Abstract The properties of a precipitation flotation process for Rb+ and Cs+ extraction from the aqueous solutions are investigated using ammonium phosphowolframate (AWP) as the precipitating agent and cetyltrimethylammonium bromide (CTAB) as the collector and foaming agent in this research. Different parameters including precipitation reaction time, solution pH, ions concentrations, molar ratio of AWP to Rb+/Cs+, and surfactant dosage, were studied. The results show that the extraction efficiency can up to almost 100 % under the optimum experimental conditions as: Contact time at 30 min, mixing speed at 500 rpm, pH at 10, CTAB concentration at 0.15 mmol L−1, Rb+/Cs+ concentration at 1 mmol L−1, the molar ratio of AWP to Rb+/Cs+ at 1:1. The energy analysis of DFT calculation determined that the binding site of Rb+/Cs+ is a four-membered ring of phosphowolframate. IGM reveals the non-covalent interaction between Rb+/Cs+ and phosphowolframate, proving that there are electrostatic attraction and Van der Waals effect between Rb+/Cs+ and the bridge oxygen of the four-membered ring of phosphowolframate ion. The analysis of flotation mechanism reveals that electrostatic attraction is the main force in the flotation process. The results of this research prove that precipitation flotation method has great potential in Rb+ and Cs+ separation as a salt lake brine treatment technology.

中文翻译：

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以磷钨酸铵为沉淀剂的沉淀浮选法高效提取 Rb+ 和 Cs+

摘要 本研究以磷钨酸铵（AWP）为沉淀剂，十六烷基三甲基溴化铵（CTAB）为捕收剂和发泡剂，研究了沉淀浮选工艺从水溶液中提取Rb+和Cs+的性能。研究了不同的参数，包括沉淀反应时间、溶液 pH 值、离子浓度、AWP 与 Rb+/Cs+ 的摩尔比和表面活性剂用量。结果表明，在以下最佳实验条件下，提取效率可以达到近 100%：接触时间为 30 min，混合速度为 500 rpm，pH 为 10，CTAB 浓度为 0.15 mmol L−1，Rb+/Cs+ 浓度为1 mmol L−1，AWP 与 Rb+/Cs+ 的摩尔比为 1:1。DFT计算的能量分析确定Rb+/Cs+的结合位点是磷钨酸盐的四元环。IGM揭示了Rb+/Cs+与磷钨酸盐之间的非共价相互作用，证明Rb+/Cs+与磷钨酸盐离子四元环的桥氧之间存在静电引力和范德华效应。浮选机理分析表明，静电引力是浮选过程中的主要作用力。本研究结果证明，沉淀浮选法作为盐湖卤水处理技术在Rb+和Cs+分离方面具有很大的潜力。证明Rb+/Cs+与磷钨酸根离子四元环的桥氧之间存在静电引力和范德华效应。浮选机理分析表明，静电引力是浮选过程中的主要作用力。本研究结果证明，沉淀浮选法作为盐湖卤水处理技术在Rb+和Cs+分离方面具有很大的潜力。证明Rb+/Cs+与磷钨酸根离子四元环的桥氧之间存在静电引力和范德华效应。浮选机理分析表明，静电引力是浮选过程中的主要作用力。本研究结果证明，沉淀浮选法作为盐湖卤水处理技术在Rb+和Cs+分离方面具有很大的潜力。