The development of efficient membrane-based water desalination and purification technologies is essential for addressing the global challenges of water scarcity and pollution. An ideal separation membrane should show high permeance (transport of desired species) and high selectivity (rejection of undesired species), two properties that are often inversely correlated. In processes such as water desalination and removal of heavy metals from water, charged ions are separated from water by size exclusion or electrostatic interactions with a membrane. Two-dimensional (2D) materials are crystalline materials consisting of one or few layers of atoms and have attracted much interest in recent years for the fabrication of efficient membranes. Nanoporous or lamellar membranes based on 2D materials can potentially separate ionic species from water at higher rates and more efficiently compared to current membranes. The main goal of this project is to understand the effects of applied electrochemical potential on the separation performance of conductive membranes based on 2D transition metal carbides (MXenes). To achieve this goal, the PI will partner with researchers at Northeastern University to fabricate nanoporous and lamellar MXene membranes and study their separation properties. In addition, this project will provide opportunities to train graduate students in advanced membrane materials synthesis and characterization methods and will establish a long-term collaboration between Auburn University and Northeastern University. The PI will also integrate the result of this research into a recently developed course focused on applications of 2D materials.
Electroactive membranes based on 2D MXenes can potentially separate metal ions and other charged species from water at higher rates and efficiencies compared to current membranes. This project will provide a scientific framework for designing electroactive nanoporous and lamellar membranes based on conductive 2D MXenes. Single-layer flakes of two different MXenes, Ti3C2 and Ti2C, will be synthesized and used for the fabrication of the membranes. Experimental measurement setups and procedures used in this project will enable accurate measurements of membrane properties to understand the effects of applied electrochemical potentials on the permeability and selectivity of the fabricated membranes. We hypothesize that by enhancing the charge exclusion mechanism of MXene membranes through an external electrochemical potential, membranes with larger nanochannels or nanopores but similar or better rejection properties can be designed. The research team will investigate the influence of the magnitude and sign of the applied potential on the selectivity of membranes towards various cations and anions in water. While this project is specifically focused on MXenes as membrane materials, its research plan addresses fundamental questions about the interactions of ions and charged membranes, and the results of the proposed research may apply to membranes fabricated using other 2D materials. The research results and conclusions will be disseminated through publications and presentations to both scientific and public audiences.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
