SEPARATION OF COBALT(II) AND NICKEL(II) IONS FROM ACID AQUEOUS-SOLUTION BY CO2-EXCHANGE INTO GAMMA-TITANIUM PHOSPHATE( 2H(+) ION)

The Co2+-2H(+), Ni2+-2H(+), and Co2+-Ni2+-2H(+) ion exchange processes into gamma-Ti(H2PO4)(PO4).2H(2)O were studied. Exchange isotherms and titration curves were obtained. Monometallic half ion exchange phases were formed by using MCl(2)+HCl (M=Co,Ni) solutions. Equilibrium cons tants, free energy, enthalpy, and entropy of the Co2+-2H(+) ion exchan ge reaction were determined. In (Co,Ni)Cl-2 solutions, bimetallic a ha lf ion exchange substitution solid solution is detected. Equilibrium c onstant of the Co2+Ni2+ substitution process in the gamma-Ti(CoxNi0.5- xHPO4)(PO4).nH(2)O phase at 85 degrees C was determined. In (Co,Ni)Cl- 2+HCl solutions, total separation of Co2+ and Ni2+ is obtained.