Rational Design of Two-Dimensional Hydrocarbon Polymer as Ultrathin-Film Nanoporous Membranes for Water Desalination

Abstract

Membrane-based water desalination has drawn considerable attention for its potential in addressing the increasingly limited water resources, but progress remains limited due to the inherent constraints of conventional membrane materials. In this work, by employing state-of-the-art molecular simulation techniques, we demonstrated that two-dimensional hydrocarbon polymer membranes, materials that possess intrinsic and tunable nanopores, can provide opportunities as molecular sieves for producing drinkable water from saline sources. Moreover, we identified a unique relationship between the permeation and selectivity for membranes with elliptical pores, which breaks the commonly known trade-off between the pore size and desalination performance. Specifically, increase in the area of elliptical pores with a controlled minor diameter can offer an improved water flux without compromising the ability to reject salts. Water distributions and water dynamics at atomic levels with the potential of mean force profiles for water and ions were also analyzed to understand the dependence of permeation and selectivity on the pore geometry. The outcomes of this work are instrumental to the future development of ultrathin-film reverse osmosis membranes and provide guidelines for the design of membranes with more effective and efficient pore structures.

Recent developments in polymeric electrospun nanofibrous membranes for seawater desalination

“…Non-polymeric materials include carbon-based particles (carbon nanotubes (CNTs) and graphene), zeolites, aquaporin (AQP), 87,[119][120][121][122] and molecular sieves. 90,[123][124][125][126][127] Nanomaterials, such as CNTs, increase nanober roughness through the creation of air pockets; 128 they enhance the uxes of RO TFNC membranes and MD, which increases with higher nanoparticle content. Incorporation of CNTs within the nano-ber polymer matrix provides the added advantage of ber thinning during electrospinning due to their high conductivities.…”

Theoretical Prediction of Mechanical Strength and Desalination Performance of One-Atom-Thick Hydrocarbon Polymer in Pressure-Driven Separation

“…Overall, compared with the polymeric RO membrane with the water permeability of ~0.17 L·cm −2 ·day −1 ·MPa −1 , PG-TP2 evidently achieves two orders of magnitude higher permeability and comparable salt rejection to those promising ultrathin-film membranes that have been computationally identified [21,22]. Therefore, the simulation results indicate that it can potentially act as a high-permeability RO membrane for one-step water desalination.…”

“…To date, graphene oxides [7], covalent organic frameworks (COFs) [8,9], metal organic frameworks (MOFs) [10,11,12], zeolite [13], carbon nano tube (CNT) [14,15], and other advanced materials are considered as separation membrane materials. Among numerous membrane materials, nanoporous ultrathin-film materials, such as one-atom-thick porous graphene (PG), have drawn considerable attention in the scientific community for their potential as the next generation of separation membrane materials [16,17,18,19,20,21,22,23]. To date, PG has been prepared by drilling nanopores in original graphene sheets, denoted as the so-called top-down approach [24,25,26,27].…”

Interfacial Synthesis of a Monolayered Fluorescent Two‐Dimensional Polymer through Dynamic Imine Chemistry

“…The structure change from 1D to 2D at the molecular level is particularly interesting and promising for applications in optoelectronic devices, energy conversion, sensors, and biomimetic devices . In addition, the 2D, ultrathin and porous natures of the 2DPs are efficiently utilized in osmotic energy conversion, also demonstrating high‐performance power capture by mixing artificial river water and sea water . Therefore, the 2DPs provide new prospects of potential applications in promising fields such as the salinity gradient energy conversion and ion screening .…”

“…[27][28][29] In addition, the 2D, ultrathin and porous natures of the 2DPs are efficiently utilized in osmotic energy conversion, also demonstrating high-performance power capture by mixing artificial river water and sea water. [30][31][32] Therefore, the 2DPs provide new prospects of potential applications in promising fields such as the salinity gradient energy conversion and ion screening. [33][34][35] Nevertheless, the synthesis of the 2DPs is usually challenging, especially the monolayer synthesis.…”