ISSN 00201685, Inorganic Materials, 2010, Vol. 46, No. 5, pp. 480–486. © Pleiades Publishing, Ltd., 2010. Original Russian Text © T.S. Golovizina, L.M. Levchenko, V.N. Mit’kin, L.A. Sheludyakova, V.E. Kerzhentseva, 2010, published in Neorganicheskie Materialy, 2010, Vol. 46, No. 5, pp. 548–554.
OxygenContaining Functional Groups on the Oxidized Surface of a Carbon Nanomaterial T. S. Golovizina, L. M. Levchenko, V. N. Mit’kin, L. A. Sheludyakova, and V. E. Kerzhentseva Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia email:
[email protected] Received March 12, 2009; in final form, October 22, 2009
Abstract—The composition of the oxygencontaining surface functional groups produced by the oxidation of the Tekhnosorb carbon nanocomposite material is studied using chemical analysis and titrimetry. The oxy gencontaining groups on the carbon surface are identified by IR spectroscopy. The oxygen content of the surface functional groups is determined as a function of oxidation conditions, and the static exchange capac ity of the material is shown to correlate with its surface composition. DOI: 10.1134/S0020168510050080
INTRODUCTION As shown earlier [1, 2], the Tekhnosorb carbon nano material (CM), which is produced by rapid hightemper ature pyrolysis of hydrocarbons and deposition of the products on carbon black particles, followed by activa tion, is a promising matrix for the fabrication of modified sorbents with tailored properties. The development of processes for the preparation of new sorbents on this matrix requires knowledge of the carbon surface modifi cation processes involved and the qualitative and quanti tative compositions of oxygencontaining surface func tional groups. The surface composition of activated carbon is known to include various oxygencontaining species: carboxyl, carbonyl, phenolic, and lactonic groups [3–9]. It is car boxyls and hydroxyls which determine the ionexchange function of the sorbent [10] and are of most interest. The purpose of this work was to study the composition of the oxygencontaining functional groups that form during the oxidation of Tekhnosorb and their effect on the sorption capacity of the material. EXPERIMENTAL In our studies, we used the Tekhnosorb carbon nano composite material, manufactured at the Omsk Institute of Hydrocarbon Processing Problems, Siberian Division, Russian Academy of Sciences (Purity Standard TU 38 4153894; particle size, 0.7–1.5 mm; pore diameter, 4 nm; specific surface area, 300–400 m2/g; apparent density, 2.05–2.08 g/cm3; open porosity, 62.1–63.9%). Using chemical analysis, the composition of the CM was determined to be С8.213О0.077Н0.0875. The total impurity content of the CM was 239.6 ppm (116.4 ppm after treat ment with hydrochloric acid).
The CM was oxidized with hydrogen peroxide solu tions as follows: To a weighed sample of the CM was added a Н2О2 solution (in the ratio 1 g : 10 ml), whose concentration was varied from 2 to 30%. The flask con taining the CM sample and Н2О2 was placed in a ther mostat (maintained at a constant temperature from 23 to 70°С) for 2 h. The hydrogen peroxide concentration was determined by a permanganate method [11]. Next, the CM was filtered off and placed in a drying chamber at 100°С for 5 h. In this way, we obtained 24 oxidized CM samples at hydrogen peroxide concentrations of 2, 5, 10, 15, 20, and 30% and temperatures of 23, 35, 50, and 70°С. The CM samples (oxidized under various condi tions) were analyzed for macro and microcomponents and characterized by apparent density, specific surface area, and open porosity measurements. In addition, we determined the carboxyl and hydroxyl contents, the oxy gen content of the surface functional groups, and the static exchange capacity (SEC) in 0.1 N NaOH. The CM (asreceived and oxidized) was analyzed on a Euro EA3000 CHN analyzer. Microimpurities