6f-- 6x ope 2 ud oO 2 oO 3 }— 3M HNO3 Rb 4h Po 3K 9M HNO3 > - Cs <t mT oa ef _— 0 0 tT | oO [ 2 ft EY 3 | 4 5 6 7 8 Jj 9 | lo { oT J l2 J 43 14 J 15 | 6 ™ I7 J J8 VOLUME (milliliters) 0.0 pa oe. 2M NH4NO3 Cs| 9MNH,NO, z 2 <q ira z e Ke ui oO z 3 Oo LJ > = <I i li or o 2 3 4 5 6 | 7 | 8 l 9 I io { «6 Lot I2 13 14 15 VOLUME (milfititers) Fies. 15 anp 16.—Separation of rubidium and cesium using columns of zine ferrocyanide of rubidium from cesium may be obtained using either nitric acid or ammonium nitrate as an eluant, but because the values of Kp for cesium remain large, even at the highest concentration of the eluents tested, the recovery of cesium from the column is likely to be poor. However, under acid conditions, this exchanger tends to coalesce and not allow the passage of the eluent through the column, so elution curves were obtained using only ammonium nitrate (Figure 18). Rubidium is eluted with 6 M ammonium nitrate,