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Organic solvent nanofiltration (OSN) offers an energy-efficient alternative to conventional thermal distillation processes for organic solvent separations. However, the fabrication of polymeric OSN membranes with adequate chemical stability in strong polar aprotic solvents remains a remarkable challenge. In this work, chemically robust polyamide thin-film composite (TFC) OSN membranes were fabricated by utilizing an innovative chemical modification of polyimide (PI) nanofiber substrate via one-step crosslinking and thermal cyclodehydration of terephthalic hydrazide (TPDH). The crosslinking and cyclodehydration reaction mechanisms were thoroughly elucidated and the effects of TPDH loading and thermal treatment conditions on solvent resistance and pore structure of the resulting TPDH/PI nanofiber substrates as well as the formation of the polyamide selective layer were systematically studied. The resulting TFC membranes show excellent stability in polar aprotic solvents (i.e., DMF, DMAC, and NMP), and a high DMF permeance of 9.4 L m−2 h−1 bar−1 was achieved with a 99.8% rejection to Rose Bengal at 2.0 bar. The outstanding long-term performance stability revealed the robust structure of the developed TFC OSN membranes. This work demonstrates a facile strategy to address the chemical stability limitations of TFC OSN membranes through a multifaceted yet generalizable approach of chemical crosslinking and thermal cyclodehydration. We believe this strategy can be broadly applied to different substrates, enabling TFC membranes to address a wide variety of unmet OSN needs. (TFC membranes with chemically robust TPDH/PI nanofiber substrates for polar solvent filtration). [Display omitted] • Polyimide (PI) nanofiber substrate was chemically crosslinked by terephthalic dihydrazide (TPDH). • Thermal cyclodehydration further improves the chemical robustness of the crosslinked TPDH/PI nanofiber substrates. • The modified TPDH/PI nanofiber substrates show outstanding stability in polar aprotic solvents. • The resulting polyamide TFC membranes exhibit excellent performance in organic solvent filtration. [ABSTRACT FROM AUTHOR]

Membranes with high permeance, excellent selectivity coupled with adequate solvent resistance are required for organic solvent nanofiltration (OSN) applications. But the "trade-off" relationship between the solvent resistance and permeance remains a critical challenge for polymeric-based thin film composite (TFC) membranes with necessary chemical crosslinking. Herein, a novel facile cyclization modification of polyacrylonitrile (PAN) nanofiber substrate is proposed by a simply thermal treatment and subsequent alkaline hydrolysis, and employed for the fabrication of TFC-OSN membrane for the first time in strong polar aprotic solvent systems. The reaction mechanism involved, solvent resistance and pore structure of PAN nanofiber substrate brought by the modification are investigated. TFC-OSN membrane supported by the modified PAN nanofiber substrate exhibits ultrahigh solvent permeance up to 13.3 L m−2 h−1 bar−1 coupled with a 99.7% rejection in rose bengal/DMF system and a good long-term stability. This study is therefore believed to provide useful guidelines for the development of next-generation OSN membranes. [Display omitted] • A facile cyclization modification of PAN with thermal and alkaline treatment is proposed. • Modified PAN nanofiber substrate shows enhanced resistance in strong polar aprotic solvents. • The substrate with high porosity shows superior pure solvent permeance. • TFC membrane exhibits superior OSN performance to most previous works. [ABSTRACT FROM AUTHOR]

