Carbonaceous sorbent materials

Separation of sulphur compounds from gases has been described widely in literature, cf., e.g., [7-19]. A series of papers is specifically dedicated to the removal of H2S. For this particular purpose, several methods were recommended, e.g., physical gas washing , including absorption/extraction by means of organic solvents, e.g., amines, neutralization of acidic components, oxidation, chemical drying, purification by means of membranes and adsorption by carbonaceous sorbent materials. 

Sorption isosteres were investigated for CO2 on a series of carbonaceous sorbents, specifically on materials D 47/2, D 55/2 and DGK that were kindly provided by CarboTech, Germany. These materials differ in their degree of activation (as manufacture step) and, thus, in their sorption capacity for CO2, especially in the micro-mesoporous range. As an example, sorption isosteres for CO2 on the D 47/2 sorbent are shown in Figure 12. 

Finally, the abatement of NO pollution by using sorbing catalytic materials [59,60] must also be cited. Several solid sorbents for NO removal (metal oxides, spinels, perovskites, double-layered cuprates, zeolites, carbonaceous materials, heteropolyacids and supported heteropolyacids) have been tested. The results are interesting, but not competitive to actual technologies. To mention that the use of sorbing materials allows... 

In summary, we should realize that, when applying Kioi values determined at high concentrations or derived from LFERs such as Eq. 9-26 (Table 9.2), we may underestimate equilibrium sorption at low concentrations (i.e., below 1% of the compound s solubility) by a factor of 2 or more. Due to competition with other sorbates present in a natural system, the effect of specific adsorption could, however, be significantly attenuated (Chiou et al., 2000). Furthermore, the abundance of specific adsorption sites may be rather low in certain environments. Hence, in cases in which the effect can be expected to be moderate and in which we need only to get an order of magnitude estimate of Kioc, we may decide to neglect the nonlinearity of the isotherm. In other situations, however, such as the PAH case discussed in Illustrative Example 9.3, adsorption to carbonaceous materials or other high-affinity sorbents present in significant abundances has to be taken into account. 

Solubility The amount of mass of a substance or chemical that will dissolve in a unit volume of solution aqueous solubility is the maximum concentration of a chemical that will dissolve in pure water at a reference temperature Solution A mixture in which the components are uniformly dispersed Solvent A liquid capable of dissolving or dispersing one or more chemical substances in certain instances the solvents can dissolve many different chemical substances—for instance, water, ethanol, acetone, hexane, and toluene Soot An agglomeration of particles of carbon impregnated with tar formed in the incomplete combustion of carbonaceous material Sorbent A solid or liquid medium in or upon which materials are retained by absorption or adsorption... 

Presented are the examinations of the multifimctional mineral-earbon and zeolite-carbon sorbents prepared from kaolinite with an admixture of carbonaceous materials industrial waste deposits, municipal sewage sludge and cellulose. The mixture of raw materials was thermally and hydrothermally pretreated in order to facilitate their specific structure. The parameters of capillary structure (micro and mesopores) were determined. For examinations of porous structure the mereury porosimetry method was used. In order to evaluate the solid phase transformation during the each step of sorbent preparation the SEM observation with quantitative X-ray mieroanalysis were made. 

In many respects, activated carbons meet these requirements and today a vast assortment of microporous and macroporous activated carbons are commercially available. These sorbents are very attractive due to their low cost, particularly if prepared by pyrolysis of natural raw materials. The main advantage of carbonaceous materials consists in their high adsorption capacity with respect to a variety of organic compounds. 

The sorption properties of the above carbonaceous materials were examined by means of gas chromatography [420], which allows quantitative characterization of sorbent-sorbate interactions at a small coverage of sorbent surface. Table 17.3 presents the specific retention volumes of various organic compounds measured for different carbons. 

An amorphous form of carbon made by the burning of wood, nutshells, animal bones, or other carbonaceous materials. Charcoal becomes activated by heating with steam to 800°C-900°C. During the heating process, a porous, submicroscopic internal structure is formed that provides an extensive internal surface area. Activated charcoal is commonly used as a gas or vapor adsorbent in air purifying respirators and as a solid sorbent in air sampling. 

The use of carbons as sorbents for preconcentration of pollutants, an application that has much in common with the preceding one, was recently reviewed by Matisova and Skrabakova [23], who investigated the applicability of carbon sorbents (active carbon, graphitized carbon black, molecular sieves, and porous carbon) for preconcentration of organic pollutants in environmental samples and their analysis by GC and HPLC. Another example of an application of carbonaceous materials in which surface chemistry is involved is the reduction of pollutant emissions from aqueous and gaseous media [24]. 

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