Találati lista | Tudóstér

001-es BibID:	BIBFORM071491
Első szerző:	Kovács Eszter Mária (anyagkutató)
Cím:	Environmental importance of preparation and structure's analyzes of trivalent clays / Kovács Eszter Mária, Harangi Sándor, Kuzmann Ernő, Kónya József, M. Nagy Noémi
Dátum:	2017
Megjegyzések:	REE-exchanged bentonites were prepared from Ca-bentonite (Istenmezeje, Hungary) by ion exchange in three consecutive washings with rare-earth solutions [1]. The structure of lanthanide-bentonites was primarily analyzed for environmental protection purpose. Scanning Eletronmicroscopy Energy Dispersive X-ray spectroscopy (SEM-EDX) studies showed even distribution of REEs and other components of bentonite. The natural bentonite and the rare earth exchanged bentonites were characterized by X-ray diffraction (XRD), which revealed the same mineral composition, and the increase of the basal spacing of montmorillonite from 1.465 (Ca2+) to 1.577 nm (REE3+). The d001 basal spacing of rare earth montmorillonite increases as the ion radius of the rare earth cation increases. The Fe3+, and REEs3+ amount on the bentonite were determined by X-ray-fluorescence spectrometry (XRF). The amount of exchanged REEs were determined by washing the REE-bentonite with 1M ammonium-acetate, and measuring the amount of REE released, using inductively coupled plasma optical emission spectrometry (ICP-OES). In most REE-bentonites, the quantity of the exchanged REE ions was about 80-90% of the cation exchange capacity (CEC) of the bentonite. In case of some rare earth bentonite (La3+, Ce3+, and Gd3+), however, the sorbed quantity of lanthanum ions was higher that the cation exchange capacity. In case of lanthanum-bentonite, the rare earth quantity is as high as 136% of CEC. Moreover, the iron(III) content of lanthanum bentonite is less than that of the original Ca-bentonite. Mössbauer spectra of the La-, Ce-, and Gd-exchanged samples at 78 K revealed an unexpected magnetically split component that was absent from the Ca-bentonite [2]. This component may belong to interlayer Fe. We assume that the departure of positively charged iron ions from the lattice increases the negative layer charge and the cation exchange capacity. This can motivate the enhance sorption of lanthanum. This hypothesis is attempted to prove by molecular dynamic calculations.
ISBN:	9786177404285
Tárgyszavak:	Természettudományok Kémiai tudományok előadáskivonat
Megjelenés:	Proceedings the 6th International Conference on Carpathian Euroregion ECOLOGY CERECO / ed. Bárány Sándor, Buczkó István, Kohut Erzsébet, Csoma Zoltán, Komonyi Éva, Szabó Marján, Filep Mihály. - p. 45-57. -
További szerzők:	Harangi Sándor (1987-) (vegyész) Kuzmann Ernő Kónya József (1937-) (vegyész) Nagy Noémi, M. (1960-) (vegyész, angol szakfordító)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon: