ION FLOTATION OF METAL-(1-HYDROXYETHYLIDENE)BISPHOSPHONATE COMPLEXES AND DETERMINATION OF STABILITY-CONSTANTS OF THE COMPLEXES

Ion flotation of sixteen metal ions (Mn(II), Co(II), Cd(II), Zn(II), Ni(II), Cu(II), Pb(II), Bi(III), Fe(III), In(III), Ga(III), Cr(III), Y(III), V(V), Mo(VI), Cr(VI)) was investigated in (1-hydroxyethylidene)bisphosphonic acid (HEBP) solutions with dodecylammonium acetate (DAA) as a surfactant. A 20 cm3 aliquot of 4.38 x 10(-4) mol.dm-3 HEBP solution containing (3.94 approximately 4.32) x 10(-4) mol.dm-3 of the above-mentioned metal ions and 8.77 x 10(-4) mol.dm-3 of DAA was adjusted to the desired pH and subjected to flotation in a cell (20 cm x 2.5 cm i.d.) for 10 approximately 20 min with nitrogen bubbles. The effect of pH on the recovery of metal ions was examined and recoveries of 98 approximately 100% (except for Cr(VI)) were obtained at the appropriate pH ranges. The compositions of the floated complexes were determined to be a metal/HEBP ratio of 1:1 for the divalent metal ions. The stability constants of the complexes were also determined from the pH approximately percent flotation curves by nonlinear least-squares method.