| Popis: |
The extraction of niobium and tantalum from sulphate solutions with bis(di- n -hexylphosphinyl) methane [(C 6 H 13 ) 2 OPCH 2 PO(C 6 H 13 ) 2 ), di- n -octyl, 1-oxo-octanephosphonate [C 7 H 15 COPO(OC 8 H 17 ) 2 ] and di- n -octyl, 2-oxo-propane-phosphonate [CH 3 COCH 2 PO(OC 8 H 17 ) 2 ] has been studied. The ligand/metal and hydrogen/metal ratios have been determined by slope analyses. On the basis of the evidence obtained, the extraction mechanism has been deduced. In the systems investigated at low acidity in the aqueous phase, the presence of the extraction species Me(OH) 4 L·HL n ( n = 1 or 2) and Me(OH) 3 L 2 (Me = Nb, Ta) in the organic phase has been proposed. |
