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Inorganic ion exchangers seem to be very helpful in solving diverse problems due to
their selectivity and stability under certain conditions. Apart from the practical utility of
the selectivity for the purpose of chemical separation, an understanding of the
factors contributing to the selectivity pattern is of considerable theoretical interest.
Some zirconium (IV)-based ion exchangers have been synthesized and reported in
the literature (Pauling, 1963; Amphlett, 1964; Bassett et al., 1978; Qureshi and Rahman, 1987a, 1987b and 1989; Qureshi et al., 1989; Gupta et al., 2004; and 2005). The
exchange characteristics of these zirconium (IV)-based ion exchangers for a number of metal
ions have been described in terms of distribution coefficient values. Although
distribution coefficient values
(KD) are of practical importance, the influence of certain
factorslike pore size in the exchanger material, valence and hydrated radius of ingoing cation, pH
of external solution and interaction of counter ion with the matrixon the exchange
behavior cannot be well understood on the basis of KD values alone. Therefore, with the aim
of having an insight into the selectivity pattern of zirconium (IV) iodomolybdate, the
sorption behavior of ammine complexes of Ni (II), Cu (II), Cd (II) and Zn (II) ,which have
identical charge but different sizes and shapes, is reported in the present paper. |
