Synthesis and ion-exchange properties of crystalline titanium and zirconium phosphates

The preparation of novel types of inorganic ion-exchangers, titanium and zirconium phosphates and their ion-exchange properties towards strontium ions, are reported and discussed. Ti(HPO4)(2).2H(2)O is shown to be very stable to hydrolysis and to have high exchange capacity in strongly acid medium. In the case of zirconium phosphate, the titration curves with alkaline earth metal hydroxides are strongly affected by hydrolysis of the exchanger and precipitation of insoluble phosphate. The degree of conversion of the exchanger at which phosphate precipitation begins was found to be 80% for Sr2+. The comparison of Ti(HPO4)(2).2H(2)O with the corresponding zirconium phosphate dihydrated phase suggests that the former possesses a lattice structure different from that reported for the monohydrated exchanger.