Rejection of endocrine-disrupting compounds (EDCs) by thin-film composite (TFC) polyamide membranes remains a challenging issue in wastewater reclamation applications because of the unfavorable hydrophobic interaction between EDCs and membranes. Herein, we investigated the incorporation of hydrophilic metal organic frameworks (MOFs) into the polyamide layer to create water/EDC selective nanochannels for enhancing EDC rejection. Using MIL-101­(Cr) MOF as a nanofiller, the water flux of the MOF0.20 TFC membrane (0.20 wt/v % MOF in n-hexane) was 2.3 times that of the control. The rejection rates against EDCs involving methylparaben, propylparaben, benzylparaben, and bisphenol A (BPA) by MOF0.20 were also significantly higher than the respective values of the control membrane, with the water/EDC selectivity (e.g., A/B BPA) of MOF0.20 approximately doubled compared to that of the control. Further single salt rejection and gold nanoparticle filtration tests confirmed that the hydrophilic nanochannels created by MOFs played a critical role in membrane transport, accounting for the significant enhancement of EDC rejection of the modified TFC membrane. This study demonstrates a promising membrane modification protocol using hydrophilic MOFs for achieving selective removal of EDCs and high-efficient wastewater reclamation using TFC membranes.

No abstract

No abstract

Removal of pharmaceutically active compounds (PhACs) is of great importance in wastewater reclamation due to their potent negative impacts on human health. Typical polyamide nanofiltration (NF) membranes are negatively charged, which compromises their rejection rate of positively charged PhACs. Herein, we propose to rationally design a novel thin-film nanocomposite (TFN) NF membrane featuring a dually charged metal organic framework (MOF) to effectively remove both positively and negatively charged PhACs. Ethylenediamine (ED) was grafted to the coordinately unsaturated metal sites inside the MIL-101(Cr). The resulting ED-MIL-101(Cr) contained both strong positively charged amine groups inside its channels and negatively charged carboxyl groups at its surface. This dually charged nature of the MOF nanoparticles enabled the ED-MIL-101(Cr)-containing TFN membrane to achieve high rejection rates (mostly >90%) for both positively (terbutaline, atenolol, fluoxetine) and negatively charged PhACs (ketoprofen, diclofenac, bezafibrate). At the same time, the ED-MIL-101(Cr) TFN membrane had greatly improved water permeance (140% over the control membrane with MOF loading). Calculations based on density functional theory further confirmed the large energy barrier for the migration of both negatively and positively charged PhACs across the nanochannels of ED-MIL-101(Cr). This study highlights a promising potential of dually charged MOF-TFN membranes for efficient removal of trace organic contaminants in wastewater reclamation.

While reverse osmosis (RO) is the leading technology to address the global challenge of water scarcity through desalination and potable reuse of wastewater, current RO membranes fall short in rejecting certain harmful constituents from seawater (e.g., boron) and wastewater [e.g., N -nitrosodimethylamine (NDMA)]. In this study, we develop an ultraselective polyamide (PA) membrane by enhancing interfacial polymerization with amphiphilic metal-organic framework (MOF) nanoflakes. These MOF nanoflakes horizontally align at the water/hexane interface to accelerate the transport of diamine monomers across the interface and retain gas bubbles and heat of the reaction in the interfacial reaction zone. These mechanisms synergistically lead to the formation of a crumpled and ultrathin PA nanofilm with an intrinsic thickness of ~5 nm and a high cross-linking degree of ~98%. The resulting PA membrane delivers exceptional desalination performance that is beyond the existing upper bound of permselectivity and exhibited very high rejection (>90%) of boron and NDMA unmatched by state-of-the-art RO membranes.

No abstract

Upcycling fouled microfiltration membranes for fabricating new high-pressure polyamide (PA) thin-film composite membranes via interfacial polymerization (IP) is developed.

No abstract