where q is the amount of neodymium in the sample fraction, Q is the total amount of sorbed neodymium in the column packed resin, ri is the isotopic ratio of nNd/142Nd, and the subscripts i and o denoted the fraction number and the original feed, respectively. In general, the isotope exchange reaction effectively proceeds and reaches the equilibrium between two phases of the solution and the resin at lower flow rate condition. In such a case, effective isotope accumulation is expected.
The mathematical averages of the two separation coefficient values obtained from the front and rear boundaries were taken to calculate the process separation coefficient (ε). The average values of the separation coefficients of each isotope relative to 142Nd for different ligands are given in Table 3 with an estimated error factor of ±5.0%. From the data shown in Table 3 it can be easily noticed that the separation coefficient increases with the increase of the mass number. This trend agrees with the previous findings in case of U [15] and [23], Zn [19], [20] and [21], Gd [2] Nd citrate system [10] and Nd malate system [11]. The arrangement of the ligands takes the following direction with respect to the increasing capacity of each ligand to increase the separation coefficient of each isotope: