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  • Sorption of ▫$Cr^{3+}$▫ on clinoptilolite tuff
    Zabukovec Logar, Nataša ...
    A Cr3+-modified natural zeolite sample from the deposit of Donje Jesenje (Croatia) was structurally studied using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy ... dispersive X-ray analysis (EDXS), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The analyses revealed the presence of up to 0.4 wt% of chromium in the clinoptilolite crystals. The X-ray photoelectron spectroscopy depth analysis suggested a uniform distribution of chromium from the surface of the crystallites to the depth of 50(3) nm. The study of local environment of chromium by XANES (X-ray absorption near edge structure) showed that chromium cations in the sample were predominantly in the 3+ oxidation state. EXAFS (extended X-ray absorptionfine structure) analysis revealed that Cr3+ cations bond to six oxygen atoms at the distance of 1.97(2) and two chromium atoms at the distance of 2.54(2) suggesting that Cr3+ cations most probably arrange in thezeolite pores in the form of small clusters of CrO6 octahedra. The chromiumcould not be completely desorbed from the sample after post-treatment with NaCl or HCl solutions thus indicating mostly irreversible sorption of chromium in the zeolite.
    Vir: Microporous and mesoporous materials : zeolites, clays, carbons and related materials. - ISSN 1387-1811 (Vol. 93, no. 1/3, 2006, str. 275-284)
    Vrsta gradiva - članek, sestavni del
    Leto - 2006
    Jezik - angleški
    COBISS.SI-ID - 3523866

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