Polyamide thin-film nanocomposite membrane containing star-shaped ZIF-8 with enhanced water permeance and PPCPs removal

Facile Fabrication of Zeolitic Imidazolate Framework-8@Regenerated Cellulose Nanofibrous Membranes for Effective Adsorption of Tetracycline Hydrochloride

The excessive utilization of antimicrobials in humans and animals has resulted in considerable environmental contamination, necessitating the development of high-performance antibiotic adsorption media. A significant challenge is the development of composite nanofibrous materials that are both beneficial and easy to fabricate, with the aim of improving adsorption capacity. Herein, a new kind of zeolitic imidazolate framework-8 (ZIF-8)-modified regenerated cellulose nanofibrous membrane (ZIF-8@RC NFM) was designed and fabricated by combining electrospinning and in situ surface modification technologies. Benefiting from its favorable surface wettability, enhanced tensile strength, interconnected porous structure, and relatively large specific surface area, the resulting ZIF-8@RC NFMs exhibit a relatively high adsorption capacity for tetracycline hydrochloride (TCH) of 105 mg g-1 within 3 h. Moreover, a Langmuir isotherm model and a pseudo-second-order model have been demonstrated to be more appropriate for the description of the TCH adsorption process of ZIF-8@RC-3 NFMs. Additionally, this composite fibrous material could keep a relatively stable adsorption capability under various ionic strengths. The successful fabrication of the novel ZIF-8@RC NFMs may shed light on the further development of wastewater adsorption treatment materials.

Fabrication and characterization of carrageenan-based multifunctional films integrated with gallic acid@ZIF-8 for beef preservation

The development of environmentally friendly biodegradable films is urgently required for reducing the plastic pollution crisis and ensuring food safety. Thus, here we aimed to prepare ZIF-8 that has delivery ability for gallic acid (GA) and further incorporated this material (GA@ZIF-8) into carrageenan (CA) matrix to obtain a series of CA-GA@ZIF-8 films. This design significantly improved the mechanical strength and UV barrier and reduced water vapor permeability, moisture content, and swelling rate of the CA films. CA-GA@ZIF-8 films exhibited sustainable release of GA and controlled migration of Zn2+ up to 144 h in a high-fat food simulator. Also, the composite films performed high-efficiency antioxidant activities (83.29 % for DPPH and 62.11 % for ABTS radical scavenging activity) and 99.51 % antimicrobial effects against Escherichia coli O157:H7 after 24 h. The great biocompatibility of GA@ZIF-8 and CA-GA@ZIF-8-10 % was confirmed by hemolysis, cell cytotoxicity, and mice model. Finally, the preservation experiments showed that CA-GA@ZIF-8 films could effectively maintain freshness and reduce the growth of microorganisms and oxidation of lipids during the preservation of beef. These results suggest that CA-GA@ZIF-8 films hold promising potential for improving the quality preservation of beef.

A review on artificial water channels incorporated polyamide membranes for water purification: Transport mechanisms and performance

While thin-film composite (TFC) polyamide (PA) membranes are advanced for removing salts and trace organic contaminants (TrOCs) from water, TFC PA membranes encounter a water permeance-selectivity trade-off due to PA layer structural characteristics. Drawing inspiration from the excellent water permeance and solute rejection of natural biological channels, the development of analogous artificial water channels (AWCs) in TFC PA membranes (abbreviated as AWCM) promises to achieve superior mass transfer efficiency, enabling breaking the upper bound of water permeance and selectivity. Herein, we first discussed the types and structural characteristics of AWCs, followed by summarizing the methods for constructing AWCM. We discussed whether the AWCs acted as the primary mass transfer channels in AWCM and emphasized the important role of the AWCs in water transport and ion/TrOCs rejection. We thoroughly summarized the molecular-level mechanisms and structure-performance relationship of water molecules, ions, and TrOCs transport in the confined nanospace of AWCs, which laid the foundation for illustrating the enhanced water permeance and salt/TrOCs selectivity of AWCM. Finally, we discussed the challenges encountered in the field of AWCM and proposed future perspectives for practical applications. This review is expected to offer guidance for understanding the transport mechanisms of AWCM and developing next-generation membrane for effective water treatment.

