• Fire Science and Engineering
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• 제12권4호
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• pp.13-19
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• 1998

We investigated the weight loss according to temperature using Thermal Gravimetric Analysis(TGA) in order to find the thermal hazard of carbon black(Hi-Black 10, Hi-Black 50L) dusts, and the properties of dust explosion in variation of the surface functional groups and specific surface area of their dust with the same particle size. Using Hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of carbon black dust. The explosion pressure of both carbon black increased as the specific surface area increased. The results indicated that Hi-Block 50L of which specific surface area was larger three to four times than that of Hi-Black 10 was much easier of dust explosion.

• Carbon letters
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• 제4권4호
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• pp.168-174
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• 2003

Silver nitrate ($AgNO_3$) powder was mixed into a reformed pitch precursor. Then, the silver-containing pitch was melt spun to form round and "C" shape fibers. A wire mesh was inserted prior to the nozzle to improve the spinnability of the silvercontaining precursor pitch. Silver particles in the carbon fibers (CFs) were detected by XRD and TEM. These tests showed that silver particles were uniformly distributed and the total amount of silver remained constant during stabilization and carbonization. Next, the silver-containing CFs were activated by steam diluted in nitrogen gas. Silver particles accelerated the activation rate, but the specific surface areas of the silver-containing ACFs were similar to those of non-silver containing ACFs at the same burn-off levels. The specific surface area of the C-shaped activated carbon fibers was larger than that of the round activated carbon fibers. The likely reason is that the surface area of a C-shaped CF is about two times larger than that of a round CF when equivalent cross-sectional areas are compared. A small amount of silver particles in the periphery of the CFs was removed during the activation, but the remainder of silver was stayed within the ACFs.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제19권1호
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• pp.85-107
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• 1993

The cosmetic fine powders were mixed with variation of mixing time(5) in the mixers (ribbon mixer, powder mixer, micropulverizer and fine impact mill). The powders were nixed with small amount of ferric oxide. as tracer. The mixed powders ere measured the particle size distribution, specific surface area and surface color with mixing time (s). The color variation, particle size distribution and specific surface area of the mixed powder exist a relationship with mining time(s) that can be expressed as mathematical equations to show the degree of the mixing of the powder mixture. The linear velocity of the impellar tip is the main factor contributing to he mixing efficiency of the mixers un this study. According to the linear velocity, he mixers used are devieded as convection mixing (ribbon mixer), sclera mixing powder mixer) and diffusion mixing (micropulverizer/fine impact mill).

• Journal of Powder Materials
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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.

• Journal of the Korean Wood Science and Technology
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• 제49권4호
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• pp.299-314
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• 2021

In this study, we investigated the effect of temperature on specific surface area and electrochemical properties when lignin-based porous carbon (LBPC) with potassium hydroxide (KOH) is activated. After preparing LBPCs using lignin-polyacrylonitrile (PAN) copolymer, which was synthesized by graft polymerizing lignin and acrylonitrile as a precursor, activated LBPCs (KA-LBPC-6, 7, 8, 9) were manufactured by activating LBPC with KOH at 600℃, 700℃, 800℃ and 900℃. To identify the surface characteristics of KA-LBPC, observations were made with a scanning electron microscopy (SEM), and the pore characteristics were identified via specific surface area analysis. The electrochemical properties were analyzed using a three-electrode system. The experiment has shown that micropores formed by activation can be observed in SEM images. KA-LBPC-7 had the best pore characteristics among KA-LBPCs, with a specific surface area of 2480.1 m²/g, a micropore volume of 0.64 cm³/g, and a mesopore volume of 0.76 cm³/g. KA-LBPC-7 showed the best electrochemical properties with a specific capacitance of 151.3 F/g at the scan rate of 2 mV/s.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1507-1510
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• 2011

In this study, mercury vapor adsorption behaviors for some kinds of porous materials having various pore structures were investigated. The specific surface area and pore structures were studied by BET and D-R plot methods from $N_2$/77 K adsorption isotherms. It was found that the micropore materials (activated carbons, ACs) showed the highest mercury adsorption capacity. In a comparative study of mesoporous materials (SBA-15 and MCM-41), the adsorption capacity of the SBA-15 was higher than that of MCM-41. From the pore structure analysis, it was found that SBA-15 has a higher micropore fraction compared to MCM-41. This result indicates that the mercury vapor adsorptions can be determined by two factors. The first factor is the specific surface area of the adsorbent, and the second is the micropore fraction when the specific surface areas of the adsorbent are similar.

• International Journal of Concrete Structures and Materials
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• 제8권4호
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• pp.327-333
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• 2014

The objective of this work was to examine the influence of carbonation on the microstructure of cement materials. Different materials, which were CEM I mortar and paste, CEM II mortar and paste, were carbonated at $20^{\circ}C$, 65 % relative humidity and 20 % of $CO_2$ concentration. The specific surface area and pore size distribution were determined from two methods: nitrogen adsorption and water adsorption. The results showed that: (1) nitrogen adsorption and water adsorption do not cover the same porous domains and thus, we observed conflicts in the results obtained by these two techniques; (2) the CEM II based materials seemed to be more sensible to a creation of mesoporosity after carbonation than the CEM I based materials. The results of this study also helped to explain why observations in the literature diverge greatly on the influence of carbonation on specific surface area.

• Journal of Forest and Environmental Science
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• 제35권3호
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• pp.141-149
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• 2019

Nanocellulose, which can exist as either cellulose nanocrystals or cellulose nanofibrils, has been used as a biomaterial for drug delivery owing to its non-immunogenicity, biocompatibility, high specific area, good mechanical properties, and variability for chemical modification. Various water-soluble drugs can be bound to and released from nanocelluloses through electrostatic interactions. The high specific surface area of nanocellulose allows for high specific drug loading. Additionally, a broad spectrum of drugs can bind to nanocellulose after facile chemical modifications of its surface. Controlled release can be achieved for various pharmaceuticals when the nanocellulose surface is chemically modified or physically formulated in an adequate manner. This review summarizes the potential applications of nanocelluloses in drug delivery according to published studies on drug delivery systems.

• Carbon letters
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• 제1권1호
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• pp.6-11
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• 2000

Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at $900^{\circ}C$. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.

• Journal of the Korean Society of Tobacco Science
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• 제10권1호
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• pp.75-82
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• 1988

Cigarettes were made using a triple filter with several porous materials in its cavity. The removal effect of the adsorbents on carbon monoxide and hydrogen cyanide in cigarette smoke was investigated with the variation of their surface area and pore volume distributions. Several attempts were made to activated coconut shell based char under the fixed steam purging rate. 1. The specific surface area increased in number of micropore. It was found for transitional pore to have a little effect on the total surface area. 2. A Small amount of the particulate matter adsorbed on the adsorbents with transitional pores, Zeolite showed a little effect on the carbon monoxide adsorption though its small pore volume, but there was no significant difference in the adsorption capacity zeolite and the others. 3. In the adsorption for hydrogen cyanide as a vapor phase in cigarette smoke, the adsorption effect of the adsorbents increased remarkably with increasing their surface area and number of micropore. It was considered that the adsorbents with small pore volume like molecular seive 4A, in which the capillary diffusion of adsorbates could not be able, would not be effective for the adsorption of hydrogen cyanide.