were determined by twojet plasma atomic emission spectros copy. The apparent density was measured in toluene [12]. Specific surface area was determined on a SorbtometrM analyzer by a standard technique. Open porosity was determined using decane. To a 0.2g CM sample was added 5 ml of decane. After an hour, the CM was col lected on filter paper (yellow ribbon), the excess decane was removed from the CM surface, and the sample was weighed. The weight gain was used to evaluate the pore volume. Although oxygencontaining groups on the surface of various CMs have been studied by many groups, we found no detailed description of any experimental proce dure in the literature [3–9]. We determined oxygencon
480
OXYGENCONTAINING FUNCTIONAL GROUPS ON THE OXIDIZED SURFACE
481
Table 1. Chemical analysis data for the asreceived and oxidized CM samples* CM
wt % N
wt % C
wt % H
wt % O (calc)
wt % O (titr)
CMunox
0.7
98.3
0.20
232
0.067
98.3
0.20
1.38
1.35
235
0.065
97.8
0.20
1.87
1.92
7015
0.065
97.4
0.20
2.31
2.78
7020
0.090
97.1
0.15
2.63
3.16
7030
0.076
96.5
0.15
3.30
4.03
* In the sample designations in Tables 1–3, the first number indicates the oxidation temperature, and the second indicates the hydrogen per oxide concentration.
The SEC was determined in conformity with the RF State Standard GOST 2025574. The IR spectra of the oxidized CM samples were measured on a SCIMITAR FTS 2000 Fourier transform IR spectrometer in the range 400–4000 cm–1. The sam ples (0.4–2.0 mg) were pressed with KBr in the weight ratio 1–1.5 : 150. Composite IR bands were assigned using application software, which ensured identification of even very weak signals.
metals have a small tendency to decrease with increasing oxidation temperature. Oxidation influences the apparent density, open porosity, and specific surface area of the CM. This is due to the formation of carboxyl groups on the pore walls in the CM. For the same reason, the carboxyl content cor relates with the open porosity.
Solution pH
taining groups on carbon surfaces as follows: To a weighed amount of the CM (1 g) was added 100 ml of a 0.1 N NаНСО3 solution (carboxyl determination) or 100 ml of a 0.1 N NaOH solution (hydroxyl determina tion). The CM was held for 1 h in the NaHCO3 solution or for 24 h in the NaOH solution and then filtered off. Aliquots of the solutions (50 ml for NaHCO3 and 20 ml for NaOH) were titrated with 0.1 N HCl. From the dif ference in sodium ion content in the solution before and after the reaction, we determined the content of oxygen containing groups (carboxyls and hydroxyls) and the total oxygen in all of the surface functional groups.
10 9 8 7 6 5 4 3 2 1 0
50
100
150
RESULTS AND DISCUSSION
Table 2 presents the microimpurity compositions, apparent densities, specific surface areas, open porosi ties, and SECs of the oxidized CM samples and the con tents of surface functional groups. It can be seen from Table 2 that oxidation has little effect on the microimpu rity composition of the samples. The contents of most INORGANIC MATERIALS
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Fig. 1. Titration of sodium hydrogen carbonate with 0.1 N HCl after reaction with CM 5010.
12 Solution pH
The chemical analysis data for the oxidized CM sam ples are presented in Table 1. It can be seen that the oxi dation of the CM increases the oxygen content of the samples. Together with the CHN analysis data, Table 1 presents the calculated oxygen contents (with allowance for microimpurities) and titration results, which differ very little for some of the samples. The correlation between the two data sets suggests that the proposed pro cedure for the determination of surface functional groups is sufficiently accurate.
200 V HCl, ml
0 8 6 4 2 0
2
4
6
8
10
12
14
16 18 V HCl, ml
Fig. 2. Titration of sodium hydroxide with 0.1 N HCl after reaction with CM 5010.
