Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	On the unusual temperature dependence of kaolinite intercalation capacity for Nmethyl formamide
Δημιουργός/Συγγραφέας:	Andreou, Fevronia T. Siranidi, Eirini Derkowski, Arkadiusz [EL] Χρυσικός, Γεώργιος Δ.[EN] Chryssikos, Georgios D.
Εκδότης:	Springer
Ημερομηνία:	2022
Γλώσσα:	Αγγλικά
DOI:	10.1007/s42860-023-00217-9
Περίληψη:	Many kaolinites are known to exhibit limited intercalation capacity which affects their usage. Some reports have linked this lack of reactivity to particular structural features or to slow kinetics; others recommended increasing intercalation temperature as a remedy. The purpose of the current study was to investigate systematically the N-methylformamide (NMF) intercalation capacity of three kaolinites differing in layer stacking order (KGa-1b, KGa-2, and Imerys Hywite Alum) in the 5–150°C temperature range. Near-infrared spectroscopy (NIR) was employed to record the full kinetics of intercalation in closed systems with excess NMF. Increasing intercalation temperature accelerated the reaction, but the NMF uptake decreased and eventually vanished. Complementary thermogravimetric analysis (TGA) confirmed this unexpected trend. All kaolinites exhibited the same behavior, but the amount of inert material was in the order of their stacking-fault concentration at all temperatures: KGa-2 > Hywite > KGa-1b. Subjecting the samples to stepwise temperature changes showed that, once intercalated, the NMF could not deintercalate and was removed from equilibrium with the surrounding fluid. Thus, intercalation capacity was not a unique feature of the material because it depended on thermal history. As stacking order and thermal history had no detectable effect on the NMF-hosting environment, the unusual temperature dependence was attributed tentatively to the adverse effect of temperature on the adsorption of NMF on the edges of the crystallites, which is a prerequisite for intercalation.
Τίτλος πηγής δημοσίευσης:	Clays and Clay Minerals
Τόμος/Κεφάλαιο:	70
Σελίδες:	796-807
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Χημεία (Γενικά)[EN] Chemistry (General)
Λέξεις-Κλειδιά:	Intercalation capacity Kaolinite N-methylformamide Near-infrared spectroscopy (NIR) Thermogravimetric analysis (TGA)
Κάτοχος πνευματικών δικαιωμάτων:	The Author(s) 2023
Ηλεκτρονική διεύθυνση με ανοικτή πρόσβαση (link):	https://link.springer.com/article/10.1007/s42860-023-00217-9
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο