• Carbon letters
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• 제7권1호
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• pp.34-41
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• 2006

The objective of this paper is to compare the variation of surface properties by hydrochloric acid pre-treatment and of metallic potassium and their salts loading effect for activated carbon after surfaces transformation by acid. From the results of nitrogen adsorption, each isotherm shows a distinct knee band, which is closely related to the characteristic of microporous carbons with capillary condensation in micropores. In order to present the causes of the differences in surface properties and $S_{BET}$ after the samples were treated with hydrochloric acid, pore structure and surface morphology are investigated by adsorption analysis. X-ray diffraction (XRD) patterns indicate that activated carbons show better performance for metallic potassium and potassium salts by pre-treatment with hydrochloric acid. Scanning electron microscopy (SEM) pictures of potassium/activated carbon particles provide information about the homogeneous distribution of metal or metal complex on the surface. For the chemical composition microanalysis for potassium treatment of the activated carbon pre-treated with hydrochloric acid, samples were analyzed by energy disperse X-ray (EDX). Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm. A positive influence of the acidic groups on the carbon surface by acid treatment is also demonstrated by an increase in the contents of potassium salts with increasing of acidic groups calculated from Boehm titration.

• Carbon letters
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• 제8권2호
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• pp.101-107
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• 2007

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at $600^{\circ}C$. Steam-activated carbon was prepared by gasifying $600^{\circ}C$-carbonization product at $950^{\circ}C$ to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at $450^{\circ}C$ in concentrated KOH solution followed by carbonization at $840^{\circ}C$. Textural properties of these carbons were determined from nitrogen adsorption at $-196^{\circ}C$ and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at $27^{\circ}C$ on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and $37^{\circ}C$ was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 $m^2/g$ and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.

• 한국표면공학회지
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• 제52권6호
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• pp.326-333
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• 2019

The microporous carbon derived from PVDC-resin by a simple heat-treatment under an inert atmosphere exhibits a reasonable specific capacitance for a supercapacitor's electrode. However, the capacitance was rapidly decreased at high charge/discharge rate. The micropores present in an electrode surface hinder the entrance of an electrolyte ion onto the entire surface. To induce the meso-sized pores during the carbonization of PVDC-resin, Mg(OH)₂ was utilized as a hard template. The porous carbon made from the mixture of PVD-Cresin and Mg(OH)₂ include mesopores as well as micropores. The induced mesopores does not homogeneously distributed on the entire surface of the synthesized carbon. The PVDC-resin and Mg(OH)₂ are dissolved in the dimethylformamide for the hard template to evolve the pores on the synthesized carbon uniformly. The carbon made from PVDC-resin with solvent and a hard template contains mostly mesopores resulting in the high power performance. The reduced amount of solvent in the precursor derives the carbon with high specific surface area and high power density.

• 한국재료학회지
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• 제26권6호
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• pp.332-336
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• 2016

Three kinds of porous polymer were synthesized using a solvothermal of tri-4,4'-diphenylmethane diisocyanate (MDI-trimer) and different diamino monomers. The effects of the synthesis conditions and the monomer selection on the synthesis of porous polymer properties were studied. The results show that the synthesis of $NH_2$-containing monomer molecules smaller the microporous polymers was easy to implement; the specific surface areas of the polymers are related to the monomer ratio and the reaction time. The results show that the synthesized porous polymer had good hydrogen storage performance; the hydrogen storage ability improved with the addition of heterocyclic nitrogen.

• Carbon letters
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• 제6권3호
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• pp.141-147
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• 2005

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of $Pb^{2+}$ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of $Pb^{2+}$ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of $Pb^{2+}$ ions were related to the chemistry of the surface rather than to the textural properties.

• Rapid Communication in Photoscience
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• 제4권1호
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• pp.19-21
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• 2015

Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

• 임산에너지
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• 제21권2호
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• pp.17-24
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• 2002

소나무 수피로 부터 수증기 활성화 의하여 활성탄을 제조하였으며, 제조된 활성탄은 세공 구조 및 표면적에 대한 검토를 행하였다. 활성화를 위하여 3종류의 서로 다른 형태의 로(정치식 수직, 수평로 및 회전식 수평로)가 본 실험에 사용되었다. 정치식 수직 및 수평로를 이용하여 수피를 탄화시키고 이를 수증기 활성화시키면, 1,000 ㎡／g이상의 높은 비표면적을 얻기는 어려웠다. 분말상태의 시료를 사용하면 비표면적이 약간 향상되었지만, 여전히 정치식 로의 경우 높은 비표면적의 결과를 얻기는 어려웠다. 로타리식 수평로에서 수피를 수증기 활성화시키면, 시판 1급 활성탄과 유사한 1,000 ㎡／g 이상의 비표면적을 나타내는 활성탄을 제조할 수 있었다. 로타리식 수평로에서 제조된 활성탄은 미세공에서 중세공까지 다양한 공극 분포를 나타내었다.

• Carbon letters
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• 제12권3호
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• pp.152-161
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• 2011

Activated carbon was prepared from pre-carbonized petroleum coke. Textural properties were determined from studies of the adsorption of nitrogen at 77 K and the surface chemistry was obtained using the Fourier-transform infrared spectrometer technique and the Boehm titration process. The adsorption of three aromatic compounds, namely phenol (P), p-nitrophenol (PNP) and benzoic acid (BA) onto APC in aqueous solution was studied in a batch system with respect to contact time, pH, initial concentration of solutes and temperature. Active carbon APC obtained was found to possess a high surface area and a predominantly microporous structure; it also had an acidic surface character. The experimental data fitted the pseudo-second-order kinetic model well; also, the intraparticle diffusion was the only controlling process in determining the adsorption of the three pollutants investigated. The adsorption data fit well with the Langmuir and Freundlich models. The uptake of the three pollutants was found to be strongly dependent on the pH value and the temperature of the solution. Most of the experiments were conducted at pH 7; the $pH_{(PZC)}$ of the active carbon under study was 5.0; the surface of the active carbon was negatively charged. The thermodynamic parameters evaluated for APC revealed that the adsorption of P was spontaneous and exothermic in nature, while PNP and BA showed no-spontaneity of the adsorption process and that process was endothermic in nature.

• 한국분말재료학회지
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• 제16권1호
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• pp.22-27
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• 2009

To improve the filtration efficiency of porous materials used in filters, an extensive specific surface area is required to serve as a site for adsorption of impurities. In this paper, a method for creating a hybridized porous alloy using a powder metallurgical technique to build macropores in an Al-4 wt.% Cu alloy and subsequent surface modification for a microporous surface with a considerably increased specific surface area is suggested. The macropore structure was controlled by granulation, compacting pressure, and sintering; the micropore structure was obtained by a surface modification using a dilute NaOH solution. The specific surface area of surface-modified specimen increased about 10 times compare to as-sintered specimen that comprised of the macropore structure. Also, the surface-modified specimens showed a remarkable increase in micropores larger than 10 nm. Such a hybridized porous structure has potential for application in water and air purification filters, as well as membrane pre-treatment and catalysis.

• Carbon letters
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• 제10권1호
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• pp.33-37
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• 2009

Activated carbon (AC) is one of the most effective adsorbents for organic compounds because of their extended surface area, high adsorption capacity, microporous structure and special surface reactivity. The composites of pH-sensitive hydrogel and activated carbon were prepared in order to improve the loading capacity of drug. The pH-sensitive hydrogel matrix swelled well in the basic condition to release the drug loaded in AC. The release of drug was controlled depending on both the pH due to the ionization of the carboxylic acid group and the AC due to the surface properties.