Kaolin derivatives
AssigneeThe University of Queensland
InventorsJohn Gerard Thompson, Ian Donald Richard Mackinnon, Sasha Koun, Neil Gabbitas
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Abstract
Amorphous derivatives of kaolin group minerals characterized by high specific surfaces and/or high cation exchange capacities and a .sup.27 AL MAS NMR spectrum having a dominant peak at about 55 ppm relative to Al(H.sub.2 O).sub.6.sup.3+. Such derivatives are prepared by reacting a kaolin group mineral with a reagent, such as, an alkali metal halide or an ammonium halide which converts the majority of the octahedrally coordinated aluminum in the kaolin group mineral to tetrahedrally coordinated aluminum. Such derivatives show high selectivity in its cation exchange towards the metals: Pb.sup.2+, Cu.sup.2+, Cd.sup.2+, Ni.sup.2+, CO.sup.2+, Cr.sup.3+, Sr.sup.2-, Zn.sup.2+, Nd.sup.3+ and UO.sub.2.sup.+.
Claims18
A high surface area cation exchange material comprising a kaolin amorphous derivative of the formula M.sub.p Al.sub.q Si.sub.2 O.sub.r (OH).sub.s X.sub.t.uH.sub.2 O, wherein M is an exchangeable alkali metal cation or ammonium cation, X is a halide, 0.5.ltoreq.p.ltoreq.2.0, 1.0.ltoreq.q.ltoreq.2.2, 4.5.ltoreq.r.ltoreq.8.0, 1.0.ltoreq.s.ltoreq.3.0, 0.0.ltoreq.t 1.0, and 0.0.ltoreq.u.ltoreq.3.0, said material having:
- (a) a surface area between 45 and 400 m.sup.2 g.sup.-1 as measured by BET isotherm;
- (b) an amorphous X-ray diffraction signal with a peak between 14.degree. and 40.degree. 2.theta. for CuK.alpha. radiation;
- (c) a primarily tetrahedrally-coordinated Al;
- (d) a .sup.27 Al Magic-Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) with a dominant peak centered on about 55 ppm relative to Al(H.sub.2 O).sub.6.sup.3+ ;
- (e) a .sup.29 Si MAS NMR spectrum having a broad signal (FWHM about 13 ppm) centered on about -86 ppm;
- and
- (f) a cation exchange capacity of 50-450 milli-equivalents per 100 grams as measured by exchange of ammonium metal cations from aqueous solution.
Dependencies are inferred from the claim text.