Abstract
An ethanol-formic acid-nitric acid mixture containing 0.0050 m mol of sevral rare earth pairs from Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y was passed through a column packed with strong-base anion exchange resin, Amberlyst-A29 in the nitrate form (φ 1.2 cm×21 cm bed), and the rare earth band formed on the column was eluted with the various mixtures of ethanol, formic acid, and nitric acid. In general the heavier rare earth passed through the column at the faster rate than the lighter one, and Y is eluted between Er and Tm. The most effective compositions of the mixtures for separations of adjoining rare earth groups are,
(1) for Yb and Lu, C2H5OH-26 M HCOOH-13 M HNO3 (volume ratio, 93 : 3 : 4)
(2) for Tm and Yb, C2H5OH-26 M HCOOH-13 M HNO3 (90 : 5 : 5)
(3) for Er, Y, and Tm, C2H5OH-20 M HCOOH-13 M HNO3 (90 : 5 : 5)
(4) for Ho and Er, C2H5OH-15 M HCOOH-7 M HNO3 (90 : 5 : 5)
(5) for Tb, Dy, and Ho, C2H5OH-23 M HCOOH-13 M HNO3 (85 : 7 : 8)
(6) for Gd and Tb, C2H5OH-20 M HCOOH-13 M HNO3 (80 : 10 : 10)
