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Separation among rubidium and potassium ions from salt lake brines remains challenging. In this work, a typical room temperature ionic liquid 1-ethyl-3-metyhlimidazaolium bis(trifluoromethylsulfonyl)imide ([C2mim+][NTf2–]) was used as diluent and synergistic extractant, dicyclohexano-18-crown-6 (DCH18C6) was used as extractant to extract rubidium ions from brine solutions which contain high concentrations of potassium ions was investigated. Under the optimal conditions, the single extraction efficiency of rubidium ions was up 93.63%. The thermodynamic parameters of the rubidium ion extraction were obtained. Based on the slope analysis method, the extracted species in the organic phase were ascertained as 1:1 complex. UV-visible has been performed to investigate the ion concentration of ionic liquid before and after the interaction of metal ions and ligands. Rubidium ions in [Rb · DCH18C6]+complex were stripped by 2.5 mol · L–1NH4NO3. The extraction system offers high efficiency, simplicity and environmentally friendly application prospect to separate rubidium from brine solutions.

This paper presents a simple grid generation method which adopts the uni‐directional interpolation idea but only interpolates one co‐ordinate between two opposite boundaries. The use of this new scheme showed that (a) it is convenient to use; and (b) compared with the built‐in grid generator of certain commercial computational fluid dynamics (CFD) code, it saves time significantly. © 1998 John Wiley & Sons, Ltd.