Use of fumaric acid to separate lantanides from some bivalent cations

Attempts have been made at using fumaric acid to separate lantanides from the following ions: Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Ni2+, Co2+. A solution of ammonium fumarate was used as the precipitating reagent. It precipitates lantanides in form of hardly soluble sediments, while salts of bivalent cations remain in the solution. By means of one precipitation of ammonium fumarate from mixtures containng lantanides and bivalent ions it is possible to precipitate lantanides containing less than 0.01% of bivalent cations. The advantage of the method is the possibility of recovering fumaric acid in almost 95%. (author)