Confalonieri Giorgia, Vezzalini Giovanna, Maletti Laura, Di Renzo Francesco, Gozzoli Vittorio, Arletti Rossella
ID22, Structure of Materials European Synchrotron Radiation Facility 71, Avenue des Martyrs, 384043, Grenoble, France.
Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Giuseppe Campi, 103, 41125, Modena, Italy.
Environ Sci Pollut Res Int. 2022 Sep;29(43):65176-65184. doi: 10.1007/s11356-022-20429-1. Epub 2022 Apr 28.
The increasing rare earth elements' (REE) demand to meet the market request and the current political scenario show that it is essential to find good solutions to recover these elements from waste (both industrial and mining). Zeolites are microporous materials with high cation exchange capacity, up to now only little investigated for REE recycle. Here, we propose the use of NH-exchanged zeolite L for Ce recovery from a very diluted solution (0.002 M), mimicking the Ce concentration of the liquors deriving from the leaching of spent catalysts. The aim of this work is twofold: (i) to investigate the exploitability of zeolite L as cation exchanger in the Ce recovery; and (ii) to determine the best working conditions. The investigated process consists of a coupled cation exchange: (1) in the first exchange the NH cations - present in the zeolite porosities - are exchanged with the Ce ions in the solution; and (2) in the second experiment, the Ce trapped into the zeolite is recovered through a further exchange with NH. The best working conditions for Ce exchange of NH-zeolite L are: batch system, liquid/solid ratio equal to 90 mL/g and 180 mL/g, 24 h of contact at 25 °C. The resulting Ce adsorption capacity (q) is equal to 25 mg/g and ~39 mg/g and the removal efficiency 100% and 77% for the two tested liquid/solid ratios, respectively. The kinetics was proved to be fast and consistent with industrial timing; no energy cost for temperature setting is required; and the acid pH (4) of the solutions does not affect the zeolite structure stability and its exchange performance. It has been demonstrated that the zeolite framework is not affected by the exchange so that the same absorbent material can be employed many times.
为满足市场需求，对稀土元素（REE）的需求日益增加，当前的政治形势表明，找到从废物（工业废物和采矿废物）中回收这些元素的良好解决方案至关重要。沸石是具有高阳离子交换容量的微孔材料，到目前为止，对其在REE回收方面的研究还很少。在此，我们提出使用NH交换的L型沸石从非常稀的溶液（0.002 M）中回收铈，该溶液模拟了废催化剂浸出液中的铈浓度。这项工作的目的有两个：（i）研究L型沸石作为阳离子交换剂在铈回收中的可利用性；（ii）确定最佳工作条件。所研究的过程包括耦合阳离子交换：（1）在第一次交换中，存在于沸石孔隙中的NH阳离子与溶液中的铈离子进行交换；（2）在第二个实验中，通过与NH进一步交换，回收捕获在沸石中的铈。NH-L型沸石对铈交换的最佳工作条件是：间歇系统，液固比分别等于90 mL/g和180 mL/g，在25°C下接触24小时。对于两种测试的液固比，所得的铈吸附容量（q）分别等于约25 mg/g和约39 mg/g，去除效率分别为100%和77%。动力学被证明是快速的，并且与工业时间一致；不需要设置温度的能源成本；溶液的酸性pH（约4）不影响沸石结构稳定性及其交换性能。已经证明，沸石骨架不受交换影响，因此相同的吸附材料可以多次使用。
