Pore Structure Of Activated Carbon Research Articles

Heterogeneous microporous structures and adsorption properties of carbon adsorbents

A theoretical basis for calculating parameters of the pore structure of active carbons is considered. Active carbons are classified into four types according to their dispersion and mesopore surface areas. The parameters of micro- and mesopores of active carbons produced in different countries have been determined from benzene vapor adsorption isotherms at 293 K. The differences in parameters of the Dubinin—Stoeckly equation found from adsorption isotherms of different compounds are noted.

Bimodal micropore size distribution in active carbons

The porous structure of active carbon was compared with that of the original mineral coal and its carbonization products. The parameters of the porous structure were calculated from the adsorption isotherms of CO2 (298 K) and H2O (293 K). It was shown that carbonization of the original coal at 1120 K causes changes in the chemical composition, consolidation of the part which is amorphous to X-rays, generation of an ordered defect-containing structure on its basis, an increase in the volume of the micropores, and a decrease in the mean diameter. Activation of the carbonized coal affords a microporous structure with a bimodal size distribution.

Biological Regeneration of Activated Carbon

This paper reports the results of investigations into the effect of activated carbon pore structure on the process of carbon regeneration. The suitability of several different commercial activated carbons for biological regeneration was investigated. The pore volume, pore radii, and surface area of the carbons were determined by mercury intrusion and BET methods. The adsorption capacities of the carbons were measured in completely mixed batch reactor systems. Heterogeneous micro-organism cultures and crude cell extract were used for bioregeneration of the carbons. The comparative adsorption and bioregeneration studies showed that there was no correlation between the original adsorption capacity and the regenerated adsorption capacity of activated carbons under the range of conditions used. This is due to the pore structure characteristics of the carbons. It has been found that the regenerated adsorption capacity depends on the volume of the pores with radii, r, of 5 - 50 nm (50 - 500 Å). On the basis of substrate bio-oxidation reactions and the results obtained from identification of some exo-enzymes involved in this bio-oxidation process, the probable mechanism of bioregeneration is discussed.

Study of the porous structure of active carbons by nitrogen adsorption and n-nonane preadsorption

Nitrogen isotherms have been determined at 77 K on four active carbons, used as adsorbents in gas masks, before and after n-nonane preadsorption. The four carbons contain both micro and mesopores. After n-nonane preadsorption, mesoporosity is still observed, together with a low pressure hysteresis that can be ascribed to the penetration of N 2 into the porous system through n-nonane stoppers that block some of the pore entrances. Results have been analyzed by means of the Dubinin-Radushkevich (DR) equation and the α s method.

The Effect of Activated Carbon Pore Structure on Activated Sludge Process Performance

The Effect of Activated Carbon Pore Structure on Activated Sludge Process Performance

Change in the pore structure of active carbons in precipitation of carbon from methane

1. The rates of precipitation of carbon in pyrolysis of methane in active carbons are maximum initially and decrease in time. The dependences of the initial rates of the increase in carbon in granules of active carbon with a narrow micropore size distribution in the range of 600–900°C and with methane pressures from 2.66 to 1000 hPa are similar to the dependences of the rate of precipitation of pyrocarbon on nonporous carbonaceous substances. The activation energies of the precipitation process are 230 kJ/mole with high methane pressures and 290 kj/mole with low methane pressures. 2. Precipitation of carbon from methane in the kinetic region of the process in active carbon with a narrow micropore size distribution results in a decrease in the volume of the micropores with preservation of the value of the characteristic adsorption energy. Precipitation of carbon in active carbon with a wide micropore size distribution decreases both the volume of the micropores (but to a significantly smaller degree than with a narrow size distribution) and the characteristic adsorption energy.

Pore structure of active carbons and water vapor adsorption isotherms

1. The parameters of the pore structure and water vapor sorption isotherm were analyzed for a series of samples of active carbons with a wide size distribution of the micropore volumes and with a different degree of mesopore development. 2. The maximum shift of the water sorption isotherms toward the limiting relative pressure (θ < 0.35 with h=0.90) in the presence of meso- and especially micropores in the active carbon is attained by the development of a significant volume of supermicropores whose effective size is close to the minimum size of mesopores. 3. Supermicropores, which are in all probability filled as a result of capillary condensation in the sorption of water with the formation of a hysteresis loop regardless of the presence of mesopores in the sorbent, are usually also present together with micropores in microporous active carbons.

