| 摘要 |
Amorphous derivatives of kaolin group minerals, characterised by high specific surfaces and/or high cation exchange capacities and a 27Al MAS NMR spectrum having a dominant peak at ?55 ppm relative to Al(H2O)63+. 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 co-ordinated aluminium in the kaolin group mineral to tetrahedrally co-ordinated aluminium. Such derivatives show high selectivity in its cation exchange towards the metals Pb2+, Cu2+, Cd2+, Ni2+, CO2+, Cr3+, Sr2+, Zn2+, Nd3+ and UO22+.
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