Lead exchange into zeolite and clay minerals: A [sup 29]Si, [sub 27]Al, [sup 23]Na solid-state NMR study

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Geochimica et Cosmochimica Acta; (United States)

OSTI ID:5426374

Liang, J J; Sherriff, B L ^[1]

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1. Univ. of Manitoba, Winnipeg (Canada)

Chabazite, vermiculite, montmorillonite, hectorite, and kaolinite were used to remove Pb, through ion exchange, from 0.01 M aqueous Pb(NO[sub 3])[sub 2] solutions. These minerals contained 27 (Na-chabazite), 16, 9, 9, and 0.5 wt % of Pb, respectively, after equilibration with the solutions. Ion exchange reached equilibrium within 24 h for Na-chabazite and vermiculite, but in less than 5 min for montmorillonite and hectorite. Na-chabazite took up more Pb than natural (Ca, Na)-chabazite (7 wt % Pb), whereas no such difference was observed in different cation forms of the clay minerals. Calcite impurities, associated with the clay minerals, effectively removed Pb from the aqueous solutions by the precipitation of cerussite (PbCO[sub 3]). [sup 29]Si, [sup 27]Al, and [sup 23]Na magic angle spinning (MAS) nuclear magnetic resonance (NMR), [sup 23]Na double rotation (DOR) NMR, and [sup 23]Na variable-temperature MAS NMR were used to study the ion exchange mechanisms. In Na-chabazite, cations in all three possible sites take part in the fast chemical exchange. The chemical exchange passes from the fast exchange regime to the slow regime at [minus]80 to [minus]100[degrees]C. One site contains a relatively low population of exchangeable cations. The other two more shielded sites contain most of the exchangeable cation. The exchangeable cations in chabazite and vermiculite were found to be close to the SiO[sub 4] and AlO[sub 4] tetrahedra, while those in the other clay minerals were more distant. Two sites (or groups of sites) for exchangeable cations were observed in hectorite. Lead tended to occupy the one which corresponds to the [minus]8 ppM peak on the [sup 23]Na MAS NMR spectrum. The behavior of the exchangeable cations in the interlayer sites was similar in all the clay minerals studied. 27 refs., 7 figs., 4 tabs.

• OSTI ID: 5426374
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:16; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105* -- Separation Procedures
ALKALI METAL ISOTOPES
ALUMINIUM 27
ALUMINIUM COMPOUNDS
ALUMINIUM ISOTOPES
ALUMINIUM OXIDES
ALUMINIUM SILICATES
AQUEOUS SOLUTIONS
CALCITE
CARBONATE MINERALS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CLAYS
DISPERSIONS
ELEMENTS
EVEN-ODD NUCLEI
INORGANIC ION EXCHANGERS
ION EXCHANGE
ION EXCHANGE MATERIALS
ISOTOPES
KAOLINITE
KINETICS
LEAD
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
METALS
MICA
MINERALS
MIXTURES
MONTMORILLONITE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
REMOVAL
RESONANCE
SILICATE MINERALS
SILICATES
SILICON 29
SILICON COMPOUNDS
SILICON ISOTOPES
SILICON OXIDES
SODIUM 23
SODIUM ISOTOPES
SOLUTIONS
STABLE ISOTOPES
VERMICULITE
ZEOLITES