A novel bifunctional ionic liquid [N1888][OOB] for the separation of rare earth and transition metal in NdFeB magnet

In this paper, a series of novel bifunctional ionic liquids with methyltrioctylammonium as the cation and o-alkoxybenzoic acetate as the anion were synthesized. Their extraction properties were investigated for the separation of rare earth and transition metal for NdFeB waste recycling. It was found that [methyltrioctyl ammonium][o-octyloxybenzoic acetate] ([N1888][OOB]) could preferentially extract rare earth while the extraction abilities of Fe and Co were weak. The extraction mechanism of rare earth with [N1888][OOB] was indicated to be ion association in a molar ratio of 2:1. The rare earth loaded by [N1888][OOB] could be selectively stripped with water. Based on the above research results, a novel separation process was developed to separate rare earth, Fe and Co with [N1888][OOB]. This study intensified the separation process of rare earth and transition metals. The novel separation strategy based on [N1888][OOB] has revealed the advantages of efficiency and sustainability for rare earth recovery.