In this paper, a valinomycin-functionalized nano-sized magnetic solid-phase extractant (VFE) with the core-shell structure and the Fe3O4 nanospheres as the core is prepared. Related performances are characterized and tested by SEM, PPMS, XRD, FT-IR, TGA, EDS, ICP-MS, and AAS. The optimal extraction conditions are obtained, namely, temperature 50 °C or higher, pH not less than 9.3, and equilibrium extraction time about 35 min. Recycling performance experiments show that the extraction ratio of rubidium ions after 5 extraction-elution cycles is still up to 85.3%. Extraction experiments with the simulated brine, industrial wastewater, and domestic wastewater show that the VFE exhibits good selective extraction ability for rubidium ions in these water systems. This research is expected to provide a new method or a new material for the separation, extraction, enrichment, and detection of rubidium ions in water systems.

Guo-jun Zhang, Hua Fu, Hui-yuan Chen, Huo Liu, Wei-jun Song, Chun-yan Sun, Xin Hu and Yun Zhao