Ion Separation and Molecular Sieve Process Using Functionalized Nanostructured Membranes

Research on the selective separation of various species through 2D membranes has gainedan unprecedented importance in the last decade, thanks to the development of numeroustheoretical design strategies for applications ranging from gas separation molecules, waterdesalination, and heavy metal separation. Compared with conventional separation methods,separation process with 2D nanostructured membrane is an energy-efficient andenvironmentally benign technology, which occupies less space and can be operated in acontinuous mode. Although some of the recent experiments have demonstrated successfulperformance of such carbon membranes in sieving, many of the suggested applications are yetto be realized in experiments. This review aims to draw the attention of the theoretical as well asthe experimental researchers working on 2D materials towards the recent theoreticaldevelopments probing the permeation of various species such as atoms, ions, and smallmolecules through frameworks like graphene, graphene oxide, boron nitride, silicon carbide,molybdenum disulfide and graphyne. The underlying guiding principles toward the design of2D membranes for nanofiltration are established using estimates of the adsorption energies,barrier energies for permeation, rates of permeation, selectivity, permeances, etc. The perfect2D nanostructured membranes are impermeable to ions or gas molecules. Therefore, for usingthem in selective separation process, they should be drilled and then, edge of created pores willbe functionalized using appropriate chemical functional groups. The crucial role offunctionalized groups such as –F, –H, –OH, –N, –COOH, –Fe, –Si used in nanostructuredmembranes and their features and applications is also highlighted, and paving the way to acomprehensive description of the theoretical design strategies for tailoring the applicability ofnovel nanoporous 2D membranes in sieving and separation aspects.