Rubidium ion Capture with a phosphotungstic acid-functionalized finger-citron-residue-based carbon

To solve the contradiction of diffusion and selectivity, we reported a novel finger-citron-residue-based mesoporous carbon (FMC) as a support to prepare a novel adsorbent PTA@FMC (PTA represents phosphotungstic acid) for rubidium ion capture. This new adsorbent was characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and N₂ adsorption, and the results showed that the PTA was immobilized in the FMC structure. Based on the results of batch tests, we demonstrated that PTA@FMC is the most distinctive adsorbent with a superior uptake capacity compared with some of those previously reported in the literatures. The adsorption tests in the presence of interfering ions (Na⁺, K⁺ and Cs⁺) showed that the more the added amount of the different types of interfering ions, the more severe is the degree by which the adsorption of Rb⁺ is weakened. In addition, the Rb⁺ sorption selectivity was moderately influenced by the co-ion effect in the presence of any ions (K⁺, Na⁺ and Cs⁺) due to PTA doping. In a word, due to its relatively facile preparation process and good uptake capacity, PTA@FMC might be a promising adsorption material for Rb⁺.