Cyanex 272 and 8-HQ synergistic system for the extraction and recovery of Nd(III) from waste-NdFeB magnets

The NdFeB magnets are the most widely used permanent magnetic materials in the international arena, and the recovery of Nd(III) from the growing number of waste-NdFeB magnets is becoming increasingly crucial. In this study, a novel synergistic extractant consisting of bis(2,4,4-trimethylpentyl) phosphonic acid (Cyanex 272) and 8-hydroxyquinoline (8-HQ) is proposed for the recovery of Nd(III) from waste-NdFeB magnets. First, the influence of the ratio of the two extractants on the synergistic extraction coefficient was investigated. The coextraction coefficient ratio of the two extractants Cyanex 272 and 8-HQ was 1:1. The extraction behaviors under different conditions, such as the extractant concentration, aqueous phase pH (pH = 5), and oscillation time (1 min), were investigated. Under optimal conditions, the extraction efficiency reached 99.6 %. A chelating extraction mechanism was proposed on the basis of UV–vis spectroscopy, FT-IR spectroscopy, and NMR spectroscopy methods. The excellent extraction efficiency was maintained after five cycles of extraction and stripping, indicating the potential for application in light and heavy rare earth separation processes. Overall, this study aims to provide a new economically viable method for the recovery of Nd(III) from waste-NdFeB magnets.