International Journal of Modern Research in Engineering & Management (IJMREM) ||Volume|| 1||Issue|| 8 ||Pages|| 01-06 || August 2018|| ISSN: 2581-4540
Radiolysis of Transformer Oil in The Presence of Admixtures of Polychlorinebiphenyl 1,
Z.I.Isgenderova, 2,M.A.Gurbanov
Institute of Radiation Problems of Azerbaijan National Academy of Science AZ 1143, Baku, st. B.Vahabzadeh, 9
--------------------------------------------------------ABSTRACT-------------------------------------------------: Dependence of concentration of CO2, H2O2, pH- indicator and IR-spectra of γ- irradiated transformer oil, containing polychlorinebiphenyl (PCB) admixtures from adsorbed doses in the range of 4-136 kGy was studied. It was established that radiation-chemical yields of CO2 and H2O2 are equal to 0.18 and 3.6 molec/100eV. Irradiation leads to increasing of acidity, related with dechlorination of PCB molecules. A comparative study of the radiolysis of used transformer oil and oil containing PCB under the influence of gamma radiation was carried out. The pH-value dependence and concentration of hydrogen peroxide as a function of the absorbed dose was studied. It found that during the radiolysis of transformer oil containing PCB in the presence of dissolved oxygen, radiation-initiated oxidation of the oil takes place (formation of H 2O2 and CO2, a decrease in the pH-value).
KEYWORDS: Sovtol-10, PCB, transformer oil, dose rate, radiation-chemical yield, radiation stability, IRspectra. ----------------------------------------------------------------------------------------------------------------------------- ---------Date of Submission: Date, 10 August 2018 Date of Accepted: 04August 2018 ----------------------------------------------------------------------------------------------------------------------------- ----------
I.
INTRODUCTION:
PCBs are the one of persistent chemicals, included to Stockholm Convention (SC) on POPs, although the industry production of PCBs are prohibit since of 90s of the last century, the “cross” pollution of transformers oils, widely used in energy sector is continues up to date. The are 2 approach to the PCBs containing transformer oils disposal and cleaning of oils, based on SC requirements: the oil containing more than 50 ppm of PCB have to the phase out from exploitation then utilization by various technologies [1-4]. The oils containing less than 50 ppm of PCBs may be returned to exploitation after treatment and decreasing of PCBs content ~ 2 ppm – the standard, accepted in the many countries. In this point the investigation of possibility of radiation-chemical treatment cleaning of PCBs containing oils is important. This study is devoted to establishment of kinetic regularities of oil parameters as pH, indicator, formation of CO2, H2O2, hydrocarbon gases and IR spectra at different adsorbed doses.
II.
EXPERIMENTAL
Used transformer oil T-1500, production of a refinery plant named after G. Aliyev in Azerbaijan. PCB has 209 isomers, but "Sovtol-10" contains basically ~50-60 isomers of three, tetra-pentachlorobiphenyls and 10 wt. % trichlorobenzene. The oil samples were irradiated by γ- rays from isotope Co60 at static conditions and in glass ampoules with volume 15 ml in the presence of adsorbed oxygen. The dose rate was determined by the method of ferrosulfate dosimetry and was 0,21 Gy/s. pH - measurements were provided by Instruction Manual of Basic pHS-25 pH- meter. Analysis of gases products was provided by gas chromatography Agilent Technology-7890 A with detectors: FID-hydrocarbons, TCD-carbon oxides (CO, CO2). H2O2 analysis was carried out by a permanganatometric method. IR- spectra were registered on Fure- Spectrometer Varion-640 in the range 4000400 cm-1. The spectra of the samples irradiated at different doses are treated under the same conditions in the form of thin films between two plates of KRS-5; the relative intensities (Jmax|J0) of the absorption bands are calculated and their dose dependences are obtained, where J0 and J are the intensities of absorption bands of unirradiated and γ irradiated samples, respectively.
III.
RESULTS
Two series of experiments were carried out, in which concentration dependence of CO2, H2O2 and pH value in the used transformer oil, without PCB as a function of the absorbed dose (series 1), and the dose dependence of above parameters during radiolysis of used transformer oil, containing 5-40 ppm PCB (series 2) was studied. According to [5], the oxygen content in air dissolved in transformer oil is 30.2%. In the experiments of the series 1, it was found that the pH of the used oil decreases with increasing dose, which is due to the formation of acids
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Radiolysis of Transformer Oil in The Presence‌ during irradiation. Used oil also contains products of an acidic nature, but their formation significantly increases with increasing irradiation dose. The formation of hydrogen peroxide, depending on the dose, which has a maximum at ~ 27 kGy is observed. With a further dose increase, the concentration of H 2O2 decreases, which indicates the course of secondary reactions with its participation. The maximum of CO2 concentration at 27.4 kGy is observed in the kinetic curve, and the radiation-chemical yield is 0,18 molec /100 eV. Figure 1 shows the dependence of acidity on the absorbed dose in the range up to 70 kGy for radiolysis of used transformer oil.
