(164e) Inter-Cation Selective Separation from Chemically Engineered Graphene Oxide-Based Membranes

Nanostructured graphene-based membranes have emerged as a promising avenue for ion separation, offering a highly adaptable platform that can be engineered to meet diverse and specific application needs. Despite their potential, the synthesis of graphene oxide (GO) and its derivative membranes involves significant technical challenges, particularly in achieving precise control over their intrinsic structural and chemical properties. The primary objective of this study is to conduct a systematic investigation into the material properties of various graphene oxides. By characterizing a broad spectrum of GOs, the research aims to unravel the key attributes that govern the performance of GO-based ion-selective membranes. A critical aspect of this investigation is to understand how both the structural parameters—such as defect density, layer spacing, and interplanar interactions—and the chemical characteristics—specifically the distribution and concentration of functional groups—influence ion transport mechanisms at the nanoscale. One of the pivotal findings of this study is that, within the low-defect regime, the concentration of organosulfate groups (commonly introduced via conventional synthesis methods) plays a crucial role that extends well beyond mere steric effects. These intercalated organosulfate groups not only modify the chemical landscape of the GO sheets but also significantly enhance the interplanar interactions between adjacent layers. This strengthened interaction is instrumental in regulating membrane swelling with extraordinary precision, down to angstrom-scale adjustments, which in turn critically affects the selectivity between monovalent and multivalent ions. Ultimately, this comprehensive analysis provides deep insights into the material design requirements necessary for the development of high-performance graphene-based ion-separation membranes. The enhanced understanding of the interplay between structural and chemical features offers a robust framework for advancing membrane technologies, with promising implications for applications in electrodialysis and lithium extraction.