**7. Chelating ion exchangers with the 8-hydroxyquinoline functional groups**

A simple method for immobilization of 8-hydroxyquinoline in a silica matrix is described by Lührmann (1985). The sorbent was used in the sorption of Cu(II), Ni(II), Co(II), Fe(III), Cr(III) , Mn(II), Zn(II), Cd(II), Pb(II) and Hg(II) at pH from 4 to 6. It was shown that the sorption capacity varies in the range from 0.2 to 0.7 mM /g, and the partition coefficients from 1103 to 9104. Ryan and Weber showed (1985) that this type of sorbent has better sorption properties with respect to Cu(II) than Chelex 100 with the iminodiacetate functional groups. Th sorbents based on 8-hydroxyquinoline can be used, e.g. for concentration of the trace metal ions Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Cr(III) from sea water (Pyell & Stork, 1992).
