CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal.
Central Laboratory of Analysis (LCA), University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
J Hazard Mater. 2019 Dec 15;380:120845. doi: 10.1016/j.jhazmat.2019.120845. Epub 2019 Jul 3.
Technology critical elements (TCE) are considered the vitamins of nowadays technology. Factors such as high demand, limited sources and geopolitical pressures, mining exploitation and its negative impact, point these elements as new emerging contaminants and highlight the importance for removal and recycling TCE from contaminated waters. This paper reports the synthesis, characterization and application of hybrid nanostructures to remove and recover lanthanides from water, promoting the recycling of these high value elements. The nanocomposite combines the interesting properties of graphite nanoplatelets, with the magnetic properties of magnetite, and exhibits good sorption properties towards La(III), Eu(III) and Tb(III). The sorption process was very sensitive to solution pH, evidencing that electrostatic interactions are the main binding mechanism involved. Removal efficiencies up to 80% were achieved at pH 8, using only 50 mg/L of nanocomposite. In ternary solution, occurred a preferential removal of Eu(III) and Tb(III). The equilibrium evidenced a rare but interesting behaviour, and as a proof-of-concept the recoveries and reutilization rates, at consecutive cycles, highlight the recyclability of the composite without loss of efficiency. This study evidences that surface charge and the number of active sites of the composite controls the removal process, providing new insights on the interactions between lanthanoids and magnetic-graphite-nanoplatelets.
技术关键要素（TCE）被认为是当今技术的维生素。高需求、有限的资源和地缘政治压力、采矿开发及其负面影响等因素将这些元素视为新出现的污染物，并强调了从受污染的水中去除和回收 TCE 的重要性。本文报道了用于从水中去除和回收镧系元素的杂化纳米结构的合成、表征和应用，促进了这些高价值元素的回收。该纳米复合材料结合了石墨纳米片的有趣性质和磁铁矿的磁性，对 La(III)、Eu(III) 和 Tb(III) 表现出良好的吸附性能。吸附过程对溶液 pH 非常敏感，表明静电相互作用是涉及的主要结合机制。在 pH 8 下，仅使用 50mg/L 的纳米复合材料即可达到高达 80%的去除效率。在三元溶液中，Eu(III) 和 Tb(III) 优先被去除。平衡表现出一种罕见但有趣的行为，作为概念验证，在连续循环中，回收率和再利用率突出了该复合材料的可回收性，而不会降低效率。这项研究表明，复合材料的表面电荷和活性位点数量控制着去除过程，为镧系元素与磁性-石墨-纳米片之间的相互作用提供了新的见解。
