Separation of La(III), Ce(IV) and Ca(II) from bastnaesite using acidic phosphonic chitosan and rotating disk membrane

Abstract

The separation of rare earths is difficult due to their similar properties and the complex characteristics of associated vein ores. Complexation-ultrafiltration (CUF) and shear induced orderly dissociation coupling with ultrafiltration (SIODUF) were used to separate metal ions (M, M = La(III), Ce(IV) and Ca(II)) from simulated bastnaesite leaching solution using acidic phosphonic chitosan (aPCS) and rotating disk membrane. Effect of simultaneous removal of metallic ions was investigated by CUF, and suitable conditions were obtained for C/M 10.0 (mass ratio of complexant to metal ions) and pH 5.0. The shear stabilities of aPCS-M complexes were explored at different pH values and the results show that the complexes can dissociate at a certain rotational speed, the critical one. The critical shear rates of aPCS-La, aPCS-Ce and aPCS-Ca complexes at pH 5.0 were calculated as 1.42 × 105, 1.69 × 105 and 9.75 × 104 s−1, respectively. The order of complexes shear stability is aPCS-Ca < aPCS-La < aPCS-Ce. The high selective separation of M and regeneration of aPCS were achieved by SIODUF in the light of the difference of aPCS-M complexes shear stabilities. The separation coefficients βLa/Ce and βCa/La reach 31.2 and 53.9, respectively.