Carbon as adsorbent

Recent reports describe the use of various porous carbon materials for protein adsorption. For example, Hyeon and coworkers summarized the recent development of porous carbon materials in their review [163], where the successful use of mesoporous carbons as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for protein immobilization are described. Gogotsi and coworkers synthesized novel mesoporous carbon materials using ternary MAX-phase carbides that can be optimized for efficient adsorption of large inflammatory proteins [164]. The synthesized carbons possess tunable pore size with a large volume of slit-shaped mesopores. They demonstrated that not only micropores (0.4—2 nm) but also mesopores (2-50 nm) can be tuned in a controlled way by extraction of metals from carbides, providing a mechanism for the optimization of adsorption systems for selective adsorption of a large variety of biomolecules. Furthermore, Vinu and coworkers have successfully developed the synthesis of... 

In the majority of applications of activated carbons as adsorbents of vapors and gases, the contaminants are removed owing to the enhanced adsorption potential in the small pores of activated carbons [5,134],... 

Vinke, P. and Vanbekkum, H., The dehydration of fructose towards 5-hydroxymethylfurfural using activated carbon as adsorbent. Starch-Starke 1992, 44 (3), 90-96. 

Sediment and biota samples have both been analyzed by Pruell et al. by the same method. About 10 g of sediment or tissue sample were mixed with sodium sulfate. The samples were Soxhlet-extracted with an acetone pentane (30 70, v/v) solvent mixture. Four subsequent column chromatographic purifications with series of layers of activated silica, potassium silicate, sulfuric acid treated silica, sodium sulfate, silver nitrate treated silica, neutral alumina, and activated carbon as adsorbents were used [11]. 

Accessibility to the chemical surface groups is a very important factor in order to understand the behaviour of activated carbons as adsorbents and catalysts. This factor becomes particularly important if constrictions in the pore-network are present. So dynamic techniques should be used in order to characterise these kinds of materials. 

The relatively high carbon content of Adsorbent X (2.46 %) does not cause any significant changes in the porous structure of the modified initial silica gel. Adsorbent H obtained through the pyrolysis of n-heptanol contains, in fact, the same amount (2.3 %) of carbon as Adsorbent X, but, in spite of this, as shown by Table 7, the adsorbents clearly differ in their surface characteristics. The n-heptanol carbonization products block more effectively the narrow pores of the modified silica than the carbon produced in the pyrolysis of dichloromethane. This is confirmed by the differences in the specific surface area of both adsorbents (Table 7). 

Bagreev, A., Rahman, H., and Bandosz, T.J. (2000). Wood-based activated carbons as adsorbents of hydrogen sulfide a study of adsorption and water regeneration process Ind. Eng. Chem. Res., 39, 3849—55. 

Moreno-CastiUa, C., Carrasco-Marin, F., Utrera-Hidalgo, E., and Rivera-UtiiUa, J. (1993). Activated carbons as adsorbents of sulfur dioxide in flowing air. Effect of their pore texture and surface basicity. Langmuir, 9, 1378—83. 

Finally, Chapters 24—27 deal with the environmental apphcations of carbons as adsorbents for the removal of pollutants from aqueous solutions. These four chapters are highly complementary. Thus, Chapter 24, which addresses the problems associated with the removal of inorganic species, finds its alter ego in Chapter 25, which deals with the adsorption of organic solutes from dilute aqueous solutions. Both chapters provide insights into the fundamental reasons for the performance exhibited by a carbonaceous adsorbent. The global topic of water purification using carbons as adsorbents is addressed in Chapter 26, which... 

Owing to a higher specific surface area, carbon aerogels perform better than activated carbons as adsorbent for hydrogen, exhibiting an excess adsorbed... 

As mentioned above the most important features of activated carbons for adsorption me the textural parameters. For years natural surface chemistry of carbons, however studied in details [38, 39, 40, 45], was not really strongly linked to the performance of carbons as adsorbents. Its role was rediscovered when US EPA introduced strict envirorunental regulations and activated carbons were proven to be the best adsorbents working at ppm or even ppb levels. Moreover, very often the matrix (gaseous or liquid) from which the species have to be separated can interfere with the adsorption process causing that in many cases the specific adsorption forces have to be applied. Those forces can be provided by surface chemistry of carbons. 

The bulk separation of mixtures (in contrast to the removal of trace components) into high-purity products by adsorption requires a countercurrent flow of phases as in other equilibrium-based separations. The moving-bed adsorber, which offers the eountercurrent flow of the phases, was used for the separation of a gaseous mixture of hydrocarbons using activated carbon as adsorbent.lt is known as a hypersorber. Though it performed well, it... 

CATALYTIC FILAMENTOXra CARBON AS ADSORBENT AND CATALYST SUPPORT... 

Seredych, M., Portet, C., Gogotsi, Y, and Bandosz, T.J. Nitrogen modified carbide-derived carbons as adsorbents of hydrogen sulfide. Journal of Colloid and Interface Science 330, 60-66, 2009. 

Royset, O., Thomassen, Y., Activated Carbon as Adsorbent for Alkyllead in Air, Anal. Chim. Acta 188 [1986] 247/55. 

---