Solvent extraction of technetium(VII) by cyclic amides

The extraction behavior of heptavalent technetium with cyclic amides in n-d odecane from nitric acid solution was studied. The amides investigated are N-(2-ethyl)hexylbutyrolactam(EHBLA), N-(2-ethyl)hexylvalerolactam(EHVLA), N -(2-ethyl)hexyl-caprolactam (EHCLA), N-octylcaprolactam(OCLA), a mixture of 3-octyt-N-(2-ethyl)hexyl valerolactam and 4-octyl-N-(2-ethyl)hexylvalerola ctam (3,4,OEHVLA), 2-octyl-N(2-ethyl)hexylcaprolactam(2OEHCLA), a mixture o f 3-octyl-N-(2-ethyl)hexylcaprolactam and 5-octyl-N-(2-ethyl)hexylcaprolact am(3,5,OEHCLA) and that of 3-octyl-N-octylcaprolactam and 5-octyl-N-octylca prolactam(3,5,OOCLA). From the results of the distribution ratio of Tc(VII) as a function of acid concentration, cyclic amides concentration and HTcO4 concentration, the effects of both the ring size of cyclic amide and struc ture of the substituents attached to different positions of the cyclic ring on the extraction behavior of Tc(VII) were discussed. A clear steric hindr ance was observed. For applications, 3,4,OEHVLA is proposed as the best ext ractant for Tc from acidic solution.