Isoconversional kinetic modeling and in-situ synchrotron powder diffraction analysis for dehydroxylation of antigorite

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dc.contributor.authorZahid, Sen_AU
dc.contributor.authorOskierski, HCen_AU
dc.contributor.authorSenanayake, Gen_AU
dc.contributor.authorAltarawneh, Men_AU
dc.contributor.authorXia, Fen_AU
dc.contributor.authorBrand, HEAen_AU
dc.contributor.authorOluwoye, Ien_AU
dc.contributor.authorDlugogorski, BZen_AU
dc.date.accessioned2021-12-03T04:41:44Zen_AU
dc.date.available2021-12-03T04:41:44Zen_AU
dc.date.issued2018-03-14en_AU
dc.date.statistics2021-11-05en_AU
dc.description.abstractMineral carbonation offers permanent and safe disposal of anthropogenic CO2. Well distributed and abundant resources of serpentine minerals and natural weathering of these mineral to stable and environmentally benign carbonates 1, 2 favour the exploitation of these minerals as the most suitable raw material for mineral carbonation. However, slow dissolution kinetics are impeding the large scale implementation of mineral carbonation 3. Heat treatment of serpentine minerals results in enhanced reactivity for subsequent carbonation processes at the expense of an additional energy penalty4. Heat treatment of these minerals results in the removal of structurally bound hydroxyl groups which leads to partial amorphisation of the structure and enhanced reactivity 5. Therefore, understanding the role of the mineralogical changes during dehydroxylation and determination of activation energy (Ea) is crucial for providing an energy efficient solution for commercialisation of mineral carbonation. In-situ synchrotron powder X-ray diffraction (S-PXRD) at the Australian Synchrotron was employed for detailed observation of mineralogical changes and estimation of kinetic parameters during the heat treatment from room temperature to 1000 oC under constant N2 flow. The synchrotron beamline offers high signal to noise ratio necessary for an accurate identification of minor phases and onset temperature for phase transitions. Moreover, the fast data acquisition of S-PXRD enables acquisition of data with temporal resolution, which is crucial for accurate estimation of kinetic parameters. During dehydroxylation via heat treatment, antigorite remained stable up to 520 oC. Above 520 oC, antigorite started to decompose and forsterite formation occurred at around 700 oC. Enstatite formation was observed only after the complete dissociation of antigorite. We performed prograde heating experiments at 2, 4, 6 and 8 oC/min under constant N2 flow for the estimation of Ea via isoconversional kinetic modelling. The change in activation energy with reaction progress showed the multistep nature of dehydroxylation of antigorite. The variation of Ea can be divided into three stages a) nearly constant Ea of 130 kJ/mol (α ≤ 0.25) b) increase in Ea from 130-209 kJ/mol (0.25≤ α ≥0.4) which remained constant at around 204 kJ/mol till α = 0.8. Finally, the reaction ended with an increase in Ea from 204 kJ/mol to 236 kJ/mol. In this study we exploit the potential of in-situ SXRD for determination of isoconversional kinetic parameters in comparison to conventional kinetic analysis based on TGA-DSC methods. While S-XRD based kinetic analysis appears to be sensitive to phase quantification parameters (e.g. peak integration vs. full pattern fitting) it provides valuable structural information that is not available in conventional kinetic methods. S-XRD based kinetic analysis further has the ability to resolve the formation of individual mineral phases, including reaction intermediates (talc-like phases) and products (olivine and enstatite). Consequently, this study will further advance the development of cost and energy-efficient dehydroxylation of serpentine minerals for large scale storage of CO2 by mineral carbonation. © 2018 American Institute of Chemical Engineersen_AU
dc.identifier.citationZahid, S., Oskierski, H. C., Senanayake, G., Altarawneh, M., Xia, F., Brand, H. E. A., Oluwoye, I. & Dlugogorski, B. Z. (2018). Isoconversional kinetic modeling and in-situ synchrotron powder diffraction analysis for dehydroxylation of antigorite. Paper presented at the 6th International Conference on Accelerated Carbonation for Environmental and Material Engineering (ACEME 2018), Newcastle, NSW, Australia, March 11-14, 2018, (pp. 378-389). Retrieved from:https://www.aiche.org/cei/conferences/international-conference-on-accelerated-carbonation-environmental-and-material-engineering-aceme/2018/proceeding/paper/isoconversional-kinetic-modelling-and-situ-synchrotron-powder-x-ray-diffraction-analysisen_AU
dc.identifier.conferenceenddate14 March 2014en_AU
dc.identifier.conferencename6th International Conference on Accelerated Carbonation for Environmental and Material Engineering (ACEME 2018)en_AU
dc.identifier.conferenceplaceNewcastle, Australiaen_AU
dc.identifier.conferencestartdate11 March 2018en_AU
dc.identifier.isbn978-1-5108-7281-3en_AU
dc.identifier.pagination378-389en_AU
dc.identifier.urihttps://www.aiche.org/cei/conferences/international-conference-on-accelerated-carbonation-environmental-and-material-engineering-aceme/2018/proceeding/paper/isoconversional-kinetic-modelling-and-situ-synchrotron-powder-x-ray-diffraction-analysisen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12334en_AU
dc.language.isoenen_AU
dc.publisherAmerican Institute of Chemical Engineers (AIChE)en_AU
dc.subjectSilicate mineralsen_AU
dc.subjectSerpentineen_AU
dc.subjectHeat treatmentsen_AU
dc.subjectKineticsen_AU
dc.subjectX-ray diffractionen_AU
dc.subjectSynchrotronsen_AU
dc.subjectSynchrotron radiationen_AU
dc.titleIsoconversional kinetic modeling and in-situ synchrotron powder diffraction analysis for dehydroxylation of antigoriteen_AU
dc.typeConference Paperen_AU
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