Separation and enrichment of Rb(I) in dicyclohexano 18 crown 6(DCH18C6)/PVC polymer inclusion membrane assisted by electric field

Abstract

The effective extraction of liquid rubidium resources such as salt lake brine and seawater and the recovery of rubidium(I) at the end of the extraction process of lithium resources have always been a challenge in the industry. Two series of polymer inclusion membranes(PDA-PIM and PDT-PIM) were prepared to study the separation and enrichment of Rb(I). PDA-PIM and PDT-PIM used polyvinyl chloride (PVC) and dicyclohexano 18 crown 6(DCH18C6) as carriers, and tricaprylmethylammonium chloride (Aliquat 336) and trioctylphosphine oxide (TOPO) as a plasticizer, respectively. The optimal mass ratio (W/W) of PDA-PIM and PDT-PIM were P25D3.5A25 and P25D3.5T1, respectively. The applied electric field is a core condition for the mass transfer and separation of Rb(I). With the increase of voltage, the permeability coefficient P of Rb(I) and the separation factor (S) relative to Na(I) and K(I) increases. At 180 V, the PRb of PDA-PIM and PDT-PIM were 12.08 and 2.39 µm/s, and the SRB/NA were 11.21 and 14.44. After four mass transfer cycles of PDT-PIM, PRb only decreased by 4.6%. In addition, after 81.5 h of mass transfer, the enrichment ratio of Rb(I) was 3.02 times. These results show the excellent stability and mass transfer performance of PDT-PIM. It's of great significance for low concentration Rb(I) extraction.