Dehydration of rhyolite: activation energy, water speciation and morphological investigation
Само за регистроване кориснике
2020
Аутори
Angelopoulos, Panagiotis M.Manić, Nebojša G.
Tsakiridis, Petros
Taxiarchou, Maria
Janković, Bojan Ž.
Чланак у часопису (Објављена верзија)
,
© 2020, Akadémiai Kiadó, Budapest, Hungary
Метаподаци
Приказ свих података о документуАпстракт
Rhyolite is an extrusive, igneous rock of aluminosilicate composition that upon rapid cooling forms obsidian. Obsidian is amorphous and contains limited water portions (< 2 mass%); however, secondary hydration turns it either to perlite (H2O ≈ 2–5 mass%) or pitchstone (> 5 mass%). In the current study, kinetics of hydrous rhyolite dehydration were investigated by thermogravimetry up to 1000 °C, at heating rates of 2.5, 5, 10 and 20 °C min−1 and under inert atmosphere. The mass loss is approx. 7.6 mass%, occurs along wide temperature range (100–800 °C) and is solely attributed to the release of molecular water ((H2O)m) and hydroxyl groups (OH). Rhyolite dehydration was considered as a solid-state reaction, and the apparent activation energy (Ea) of dehydration was calculated throughout the whole conversion range (a) by applying the isoconversional Friedman and advanced Vyazovkin methods. Both methods revealed inverse sigmoid trend in Ea values versus conversion degree, possessing almost... stable value of 61 ± 5 kJ mol−1 for Friedman method and 59.44 kJ mol−1 for Vyazovkin method on conversion range between 0.25 and 0.75, and sharp increase at higher conversion degree. The intensive change in Ea during dehydration progression is attributed to the change in releasing species (from (H2O)m to OH). Raman and FT-IR spectroscopy analyses of raw and partially dehydrated samples at different stages revealed that up to 300 °C mainly (H2O)m is diffused out of the material causing sample enrichment in OH groups. OH release, which occurs at relatively higher temperature, is accompanied by increase in apparent Ea value of dehydration. Concerning microstructure of raw rhyolite, it exhibits a network of micro-fractures which serve as water release routes. Upon heating, more and wider fractures are created. At 600 °C, fractures merging occurs creating voids, which constitute forerunners of the expansion phenomenon. Further temperature increase causes material softening allowing local plastic deformation, which under the high pressure that is exerted by the releasing water species incites the formation of large cavities and fractures, initiating expansion.
Кључне речи:
Hydrous rhyolite / Isoconversional methods / Expanded perlite / Volcanic glass dehydration / Dehydroxylation / Activation energyИзвор:
Journal of Thermal Analysis and Calorimetry, 2020, 142, 1, 395-407
DOI: 10.1007/s10973-020-10105-2
ISSN: 1388-6150
WoS: 000556688000003
Scopus: 2-s2.0-85089090806
Институција/група
VinčaTY - JOUR AU - Angelopoulos, Panagiotis M. AU - Manić, Nebojša G. AU - Tsakiridis, Petros AU - Taxiarchou, Maria AU - Janković, Bojan Ž. PY - 2020 UR - https://vinar.vin.bg.ac.rs/handle/123456789/9115 AB - Rhyolite is an extrusive, igneous rock of aluminosilicate composition that upon rapid cooling forms obsidian. Obsidian is amorphous and contains limited water portions (< 2 mass%); however, secondary hydration turns it either to perlite (H2O ≈ 2–5 mass%) or pitchstone (> 5 mass%). In the current study, kinetics of hydrous rhyolite dehydration were investigated by thermogravimetry up to 1000 °C, at heating rates of 2.5, 5, 10 and 20 °C min−1 and under inert atmosphere. The mass loss is approx. 7.6 mass%, occurs along wide temperature range (100–800 °C) and is solely attributed to the release of molecular water ((H2O)m) and hydroxyl groups (OH). Rhyolite dehydration was considered as a solid-state reaction, and the apparent activation energy (Ea) of dehydration was calculated throughout the whole conversion range (a) by applying the isoconversional Friedman and advanced Vyazovkin methods. Both methods revealed inverse sigmoid trend in Ea values versus conversion degree, possessing almost stable value of 61 ± 5 kJ mol−1 for Friedman method and 59.44 kJ mol−1 for Vyazovkin method on conversion range between 0.25 and 0.75, and sharp increase at higher conversion degree. The intensive change in Ea during dehydration progression is attributed to the change in releasing species (from (H2O)m to OH). Raman and FT-IR spectroscopy analyses of raw and partially dehydrated samples