Extraction of caesium(I) from HNO3 medium using room temperature ionic liquid containing calix[4] crown ligands as the selective extractants

Studies on the extraction of Cs(I) from nitric acid medium were carried out using three commercial calix-crown ligands, viz. calix[4] arene-bis-crown-6, calix[4] arene-bis-1,2-benzocrown-6 and calix[4] arene-bis-2,3-naphthocrown-6 dissolved in different room temperature ionic liquids (RTILs), viz. 1-butyl-3-methyl-imidazolium hexafluorophosphate (C(4)mim center dot PF6), 1-hexyl-3-methyl-imidazolium hexafluorophosphate (C(6)mim center dot PF6) and 1-octyl-3-methyl-imidazolium hexafluorophosphate (C(8)mim center dot PF6). The distribution ratio of Cs(I) decreased with increased alkyl chain length of RTILs. The effect of nitric acid concentration on distribution behaviour of Cs(I) by calix[4] arene-bis-1,2-benzocrown-6 was investigated. The extraction of Cs(I) from HNO3 was found to be exothermic and extraction was found to be enthalpy driven. Selective extraction of Cs(I) could be achieved from a mixture of various fission product elements like Tc, Mo, Zr, Ce, Ru, La, Ba, and Sr.