Charcoal adsorption capacity Table

The adsorption capacity of various solids for a specific gas depends primarily upon the effective area of the solids. For a series of gases, the order of increasing adsorption is the same for all solid adsorbents. These similarities hold as long as there are no chemical bonding factors intervening in the adsorption process. Gases that are the most easily liquified are the most readily adsorbed at a solid surface. Table 2.2 depicts data for the adsorption of a number of gases on 1 g of activated charcoal at 15°C(1). 

Table 5.4 Adsorption Capacities of Organic Vapors on Activated Charcoal...

Bone Char. Bone charcoal is a carbonaceous substance derived from the carbonization of selected grades of animal bones by heating dry bones in an airtight iron retort at 500-700°C for about four to six hours. Comparing the capacity of metal ions removal with aetivated carbon, bone charcoal provides not only a porous carbon surface for physical adsorption, but also a hydroxyapatite lattice—Ca,o(P04)g(OH)2 for ion exchange of metal ions. Based on these properties, this sorbent should have excellent adsorption capacities for metal ions. The charaeteristies of typieal bone char are shown in Table 15.9. 

MIL-53 materials provide a convenient model for comparison with traditional sorbents with similar geometric characteristics, such as activated charcoals and zeoUtes. The specific surface area estimated for MIL-53,1100 mVg (BET method), is similar to the average value for nanocarbon materials and exceeds that for zeolites. The framework of MIL-53 comprises unidimensional channels of 8.5 A in diameter, which is similar to the pore diameter in zeolites (6-12 A) and smaller than that in the IRMOF series, including MOF-5 (12-15 A). At the same time, the hydrogen adsorption capacity of MIL-53 is somewhat higher than that of the zeolite CaX (2.19wt.%, Table 2) and activated charcoals (2.15 wt.%) [179]. It is possible that this parameter is affected by the channel geometry, because zeolites more often have a 3D channel system, as opposed to the unbranched unidimensional channels in MIL-53. However, additional experiments on the adsorption mechanism are required to draw more definitive conclusions. 

The capacity of activated coconut-shell charcoal for several common VOCs is indicated by the data of Table 12-28. The values given, which are based on the data of Lamb and Coolidge (1920), do not represent complete equilibrium, but are very close to it for the conditions 0°C (32°F) and 10 mm Hg pressure of solvent vapor over the carbon. More detailed data for one of the solvents (benzene) are presented in Figure 12-40 to illustrate the typical effects of the partial pressure of the solvent and the temperature on the quantity adsorbed. The two upper curves represent adsorber operating cmiditions and the two lower curves represent conditions during regeneration. Adsorption isotherms for other VOCs have generally similar shapes as discussed in the previous section entitled Properties of Gas-Adsorption Carbons. ... 

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