Graphitized thermal black

Figure 9.4 Left Adsorption isotherm for benzene (CeLL) adsorbing to graphitized thermal blacks at 20° C. The insert shows the adsorption isotherm for low coverages in more detail. Dotted lines indicate mono- or multilayer coverages at multiples of 4.12 //mol/m2. The equilibrium vapor pressure of benzene at 20°C is Po = 10.2 kPa. Right Differential heat of adsorption versus adsorbed amount. The dashed line corresponds to the heat of condensation of bulk benzene. Redrawn after Ref. [369].

In the work of Isirikyan and Kiselev (1961), adsorption isotherms of nitrogen were determined at 77 K in considerable detail on four different graphitized thermal blacks (with BET areas in the range 6.5-29.1 m2g 1). The isotherms are plotted in Figure 9.3 in a normalized form, as the amount adsorbed per unit area (in pmol m-2) against the relative pressure, p/p°. Kiselev and his co-workers referred to such isotherm plots as absolute adsorption isotherms , but of course they are not stricdy absolute since they are dependent on the validity of the BET-nitrogen areas - with the usual assumption that o(N2) = 0.162 nm2. 

Figure 9.3, Adsorption isotherm of N2 at 77 K on size different graphitized thermal blacks, at various scales of pjpa (after Isirikyan and Kiselev, 1961).

It is significant that the second calorimetric peak and the associated isotherm sub-step were detectable only if the graphitized thermal black had been heated at temperatures above 1700°C. These results suggest that the 2-D phase transformation is very sensitive to the perfection of the surface basal planes and this is a further indication that the phase change leads to the development of a commensurate structure. 

Do, D.D. and Do, H.D. (2002). Analysis of adsorption data of graphitized thermal black with DFT-lattice gas theory. Adsorption, 8, 309-24. 

Figure 6 Adsorption isotherms of cytochrome c on graphitized thermal black (1) and cholesterol (2) and lecithin (3) monolayers, deposited on silica gel, at pH 7 and ionic strength 0.2. (After Ref. 11. Reprinted with permission.)...

HEAT CAPACITY OF N-PROPYL ALCOHOL ADSORBED ON GRAPHITIZED THERMAL BLACK. //ENGLISH TRANSLATION OF ZH. FIZ. KHIM. 44/2/ 523-4,1970.//... 

Relative Retention Volume (referred to nonane) on the a-BN Samples from Table 4/7 [55]. HTGTB = hydrogen-treated graphitized thermal black. 

Isirikyan AA, Kiselev AV. The absolute adsorption isotherms of vapors of nitrogen, benzene and n-hexane, and heats of adsorption of benzene and n-hexane on graphitized carbon blacks. I. Graphitized thermal blacks. J Phys Chem 1961 65 601-607. 

Graphitized carbon blacks 12-100 Carbotrap, Carbopack, Carbograph Thermal Non-polar VOCs (>60°C) Low >400°C Low... 

The first example, fig. 1.8, refers to old data on some graphltized "thermal blacks", which are carbons heated to very high temperature (several thousand degrees), after which graphite-like, fairly homogeneous surfaces are formed. The different symbols refer to different blacks which, apparently have very similar surface properties. 

We show in Figures 2 file adsorption isotherm of argon on graphitized thermal carbon black at a number of temperatures. The symbols in the figure are experimental data [13]. 

Additional evidence of the importance of adsorption of basic molecules on nonacidic sites at room temperature has been given by Derkaui and coworkers. These researchers studied the adsorption of triethylamine on silica between 294 and 486 K (71,94) and the adsorption of triethylamine, benzene, cyclohexane, and isooctane on graphitized thermal carbon black between 293 and 383 K (95). 

When using comparison methods, such as a-plots, it is important that the nonmicroporous reference compound and the sample of interest have a similar surface chemistry [49]. As outlined in the previous section, information on the surface chemistry can be obtained from the APD. A similar APD indicates a comparable graphitic character of the pore surfiice. For the samples discussed here, the APDs of the nonporous CB (Fig. 18.7) and of the OMCs (Fig. 18.8) were compared. For the OMC synthesized at 700°C, the thermal black was selected as reference compound, whereas for the other OMC samples the furnace black was chosen. The adsorption data of this furnace CB are available in the literature [50]. 

For some samples, the APD method cannot be applied to calculate the specific surface area. Thermal CB, for example, has a lower graphitic order than the other CB discussed above. In the APD of thermal black, monolayer formation is only indicated by a shoulder (Fig. 18.7). Thus, the end of the monolayer formation cannot be determined with the required precision, making a mean-ingfiil determination of the surface area impossible. It can be summarized that as long as the carbon samples have a sufficient graphitic order, from the APD a reasonable estimate for the specific surface area can be obtained. 

The retention volume has been reported377 for triethyl and tetraethyl silanes on columns packed with silanized Chromosorb W supporting 20% of Apiezon L or 15% of Carbowax 20 M and operated at 120 and 90 °C, respectively, using helium as carrier gas and thermal conductivity or flame ionisation detection. Measurements were also carried out by gas-solid chromatography on columns of Carbochrom-1 (graphitized thermal carbon black with 0.1% of Apiezon L) or Silochrom C-80. 

Theoretical and experimental investigations into resonance hybridization between benzo[6-Jselenophene and naphthalene in benzoselenophene-doped naphthalene systems provided evidence for two nonequivalent centers for the impurity <85Mi 213-03). Chromatographic structural analysis by adsorption on graphitized thermal carbon black was used for the determination of conformation in 2-phenylchalcogenophenes <87MI 213-02). The adsorption of selenophene on various solid phases allowed its direct observation by EXAFS <9iMC6). 

SPECIFIC HEAT OF N-PROPANOL ADSORBED ON GRAPHITIZED THERMAL CARBON BLACK. 

Thermal desorption Volatile compounds in gases such as pollutants in air can be trapped in a small adsorption tube, either by pumping the gas through or by passive diffusion. The packing in the trap can be chosen from a wide variety of adsorbents (molecular sieves, graphitized carbon blacks, organic polymers). After sample collection the adsorption tube is rapidly heated in a stream of purge gas which transports the released analytes to the GC column where the separation runs. 

---