Water Desalination

Water scarcity, resulting from the ever-increasing demand of freshwater has become one of the most prominent challenges of our time. Given the abundance of seawater and brackish groundwater, purifying saline water to produce freshwater could be a viable solution to this problem. Reverse osmosis (RO), which uses a semipermeable thin-film composite (TFC) membranes to remove salt ions from saline water under high pressure (a few MPa), has become the leading desalination technology. Despite the fact that TFC membranes and the associated processes have been extensively optimized, to date, the high energy consumption and high capital investment for RO desalination have limited its large-scale deployment. In general, the energy footprint and operating cost of desalinating water are largely dependent on the intrinsic permselectivity of RO membranes. Thus, there is a need to develop novel RO membranes with substantially enhanced water permeability and excellent ability to reject salt ions. This has stimulated vigorous efforts toward the discovery and design of novel membrane materials.

Recently, by employing state-of-the-art molecular simulation techniques, we demonstrated the great potential of several nanostructured materials such as aluminosilicate nanotubes (AlSiNTs)¹, nanoporous graphene (NPG)², reduced graphene oxide (rGO)³, covalent triazine frameworks (CTFs)⁴, two-dimensional hydrocarbon polymers (see the Figure 1 below)⁵, zeolites⁶, etc., as RO membranes in water desalination. A detailed understanding of permselectivity enhancement at an atomic level were also carried out to supply the transformative principles to rational design of better RO membranes for more energy-efficient and cost-effective desalination processes.