Carbonaceous sorbents

Alveolar air Collection onto carbonaceous sorbent thermal desorption GC/ITMS No data No data Phillips and Greenberg 1992 > K m... 

From another perspective chromatographic methods employing charcoal or other similsir carbonaceous sorbents can also be considered as pre-dav PIV I VdlinvInB the rmit sUitHr--Im Al driltald tt... 

As no conln>lied compariiion has been made we cannot close out the possibility that hydrocaiiwnaceous bonded phases will prove more stable than carbonaceous sorbents under conditions of RPC. 

The great interest in the possibility of replacing silici based bonded phases by carbon in RPC is understandable because the carbon is expected to be more stable toward aqueous eluents than the iflica-suppoited hydrocarbonaceous phases that are used almost exclusively today. Even if a carbonaceous sorbent with uniform surface and fovdrable porosity would be avaflable its stability may not live up to this expectation, however. The carbon surfoce is readily oxidized and can undergo other chemical transformations with concomitant changes in its retention properties. 

Radosz M, Hu X, Krutkramelis K et al (2008) Flue-gas carbon capture on carbonaceous sorbents toward a low-cost multifunctional carbon filter for green energy producers. Ind Eng Chem Res 47(10) 3783-3794... 

Characterization of porous carbonaceous sorbents using adsorption data in wide temperature and pressure ranges... 

Characterisation of porous carbonaceous sorbents using high pressure -high temperature adsorption data... 

To put to test the above suggestion, we examined nanoporous carbonaceous sorbent D4609 in combination with rather concentrated mixtures of NaCl and HCl or NaOH taken in equal proportions. In the first salt/acid pair the species that determine the rates of movement of solute fronts are hydrated Na cation and CC anion with ionic radii of 3.58 and 3.32 A, respectively. The difference in their sizes is not too large, but obviously sufficient for a successfid separation. As illustrated by Fig. 12.6, the fronts of NaCl and HCl diverge by one-third of the total bed volume (A = 0.33) in both the forward and reverse experiments. Here, HCl behaves as a clearly... 

Preconcentrations have been performed on both Cl 8 and carbonaceous sorbents. 

Activated Carbons. As there are so many varieties of activated carbons available on the market, there is probably a carbon that can sorb any chemical involved in a spill. However, sorption capacity and economics dictate the selection. Active carbons are highly porous carbonaceous sorbents with large surface areas. The carbon surface can be basic or acidic, hydrophilic or hydrophobic, or oleophilic or lipophobic. The exact properties depend on the source of the carbon, the activation temperature, and the activation chemicals used. 

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. 

Kwon S, Borguet E, Vidic RD. Impact of surface heterogeneity on mercury uptake by carbonaceous sorbents under UHV and atmospheric pressure. Environ Sci Technol 2002 36 4162-4169. 

In this paper, we have presented and tested a model which allows the calculation of adsorption isotherms for carbonaceous sorbents. The model is largely inspired of the characterization methods based on the Integration Adsorption Equation concept. The parameters which characterize the adsorbent structure are the same whatever the adsorbate. In comparison with the most powerful characterization methods, some reasonable hypothesis were made the pore walls of the adsorbent are assumed to be energetically homogenous the pores are supposed to be slit-like shaped and a simple Lennard-Jones model is used to describe the interactions between the adsorbate molecule and the pore wall the local model is obtained considering both the three-dimension gas phase and the two-dimension adsorbed phase (considered as monolayer) described by the R lich-Kwong equation of state the pore size distribution function is bimodal. All these hypotheses make the model simple to use for the calculation of equilibrium data in adsorption process simulation. Despites the announced simplifications, it was possible to represent in an efficient way adsorption isotherms of four different compounds at three different temperatures on a set of carbonaceous sorbents using a unique pore size distribution function per adsorbent. 

This paper deals with the principles, advantages and limitations of measurement of sorption equilibria under isosteric conditions. It further assesses the sorption-isosteric method (SIM) as an effective tool for providing complete sets of sorption-thermodynamic functions, viz., enthalpy, standard entropy and standard Gibbs free energy of sorption, for nanoporous solids, i.e., micro- and mesoporous ones, as functions of sorption-phase concentration, n, over its entire range, and to approach such data for mixtures. The usefulness of SIM is exemplified by sorption systems that comprise atmospheric gases on zeolites and carbon dioxide, CO2, on carbonaceous sorbents, as well as several of their mixtures. 

Figure 11. Concentration dependences of isosteric sorption heats for CO2 on NaLSX (FAU-I), NaX (FAU-n), DAY zeolites and Osaka Gas carbonaceous sorbent M-30.

Sorption Heats of Carbon Dioxide on Carbonaceous Sorbents... 

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. 

Figure 13. Concentration dependences of isosteric sorption heats of C02 0n various carbonaceous sorbents D 47/2, D 55/2, DGK from CarboTech-, M-30 from Osaka Gas.

Figure 16. Comparison of pressure envelopes for de(ad)sorptive cooling (warming) based on integral sorption heats of CO2 for various carbonaceous sorbents.

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