1.42 ± 0.01 0.94 ± 0.01 1.92 ± 0.01 13.2 ± 0.2
2.21 ± 0.25 2.10 ± 0.20 3.57 ± 0.28 40.5 ± 0.7
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50.6 ± 0.5 80.0 ± 3.9 54.2 ± 0.5 89.4 ± 4.7 45.0 ± 0.5 67.2 ± 4.8
7015 13.8 ± 1.3 101.0 ± 5.8
7020 39.5 ± 2.7 114.0 ± 6.3
7030 25.4 ± 1.9 82.0 ± 6.1
Note: N is the number of determinations.
52.6 ± 0.6 90.7 ± 5.4
7010 18.9 ± 1.7 87.1 ± 6.3
50.8 ± 0.8 80.9 ± 4.0 50.1 ± 0.6 75.1 ± 6.8
12.2 ± 1.2 80.4 ± 3.7
15.6 ± 1.4 94.6 ± 7.8
705
702
50.6 ± 4.2
84.0 ± 5.4
49.1 ± 3.3
83.9 ± 7.7
56.9 ± 4.0
50.5 ± 2.6
270.2
381.1
294.5
333.2
292.3
274.8
2.20 ± 0.30 1.25 ± 0.01 2.78 ± 0.23 28.4 ± 0.4 1.85 ± 0.04 60.4 ± 0.8 366.2 ± 17.3 3.03 ± 0.09 2.02 ± 0.01 4.03 ± 0.08 44.9 ± 0.7
1.88 ± 0.01 65.2 ± 2.5 392.1 ± 19.8 1.65 ± 0.09 2.08 ± 0.01 3.16 ± 0.08 37.1 ± 1.4
1.89 ± 0.02 65.9 ± 2.7 365.0 ± 2.4
2.03 ± 0.02 62.5 ± 1.9 384.0 ± 15.7 1.87 ± 0.15 1.34 ± 0.03 2.26 ± 0.12 27.9 ± 0.4
2.11 ± 0.03 61.9 ± 1.4 358.7 ± 17.2 1.30 ± 0.14 1.59 ± 0.02 2.44 ± 0.12 26.3 ± 0.9
2.08 ± 0.03 61.3 ± 2.1 377.1 ± 21.2 1.80 ± 0.10 1.26 ± 0.01 2.51 ± 0.07 26.5 ± 0.4
2.01 ± 0.01 62.4 ± 1.6 351.0 ± 25.0 1.98 ± 0.08 2.29 ± 0.01 3.73 ± 0.06 43.1 ± 1.3
5030
1.44 ± 0.03 1.40 ± 0.01 2.37 ± 0.02 26.1 ± 0.2
2.01 ± 0.01 62.3 ± 1.8 347.9 ± 19.7 1.86 ± 0.05 1.39 ± 0.05 2.75 ± 0.09 26.2 ± 0.1
2.01 ± 0.01 58.7 ± 0.9 351.9 ± 3.9
2.06 ± 0.20 62.2 ± 2.5 387.3 ± 16.1 1.60 ± 0.20 1.42 ± 0.23 2.58 ± 0.32 13.8 ± 0.1
2.10 ± 0.03 62.4 ± 3.2 402.1 ± 10.5 1.50 ± 0.09 1.01 ± 0.03 2.04 ± 0.08 21.5 ± 0.5
2.09 ± 0.03 62.8 ± 1.8 410.8 ± 1.6
448.9
218.4
394.0
224.8
5020
58.8 ± 0.8 180.0 ± 15.0 114.0 ± 11.0
5015 22.8 ± 1.4 73.3 ± 6.7
42.0 ± 2.2
63.1 ± 0.5 111.0 ± 6.9 111.0 ± 7.5
50.2 ± 3.4
41.7 ± 0.4 60.7 ± 3.0
24.2 ± 1.5 84.7 ± 4.6
505
39.5 ± 0.3 64.7 ± 3.3
5010 11.3 ± 0.9 62.7 ± 3.0
9.1 ± 0.6 61.3 ± 4.0
502
1.20 ± 0.20 1.53 ± 0.01 2.40 ± 0.01 29.3 ± 0.2
2.00 ± 0.01 61.7 ± 2.9 363.0 ± 8.8
1.50 ± 0.20 1.04 ± 0.04 2.07 ± 0.19 21.7 ± 0.3
3530
339.8
2.02 ± 0.01 59.2 ± 1.5 349.3 ± 3.8
