Candeago Riccardo, Wang Hanyu, Nguyen Manh-Thuong, Doucet Mathieu, Glezakou Vassiliki-Alexandra, Browning James F, Su Xiao
Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
JACS Au. 2024 Feb 1;4(3):919-929. doi: 10.1021/jacsau.3c00705. eCollection 2024 Mar 25.
Solvation and ion valency effects on selectivity of metal oxyanions at redox-polymer interfaces are explored through in situ spatial-temporally resolved neutron reflectometry combined with large scale ab initio molecular dynamics. The selectivity of ReO vs MoO for two redox-metallopolymers, poly(vinyl ferrocene) (PVFc) and poly(3-ferrocenylpropyl methacrylamide) (PFPMAm) is evaluated. PVFc has a higher Re/Mo separation factor compared to PFPMAm at 0.6 V vs Ag/AgCl. In situ techniques show that both PVFc and PFPMAm swell in the presence of ReO (having higher solvation with PFPMAm), but do not swell in contact with MoO. Ab initio molecular simulations suggest that MoO maintains a well-defined double solvation shell compared to ReO. The more loosely solvated anion (ReO) is preferably adsorbed by the more hydrophobic redox polymer (PVFc), and electrostatic cross-linking driven by divalent anionic interactions could impair film swelling. Thus, the in-depth understanding of selectivity mechanisms can accelerate the design of ion-selective redox-mediated separation systems for transition metal recovery and recycling.
通过原位时空分辨中子反射测量结合大规模从头算分子动力学，研究了溶剂化和离子价态对氧化还原聚合物界面上金属氧阴离子选择性的影响。评估了两种氧化还原金属聚合物聚（乙烯基二茂铁）（PVFc）和聚（3-二茂铁基丙基甲基丙烯酰胺）（PFPMAm）对ReO与MoO的选择性。在相对于Ag/AgCl为0.6 V时，PVFc比PFPMAm具有更高的Re/Mo分离因子。原位技术表明，PVFc和PFPMAm在ReO存在下都会膨胀（PFPMAm的溶剂化程度更高），但与MoO接触时不会膨胀。从头算分子模拟表明，与ReO相比，MoO保持着明确的双溶剂化层。溶剂化程度较松散的阴离子（ReO）更倾向于被疏水性更强的氧化还原聚合物（PVFc）吸附，并且由二价阴离子相互作用驱动的静电交联会损害膜的膨胀。因此，对选择性机制的深入理解可以加速用于过渡金属回收和循环利用的离子选择性氧化还原介导分离系统的设计。
