Solvation‐amination‐synergy that neutralizes interfacially polymerized membranes for ultrahigh selective nanofiltration

Abstract

Molecular desalination is broadly used in chemical, food, and textile industries, which needs efficient and anti‐fouling separation technologies to reach this goal. Interfacial polymerization is one of the most promising routes to construct ultrahigh selective nanofiltration membranes. However, the irreversible hydrolysis of residual acyl chlorides makes Donnan charges of nascent films distribute unevenly which hinders fine molecular desalination and anti‐fouling. Here, we propose a pioneering solvation‐amination‐synergy strategy to synchronously inhibit the hydrolysis of residual acyl chlorides and promote their amination. The electroneutral nanofiltration membrane with high water permeance (13.2 L m−2 h−1 bar−1) is quantitatively fabricated that has superb anti‐fouling abilities and minimizes Donnan impacts on competitive ion penetrations, so it transmits Na2SO4 and NaCl while fully obstructs cationic or anionic dyes (< 500 Da). The ultrahigh molecule to ion selectivities outperform state‐of‐art nanofiltration membranes, which may provide a paradigm shift for scalable membrane fabrication for various industrial product desalination.

Voltage-Gated Membranes Incorporating Cucurbit[n]uril Molecular Containers for Molecular Nanofiltration

“…As the result of the unique responsive properties, the membrane exhibits exceptional performance over previously reported membranes (Figure S12). − For the BABD membrane that does not have CB[7], the BABD molecules are prone to dimerization of their cation radical forms (Figure E). In the dimeric form, the two BABD molecules undergo π–π stacking interactions, ,, which decreases the free volume and pore size of the membrane.…”

Ionic liquid‐induced deep grafting of polyelectrolyte to reform polyamide layer for antifouling nanofiltration membrane

“…The use of IL‐EtOH solution instead of water as a medium for the secondary reaction not only inhibits the hydrolysis of acyl chloride into carboxyl groups, but also dissolves off the small PA fragments and reformed PA network (Figure 1B). Meanwhile, compared with the previously reported solvation‐amination‐synergy strategy, 28,29 the weak interaction of PEI with IL solvent and the swollen PA layer (looser structure) facilitate deep grafting, thus introducing more positively charged groups inside the PA layer without sacrificing free volume and compromising membrane permeability (Figure 1C). Due to the near charge‐neutral and uniform pore size distribution, the NF membranes have significantly enhanced fouling resistance and outstanding size sieving, which offers new insights in designing antifouling membranes for wastewater reuse and resource recovery.…”

“…Such problem can be solved by executing the grafting in organic solvents. Ethanol (EtOH) and dimethylsulfoxide are used as solvents for the secondary reaction, which synchronously inhibits the hydrolysis of acyl chloride and improves the grafting amount 28,29 . However, the choice of solvent usually ignores its affinity to the membrane and its interaction with the amine‐bearing solutes, which may affect the PA layer swelling degree and the grafting reactivity, respectively, thus determining the physicochemical properties of the resulting membrane.…”

Double Polyamide Layers with CaCO3 Nanoparticles as Scaffolds for High Performance Nanofiltration Membranes

“…Nanofiltration (NF) has become one of the key technologies in the fields of wastewater treatment, desalination, and so on, for separation and purification. − The thin-film composite membrane composed of a polyamide (PA) barrier layer is the main type of NF membrane, , which is the core material for NF technology. Generally, the PA barrier layer is formed on a support membrane through interfacial polymerization (IP) between diamine [such as piperazine (PIP)] and polyacyl chloride [such as trimesoyl chloride (TMC)] monomers, which plays a decisive role in permeability and selectivity. − The morphology and structure of the PA layer largely determine the permeation selectivity of the NF membrane. ,− Therefore, regulating the PA layer structure of the NF membrane is a critical issue in the preparation of the NF membrane …”