1.00 ± 0.05 0.95 ± 0.02 1.62 ± 0.05 18.1 ± 0.1
78.0 ± 4.6
273.3
2.08 ± 0.01 62.1 ± 1.9 384.9 ± 22.4 0.99 ± 0.16 0.17 ± 0.01 1.38 ± 0.13 12.1 ± 0.1
2.06 ± 0.03 62.4 ± 1.4 384.1 ± 8.2
55.9 ± 0.4 118.0 ± 5.4
3515 24.5 ± 1.4 63.4 ± 2.5
65.6 ± 4.3
296.4
2.02 ± 0.01 62.7 ± 0.9 376.5 ± 15.4 1.36 ± 0.15 1.94 ± 0.04 2.82 ± 0.15 33.3 ± 0.1
3520
49.9 ± 0.5 77.2 ± 5.1
3510 15.2 ± 1.4 64.4 ± 4.3
68.4 ± 2.8
282.1
1.17 ± 0.09 0.76 ± 0.03 1.57 ± 0.09 16.4 ± 0.1
53.7 ± 0.6 88.9 ± 5.3
15.5 ± 0.4 69.9 ± 4.8
355
54.3 ± 3.6
2.06 ± 0.02 62.8 ± 0.7 373.1 ± 1.8
51.1 ± 0.6 94.0 ± 7.4
12.5 ± 1.1 70.2 ± 5.5
1.30 ± 0.13 0.95 ± 0.02 1.84 ± 0.11 19.5 ± 0.3
2.05 ± 0.01 61.7 ± 0.9 387.4 ± 0.1
2330
352
1.20 ± 0.10 0.77 ± 0.01 1.61 ± 0.08 16.6 ± 0.5
2.10 ± 0.10 62.1 ± 0.9 369.9 ± 8.7
2320
2.00 ± 0.16 60.9 ± 1.4 433.1 ± 27.3 1.19 ± 0.18 0.88 ± 0.02 1.69 ± 0.15 14.1 ± 0.3
2.20 ± 0.10 61.6 ± 0.9 373.4 ± 4.7
SEC, mg/g (N = 4)
0.98 ± 0.02 0.68 ± 0.01 0.35 ± 0.02 14.4 ± 0.2
wt % O wt % wt % –OH in –COOH –COOH (N = 6) and –OH (N=6) (N = 6)
1.05 ± 0.14 0.84 ± 0.04 1.56 ± 0.15 16.9 ± 0.2
495.4
309.4
Vopen, % (N = 3)
S, m2/g (N = 2)
1.98 ± 0.08 63.0 ± 1.8 388.8 ± 8.2
ρ, (N = 4) g/cm3
2.09 ± 0.02 61.3 ± 2.3 361.8 ± 7.4
72.9 ± 0.6 147.0 ± 5.0 140.0 ± 9.2
2315 44.5 ± 3.8 91.0 ± 3.9
71.8 ± 5.9
53.6 ± 0.6 88.6 ± 4.2
2310 21.6 ± 3.4 73.8 ± 3.3
828.0
Total
74.8 ± 7.0 129.0 ± 1.8 135.2 ± 1.4 212.0 ± 5.8 277.0 ± 11.0
Si
235
Fe 662.3
Co,Cr,Cu, Ni,Pb,Mg 89.4 ± 0.7 163.0 ± 8.2 212.0 ± 8.1
Ca
96.9 ± 4.2 101.0 ± 4.8
Al
232
Sample
Microimpurities, ppm
Table 2. Physicochemical characteristics of the oxidized CM samples
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OXYGENCONTAINING FUNCTIONAL GROUPS ON THE OXIDIZED SURFACE wt % 4.5 4.0 3.5 3.0 2.5 2.5 1.8 2.0 1.5 1.0 1.26 0.5 0
483
Carboxyls 4.03
Hydroxyls Total oxygen
3.03
3.16 2.44 2.62 1.59 1.3
5
1.87
2.78 2.08 2.02
2.2 1.65
1.34
1.25
10
15
20 CH2O2, %
25
30
35
Fig. 3. Contents of surface functional groups and total oxygen as functions of hydrogen peroxide concentration at 70°С.
