Rare earth elements (REE) are essential components of equipment used for renewable energy, green technologies, and more traditional sectors such as chemical catalysis and metallurgy. Interest has been growing in alternative REE sources to supplement current ore sources and related refining, which have historically supplied the bulk of REE oxides. This study investigated the capability of adsorbent silica particles functionalized with three different ligands – phosphonoacetic acid (PAA), N,N-bisphosphono(methyl)glycine (BPG), and diethylenetriaminepentaacetic dianhydride (DTPADA) – to selectively extract REE from acidic to circumneutral aqueous brine solutions in equilibrium conditions. Maximum REE removal from 0.5 M NaCl solutions was displayed at pH 7 for PAA, pH 2 for DTPADA, and in both acidic and basic conditions for BPG functionalized materials. The REE adsorption performance for functionalized materials was largely unimpeded by the presence of competing ions (Ca, Mg, Zn, Fe, Al). Tests with real brines (I ∼ 3 M) showed >90% efficiency in REE recovery, which improved at higher temperatures (up to 100 °C). Effective elution of REE was accomplished with 0.7 N HNO₃, and performance of the adsorbents improved with additional usage cycles.

中文翻译：

---

稀土元素到功能化二氧化硅颗粒上的选择性吸附

稀土元素（REE）是用于可再生能源，绿色技术以及化学催化和冶金等更传统领域的设备的重要组成部分。人们一直对替代稀土来源以补充当前矿石来源和相关精炼的兴趣不断增长，这些来源过去一直提供大量的稀土氧化物。这项研究研究了用三种不同的配体（膦酸乙酸（PAA），N，N-双膦酰基（甲基）甘氨酸（BPG）和二亚乙基三胺五乙酸二酐（DTPADA）–在平衡条件下从酸性到环境中性盐水溶液中选择性提取REE。在PAA的pH值为7，DTPADA的pH值为2以及BPG官能化材料在酸性和碱性条件下，从0.5 M NaCl溶液中去除的REE最高。功能性材料的REE吸附性能在很大程度上不受竞争离子（Ca，Mg，Zn，Fe，Al）的影响。用真实盐水（I〜3 M）进行的测试表明，REE回收效率> 90％，在较高温度下（最高100°C）有所改善。用0.7 N HNO ₃可以有效洗脱REE ，并通过额外的使用周期提高吸附剂的性能。