How Intercalated Sodium, Copper, and Iron Cations Influence the Structural Arrangement of Zirconium Sulfophenylphosphonate Layers? Theoretical and Experimental Points of View

Abstract

A structural arrangement of sodium, copper, and iron cations intercalated in zirconium 4-sulfophenylphosphonate (ZrSPhP), as a potential material for ion-exchange applications, was suggested by molecular simulation methods. The calculations were focused on a detailed description of the influence of individual cations on mutual positions of the ZrSPhP layers and arrangement of sulfo groups and water molecules. Results of the calculations were compared with experimental measurements (X-ray diffraction, thermogravimetric analysis, and chemical analysis). A very good agreement between the experimental and calculated basal peaks was achieved, and the correspondence for the nonbasal peaks was improved by cell refinement. A model with sodium cations shows that the cations remain immersed between the sulfo groups of the individual sulfo sheets and that the water molecules are homogeneously spread in the interlayer. The copper cations are placed in the interlayer more homogeneously and are shifted from the central part of the interlayer space to the positions close to the sulfo sheets. The iron cations are positioned in the middle of the interlayer. The water molecules remain randomly scattered in the interlayer space, and the sulfo groups are connected with the intercalated cations and water molecules by nonbond interactions.