New crystalline forms of thorium arsenate: Preparation and characterisation of Th(HAsO4)2·4H2O and Th(HAsO4)2·2.5H2O

摘要: Abstract Two new forms of microcrystalline thorium arsenate have been synthesised. They characterised as Th(HAsO4)2·4H2O and Th(HAsO4)·2.5H2O by chemical analysis thermal, X-ray, IR ion exchange studies. The interlayer distances are: Th(HAsO4)2·4H2O: 8.23 A Th(HAsO4)2·2.5H2O: 8.59 A. However, thermally chemically, both these exchangers are less stable than Th(HAsO4)2·H2O; Th(HAsO4)2·2.5H2O being more Th(HAsO4)·4H2O. maximum lithium uptake the corresponding released, respectively 1.75 1.20 mmol/g for at pH 9.0 3.42 0.28 11.8. For exchangers, loss zeolitic water well that released on formation pyroarsenate takes place in one step between 383 773 K.