Water security is one of the most pressing global challenges due to its effects on human health. To face the challenge of water pollution, membrane technology was widely applied for the removal of pollutants and desalination. In this work, an enzyme-like ligand, Iron (III)-tetraamidomacrocyclic ligand (Fe(III)-TAML), was for the first time immobilized into a polyethersulfone (PES) membrane for the catalytic oxidation removal of micropollutants during the ultrafiltration process. Through the introduction of graphene oxide-polyethyleneimine (GO-PEI), Fe(III)-TAML was successfully immobilized into the membrane. Results shown that porosity and hydrophilicity of the PES membrane were significantly enhanced after GO-PEI modification. Furthermore, about 100% of bisphenol A (BPA) in the feed water was removed after filtration using the Fe(III)-TAML immobilized membrane at a high flux of 192 L/m2 h, which was attributed to the generation of high valence Fe through activating Fe(III)-TAML by H 2 O 2. Moreover, the Fe(III)-TAML in the membrane could be simply regenerated by a re-adsorption process, and the flux and removal efficiency of BPA were stabled during five cycles. Additionally, the TAML/GO-PEI/PES membrane maintained a high water flux and BPA removal efficiency for the filtration of actual surface water. Overall, these results highlight the potential of enzyme-like ligand catalytic oxidation coupled with ultrafiltration to remove micropollutants at a high flux for ensuring the water safety. [Display omitted] • Enzyme-like ligand was first coupled with UF membrane for micropollutant removal. • BPA in actual water was well removed by filtration using TAML/GO-PEI/PES membrane. • TAML on the membrane could be regenerated by a simple re-adsorption process. • The oxidation process of TAML/H 2 O 2 was helpful for the membrane antifouling. [ABSTRACT FROM AUTHOR]

Substrate construction is considered as the most effective approach to alleviate the internal concentration polarization (ICP) effect, and therefore achieves the excellent performance of resultant thin-film composite (TFC) membrane in forward osmosis (FO) process. In this work, a well-aligned nanofiber substrate was prepared and employed for constructing the high-performance TFC-FO membrane for the first time. The physicochemical properties of the substrate, the micro-structure of polyamide layer and the separation performance of resultant TFC-FO membranes were systematically investigated. Taking advantages of the larger pore size and the better pore interconnectivity of the well-aligned nanofiber substrate, the resultant TFC-FO membrane achieves the best water fluxes of 50.7 and 62.9 LMH, accompanied with the ultralow reverse salt flux in FO and PRO modes, using deionized water feed solution and 1 M NaCl aqueous draw solution. This work may provide a new orientation in developing high-performance TFC membranes. Image 1 • Aligned nanofiber substrate with slit-shape pore structure was facilely prepared. • TFC membrane with aligned nanofiber substrate was reported for the first time. • Aligned nanofiber substrate alleviates internal concentration polarization effect. • TFC membrane with aligned nanofiber substrate shows excellent FO performance. [ABSTRACT FROM AUTHOR]

Ultrafiltration membranes have gained significant prominence in water and wastewater treatment, holding potential for application in combating antibiotic resistance. Herein, we successfully fabricated a polyvinylidene fluoride copolymer-based ultrafiltration membrane capable of effectively removing antibiotic-resistant bacteria (ARB) from water and wastewater through the molecular design approach, incorporating polyionic liquid (PIL) via atom transfer radical polymerization. The as-prepared membrane exhibited bactericidal properties against wild-type bacteria, ARB and opportunistic pathogens, showcasing an inactivation efficiency exceeding 70 %. These properties were attributed to the increased intracellular accumulation of reactive oxygen species and enhanced membrane permeability, suggesting the involvement of oxidative stress and disruption of the cell outer membrane in bacterial cell lysis. To investigate the interaction with bacterial cells, we utilized liposome vesicles as a model, revealing that the PIL brush effectively disrupted the integrity of the bacterial cell's phospholipid bilayer through its alkyl chain. Furthermore, zeta potential measurements indicated that the role of electrostatic interactions between the imidazole ring and bacteria in bacterial inactivation mechanisms. During wastewater filtration, the PIL-M membrane demonstrated outstanding efficiency in total bacteria removal, exceeding 99.1 %. Additionally, the PIL-M membrane displayed significant bacterial inactivation capabilities against total bacteria as well as sulfamethoxazole-resistant bacteria, chloramphenicol-resistant bacteria, and tetracycline-resi8stant bacteria, achieving respective inactivation efficiencies of 91 %, 93 %, 87 %, and 85 %. These results highlight the membrane's potential in mitigating membrane fouling and inactivating antibiotic-resistant bacteria. Overall, the findings of this study suggest that the PIL-M membrane can effectively contribute to controlling bacterial resistance in water and wastewater environments. [Display omitted] • The membrane composed of PIL-P copolymer was successfully synthesized. • The PIL-M membrane demonstrated broad-spectrum antibacterial activity. • The PIL-M membrane exhibited remarkable capabilities in retention and inactivation ARB. • The bactericidal mechanism of PIL brush was proved. • The PIL brushes exhibit enhanced antifouling performance. [ABSTRACT FROM AUTHOR]

