Complexation of transition metal ions on the surface of carboxyethylated aminopolysiloxanes

Abstract

The effect of the nature of the sorbent matrix and the state of ions of some transition metals in solution on their sorption by carboxyethylated alumino-, zircono-, and titano-aminopolysiloxanes was studied. Modification of the aminopolysiloxane matrix with zirconia, alumina, or titania results in displacement of the optimal sorption ranges for copper(II), nickel(II), and cobalt(II) to alkaline pH. Comparison of the results of structural studies of the complexes of N-aryl-3-aminopropionic acids in solutions and compositions of equilibrium solutions upon sorption of metal ions from ammonia-acetate buffer systems demonstrated that metal ions are simultaneously coordinated by the functional groups of iminodipropionic acid, which are rigidly attached to on the polysiloxane matrix, and by monodentate molecular ligands (ammonia molecules) present in the buffer solution. A competitive influence of copper(II), nickel(II), and cobalt(II) on the sorption from mixed solutions was established.