Synthesis of succinimide based ionic liquids and comparison of extraction behavior of Co(II) and Ni(II) with bi-functional ionic liquids synthesized by Aliquat336 and organophosphorus acids

Abstract

Two new succinimide compounds such as 3-butyl-1-methyl-1H-imidazol-3-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]−[C4min]+) and 1-butylpyridin-1-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]−[C4Py]+) were synthesized as task-specific ionic liquids (TSILs) for the extraction of metal ions. The extraction behavior of Co(II) and Ni(II) from chloride solution was compared between these TSILs and Bif-ILs synthesized from Aliquat336 and organophosphorus acids such as Cyanex 272, PC 88A and D2EHPA. The extraction percentage of Co(II) and Ni(II) by TSILs was eight times higher than that by Bif-ILs at the initial pH of 4.0. Moreover, the extraction percentage of Ni(II) by the TSILs was slightly higher than that of Co(II). However, Bif-ILs extracted more hydrogen ions than TSILs. The extraction of Co(II) and Ni(II) by [N88SA]−[C4min]+ was higher than that by [N88SA]−[C4Py]+. The addition of TBP to TSILs reduced the extraction of metals but the loss of TSILs into the aqueous was significantly decreased. Succinimide ionic liquids can be employed for the extraction of metals from weak acidic solutions.