at different stages revealed that up to 300 °C mainly (H2O)m is diffused out of the material causing sample enrichment in OH groups. OH release, which occurs at relatively higher temperature, is accompanied by increase in apparent Ea value of dehydration. Concerning microstructure of raw rhyolite, it exhibits a network of micro-fractures which serve as water release routes. Upon heating, more and wider fractures are created. At 600 °C, fractures merging occurs creating voids, which constitute forerunners of the expansion phenomenon. Further temperature increase causes material softening allowing local plastic deformation, which under the high pressure that is exerted by the releasing water species incites the formation of large cavities and fractures, initiating expansion. T2 - Journal of Thermal Analysis and Calorimetry T1 - Dehydration of rhyolite: activation energy, water speciation and morphological investigation VL - 142 IS - 1 SP - 395 EP - 407 DO - 10.1007/s10973-020-10105-2 ER -
@article{ author = "Angelopoulos, Panagiotis M. and Manić, Nebojša G. and Tsakiridis, Petros and Taxiarchou, Maria and Janković, Bojan Ž.", year = "2020", abstract = "Rhyolite is an extrusive, igneous rock of aluminosilicate composition that upon rapid cooling forms obsidian. Obsidian is amorphous and contains limited water portions (< 2 mass%); however, secondary hydration turns it either to perlite (H2O ≈ 2–5 mass%) or pitchstone (> 5 mass%). In the current study, kinetics of hydrous rhyolite dehydration were investigated by thermogravimetry up to 1000 °C, at heating rates of 2.5, 5, 10 and 20 °C min−1 and under inert atmosphere. The mass loss is approx. 7.6 mass%, occurs along wide temperature range (100–800 °C) and is solely attributed to the release of molecular water ((H2O)m) and hydroxyl groups (OH). Rhyolite dehydration was considered as a solid-state reaction, and the apparent activation energy (Ea) of dehydration was calculated throughout the whole conversion range (a) by applying the isoconversional Friedman and advanced Vyazovkin methods. Both methods revealed inverse sigmoid trend in Ea values versus conversion degree, possessing almost stable value of 61 ± 5 kJ mol−1 for Friedman method and 59.44 kJ mol−1 for Vyazovkin method on conversion range between 0.25 and 0.75, and sharp increase at higher conversion degree. The intensive change in Ea during dehydration progression is attributed to the change in releasing species (from (H2O)m to OH). Raman and FT-IR spectroscopy analyses of raw and partially dehydrated samples at different stages revealed that up to 300 °C mainly (H2O)m is diffused out of the material causing sample enrichment in OH groups. OH release, which occurs at relatively higher temperature, is accompanied by increase in apparent Ea value of dehydration. Concerning microstructure of raw rhyolite, it exhibits a network of micro-fractures which serve as water release routes. Upon heating, more and wider fractures are created. At 600 °C, fractures merging occurs creating voids, which constitute forerunners of the expansion phenomenon. Further temperature increase causes material softening allowing local plastic deformation, which under the high pressure that is exerted by the releasing water species incites the formation of large cavities and fractures, initiating expansion.", journal = "Journal of Thermal Analysis and Calorimetry", title = "Dehydration of rhyolite: activation energy, water speciation and morphological investigation", volume = "142", number = "1", pages = "395-407", doi = "10.1007/s10973-020-10105-2" }
Angelopoulos, P. M., Manić, N. G., Tsakiridis, P., Taxiarchou, M.,& Janković, B. Ž.. (2020). Dehydration of rhyolite: activation energy, water speciation and morphological investigation. in Journal of Thermal Analysis and Calorimetry, 142(1), 395-407. https://doi.org/10.1007/s10973-020-10105-2
Angelopoulos PM, Manić NG, Tsakiridis P, Taxiarchou M, Janković BŽ. Dehydration of rhyolite: activation energy, water speciation and morphological investigation. in Journal of Thermal Analysis and Calorimetry. 2020;142(1):395-407. doi:10.1007/s10973-020-10105-2 .
Angelopoulos, Panagiotis M., Manić, Nebojša G., Tsakiridis, Petros, Taxiarchou, Maria, Janković, Bojan Ž., "Dehydration of rhyolite: activation energy, water speciation and morphological investigation" in Journal of Thermal Analysis and Calorimetry, 142, no. 1 (2020):395-407, https://doi.org/10.1007/s10973-020-10105-2 . .