wt % 2.5
Carboxyls
2.0
Hydroxyls Total oxygen 1.84 1.92
1.69 1.56
1.5
1.61
1.42 1.3
1.35
1.0
1.05
1.19
1.2
0.98 0.94
0.88
0.84
0.68
0.95
0.77
0.5
0
5
10
15
20 CH2O2, %
25
30
35
Fig. 4. Contents of surface functional groups and total oxygen as functions of hydrogen peroxide concentration at 23°C.
Figures 1 and 2 show the titration curves of the sodium hydroxide and sodium hydrogen carbonate solu tions after the reaction with the CM. The titration curves have several equivalence points, characteristic of solu tions containing several salts of strong bases and weak acids. Presumably, these are sodium, magnesium, and calcium silicates and aluminates. The presence of these compounds on the CM surface is supported by atomic emission data. The SEC of our samples was found to correlate with the carboxyl content on the CM surface. The oxygen content of the functional groups gradually increases with H2O2 concentration for all of the samples oxidized at 70°С (Fig. 3) and for the samples oxidized at other tem peratures and H2O2 concentrations of 15, 20, and 30%. At oxidation temperatures below 70°С and hydrogen INORGANIC MATERIALS
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peroxide concentrations under 15–30%, the total oxygen content is a nonlinear function of oxidation conditions (Fig. 4). At all temperatures, the carboxyl and hydroxyl con tents vary nonmonotonically during oxidation (Fig. 4), with a maximum at H2O2 concentrations of 2, 5, and 10% at 35, 23, and 50°С, respectively. One possible rea son for this is that the hydrogen peroxide oxidation of the CM involves two steps: Н2О2 decomposition and oxida tion of the CM surface (formation of oxygencon taining surface groups). An increase in Н2О2 con centration is accompanied primarily by an increase in decomposition rate. The lowest content of oxygencontaining groups was observed after oxidation with 2% hydrogen peroxide at 23°С (Fig. 4). Oxidation with 30% hydrogen peroxide at
3448.1
3652.4
3772
2852 2921.9
1584.1 1631.1 1728.4
1386.1
1076.4 1119.2 1197.4
448.3 615.6 708.8 390.1
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Transmission
484
500
1000
1500
2000
2500
3000
3500 4000 Wavenumber, cm–1
3429.532
1163.325
1383.248 1457.195 1559.444 1635.430 1691.579
984.125 1123.373
563.405 622.980 710.007 847.133
Transmission
Fig. 5. FTIR spectrum of the sample oxidized with 2% Н2О2 at 70°С.
500
1000
1500
2000
2500
3000 3500 Wavenumber, cm–1
Fig. 6. FTIR spectrum of the sample oxidized with 30% Н2О2 at 70°С.