6
pH
5 4 3 2 1
D, kGy
0 0
50
100
150
As can be seen from the figure, the pH value decreases with increasing absorbed dose, and by relatively
Fig. 1. Dependence of the acidity in transformer oil as of the absorbed dose at different initial PCB concentrations in the range of 5-40 ppm
- 5 ppm,
- 15 ppm,
- 40 ppm
high concentration of PCB, this decrease becomes distinctly: at a PCB concentration of 5 ppm, the pH decreases from 5.5 to 2.1 (62%), at PCB 40 ppm from 5.0 to 1.6 (68%). Figure 2 shows concentration dependence of CO2 from the absorbed dose at different initial concentrations of PCB in transformer oil.
14 2ďƒ—1017molek/q NCO 12 10 8 6 4 2 D, kQr
0 0
20
40
60
80
100
120
140
Fig. 2. Concentration dependence of CO2 as a function of the absorbed dose at different initial concentration of PCB in transformer oil. - 5 ppm,
- 15 ppm,
- 40 ppm
Figure 3 shows concentration dependence of H2O2 as a function of the absorbed dose at different initial concentrations of PCB in transformer oil.
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Radiolysis of Transformer Oil in The Presence…
N(H2O2)10-5, q/ml
12
8 D, kQr 4 It can be seen that the concentration of CO2 and H2O2 increases and reaches a steady-state
- 5 ppm,
- 15 ppm,
- 40 ppm
0 0
50
100
150
concentration with dose increasing. The steady-state concentration is achieved at a dose range 4.1-10
Fig. 3. Concentration dependence of H2O2 as a function of the absorbed dose at different initial concentrations of PCB in transformer oil. kGy. Further growth of the absorbed dose leads to a decrease of the concentration of both products. From the initial parts of the kinetic curves, the radiation-chemical yields of formation of CO2 and H2O2 are determined, which are given in Table 1. Table 1. Radiation-chemical yields of H2O2, CO2 and pH values at different initial concentrations of PCB in transformer oil. СPCB, ppm 0 5 15 40
G, molec/100eV H2O2
CO2
3,6 3,9 4,7 5,9
0,18 1,1 1,9 2,3
As can be seen from the table, the radiation-chemical yield of CO2 and H2O2 increases with increasing of PCB concentration. The related wiht oxidation process and the formation of acid products during the radiolysis of transformer oil in the presence of PCB. Along with oxidation processes, the molecules of transformer oil components undergo decomposition under the action of ionizing radiation, which leads to the formation of gaseous products - hydrogen and hydrocarbons. Hydrogen and hydrocarbon products as H2, CH4, C2H4, C2H6 have been identified. Table 2. Radiation-chemical yields of gaseous products at different initial concentrations of PCB in transformer oil. G, molec/100eV СPCB, ppm H2 CH4 C2H4 C2H6 0 0,375 0,65 *10-3 0,3*10-3 0,13*10-3 5 0,24 0,47*10-3 0,29*10-3 0,19*10-3 -3 -3 15 0,35 0,44*10 0,15*10 0,11*10-3 40 0,41 0,51*10-3 0,20*10-3 0,12*10-3 As can it be seen from the table molecular hydrogen is formed with the higher radiation-chemical yield, which slightly increases with the growth of PCB concentration in transformer oil. The radiation-chemical yield of the
