With the increasing demand for rare earth elements (REEs) due to their wide application in high technology, their recovery and separation from waste sources has gradually come onto the agenda. Herein, a new kind of MIL-101-NH2 (M1N) MOF functionalized with diethanol anhydride (DGA) incorporated into a polyvinylidene fluoride (PVDF) membrane (DGA-M1N@PVDF) has been fabricated for the sorption of REEs from a simulated acid leaching solution of waste phosphor, which contains a large amount of REEs. FTIR, TGA, XRD, fluorescence spectra and XPS analysis were used to characterize the synthesized composite membrane. Batch tests were employed to determine the optimal sorption conditions for Y and Eu adsorbed on DGA-M1N@PVDF adsorbent, such as pH (1–5), content of M1N MOFs (0–40 wt%), contact time (10–180 min) and ion concentration (0–20 mg L−1). Maximum adsorption capacities for Y and Eu on DGA-M1N@PVDF reached 991.7 μg g−1 and 98.76 μg g−1 for trace REE solution, respectively. Moreover, a pseudo-second-order kinetic model accurately described the sorption process, and the plotted isothermal data indicated that the Langmuir model was more suitable than the Freundlich model for Y and Eu sorption with monolayer and chemical adsorption. Meanwhile, FTIR and XPS analyses revealed that the Y and Eu adsorption on the DGA-M1N@PVDF composite membrane was mainly caused by the N and O atoms of the –CONH or –COOH groups coordinated with metal ions. Furthermore, after five cycles, the recovery efficiency by DGA-M1N@PVDF for REEs remains above 82% and the XRD patterns were consistent with the original sample, which implied that the DGA-M1N@PVDF membrane has preferable stability, recyclability and good efficiency in REE separation from waste phosphor solutions.
Ruixi Bai,Fan Yang,Yang Zhang,Zhigang Zhao,Qiuxia Liao,Peng Chen,Panpan Zhao,Wanghuan Guo,Chunqing Cai
Inspired by the phenomenon of sponges soaking up water, a novel syringe-like adsorption device used diglycolamic-acid modified chitosan sponges (CSs-DGAA) as adsorbents is reported for recycling of rare-earth elements (REEs) by Squeezing & Soaking (S&S) operation. Integrating the elasticity of sponges and selective extraction ability of diglycolamic acid groups, the new device can efficiently recycle REEs from aqueous solutions. This device only needs 10 min to achieve adsorption equilibrium; squeezing the water from the sponges achieves solid-liquid separation. This syringe-like adsorption method not only solves the pollution problem caused by the organic solvents used during liquidliquid extractions, but also improves the time needed to achieve adsorption equilibrium and uses significantly less energy than energy intensive solid-phase extractions of solid-liquid separations. Moreover, the environment-friendly adsorbents effectively recycle yttrium and europium from waste phosphor powders. These experimental results demonstrated that the S&S method based on polymeric sponges has potential application in hydrometallurgy and environmental remediation.
危险品化学品经营许可证（带存储）