Synthesis and assessment of spherogranular composite tin pyrophosphate antimonate adsorbent for selective extraction of rubidium and cesium from salt lakes

In this study, a spherogranular porous composite tin pyrophosphate antimonate (SSbPP) adsorbent was developed for the efficient extraction of rubidium (Rb) and cesium (Cs) resources. This granular composite adsorbent was prepared using the anti-solvent method with polyvinyl chloride (PVC) as carrier and the incorporated SSbPP powder as adsorbent. The composition , molecular structure, and adsorption performance of SSbPP, along with the microstructure and adsorption behavior of the granulated PVC-SSbPP adsorbent, were comprehensively investigated. The results showed that the SSbPP adsorbent with superior performance was synthesized at a Sn:Sb:P molar ratio of 0.5:0.25:2. The adsorption behavior of PVC-SSbPP was evaluated using the pseudo-second-order kinetic model and Langmuir isotherm. The maximal adsorption capacities of PVC-SSbPP for Rb + and Cs + were found to be 81.3 mg g −1 and 95.23 mg g −1 at optimal condition, respectively. The PVC-SSbPP also exhibited high adsorption selectivity for Rb + /Cs + in the presence of competitive metal ions such as K + , Na + , Li + , Mg 2+ and Ca 2+ . Furthermore, through dynamic adsorption-desorption experiment using a fixed-bed column, a low-concentration Rb + /Cs + solution (10 mg L −1 ) could be concentrated by approximately 140 times. This research offers a promising approach for the selective extraction of low-concentration Rb and Cs resources from highly saline solutions.