{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["15(39)"],"submitter":["Fotsop CG"],"pubmed_abstract":["This work elucidates the thermo-kinetics of the thermal conversion of cameroonian kaolin to metakaolin as the main product. The thermokinetical parameters (activation energy <i>E</i> <sub>a</sub> and pre-exponential factor <i>A</i>) for the kaolin conversion were calculated using model-free methods, <i>i.e.</i> the Kissinger-Akahira-Sunrose (KAS) and the Flynn-Wall-Ozawa (FWO) method, and differential methods (Kissinger and Ozawa) additionally including iterative procedures for KAS and FWO methods (KAS-Ir; FWO-Ir). The cameroonian kaolin was heat-treated using three different heating rates, <i>i.e.</i> 5, 20 and 40 K min<sup>-1</sup>, leading to metakaolin samples named MK-(5), MK-(20) and MK-(40). The TGA analysis showed a total mass loss of ∼12.5% in two steps related to the dehydration (step 1) and dehydroxylation (step 2). The <i>E</i> <sub>a</sub> of the two steps were most accurately determined using the iterative procedures KAS-Ir and FWO-Ir. The average <i>E</i> <sub>a</sub> values were 88.44/88.58 kJ mol<sup>-1</sup> for step 1 and 261.85/261.91 kJ mol<sup>-1</sup> for step 2, for the KAS-Ir and FWO-Ir models, respectively. The most probable mechanism function was determined by the multiple heating rate method (MHR) and the Coats-Redfern method. The kinetic analyses showed that the dehydroxylation of kaolin is controlled by a random nucleation and subsequent growth mechanism (G<sub>4</sub>) and a second order chemical reaction (F<sub>2</sub>). Thermodynamic parameters, namely the entropy Δ<i>S</i> <sup>≠</sup>, the enthalpy Δ<i>H</i> <sup>≠</sup> and Gibbs free energy Δ<i>G</i> <sup>≠</sup>, were evaluated. The average values of Δ<i>S</i> <sup>≠</sup>, Δ<i>H</i> <sup>≠</sup> and Δ<i>G</i> <sup>≠</sup> using both the KAS-Ir and FWO-Ir models exhibited less than 5% deviation. The obtained metakaolin samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FT-IR)."],"journal":["RSC advances"],"pagination":["32172-32187"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC12415547"],"repository":["biostudies-literature"],"pubmed_title":["Elucidation of the thermo-kinetics of the thermal decomposition of cameroonian kaolin: mechanism, thermodynamic study and identification of its by-products."],"pmcid":["PMC12415547"],"pubmed_authors":["Fotsop CG","Scheffler F","Lieb A"],"additional_accession":[]},"is_claimable":false,"name":"Elucidation of the thermo-kinetics of the thermal decomposition of cameroonian kaolin: mechanism, thermodynamic study and identification of its by-products.","description":"This work elucidates the thermo-kinetics of the thermal conversion of cameroonian kaolin to metakaolin as the main product. The thermokinetical parameters (activation energy <i>E</i> <sub>a</sub> and pre-exponential factor <i>A</i>) for the kaolin conversion were calculated using model-free methods, <i>i.e.</i> the Kissinger-Akahira-Sunrose (KAS) and the Flynn-Wall-Ozawa (FWO) method, and differential methods (Kissinger and Ozawa) additionally including iterative procedures for KAS and FWO methods (KAS-Ir; FWO-Ir). The cameroonian kaolin was heat-treated using three different heating rates, <i>i.e.</i> 5, 20 and 40 K min<sup>-1</sup>, leading to metakaolin samples named MK-(5), MK-(20) and MK-(40). The TGA analysis showed a total mass loss of ∼12.5% in two steps related to the dehydration (step 1) and dehydroxylation (step 2). The <i>E</i> <sub>a</sub> of the two steps were most accurately determined using the iterative procedures KAS-Ir and FWO-Ir. The average <i>E</i> <sub>a</sub> values were 88.44/88.58 kJ mol<sup>-1</sup> for step 1 and 261.85/261.91 kJ mol<sup>-1</sup> for step 2, for the KAS-Ir and FWO-Ir models, respectively. The most probable mechanism function was determined by the multiple heating rate method (MHR) and the Coats-Redfern method. The kinetic analyses showed that the dehydroxylation of kaolin is controlled by a random nucleation and subsequent growth mechanism (G<sub>4</sub>) and a second order chemical reaction (F<sub>2</sub>). Thermodynamic parameters, namely the entropy Δ<i>S</i> <sup>≠</sup>, the enthalpy Δ<i>H</i> <sup>≠</sup> and Gibbs free energy Δ<i>G</i> <sup>≠</sup>, were evaluated. The average values of Δ<i>S</i> <sup>≠</sup>, Δ<i>H</i> <sup>≠</sup> and Δ<i>G</i> <sup>≠</sup> using both the KAS-Ir and FWO-Ir models exhibited less than 5% deviation. The obtained metakaolin samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FT-IR).","dates":{"release":"2025-01-01T00:00:00Z","publication":"2025 Sep","modification":"2026-06-01T16:09:56.806Z","creation":"2026-04-08T13:57:16.348Z"},"accession":"S-EPMC12415547","cross_references":{"pubmed":["40927475"],"doi":["10.1039/d5ra05149e"]}}