Preconcentration and Separation of Rubidium from Salt Lake Brine by Ammonium Phosphomolybdate - Polyacrylonitrile (AMP-PAN) Composite Adsorbent

In this study, a novel composite adsorbent of ammonium phosphomolybdate – polyacrylonitrile (AMP–PAN) was prepared for sensitive and selective preconcentration and separation of rubidium (Rb(I)) ion from salt lake brine. Several experimental parameters, such as pH value, shaking time, concentration, interference ions, regeneration, stability and reusability were systematically investigated. The experimental results clarified that the Rb(I) ion was adsorbed by the adsorbent of AMP-PAN at pH 7. Under optimum condition, the maximum sorption capacity for Rb(I) ion by the adsorbent was 500 mg g−1 based on the Langmuir adsorption isotherm study. The adsorption equilibrium was achieved within 2 h. The presence of co-existing ions did not interfere with Rb(I) adsorption, indicating the high selectivity toward Rb(I) ion. The desorption results demonstrated that Rb(I) ion adsorbed the composite adsorbent of AMP-PAN could be effectively desorbed by 0.5 mol L−1 NH4Cl and regenerated into the initial form without significant deterioration in its original functionality at the same time, which exhibited good stability of the adsorbent. Therefore, the proposed adsorbent of AMP-PAN allowed the sensitive, selective, easy to use, cost-effective, high efficiency, fast kinetics, stable and reusability preconcentation and separation of Rb(I) ion even in the presence of competing ions. As a consequence, the AMP-PAN adsorbent can be used potentially to preconcentration and separation of Rb(I) ion from water samples in a wide range of practical applications for extracting Rb(I) ion in environmental aqueous resources.