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Fraction of aromatic carbon

Fraction (%) of aromatic carbon in humic acids as determined by 13C NMR... [Pg.127]

Fig. 1. Relationship between the Koc of HOCs and the fraction of aromatic carbon in the sorbents as determined by 13C NMR (a) Koc of pyrene for humic acids from three soils and a sediment as sorbents (Gauthier et al. 1987), (b) Koc of naphthalene for five different whole soils as sorbents (Xing 1997). Fig. 1. Relationship between the Koc of HOCs and the fraction of aromatic carbon in the sorbents as determined by 13C NMR (a) Koc of pyrene for humic acids from three soils and a sediment as sorbents (Gauthier et al. 1987), (b) Koc of naphthalene for five different whole soils as sorbents (Xing 1997).
Fig. 2. Relationship between log Koc of phenanthrene and the fraction of aromatic carbon in the humic acids extracted from soil horizons as determined by 13C NMR. O, organic horizons A, surface mineral horizons 1-3, subhorizons. Modified from Xing (2001). Fig. 2. Relationship between log Koc of phenanthrene and the fraction of aromatic carbon in the humic acids extracted from soil horizons as determined by 13C NMR. O, organic horizons A, surface mineral horizons 1-3, subhorizons. Modified from Xing (2001).
To evaluate further the CAMD results, a number of atomic and chemical parameters from each structure (number of atoms, fractions of aromatic carbon and hydrogen, weight fraction or each atomic species, empirical formula) were compared with the original literature for each structure. This provided a useful check on the accuracy of the computer models. Results of the computer analyses for the four coal structures are given in Table I. The total numbers of atoms only appear as guides to the size and complexity of each structure, and bear no relationship to the size of a "coal molecule" or a decomposition product. [Pg.162]

High-resolution techniques for NMR in solids have been used to obtain spectra of and in an Iowa and a Virginia vitrain. The carbon spectrum separated into two well-defined peaks from which an aromatic and an aliphatic portion were estimated. A superposition of Lorentzian lines was used to represent the aliphatic and aromatic proton signals, which were not well separated under high-resolution techniques. The fractions of aromatic carbon and hydrogen thus obtained were used to estimate an average polynuclear aromatic ring size in the coals studied. [Pg.15]

Treating a bituminous coal with potassium hydroxide in glycols at 250°C yields a largely soluble product that results from the reduction of polycyclic aromatics and the cleavage of aryl ether linkages. The reduction in aromaticity was demonstrated in two ways. First, the fraction of aromatic carbons ( J of the soluble product, which was determined by NMR, was compared with the of the whole coal determined by fluorination. Secondly, the aromatic acids produced in a selective oxidation of both the product and coal were compared, and evidence for ether cleavage was obtained from the oxidation results. The effects of rank and different protic solvents on the reaction were examined. [Pg.161]

FIGURE 7 Plot of fraction of aromatic carbon (fa) vs percent carbon for 63 coals and coal macerals. [Reprinted with permission from Wilson, M. A., Pugmire. R. J., Karas, J., Alemany, L. B., Wolfenden, W. R., Grant, D. M., and Given, P H. (1984). Anal. Chem. 56, 933.]... [Pg.39]

FIGURE 10.13 Variation of the fraction of aromatic carbon with the molar volume and atomic H/C ratio. (From Van Krevelen, D.W. and Schuyer, J., Coal Science, Elsevier, Amsterdam, the Netherlands, 1957.)... [Pg.307]

In recent decades, NMR has been used as a tool for the characterization of mixtures, especially the NMR, providing relevant information about the structure of complex systems such as asphaltenes. Simultaneous use of and NMR allows the determination of a series of structural parameters such as fraction of aromatic carbon, the average number of carbons in an alkyl attached to aromatic systems and the percentage replacement of this system (Skoog et al, 2002). [Pg.15]


See other pages where Fraction of aromatic carbon is mentioned: [Pg.227]    [Pg.129]    [Pg.18]    [Pg.92]    [Pg.149]    [Pg.31]    [Pg.68]    [Pg.226]    [Pg.102]    [Pg.125]    [Pg.125]    [Pg.282]    [Pg.21]    [Pg.78]    [Pg.162]    [Pg.169]    [Pg.133]    [Pg.137]    [Pg.325]    [Pg.342]    [Pg.39]    [Pg.192]    [Pg.69]    [Pg.116]    [Pg.143]   
See also in sourсe #XX -- [ Pg.23 ]




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Aromatic carbon

Aromatic carbonates

Aromatic fraction

Carbon aromaticity

Carbon fraction

Carbonate fraction

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