Advanced Membranes最新文献

Mineral scaling caused by multivalent metal ions can significantly hinder the long-term operation of nanofiltration membranes. In this study, in-situ interfacial polymerization including a posttreatment by using a citric acid solution was employed in order to mitigate scaling on the membrane surface. Under the optimal conditions (15 ​min of posttreatment with a 2 ​M citric acid solution), the membrane water permeance increased from 5.76 ​± ​0.2 to 15.1 ​± ​1.8 ​L⋅m⁻²⋅h⁻¹·bar⁻¹ for the pristine and the optimal membrane, respectively. The molecular weight cut-off of the optimal membrane was 399 ​Da, which allows for the removal of organic micropollutants in groundwater. Furthermore, the resulting membrane showed a Na₂SO₄ and CaCl₂ rejection of 92.5 ​± ​1.9 and 11.4 ​± ​1.3%, respectively. During the anti-scaling tests, the membrane fabricated with this strategy exhibited a minor decline of the water permeance of 33.5% when subjected to the same water recovery process, opposed to 65.8% for the pristine membrane. This proposed fabricating procedure thus provides an effective strategy for retarding membrane scaling in desalination applications.

Driven by the diverse functionalization of halloysite nanotubes (HNTs) and advanced membrane preparation technologies, a tremendous progress in HNTs-polymer nanocomposite membranes has been made during the last dozen years. Yet even with these achievements, an elaborate and comprehensive overview on the rational design of HNTs-polymer nanocomposite membranes, their various application areas as well as the corresponding membrane performance status is still missing. Herein, we provide a timeline of the ongoing research on the advanced HNTs-polymer nanocomposite membranes and then outline the progress on: (1) versatile functionalization methods of the HNTs for the state-of-the-art HNTs-polymer nanocomposite membranes. (2) key routes to prepare and design the HNTs-polymer nanocomposite membranes, and the corresponding influences of the modified HNTs on their membrane structures and performances. (3) the overall inductive performances for specific applications in the areas of water treatment, gas treatment, energy conversion, as well as biomedicine. We envision that an insightful perspective will be timely presented in this review to stimulate the innovation in developing more advanced HNTs-polymer nanocomposite membranes, and then motivating and extending their applications.

Superacid catalysis, a suitable method for the synthesis of membrane materials owing to its facile polymerization procedure, has been extensively studied. However, superacid-catalyzed binary coplanar polymer membranes generally exhibit low permeabilities. In this study, a rigid 3D triptycene-based polymer was synthesized by the superacid catalysis of triptycene with trifluoroacetophenone and diphenyl ether to enhance membrane permeability for the molecular sieving of nitrogen over volatile organic compound (VOC). The synthesis of polymers with (CF₃PhET) or without triptycene (CF₃PhE) was investigated using different characterizations. The triptycene content of the synthesized polymers was optimized based on an analysis of the molecular weight, membrane-forming properties, and separation performance. The separation performances of membranes fabricated using CF₃PhE, CF₃PhET, and a mixture of CF₃PhE and triptycene were compared. Results showed that the introduction of non-coplanar triptycene in the membrane can increase permeability by nearly 60 times due to the enhanced free volume, from 30 Barrer for the CF₃PhE membrane to 1755 Barrer for the membrane with 5 ​mol% triptycene content for the separation of a 3 ​mol% nitrogen/cyclohexane mixture at 1 ​L/(m²·min). Furthermore, the rejection remains constant, which provides an effective idea for the synthesis of membrane materials with high performance using superacid catalysis.

Commercial nanofiltration (NF) membranes based on polyamides may experience a decline in permeation performance after prolonged operation. The short lifespan of NF membranes will lead to waste and additional carbon emissions. Thus, rejuvenating membranes and extending their lifespan seem more meaningful than investigating new materials. In this paper, polyamide NF membranes were modified with various polyphenol monomers to improve their permeation performance. The effects of different polyphenols on pore size, surface morphology, and permeation performance of the NF membranes were thoroughly investigated. After modification with tannic acid, the NF membrane exhibits improved salt rejection while experiencing an acceptable decrease in water flux. It should be noted that the commercial NF membrane element fabricated by Koch can recover its Na₂SO₄ rejection from 83.0% to 94.2% and demonstrate long-term stability after rejuvenation with tannic acid. Combined with the environmental friendliness of polyphenols, this straightforward modification method has the potential for prolonging the operational lifespan of industrial NF membrane products.

Organic solvent nanofiltration (OSN) is an emerging energy-efficient separations technology, which urgently requires easily processable OSN membranes with high selectivity and broad-spectrum organic solvent applicability to facilitate enhanced industrial applications. Herein, we describe the preparation of microporous polyesteramide (PEA) membranes through interfacial polymerization (IP) between amino-diphenol monomers and trimesoyl chloride (TMC) on a poly(ether ether ketone) (PEEK) support. The crosslinked network structures and large twisted monomers enhance the microporosity of PEA membranes, leading to a significant improvement in solvent permeance while maintaining high selectivity. The optimized PEA membrane demonstrates exceptional permeance for acetone (21.0 ​L ​m⁻² ​h⁻¹ bar⁻¹) and methanol (14.3 ​L ​m⁻² ​h⁻¹·bar⁻¹), with a molecular weight cut-off of 296 ​g ​mol⁻¹. Additionally, the PEA/APH-diphenol membrane exhibits ultrafast permeance for the nonpolar solvent toluene (8.3 ​L ​m⁻² ​h⁻¹·bar⁻¹), owing to the introduction of a large number of ester groups. Overall, PEA membranes prepared through the molecular-level structure design of IP monomers possess enormous industrial application potential owing to their high performance and broad-spectrum applications.