The Separation of Europium From Other Rare Earths

Stabilization of Eu(II) Ions by Macrocyclic Compounds in the Oxidation Reaction with Hydrogen Peroxide

“…Solutions of EuCl 2 were obtained by reduction of EuCl 3 according to the McCoy method[6]. The macrocyclic compounds 1,4,7,10,13-Pentaoxacyclododecane (15C5), 1,4,7,10,13,16-Hexaoxacyclooctadecane (18C6), 4,7,13,16,21-Pentaoxa-1,10-diazabicylo[8.8.8]tricosane (Krypto®x 2.2.1), and 4,7,13,16,21,24-Hexaoxa-1,10-diazabicylo[8.8.8]hexacosane (Krypto®x 2.2.2) (98%, Merck) were used without further puri®cation…”

The Influence of the Donor Atom on the Chemiluminescence of Eu(III) Ions in the System Eu(II)/(III)-Ligand-H2O2

“…Reduction of EuCl 3 to EuCl 2 was performed by the McCoy method [12]. The degree of reduction was determined by the iodometric method directly prior to measurement.…”

Stability Constants of the Trivalent Lanthanons With Some Alpha- Hydroxycarboxylic Acids

“…The values of the t o t a l l i g a n d concentration, metal concent r a t i o n , and f r e e l i g a n d concentration and estimates of t h e pn 1s a r e i n s e r t e d i n t o Equation 3. Instead of g e t t i n g zero, one g e t s a r e s i d u a l , f o r a given s e t of data.…”

“…A l l p r e v i o u s methods of s e p a r a t i o n except f o r s p e c i a l Cases (such a s removal oi' europium by r e d u c t i o n t o t h e d i v a l e n t s t a t e and p r e c i p i t a t i o n a s EuS04 (3) and removal of cerium i n t h e t e t r a v a l e n t s t a t e ( 4 ) ) have been r e p l a c e d by ion-exchange r e s i n s e p a r a t i o n s developed during [1941][1942][1943][1944][1945][1946] and p e r f e c t e d f o r use on 'a l a r g e s c a l e during t h e following decade. Although t h e c h e m i s t r i e s of a l l t h e r a r e -e a r t h elements i n t h e +3 o x i d a t i o n s t a t e a r e almost i d e n t i c a l , t h e r e a r e small q u a n t i t a t i v e d i f f e r e n c e s which vary s y s t em a t i c a l l y from lanthanum t o l u t e t i u m w i t h y t t r i u m u s u a l l y f a l l i n g somewhere between samarium and holmium, The ionexchange method of s e p a r a t i o n i s based on t h e f a c t t h a t t h e s t e a d y decrease i n s i z e of t h e r a r e -e a r t h i o n and consequent d e c r e a s e i n b a s i c i t y means t h a t t h e r e should be a s t e a d y i n c r e a s e i n t h e s t a b i l i t y of t h e c h e l a t e s formed by t h e raree a r t h ions a s t h e atomic number.of t h e r a r e e a r t h i n c r e a s e s .…”