfaces. Also, the NO removal was increased, in the case of basic treatment, due to the improvement of basic functional groups, in spite of significant decreases of BET's specific surface area and total pore volume. It was found that the adsorption capacity of ACs was not only determined by the textural characteristics but also correlated with the surface functional groups in the acid-base intermolecular interactions.
4,000원
7.
2003.03
구독 인증기관 무료, 개인회원 유료
Carbon and carbon-based materials are used in nuclear reactors and there has recently been growing interest to develop graphite and carbon based materials for high temperature nuclear and fusion reactors. Efforts are underway to develop high density carbon materials as well as amorphous isotropic carbon for the application in thermal reactors. There has been research on coated nuclear fuel for high temperature reactor and research and development on coated fuels are now focused on fuel particles with high endurance during normal lifetime of the reactor. Since graphite as a moderator as well as structural material in high temperature reactors is one of the most favored choices, it is now felt to develop high density isotropic graphite with suitable coating for safe application of carbon based materials even in oxidizing or water vapor environment. Carboncarbon composite materials compared to conventional graphite materials are now being looked into as the promising materials for the fusion reactor due their ability to have high thermal conductivity and high thermal shock resistance. This paper deals with the application of carbon materials on various nuclear reactors related issues and addresses the current need for focused research on novel carbon materials for future new generation nuclear reactors.
3,000원