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Radiolysis of Transformer Oil in The Presence‌ remaining identified gaseous products is less than 10-4 molec / 100 eV, although the tendency of growth of the radiation-chemical yield with increasing PCB concentration in oil also occurs for these products. Radiolytic decomposition of polychlorobiphenyl in transformer oil mainly occurs in reactions with solvated electrons due to high electron affinity of the molecules of PCB, which is typically for chlorogenic compounds. [7] Below given the rate constants of solvated electrons with molecules of chlorine-containing aromatic compounds and oxygen. Table 3. The rate constants of the esolv. with molecules of chlorogenic compounds. [1], [4], [6], [7]. Rate constants, M-1 s-1 109-1010 3,8·109 3·109 7·109 2·1010
Chlororganic compounds and oxygen Chlorbiphenils (КХ 300, КХ 400) Dichlorobiphenyl Tetrachlorobiphenyl Decahlorobiphenyl O2
At a concentration of PCB in oil equal to 40 ppm, the ratio of the rates of the electron capture by the molecules of PCB and oxygen under the experimental conditions is: đ?œ”1 đ?‘˜1 [đ?‘ƒđ??śđ??ľ] 1 ∙ 109 ∙ 2,2 ∙ 10−4 = = ~3 ∙ 10−2 đ?œ”2 đ?‘˜2 [đ?‘‚2 ] 2 ∙ 1010 ∙ 2,97 ∙ 10−4 Calculation shows that electrons are mainly captured by oxygen and the expected yield of the PCB molecules decomposition is approximately 10-2 of the radiation-chemical yield of the esolv, that was observed. Chemical changes at PCB radiolysis is shown also by the IR- spectroscopy. In fig. 4. the IR-spectra of irradiated PCB samples at various adsorbed doses in the range to 136,8 kGy were presented. 1.3 1.2
1.3
(2)
(2)
1.2
1.1
1.1 3853.462 0.055
1.0
1.0
0.9
0.9
0.8
0.8
3853.462 0.055
1453.140 9.778
Absorbance
Absorbance
3053.019 128.321
0.7 0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
3800
2.2
(2)
3600
3966.039 6.871
2.0
1244.694 0.784
(2)
1.6
1.6
1.4
1.4
1.2
3800 3200
3600 3000
3400 2800
3200 2600
3000 2400
2800 2200 Wavenumber
1.0
0.8
0.8
0.6
0.6
2600 2000
2400 1800
2200 1600 Wavenumber
1244.694 0.784 1137.297 2.025 2000 1400
1800 1200
1600 1000
634.493 0.988
1137.297 2.025
1400 800
1200 600
1000
800
3143.899 41.195
3143.899 41.195 2923.182 6.540
2923.182 6.540
2956.370 -1.149
2956.370 -1.149
2853.694 -39.656
2853.694 -39.656
2068.263 -0.001
2068.263 -0.001 1462.203 7.399
(2)
1462.203 7.399
1376.415 2.563
1376.415 2.563
774.301 1.280
0.4
600
3966.039 6.871
1.2
1.0
884.839 3.122
634.493 0.988
2.2
1.8
(1)
3593.480 1.975
884.839 3.122
3400
1.8
1095.467 3.010 1095.467 3.010 1382.895 1.058 1382.895 1.058 1031.675 2.678 1031.675 2.678 1176.451 1.009 1176.451 1.009 814.539 4.416 814.539 4.416 1555.647 2.020
1555.647 2.020
2.0
Absorbance
Absorbance
3593.480 1.975 0.7
1453.140 9.778
3053.019 128.321
774.301 1.280
0.4 3800
3600
3400
3800 3200
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Radiolysis of Transformer Oil in The Presence‌ 1.2
3979.802 6.224
(8)
3979.802 6.224
1.2
(8) 2950.585 -0.853
1.0
1.0 3141.227 2.894
0.8
2921.099 6.079
3141.227 2.894 2852.317 4.488
2852.317 4.488
0.8 Absorbance
Absorbance
2950.585 -0.853 2921.099 6.079
0.6
0.4
2375.126 0.909
2375.126 0.909
0.6
1461.923 10.352
2146.420 27.741
1461.923 10.352
2146.420 27.741 1376.415 3.200
(3)
1376.415 3.200
0.4 971.361 0.645
0.2
0.2
0.0
0.0
3800
3400
1.8
(9)
1.6
1.6
1.4
1.4
1.2
1.2
3200 3800
3000 3600
2800 3400
2600 3200
2400 3000
0.8 0.6
2000 2600
1800 2400
1600 1400 2200 2000 Wavenumber
2160.359 23.343
0.2
600 1200
400 1000
0.0
0.0 -0.2
3800
3600
1.0
971.565 0.910
3800 3200
3600 3000
3400 2800
3200 2600
3000 2400
3215.735 136.430
2200 2000 1600 1400 Wavenumber
1800 1200
1600 1000
1400 800
1200 600
1000 400
800
600
400
3215.735 136.430
0.8
0.7
0.7
0.6
0.6
2952.826 1.879
0.5
0.5
2853.886 4.175
0.4 0.3
2923.056 4.706
2923.056 4.706 2376.778 4.242 2952.826 1.879
2376.778 4.242