70°С led to the highest total oxygen and carboxyl con tents (Fig. 3). The nonlinear effect of oxidation conditions on the content of surface functional groups can be interpreted in terms of an interplay between different factors that influ ence the oxidation of the CM (e.g., different oxidation rates of the basal and lateral planes of the nanograins in
the CM) and the titration process. One such factor is interconversion of functional groups when the CM is placed in an alkali solution for qualitative determination of its surface composition. It is known that, in an alkali solution, lactonic groups may convert to carboxyls, and carbonyl groups may convert to lactonic groups [6], which would give rise to oscillations in the content of sur INORGANIC MATERIALS
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OXYGENCONTAINING FUNCTIONAL GROUPS ON THE OXIDIZED SURFACE Table 3. Assignment of the surface functional groups in the IR spectra of the oxidized CM samples 702 and 7030 Frequency, cm–1 Vibrational mode 702 615.6 1076.4 1119.2 1386.1 1450 1560 1584.1 1631 1728.4 2852 2921 3448.1 3652.4
Ref.
7030 622.9 847.1 1070 1123.3 1383.2 1457.1 1559.4 1580 1635.4 1725 2850 2925 3428.5 3660
δ (–C–C– cycles) δ (C=C) δ (C–O–C) ν (C–OH) ν (C–O in –COOH) δ (C–H) νas (–COO–) ν (–C=O) δs (H2O and –COOH) νas (O–C=O) ν (–CH2 and –CH3)
[14] [15] [15] [18] [18] [15] [14] [14] [18] [8, 17] [8, 16]
ν (–OH)
[14, 8, 16]
face functional groups as a function of oxidation condi tions. This seems to account for the variation of the con tent of functional groups from IR spectroscopy data. The oscillations in the hydroxyl content are attributable to the fact that the alkali solution reacts only with those carbox yls on the CM surface which are similar in structure to polyatomic alcohols [13]. IR spectroscopic characterization of the oxidized CM samples (Figs. 5, 6) enabled identification of most oxy gencontaining surface functional groups (Table 3) using earlier data [14–18]. As seen in Figs. 5 and 6, the IR spectra of the oxidized CM samples contain a broad strong band around 3400 cm–1, due to hydroxyls. There are also quite prominent bands in the ranges 2800–3000 and 1000–1700 cm–1, arising from the stretching modes of the –СН2 and –CH3 groups and vibrations of different oxygencontaining groups. Judging from the intensities of the IR bands of various groups, the content of surface groups is influenced by the hydrogen peroxide concen tration. In addition, the IR spectra show composite bands, which can be contributed by several surface spe cies (Table 3). For example, the band around 1630 cm–1 may be contributed by adsorbed water and the stretching mode of carboxyls. CONCLUSIONS The oxidation of the CM studied with hydrogen per oxide increases the surface oxygen content. The microimpurity composition varies only slightly during oxidation, with only a small tendency for the microimpurity content to decrease with increasing oxi dation temperature. INORGANIC MATERIALS
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Oxidation increases the carboxyl content on the CM surface and, accordingly, reduces the open porosity and increases the apparent density of the material. The static exchange capacity varies from 12 to 44.9 mg/g, depending on the surface carboxyl content. With increasing carboxyl content (from 1 to 3 wt %), the static exchange capacity increases. The lowest content of oxygencontaining groups is observed after oxidation with 2% hydrogen peroxide at 23°С. Oxidation with 30% hydrogen peroxide at 70°С led to the highest total oxygen and carboxyl contents. The carboxyl content is the most