Alemayehu Adam, Zakharanka Anastasiya, Tyrpekl Vaclav
Department of Inorganic Chemistry, Charles University, Hlavova 2030/8, 128 00 Prague, Czech Republic.
ACS Omega. 2022 Mar 29;7(14):12288-12295. doi: 10.1021/acsomega.2c00763. eCollection 2022 Apr 12.
Oxalic acid is an important separation agent in the technology of lanthanides, actinides, and transition metals. Thanks to the low solubility of the oxalate salts, the metal ions can be easily precipitated into crystalline material, which is a convenient precursor for oxide preparation. However, it is difficult to obtain oxalate monocrystals due to the fast precipitation. We have developed a synthetic route for homogeneous precipitation of oxalates based on the thermal decomposition of oxamic acid. This work primarily concerns lanthanide oxalates; however, since no information was found about oxamic acid, a brief characterization was included. The precipitation method was tested on selected elements (Ce, Pr, Gd, Er, and Yb), for which the kinetics was determined at 100 °C. Several scoping tests at 90 °C or using different starting concentrations were performed on Ce and Gd. The reaction products were studied by means of solid-state analysis with focus on the structure and morphology. Well-developed microcrystals were successfully synthesized with the largest size for gadolinium oxalate.
草酸是镧系元素、锕系元素和过渡金属工艺中一种重要的分离剂。由于草酸盐的低溶解度，金属离子可以很容易地沉淀为晶体材料，这是制备氧化物的方便前驱体。然而，由于快速沉淀，很难获得草酸单晶。我们基于草酰胺的热分解开发了一种草酸盐均匀沉淀的合成路线。这项工作主要涉及镧系草酸盐；然而，由于未找到关于草酰胺的信息，因此包含了简要的表征。对选定元素（铈、镨、钆、铒和镱）测试了沉淀方法，并在100°C下测定了其动力学。对铈和钆在90°C或使用不同起始浓度进行了几次范围测试。通过固态分析研究了反应产物，重点关注结构和形态。成功合成了发育良好的微晶，草酸钆的尺寸最大。
