ESR dosimetry and radical kinetics of gamma-irradiated propyl gallate

Bal, Mariusz; Tuner, Hasan

doi:10.1016/j.molstruc.2014.04.083

Cited by 11 publications

(6 citation statements)

References 32 publications

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“…The EPR signals were located in experiments by their g value defined by where h is the Planck’s constant, ν the resonance frequency, β the Bohr magneton, and H the magnetic field at which resonance occurs . The free radical concentration of thermal bitumen served as a quantified reference to the standard curve of 1,1-diphenyl-2-picrylhydrazyl (DPPH; g = 2.0036). , For each test, 0.05 g of the sample was diluted 40 times with methylbenzene, and this step was repeated three times to ensure repeatability.…”

Section: Methodsmentioning

confidence: 99%

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Jian

et al. 2017

Energy Fuels

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The effects of pyrolysis temperature on the structure of thermal bitumen as the pyrolysis intermediate of Longkou oil shale are investigated through electron paramagnetic resonance spectroscopy, Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gas chromatography–mass spectrometry (GC-MS), and X-ray photoelectron spectroscopy (XPS). Results indicate that the free radical concentration of thermal bitumen increases at a maximum temperature of 410 °C and then decreases between 410 and 450 °C. Moreover, the g factors of thermal bitumen are slightly higher than 2 and decrease with increasing temperature because of the aromatization of saturates and decarboxylation. FTIR analysis indicates that decarboxylation is completed before the temperature reaches 370 °C. NMR analysis shows that aliphatic and aromatic compounds comprise more than 80% and 15–16% thermal bitumen, respectively. During pyrolysis, the fraction of aliphatic compounds, branched alkane, and the average methylene chain length decrease because of secondary cracking, and the C–C bond at the branch chain is easily cracked into gas and light oil.

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Section: Methodsmentioning

confidence: 99%

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Jian

et al. 2017

Energy Fuels

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“…EPR measurements were performed using a Bruker A200 spectrometer with 100 kHz field modulation. The free radical concentration ( N g ) of thermal bitumen was quantified with reference to the standard curve of 1,1-diphenyl-2-picryhylhydrazyl (DPPH, g = 2.0036). , To maintain N g of the samples within the range of measurement, thermal bitumen and semi-coke were diluted 20- and 40-fold with methylbenzene and CaCO 3 , respectively.…”

Section: Experimental Sectionmentioning

confidence: 99%

Characteristics of Estonian Oil Shale Kerogen and Its Pyrolysates with Thermal Bitumen as a Pyrolytic Intermediate

Jian

et al. 2017

Energy Fuels

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Preparation and collection of thermal bitumen, a pyrolytic intermediate, are key factors in elucidating the mechanism of oil shale pyrolysis. Electron paramagnetic resonance (EPR), gas chromatography, Fourier transform infrared spectrophotometry, nuclear magnetic resonance (NMR) spectrometry, distortionless enhancement by polarization transfer (DEPT), and X-ray photoelectron spectroscopy were employed to investigate the thermochemical transformation in oil shale pyrolysis. Results showed that thermal bitumen was continuously generated and decomposed during the pyrolysis process. The maximum yield of thermal bitumen at 380 °C was 11.17%. EPR analysis showed that the g factor of kerogen and the pyrolysates was slightly higher than 2 and increased as pyrolysis progressed because of the aromatization of saturates and decarboxylation. CO2 and CO were mainly generated at temperatures lower than 340 °C, and less was obtained in the subsequent pyrolysis process. In contrast, C2–C5 organic gases were mainly generated at temperatures higher than 340 °C. NMR and DEPT analyses indicated that kerogen, thermal bitumen, and shale oil were mainly composed of aliphatic structures. During the pyrolysis process, aliphatic structures were constantly transformed into aromatic compounds, which were easily retained in shale oil and semi-coke. Pyrrolic, pyridinic, and quaternary compounds constituted 80% of the nitrogen compounds in kerogen and the pyrolysates. The sulfoxide content of thermal bitumen and semi-coke was considerably higher than that of kerogen, indicating that sulfoxide compounds present better thermostability during the pyrolysis process.

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“…Nowadays, electron paramagnetic resonance (EPR) dosimetry is widely employed for radiation measurements with several compounds such as ammonium tartrate [1][2][3][4][5], lithium formate [6], dithionates, [7], phenolic compounds [8][9][10][11][12] and sugar [13,14] and others [15][16][17][18][19]. However, crystalline L-α-alanine is the most adopted material and is formally accepted as a secondary standard for high-dose measurements (kGy) and transfer dosimetry [20][21][22][23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Alanine films for EPR dosimetry of low-energy (1–30 keV) X-ray photons

D'Oca

Marrale

Abbene

et al. 2019

Nuclear Instruments and Methods in Physics Research Section B:

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L-α-alanine has aroused considerable interest for use in radiation EPR dosimetry and has been formally accepted as a secondary standard for high-dose (kGy) and transfer dosimetry of high-energy photons and electrons. In this work, we extended the investigation of the energy response of alanine EPR films in the low energy range for X-photons (1-30 keV). Electron Paramagnetic Spin Resonance (EPR) measurements were performed on Kodak BioMax alanine films exposed to low-energy X-rays from a Cu-, Wand Mo-targets tube operating at voltages up to 30 kV. Films were chosen because of the low penetration of the soft X-rays used. The response of alanine to low-energy X-rays was characterized experimentally and the relative response (with respect to high energy photons) was found to be between 0.8 and 0.9 for Cu-and Wtube X-rays, and 1.0 for Mo-tube X-rays. The attenuation profiles were investigated and it was found that 1 mm of film material reduces the intensity of the X-ray-beam by about 70%, 50% and 40% for Cu-, Wand Mo-tube X-rays, respectively. Monte Carlo simulations were performed to model the energy release as well as the depth dose profiles for the various radiation beams used. These data are considered relevant

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ESR dosimetry and radical kinetics of gamma-irradiated propyl gallate

Cited by 11 publications

References 32 publications

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Characteristics of Estonian Oil Shale Kerogen and Its Pyrolysates with Thermal Bitumen as a Pyrolytic Intermediate

Alanine films for EPR dosimetry of low-energy (1–30 keV) X-ray photons

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ESR dosimetry and radical kinetics of gamma-irradiated propyl gallate

Cited by 11 publications

References 32 publications

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Characteristics of Thermal Bitumen Structure as the Pyrolysis Intermediate of Longkou Oil Shale

Characteristics of Estonian Oil Shale Kerogen and Its Pyrolysates with Thermal Bitumen as a Pyrolytic Intermediate

Alanine films for EPR dosimetry of low-energy (1–30 keV) X-ray photons

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Alanine films for EPR dosimetry of low-energy (1–30 keV) X-ray photons