Ion exchange behaviour of some amine intercalates of α-Tin(IV) hydrogen phosphate monohydrate

Abstract

The ion exchange behaviour of some amine intercalation compounds of α-tin (IV) hydrogen phosphate (α-SnP) has been investigated in the presence of transition metal ions. It has been found that the behaviour of these intercalates depends upon whether the guest molecule is a mono- or a poly-aamine. For each of the intercalation samples studied the rate of uptake of the metal ion is rapid ( t 1 2 less than 5 min). When the guest molecule is a water-soluble primary mono-amine the uptake of the metal ion is accompanied by the loss of the amine in the form of a soluble alkylammonium ion. The resultant solid product of this reaction is essentially amorphous due to the delamination of the lamellar α-SnP. The surface areas, however are approximately the same (α-SnP 51.6 m 2 g −1, the delamination product 55.9 m 2 g −1). The retention capacities of the α-SnP/allylamine intercalate for Ni 2+, Co 2+ and Cu 2+ were 6.3, 5.9 and 3.5 meq g −1 respectively. This intercalate appeared to be selective for Cu 2+, especially at low copper concentrations in mixed solutions. Intercalation compounds with poly-amines (e.g. 1,2-diaminoethane) also react rapidly with aqueous transition metal ions but this reaction is not accompanied by a loss of the intercalated amine or by delamination and the characteristic d 002 spacing of the intercalate is retained, and the total amount of metal ions absorbed did not exceed 20% of the theoretical cation exchange capacity (C.E.C.).