Porous structure of active carbon and ASC whetlerites produced therefrom

A set of samples, including active carbon and ASC-whetlerites, both in their original form and after extraction, all with an identical carbonaceous skeleton, was investigated to specify the porous structure and the deposition of the impregnant. Mercury porosimetry and adsorption of nitrogen and carbon dioxide were used for this purpose. The thickness of the deposited layer increases with pore radius. In macropores of r ~ 1000 nm with the largest relative frequency, the thickness of the impregnant is about 120 nm. The deposit may somewhat remove unevenness in the pore walls, but, on the other hand, it creates a secondary pore structure in macropores, where the thickness of the deposit is high enough. Also a partial clogging of small pores takes place.

156. Effect of activated carbon pore structure on dynamic adsorption zone

156. Effect of activated carbon pore structure on dynamic adsorption zone

111. Porous structure of active carbons and adsorption kinetics

111. Porous structure of active carbons and adsorption kinetics

The complete pore structure analysis of fine porous solids

A new method is presented for the determination of the distribution of pore volume and surface in micropores. The analysis facilitates obtaining typical parameters of micropore structure from the adsorption isotherm. The calculated characteristic micropore radii and the micropore surface area for a model of cylindrical pores agree with the data from small-angle X-ray scattering. Micropore cumulative distribution curves for two typical active carbons were joined together with a high pressure mercury porosimetry data. The overall porosity cumulative distribution curve agrees with the Dubinin model of the porous structure of active carbons.

Properties of Active Carbon from Australian Bituminous Coal

The porous structure of active carbon prepared by the steam activatibn of Australian bituminous coal char at 800. -v900eC was studied b. y measuring specific surface area and pore size distribution. Bituminous coal used was Moura, Big Ben and Black Water.The specific surface area and the decolorizing power for methylene blue (JIS) of active carbon were 700. v950 m2/g and 160 v190 ml/g, respectively, in the case of 60- 70% weight loss. Under low relative pressures, low-activated coal char adserbed more water than highactivated one. However, u high relative pressures, the reverse was true for the-wa- adsorption capacities of active. carbon (Fig.6).The effect of activation temperature en micro-pore volume (r-fs 16 A) was negligible when micro-pore volume was compared in the case of the same weaight loss, Active carbons prepared at 9000C have larger transitional-pore volume (16srs.1000 A)-C macro-pore volume (r; 10 OO A)and wider pores, within the pore radius of g to loo A, than those pM at soboc, , in th6case of the same weight loss (Fig.7, 9).

A Study on Desulphurization of Flue Gases by the Active Carbon Process Using Steam Desorption (Part 3)

Variation of properties of active carbon used in continuous run of a test plant employing the active carbon process using steam desorption was measured, and the relationship between these properties and sulphur dioxide adsorption capacity was studied.During the continuous run, the porous structure of active carbon developed, and the BET surface area expanded slightly. The total oxygen content of active carbon also increased. Thus it reached at 17.6wt% being over two times of that in the original active carbon after 1, 200 hours. The oxygen existed mainly as surface oxides in active carbon. The surface oxides were classified into basic surface group and acidic surface group for quantitative analysis. The results indicated decrease in the amount of basic surface group and increase in the acidic surface group.The sulphur dioxide adsorption capacity of active carbon did not show a relationship with its structural properties. It was found that the adsorption capacity is influenced by the chemical properties of surface oxides.It was estimated that the basic surface group functions as the activation point of chemisorption with oxidation for sulphur dioxide adsorption.

Structure of pores of active carbons prepared by water-vapour and zinc-dichloride activation

The results of the study of the porous structure of active carbons by independent methods have shown differences in the shapes of the pores of active carbons, prepared by different methods of activation. These differences are explained by the different mechanisms of formation of the porous structure, which occur in the case of both principal types of activation. It has been proved that the course of the desorption branch of the water isotherm, corresponding to desorption from micropores, is not determined by their dimensions. The mechanism of water adsorption on active carbon and the connection between the adsorption isotherms and the micropores structure is discussed.