2853.886 2159.507 4.175 38.443
2159.507 1455.959 38.443 4.835
0.4
1455.959 4.835
1375.873 1.498
0.2
0.1
0.1
0.0
0.0
-0.1
-0.1
1375.873 1.498 971.237 1.044
0.3
0.2
-0.2
(5)
971.237 1.044
-0.2
3800
3600
3400
3800 3200
3600 3000
3400 2800
3200 2600
3000 2400
2923.356 7.201
(12)
2800 2200 2600 2000 Wavenumber
2400 1800
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2000 1400
1800 1200
1600 1000
1400 800
1200 600
1000
800
600
2923.356 7.201
(12)
0.9 3215.093 128.432
0.8
0.8
0.7
0.7
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0.6
0.5
0.5
Absorbance
Absorbance
2400 1800
(10)
0.9
0.8
0.9
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1.0
(10)
Absorbance
Absorbance
0.9
400
1376.051 3.492
1376.051 3.492
3400
600
(4)
1457.309 12.053
1457.309 12.053 2160.359 23.343
971.565 0.910
-0.2
800
2853.136 6.272
0.6 0.4
800 1400
3204.357 89.208
0.8
0.2
1000 1600
2951.924 3.222
2951.924 3.222
1.0 3204.357 89.208
0.4
1200 1800
2921.010 15.882
2921.010 15.882
(9)
2200 2800 Wavenumber
2853.136 6.272
1.0
Absorbance
Absorbance
1.8
3600
971.361 0.645
0.4 0.3
2949.871 2.324
2853.129 5.233
2853.129 5.233 1458.071 11.750 2363.072 0.275
2363.072 0.275 2200.737 0.619 2164.909 4.987
1458.071 11.750
2200.737 0.619 1376.033 3.598 2164.909 4.987
1376.033 3.598
0.4
(6)
0.3
0.2
0.2
0.1
0.1
0.0
0.0
-0.1
-0.1
-0.2
3215.093 128.432 2949.871 2.324
-0.2 3800
3600
3400
3200 3800
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Radiolysis of Transformer Oil in The Presence… 1.0 0.9 0.8
1.0 2949.832 1.595 (13) 3234.891 0.9 7.130
(13) 3256.614 3.346
0.8
0.7
0.7
0.6
0.6
0.5
0.5
2922.930 5.6361.595 2949.832 3234.891 7.130
2922.930 5.636
2852.593 4.326
2852.593 4.326
3256.614 3.346
Absorbance
Absorbance
1461.573 11.892
0.4 0.3
1376.331 3.817
2220.373 13.746
(7)
0.3 0.2
0.1
0.1
0.0
0.0
-0.1
-0.1
-0.2
-0.2
3600
2220.373 13.746
0.4
0.2
3800
1461.573 11.892
1376.331 3.817
3400
3200 3800
3000 3600
2800 3400
2600 3200
2400 3000
2200 2800 Wavenumber
2000 2600
1800 2400
1600 2200 Wavenumber
1400 2000
1200 1800
1000 1600
1400 800
1200 600
1000 400
800
600
Fig. 4. IR-spectra of oil samples at various adsorbed doses (1- Sovtol; 2-transformer oil; 3oil+15ppm PCBs; 4- D=4.1; 5- D=27.4; 6- D=68.4; 7- D=136.8 kGy, 15 ppm PCBs in oil) The following bonds were identified in the IR- spectra =C-H (λ ~3030 cm-1) –C=C- (1600-1500 cm-1), =C-H (860690 cm-1), =C-Cl (900-500 cm-1) [8]. The intensity of bonds of –C=C is decreasing by the dose raising. The reallocation of bonds in the range at ~1000-1800 cm-1 was observed. The same takes places in the range 500-900 cm-1, related to –C-Cl.
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Getoff N., Solar S. (1988) Radiat. Phys. Chem. 31: 121-130. Chaychian M., Silverman J., Al-Sheikly M. (1999) Environmental Scientific Technologies. 33: 2461-2464. Huang S. K., Hsieh L.L., Chen C.C., Lee P.H, Hsieh B.T. (2009) Applied Radiation and Isotopes 67:4931498. Trifan A., Calinescu I., Martin D. (2009) Rev. Chim. 60:1053-1055. Solubility of gases in transformer oil. leg.co.ua/transformatori Heoriya/rastvorimost qazov-vtransformatornom-masle.html Sawai T., Shimokawa T., Shinozaki Y. (1974) Bulletin of Chemical Society of Japan. 47: 1889-1893 Chaychian M., Johnes C., Poster D., Silvermann J., Neta P., Huie R., Al-Sheikhly M. (2002) Radiation Physics and Chemistry, 65: 473-478 Tarasevich B.N. (2012) IR- spectra of main organic compounds, Moscow.
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