Precipitation and hydrolysis of thorium in aqueous solution. V. Studies of the system: thorium Nitrate-Ammonium Oxalate

摘要

The precipitation of thorium from aqueous solution of thorium nitrate (1.25 mM) and ammonium oxalate (2.5—80 mM) was investigated at pH from 1 to 10. The following precipitates were identified with the brutto formula: Th(OH)ˇ4 and Th(Cˇ2Oˇ4)ˇ2 X 6 Hˇ2O (by means of Chemical analyses). The soluble thorium oxalato complex is formed between these two precipitates and contains 4 oxalate bound to thorium, with the simplest formula [Th(Cˇ2Oˇ4)ˇ4^4~] (as determined by coulometric titration). Using log Kˇ0 = 34.8 for the dissolution constant of thorium hydroxide in ammonium oxalate bˇ4 for thorium oxalate was obtained: 1.58 X 10^24.