Efficient adsorption and separation of dysprosium from NdFeB magnets in an acidic system by ion imprinted mesoporous silica sealed in a dialysis bag

Abstract

5A straightforward, one-pot approach for novel ion imprinted mesoporous silica materials 6 (IMS) was developed by co-condensation. IMS was used for the recovery of dysprosium through 7 solid-liquid extraction in an acidic system. The dysprosium adsorption of IMS was efficiently 8 modeled using the pseudo-second order rate equation. The initial kinetics of adsorption were fast, 9and almost complete adsorption after 150 min. Adsorption isotherms were efficiently modeled 10 using the Langmuir equation. The adsorption capacity of IMS toward dysprosium was 22.33 mg 11 g -1 at pH=2.0, which was apparently greater than the adsorption capacity of non-imprinted 12 materials at pH=5.0. The value of imprint factor at pH=2.0 was higher than other pH obviously. 13The distribution coefficient relative to dysprosium was 539 mL g -1 , which was significantly higher 14 than that of other rare earth ions. IMS demonstrates enhanced selectivity towards dysprosium 15 compared to non-imprinted materials in acidic solution via solid-liquid extraction, which 16 substantially improve selective extraction process and provide a greener alternative to 17 liquid-liquid extraction. In addition, the materials demonstrated a high degree of reusability over a 18 five extraction-stripping cycles, enhancing their potential for application in real rare earth metal 19 recycling in acidic system. 20Keywords Solid-liquid extraction, dysprosium, ion imprinted mesoporous silica, acidic system 21 adsorption 22Introduction 23

Rare earth elements: Mendeleev’s bane, modern marvels

“…By grafting neutral extractant across the pores, they obtained notable "bell-shaped" RE distribution curves and confirmed a selectivity mechanism principally tied to the RE sizes (26,27). A related approach is the synthesis of RE-imprinted mesoporous silica, demonstrating preferential sorption of the templating RE (28). Similarly, Zhang et al synthesized a new functionalized titania material by controlled hydrolysis (29).…”

Preparation of an ion imprinted functionalized mesoporous silica for rapid and specific absorption Cr(iii) ions in effluents

“…For the Cr(III) ions concentration of 20, 200 mg L À1 , the time to reach equilibrium was 3 min and 5 min at pH 4.5 respectively, which was much shorter than that of typical MIPs, 43 and it corresponded with common imprinted mesoporous silica. 37,44 The short equilibrium adsorption time resulted from the nanometer-sized wall thicknesses and narrow pore size distribution of the mesoporous silica, which signicantly enhanced the specic surface area and accelerated mass diffusion and transportation of adsorption processes. 35 Therefore, the Cr(III) ions were more accessible to the binding sites of imprinted mesoporous silica.…”

“…Co-condensation is one of common strategies to modied mesoporous silica materials. 37 Compared to postsynthetic functionalization (graing), cocondensation modication is the simultaneous addition of the corresponding silica and structure-directing agents (SDAs) with organosilica precursors and templates. The organofunctional groups covalently anchor in the pore walls, and it can effectively overcome some shortcomings of graing synthesis, such as the loss of surface area, pore blocking, and heterogeneous distribution of recognition sites.…”

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials

“…The IIT has been widely used for the synthesis of ion‐imprinted porous materials and polymers for the recognition of heavy metals and actinides; therefore, its potential for REE adsorption has become obvious. In the work of Zheng et al ., for example, highly ordered Dy 3+ ‐imprinted SBA‐15‐type mesoporous silica modified with acetyl acetone (ACAC) was prepared for the recovery of Dy 3+ in acid media. In this study, the ACAC ligand was first converted into an organosilane precursor, which was then complexed with Dy 3+ and used in a one‐pot co‐condensation synthesis of the mesoporous hybrid material (Figure a).…”