Na-Influenced Bulk and Surface Properties of the So-Called Iota(ι)-Alumina: Spectroscopy and Microscopy Studies

The test alumina (the so-called ι-Al O ) was thermally recovered at 1,100°C from chitosan-AlO hybrid films and found to contain Na and Ca impurity ions inherited from the parent chitosan. Two different modifications of pure alumina, namely, γ- and α-Al O , were adopted as control samples. The test a...

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Bibliographic Details
Published in:Frontiers in chemistry 2021-02, Vol.9, p.633877-633877
Main Authors: Bumajdad, Ali, Nahar, Shamsun, Zaki, Mohamed I
Format: Article
Language:English
Subjects:
acid-base catalytic activity
adsorptive interactivity
bulk characterization
Chemistry
iota-alumina
Na-influences
surface characterization
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Summary:The test alumina (the so-called ι-Al O ) was thermally recovered at 1,100°C from chitosan-AlO hybrid films and found to contain Na and Ca impurity ions inherited from the parent chitosan. Two different modifications of pure alumina, namely, γ- and α-Al O , were adopted as control samples. The test and control aluminas were examined for 1) the bulk elemental constitution by atomic absorption spectroscopy (AAS), 2) the surface chemical composition by X-ray photoelectron spectroscopy (XPS), 3) the bulk phase composition by X-ray powder diffractometry (XRD), Fourier-transform infrared spectroscopy (IR), and Laser Raman (LRa) spectroscopy, 4) the surface area, topography, and morphology by N sorptiometry, and atomic force (AFM) and scanning electron microscopy (SEM), 5) the surface adsorptive interactions with pyridine and 2-propanol gas-phase molecules by IR spectroscopy of the adsorbed species, and 6) the surface catalytic interactions with 2-propanol gas-phase molecules by IR spectroscopy of the gas phase. Results obtained could clearly show that the test alumina (ι-Al O ) is only hypothetically pure alumina since in reality its bulk structure is majored by mullite-type Na-aluminate (Na Al O /NaAlO ) and minored by Na-β-alumina (Na Al O ) and β-alumina (NaAl O ). Consistently, observed Na-influenced modifications of the surface chemistry, topology, and morphology, as well as adsorptive and catalytic interactions with pyridine and 2-propanol gas-phase molecules, showed significant deviations from those exhibited by the control pure aluminas (γ- and α-Al O ).
ISSN:2296-2646
2296-2646
DOI:10.3389/fchem.2021.633877