Integrated study of the porous structure of active carbons from carbonized sucrose

Porous structure of carbons obtained by activation of carbonized sucrose with carbon dioxide at 850°C was studied by the methods of adsorption and small-angle X-ray scattering. Both methods yield very similar results with the exception of the initial stage of activation where some discrepancy is observed. The latter is due to the presence in the initial carbonized sucrose of a considerable number of micropores inaccessible for the molecules being adsorbed. In the course of activation, up to 35 per cent burn-out, nearly the entire volume of the burnt-out substance forms micropores thereby increasing their volume by a factor of 2·5-3. The volume of the transitional pores also increases, but remains 15 to 20 times as small as that of the micropores. Two stages of activation may be distinguished. The first is characterized by the burn-out of the most reactive loose mass consisting principally of carbon radicals. At the second stage micropores are formed mainly through the burn-out of crystallites.

The Porous Structure of Active Carbons. X. The De. hydration of Alcohols in the Presence of Active Carbons. Part I.

前報で活性炭素とイソプロピルアルコール轍相(常温)または気相(200℃)で接触させるとアルコールが脱水され,レンが生ずることを報告した。本報ではさらにこの現象を究めるために,前報と同じ活性炭素SZ4,S4を用い,これプらロにピ比較的低温(210° ～310℃)でアルコール蒸気を接触させつぎの結果を得た。k(1)第一アルコ0ルは変化しないがi第二,第三アルコールは脱水作用をうけてそれぞれのオレフィンになる。(2)これらの脱水反応における見かけの活性化エネルギーは吸着熱の大きさと逆の順序になっている。(3)脱水反応の活性中心は吸着媒の酸性基の部分である。(4)吸着媒の細孔径の大きさによって律速残階の過程が異なってくる。

Electron-microscopic investigation of the porous structure of active carbons using the replica method

1. Using the two-stage replica method, we made an electron-microscopic study of the porous structure of some active carbon specimens. The method made it possible to establish the presence in the carbons of transitional pores and macropores in the form of spherical hollows. 2. The possible mechanism for the formation of transitional pores in active carbons and the character of their interlinkage are discussed.

Studies on Porous Structure of Active Carbons. IX. The Interaction between Cdrbon and Benzoyl Peroxide in an Isopropyl Alcohol Medium

多孔性構造既知な砂糖炭(SZ4,S4,SA4),市販水蒸気賦活炭(YT)によるイソプロピルアルコール中に溶解している過酸化ベンゾイルの消費速度を接触分解,物理吸着にわけて解析した結果,表面積の大きいSZ4,YTにおいては多量の安息香酸が生ずることが判明した. これはイソプロピルァルコールが活性炭素によって脱水反応をうけ,このために過酸化ベンゾイルは水素の供与を受け安息香酸を生ずることが定性的に判明した.

Studies on Porous Structure of Active Carbons. IV. Adsorption of Nitrogen, Methane, Carbon Dioxide and Ethylene

多孔性構造既知の試料である活性炭素S3,S4,SZ3,およびモレキュラーシープ5Aに窒素,メタン,炭酸ガス,エチレンのような無極性ガスを吸着させ,吸着媒の細孔分布が吸着の速度,選択吸着等に与える影響を検討した結果つぎのような結論を得た。(1)吸着媒の細孔分布がTri-disperseの場合には,吸着速度曲線もおおむね3段階から成る。(2)吸着ガスの物理定数と平衡吸着量との関係は一義的的でなく,その間に吸着媒の細孔径が重大な役割を演じている。

Studies on Porous Structure of Active Carbons. by Akie TURUIZUMI V. The Adsorption Potential Energy of Nitrogen, Methane, Carbondioxide and Ethylene.

Studies on Porous Structure of Active Carbons. by Akie TURUIZUMI V. The Adsorption Potential Energy of Nitrogen, Methane, Carbondioxide and Ethylene.