Vallès V, de Labastida M Fernández, López J, Cortina J L
Chemical Engineering Department, Escola d'Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya (UPC)-BarcelonaTECH, C/Eduard Maristany 16, Campus Diagonal-Besòs, 08019 Barcelona, Spain; Barcelona Research Center for Multiscale Science and Engineering, C/Eduard Maristany 16, Campus Diagonal-Besòs, 08019 Barcelona, Spain.
Chemical Engineering Department, Escola d'Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya (UPC)-BarcelonaTECH, C/Eduard Maristany 16, Campus Diagonal-Besòs, 08019 Barcelona, Spain; Barcelona Research Center for Multiscale Science and Engineering, C/Eduard Maristany 16, Campus Diagonal-Besòs, 08019 Barcelona, Spain.
Sci Total Environ. 2024 May 1;923:171438. doi: 10.1016/j.scitotenv.2024.171438. Epub 2024 Mar 2.
The European Union (EU) identified a list of Critical Raw Materials (CRMs) crucial for its economy, aiming to find alternative sources. Seawater is a promising option as it contains almost all elements, although most at low concentrations. However, to the present, the CRMs' recovery from seawater is technically and economically unfeasible. Other alternatives to implement sea mining might be preferred, such as reverse osmosis brines or saltworks bitterns (after sodium chloride crystallisation). The CRMs' extraction in a selective way can be achieved using highly selective recovery processes, such as chelating sorbents. This study focuses on extracting Trace Elements (TEs) from solar saltworks brines, including boron, cobalt, gallium and germanium, using commercial N-methylglucamine sorbents (S108, CRB03, CRB05). The application of these sorbents has shown potential for boron recovery, but their selectivity for cobalt, gallium, and germanium requires further investigation. This research aims to assess these sorbents' kinetics and column mode performance for TEs recovery from synthetic bitterns. Boron and germanium were rapidly sorbed, reaching equilibrium (>90 %) within 1 h, except for S108, which took 2 h. In column mode, 20-25 pore volumes of bittern were treated to remove boron and germanium, but competition from other elements reduced treatment capacity. An acidic elution (1 M hydrochloric acid) allowed to elute them (>90 %), reaching concentration factors for germanium and boron of 35 and 11, respectively, while cobalt and gallium had less affinity for the sorbents. In addition, the experiments performed were fitted by a mass transfer model to determine the equilibrium constants and selectivities. Therefore, bittern mining has been proven as a secondary/alternative source to obtain CRMs, which can lead the EU to a position in which its dependence on other countries to obtain these raw materials would be decreased.
欧盟确定了一份对其经济至关重要的关键原材料清单，旨在寻找替代来源。海水是一个有前景的选择，因为它几乎包含所有元素，尽管大多数元素的浓度很低。然而，到目前为止，从海水中回收关键原材料在技术和经济上都是不可行的。实施海采矿的其他替代方案可能更受青睐，例如反渗透浓盐水或盐场卤水（氯化钠结晶后）。使用高度选择性的回收工艺，如螯合吸附剂，可以实现关键原材料的选择性提取。本研究重点使用商业N-甲基葡糖胺吸附剂（S108、CRB03、CRB05）从太阳能盐场卤水中提取微量元素，包括硼、钴、镓和锗。这些吸附剂的应用已显示出硼回收的潜力，但其对钴、镓和锗的选择性还需要进一步研究。本研究旨在评估这些吸附剂从合成卤水中回收微量元素的动力学和柱模式性能。硼和锗被快速吸附，除S108需要2小时外，1小时内达到平衡（>90%）。在柱模式下，处理20 - 25个孔隙体积的卤水以去除硼和锗，但其他元素引起的竞争降低了处理能力。酸性洗脱（1M盐酸）可将它们洗脱（>90%），锗和硼的浓缩系数分别达到35和11，而钴和镓对吸附剂的亲和力较小。此外，通过传质模型对所进行的实验进行拟合，以确定平衡常数和选择性。因此，卤水采矿已被证明是获取关键原材料的二次/替代来源，这可以使欧盟减少对其他国家获取这些原材料的依赖。
