Carbon adsorption method analysis

Carbon Adsorption Methods for Analysis of Organic Contamination in Water Supplies... 

The structure of this review is as follows in Section II, the activation and templating methods for preparing the porous carbons are briefly summarized. Section III surveys the structural characteristics of the porous carbons by using gas adsorption method. In Section IV, the molecular probe method and the image analysis method for quantitative characterization of the pore surface irregularity and the size distribution irregularity based upon the fractal theory are discussed in detail. Section V is devoted to... 

Fragments containing >C C< bonds compose the most numerous class of functional groups of carbons. However, methods for identification and quantification of these surface Ti-sites have not been adequately developed. Chemisorption of PdCl2 on powdered carbon from aqueous H2PdCl4 [54-57] can, in principle, be adapted for this purpose. This method, based on data of mathematical simulation of equilibria of PdCC adsorption on various carbon materials from H2PdCl4 solutions as well as XPS studies and eluent analysis of adsorbed Pd compounds, allows us to... 

Elemental analysis for nitrogen, carbon and hydrogen was carried out by the microanalysis laboratory of the University of Florida. Iron and sodium were determined by the atomic adsorption method of the zeolites dissolved in strong acids. 

The kinetics data analysis carried out using the curve fitting method were second-order reactions for chemical oxidation and carbon adsorption processes cept in the following cases K hiO and Salicylic acid 100 mg/l (zero-order reaction) BCMnO and Salicylic acid 500 mg/l (first-order reacfion), Norit PAC 20B and Resorcinol 500 mg/l (first-order reaction), while the reaction orders determined by tune analysis method confirmed the results of the curve fitting analysis in some cases, in other cases, the reaction orders were greater than 2. 

Gas and liquid chromatography, mass spectrometry, and UV and IR spectrophotometry are among the common instrumental techniques applied to analyze aromatic hydrocarbons. Benzene and alkylbenzenes pollutants in water, soils, and solid wastes may be analyzed by various GC or GC/MS methods as specified by the EPA (1984, Methods 602 and 624 1986, Methods 8020, 8024). In general, any mononuclear aromatic in any matrix may be analyzed in a similar way. Analysis of these substances in air may be performed by NIOSH Methods involving adsorption over coconut charcoal, desorption with carbon disulfide, and analysis by GC-FID. 

Even if they are usually called primary particles, spheres that constitute aggregate are partially fused together and never exist by themselves. Anyway, their size is of great importance because it defines the actual surface of interaction between carbon black and elastomeric phase the lower the size of primary particles, the higher the interface extension. Primary particle size distribution has been estimated by TEM image analysis, but carbon black surface area is usually more efficiently obtained by adsorption methods (see later section on surface area). 

Figure 2 Gas chromatographic separation of hydrocarbons found in an urban air sample. Open capillary, 0.32 mm i.d. x 60 m length stationary phase, DB-1 (dimethyl polysiloxane) film thickness, 0.25 pm carrier gas, helium temperature programme, 5°C isothermal for 3 min, 5-50°C at a rate of 3°C min 50-220°C at a rate of 5°C min detector, flame ionization. With this method, a total of 142 hydrocarbons could be separated and identified 128 of them were found in the urban air sample. (After Ciccioli P, Cecinato A, Brancaleoni E, Frattoni M, and Liberti A (1992) Use of carbon adsorption traps combined with high resolution GC-MS for the analysis of polar and nonpolar C4-C14 hydrocarbons involved in photochemical smog formation. Journal of High Resolution Chromatography 15 75.)...

There are also sample concentration/separation techniques used as pretreatment methods for trace analysis. Commonly used methods include chelating ion-exchange and, for trace organic analysis, solvent extraction, carbon adsorption, and resin adsorption using nonionic macroeticular resins. 

The advantage of this type of adsorption analysis evidently lies in the stability of the zones theoretically at.least one should be able to use as large columns as desired and therefore to carry out also very difficult separations. The main drawback of the elution method—the tailing— is eliminated. The fact that the different zones are in close contact is a difficulty which,- however, may be eliminated by interposing substances of intermediate adsorption and of a different chemical nature so that they may easily be removed afterwards. Examples of the application of tills procedure may be found in a paper by Hahn and the author (Tiselius and Hahn, 1943), in which various saccharides were separated, and some experiments on amino acids and peptides already mentioned. In case of strong adsorption, the affinity of the adsorbent has to be reduced by pre-treatment with suitable substances as described in the last mentioned paper. Nevertheless, losses are sometimes serious in this method. The experience so far seems to show that with the adsorbents now available the displacement method is applicable chiefly for mixtures of closely related substances, which are able to displace each other completely. However, for fatty acids in organic solvents on carbon the method has failed, but in the separation of gaseous hydrocarbons it seems quite satisfactory (Claesson, 1946). 

Some methods for pore structure analysis have been presented The adsorption of benzene and the evaluation of isotherms through the Dubinin - Radushkevich equation, the estimation of immersion heats in benzene, the adsorption of water at relative pressures of h=0.6 and 1.0, the size exclusion liquid chromatography with tracers of different molecular diameters and the one - point adsorption of nitrogen. Six active carbons are included in the investigations. It is not possible to obtain reliable values with the simple water adsorption method. The results obtained with other methods are compared with performances of adsorption of phenol from aqueous solutions as obtained from measuring equilibria and column dynamics. It is shown, that the rank of the results of pore structure analysis is the same as from the dynamic experiments. 

In order to describe the geometrical and structural properties of several anode electrodes of the molten carbonate fuel cell (MCFC), a fractal analysis has been applied. Four kinds of the anode electrodes, such as Ni, Ni-Cr (lOwt.%), Ni-NiaAl (7wt.%), Ni-Cr (5wt.%)-NijAl(5wt.%) were prepared [1,2] and their fractal dimensions were evaluated by nitrogen adsorption (fractal FHH equation) and mercury porosimetry. These methods of fractal analysis and the resulting values are discussed and compared with other characteristic methods and the performances as anode of MCFC. 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

Multiwall carbon nanotubes (MWCNTs) have been synthesized by catalytic chemical vapor deposition (CCVD) of ethylene on several mesoporous aluminosilicates impregnated with iron. The aluminosilicates were synthesized by sol-gel method optimizing the Si/Al ratios from 6 to 80. The catalysts are characterized by nitrogen adsorption, X-ray diffraction, 27A1 NMR, thermogravimetric analysis (TGA) and infrared. The MWCNTs are characterized by TGA and transmission and scanning electron microscope. 

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