Gradwohl Andreas, Windisch Jakob, Weissensteiner Matthias, Keppler Bernhard K, Kandioller Wolfgang, Jirsa Franz
Department of Inorganic Chemistry, University of Vienna Währinger Straße 42 Vienna 1090 Austria
Department of Zoology, University of Johannesburg PO Box 524, Auckland Park Johannesburg 2006 South Africa.
RSC Adv. 2023 Aug 21;13(36):24899-24908. doi: 10.1039/d3ra03967f.
The task-specific ionic liquid trihexyltetradecylphosphonium 3-hydroxy-2-naphthoate has been described as a suitable extraction agent for numerous metals from aqueous phases, while additionally providing reduced leaching into the used matrices. Here, we investigate the extraction properties of this extractant towards rare earth elements. Of these, La, Ce, Nd, Ho und Lu were chosen as a representative mix of light and heavy elements. Single- as well as double-element extractions were carried out under varying conditions regarding pH, temperature and extraction time. The highest extraction efficacies and minimalized precipitation of the respective metals were recorded at a pH of 2.5. Satisfactory extraction efficacies (>80%) were achieved already after 6 hours for the elements Ce, Nd and Lu in single-element extraction experiments at room temperature. Increased temperatures improved the extraction efficacy for Nd from 36% at 20 °C to 80% at 30 °C after only 2 hours. Surprisingly, this effect was not observed for Ce in single-element experiments. In double-element feed solutions containing both Ce and Nd, however, the time-dependant extraction efficacy of Ce mirrored that of Nd. The pH in the aqueous extraction matrix changed during the extraction, showing a positive correlation with the extraction efficacy and revealing the extraction mechanism to be anion exchange. The leaching was in good agreement with literature values, showed a positive correlation with extraction efficacies, and ranged for all extractions between 0.8 and 1.2%. Remarkably, increasing the temperature from 20 °C to 30 °C had no significant influence on leaching.
任务特定离子液体三己基十四烷基鏻3-羟基-2-萘酸盐已被描述为从水相中萃取多种金属的合适萃取剂，同时还能减少向使用过的基质中的浸出。在此，我们研究了这种萃取剂对稀土元素的萃取性能。其中，选择La、Ce、Nd、Ho和Lu作为轻元素和重元素的代表性混合物。在不同的pH、温度和萃取时间条件下进行了单元素和双元素萃取。在pH为2.5时记录到了各金属的最高萃取效率和最小沉淀量。在室温下单元素萃取实验中，Ce、Nd和Lu元素在6小时后就已经实现了令人满意的萃取效率（>80%）。温度升高将Nd的萃取效率从20℃时的36%提高到30℃时仅2小时后的80%。令人惊讶的是，在单元素实验中Ce未观察到这种效果。然而，在含有Ce和Nd的双元素进料溶液中，Ce的时间依赖性萃取效率与Nd的相似。水相萃取基质中的pH在萃取过程中发生变化，与萃取效率呈正相关，表明萃取机理为阴离子交换。浸出情况与文献值吻合良好，与萃取效率呈正相关，所有萃取的浸出率在0.8%至1.2%之间。值得注意的是，将温度从20℃提高到30℃对浸出没有显著影响。