A charged nanocomposite membrane via co-deposition of gallic acid and polyethyleneimine-silver for improving separation and antibacterial properties

Pharmaceuticals have been continuously detected from surface water and groundwater. In order to improve the rejection performance of pharmaceuticals by a nanofiltration membrane (NF), a positively charged membrane was prepared by co-deposition of natural gallic acid and polyethyleneimine on the polyacrylonitrile hydrolysis membrane. Effects of gallic acid concentration, polyethylene imine concentration, reaction time, and the molecular weight of polyethylene imine were documented. The physical and chemical properties of the membrane were also investigated by surface morphology, hydrophilicity, surface charge, and molecular weight cut-off. The optimized membrane had a molecular weight cut-off of about 958 Da and possessed a pure water permeability of 74.21 L·m^-2·h^-1·MPa^-1. The results exhibited salt rejection in the following order: MgCl₂ > CaCl₂ > MgSO₄ > Na₂CO₃ > NaCl > Na₂SO₄, while the rejection ability of pharmaceuticals is as follows: amlodipine > atenolol > carbamazepine > ibuprofen, suggesting that the positively charged membrane has enhanced retention to both divalent cations and charged pharmaceuticals. In addition, the antibacterial membrane was obtained by loading silver nanoparticles onto the positively charged membrane, which greatly improved the antibacterial ability of the membrane.

A Visible Light-Induced and ROS-Dependent Method for the Rapid Formation of a MOF Composite Membrane with Antibacterial Properties

The diverse application potential of metal-organic framework (MOF) materials are currently limited by their challenging and complicated preparation processes. In this study, we successfully developed a novel strategy for the rapid synthesis of a sustainable MOF composite membrane under neutral conditions with improved physicochemical and antibacterial properties. Our reaction pipeline comprised visible light that induced the production of reactive oxygen species (ROS) from ZIF-8 particles, which facilitated the rapid oxidative polymerization of dopamine to polydopamine. The physicochemical properties of the composite membrane were assessed using imaging methods, including scanning and transmission electron microscopy, X-ray photoelectron spectrometry, and nitrogen adsorption/desorption; its antibacterial effects against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were measured using optical densitometry. The bactericidal potency of the synthesized membrane was >99% against all tested strains under the conditions of simulated sunlight. Moreover, the composite membrane retained its structural integrity and antibacterial effect after multiple cycles of use and recovery, showcasing remarkable stability. Overall, this study displays a ROS-mediated method for the rapid preparation of sustainable MOF composite membranes under neutral conditions with optimal physicochemical characteristics, antibacterial properties, and performance. Our study provides insights into the use of membrane materials as design platforms for a range of diverse practical applications.

Enhanced water permeance and EDCs rejection using a UiO-66-NH2-predeposited polyamide membrane

Endocrine disrupting compounds (EDCs) have been increasingly detected in drinking water sources, and pose severe threat to human health. Polyamide (PA) based nanofiltration (NF) membrane has great potential for EDCs removal from water, but the removal of hydrophobic EDCs is not satisfying due to strong hydrophobic affinity. In this study, UiO-66-NH₂/PA membranes were prepared by predepositing hydrophilic UiO-66-NH₂ onto the substrate prior to interfacial polymerization. The UiO-66-NH₂ aggregates increased the permeable area and strengthened the "gutter effect". Therefore, the pure water flux of UiO-66-NH₂/PA increased by 115% compared with that of the thin-film composite (TFC) membrane, and its rejection of Na₂SO₄ was 96%. The hydrophilicity-enhanced PA film reduced its adsorption of EDCs and decreased the driving force for EDCs diffusion. Moreover, the UiO-66-NH₂-induced hydrophilic nanochannels, including the interfacial gaps between PA film and UiO-66-NH₂ aggregates, the gaps in UiO-66-NH₂ aggregates, and the inherent pores in UiO-66-NH₂ crystals, alleviated the hydrophobic affinity and effectively restricted EDCs diffusion. The rejection rates of methylparaben, propylparaben, bisphenol A, and benzylparaben by the optimal UiO-66-NH₂/PA were 50%, 67%, 75%, and 85%, respectively, and the water/benzylparaben selectivity was 4.4 times as high as that of TFC. The results demonstrate that incorporating hydrophilic metal-organic frameworks (MOFs) can improve the membrane hydrophilicity and create hydrophilic nanochannels, and is an effective strategy to enhance EDCs removal by nanofiltration.