Molecular landscape on electrosorption improving the desalination performance using a mixed graphene oxide/graphene nitride membrane

Abstract

Electrosorption is an alternative strategy for seawater desalination, which consist in the effective ions separation from seawater to achieve abundant freshwater. However, the molecular landscape of the electrosorption associated with desalination is not fully understood. In this work, we employ a graphene oxide/graphene nitride (GO/GN) membrane to investigate the role of electrosorption in regulating desalination, accompanied by exposing the corresponding molecular mechanism. Our results show that the electric field is capable of intensifying the adsorption of ions inside the GO and GN sheets interiors that composed the desalination membrane filter. Electrosorption induces the robustly strengthened salt rejection, while mildly interfering with the water permeability, indicating that electrosorption increases the desalination performance by improving the salt rejection capacity of the membrane filter rather than enhancing the water permeability. In addition, by evaluation different values of the interval distance, the interlayer spacing, and the applied electric field, optimal parameters for the desalination process are proposed. Therefore, our study exhibits an in-depth molecular mechanism of the critical electrosorption in advancing desalination performance, which is beneficial for an efficient utilization of electrosorption in future desalination application.