sensitive to the hydrogen peroxide concentration. IR spectroscopy and titration results indicate the presence of the following oxygencontaining species on the carbon surface: carboxyl (within 3.03 wt %), hydroxyl (within 2.29 wt %), lactonic, and carbonyl groups. ACKNOWLEDGMENTS We are grateful to S.B. Zayakina for determining the impurity composition of the carbon materials. REFERENCES 1. Levchenko, L.M., Mit’kin, V.N., Oglezneva, I.M., et al., Oxidized and Modified Carbon Materials As Sorbents of Mercury, Khim. Interesakh Ustoich. Razvit., 2004, no. 12, pp. 709–724. 2. Shavinskii, B.M., Levchenko, L.M., Mit’kin, V.N., et al., Iodinated Carbon Material As a Chemisorbent of Mer cury, Khim. Interesakh Ustoich. Razvit., 2008, no. 16, pp. 449–454. 3. Studebaker, M.L., Huffman, E.W.D., Wolfe, A.C., and Nabors, L.G., OxygenContaining Groups on Surface of Carbon Black, Ind. Eng. Chem., 1956, vol. 48, no. 1, pp. 162–166. 4. Tarkovskaya, I.A. and Tomashevskaya, A.N., Complex ation on Carbon, Adsorbts. Adsorbenty, 1984, no. 12, pp. 12–21. 5. Boehm, H.P., Chemical Identification of Surface Groups, Adv. Catal. Relat. Subj., 1966, vol. 16, pp. 179–211. 6. Boehm, H.P., Some Aspects of the Surface Chemistry of Carbon Blacks and Other Carbons, Carbon, 1994, vol. 32, no. 5, pp. 759–769. 7. Izhik, A.P. and Ur’ev, N.B., Effect of the Degree of Oxida tion on the Surface Properties and Structural Evolution of FineParticle Commercial Carbon, Kolloidn. Zh., 2002, vol. 64, no. 5, pp. 623–627. 8. Croswel Aguilar, Rafael Garcia, Gabriela SotoGarrido, and Renan Arriagada, Catalytic Wet Air Oxidation of Aqueous Ammonia with Activated Carbon, Appl. Catal., B, 2003, no. 46, pp. 229–237. 9. Strelko, V.V., Stavitskaya, S.S., Strelko, V.V., and Strit, M., Effect of O2 and HNO3 Oxidation of Activated Carbon on the Acidity, Composition, and IonExchange Properties of Its Functional Surface Groups, Teor. Eksp. Khim., 1998, vol. 34, no. 1, pp. 27–31. 10. Tarkovskaya, I.A., Okislennyi ugol (Oxidized Carbon), Kiev: Naukova Dumka, 1981, p. 198.
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11. Kreshkov, A.P., Osnovy analiticheskoi khimii (Fundamen tals of Analytical Chemistry), Moscow: Khimiya, 1971, pp. 244–245. 12. Tkachev, A.G., Mikhaleva, Z.A., Baranov, A.A., and Negrov, V.L., Tekhnologicheskoe oborudovanie dlya per erabotki gazoobraznykh materialov (Gas Processing Equipment), Tambov: TGTU, 2005. 13. Artemenko, A.I., Organicheskaya khimiya (Organic Chem istry), Moscow: Vysshaya Shkola, 2001, pp. 158–167. 14. Tarkovskaya, I.A., Tomashevskaya, A.N., Rybachenko, V.I., and Chotii, K.Yu., Surface Chemistry of Activated Car bon Studied by IR Spectroscopy, Adsorbts. Adsorbenty, 1980, no. 8, pp. 43–48. 15. Mansurov, Z.A., Zhylybaeva, N.K., Ualieva, P.S., and Mansurova, R.M., Preparation of Sorbents from Herbal
Raw Materials and Their Properties, Khim. Interesakh Ustoich. Razvit., 2002, no. 10, pp. 339–346. 16. Nakamoto, K., Infrared and Raman Spectra of Inorganic and Coordination Compounds, New York: Wiley, 1986. Translated under the title IKSpektry i spektry KR neorgan icheskikh i koordinatsionnykh soedinenii, Moscow: Mir, 1991, p. 536. 17. Platonov, V.V., Khadartsev, A.A., Shvykin, A.Yu., et al., Chemical Composition of Oxidative Degradation Prod ucts of the Organic Matter of Shungite Rock from the Zazhogino Deposit (Karelia, TransOnega Region), Zh. Prikl. Khim. (S.Peterburg), 2007, vol. 80, no. 1, pp. 132– 139. 18. Kiselev, A.V. and Lygin, V.I., Infrakrasnye spektry poverkh nostnykh soedinenii (Infrared Spectra of Surface Species), Moscow: Nauka, 1972, p. 39.
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