Two-dimensional nanocomposite membranes (NCMs) have attracted increased attention, but the effects of nanomaterials on membranes and phase inversion mechanisms are still unclear. In this study, graphene oxide (GO) was combined with nitrogen defect-modified g-C 3 N 4 (DCN) nanosheets by grinding to obtain GO@DCN, with subsequent doping into polyvinylidene fluoride (PVDF) by non-solvent induced phase separation (NIPS) to prepare a series of hydrophilic NCMs. The thermodynamic ternary phase diagram of NCMs is reported for the first time. Compared with pure PVDF, the phase inversion of NCMs was accelerated with the addition of DCN, GO and GO@DCN nanomaterials, which lead to sequential increment in porosity, providing channels for water molecules. Besides, the Density Function Theory(DFT) calculations indicated a strong interaction between PVDF and GO@DCN, which also contributes to the rapid phase inversion of the PVDF/GO@DCN. Furthermore, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory demonstrates that the attraction between PVDF/GO@DCN 2.0 and Bovine Serum Albumin (BSA) is halved compared to PVDF and BSA, indicating superior antifouling ability. At the same time, the negative zeta potential of NCMs rose, which enhanced the repulsion between NCMs and the negatively charged BSA contaminants in water. Thus, in contrast to PVDF, the permeate flux of PVDF/GO@DCN 2.0 increased from 161.6 Lm−2h−1 to 387.8 Lm−2h−1 and the rejection of BSA from 80.1% to 91.6%, respectively. The flux recovery ratio (FRR) of PVDF/GO@DCN 2.0 improved 30.4%, and irreversible fouling decreased 29.6%. After five cleaning cycles, the NCM still maintained excellent stability. [Display omitted] • PVDF/GO@DCN membrane has superior permeability due to high porosity and hydrophlicity. • The three-phase diagram is firstly established to confirm the acceleration of thermodynamics. • The DFT calculations confirmed the strong interaction between GO@DCN and PVDF. • PVDF/GO@DCN membrane enhances negative charge than original PVDF effectively. • XDLVO theory confirms the excellent contamination resistance of PVDF/GO@DCN membrane. [ABSTRACT FROM AUTHOR]

In this work, a novel combined forward osmosis (FO)-extraction process is applied for resource recovery and dye wastewater treatment simultaneously. FO process is utilized to concentrate the dye wastewater, to achieve a higher concentration factor and lower energy consumption compared with NF process. The FO pre-treatment can increase the dye concentration and reduce the stream volume, thereby reducing the reagent consumption in the subsequent extraction process and lowering the processing cost. In the extraction process, the compositions of the extractant and stripping agent are also optimized, and the recovery rates for congo red, fuchsin acid, orange acid and methyl blue are 97.8%, 82.1%, 80.1% and 76.1%, respectively. In addition, the FO process is driven by the simulated seawater (0.6 M NaCl) draw solution, which can avoid the energy-intensive operation for the draw solution regeneration. Therefore, this study provides a sustainable strategy for the dye wastewater treatment in the coastal areas. Image 1 • FO pre-treatment can reduces the reagent consumption in extraction process. • Hybrid process achieves high dye recovery from dye wastewater. • FO shows a higher concentration factor and lower energy consumption compare to NF. • Seawater-driven FO avoids energy-intensive regeneration of draw solution. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) is a promising membrane-based technology for water treatment and desalination. But, internal concentration polarization (ICP), a unique phenomenon in FO, generally leads to the sharp performance decline. In this study, a novel polyacrylonitrile (PAN) substrate with low polymer concentration (4 wt%) of the thin-film composite (TFC) membrane with a low membrane structural parameter (S) is developed with sodium chloride (NaCl) aqueous solution as the coagulation bath, and exhibits high performance for FO applications. The existence of NaCl in the coagulation bath not only affects the phase inversion process significantly, resulting in the formation of a thin substrate with finely tuned morphology structure, but also benefits the formation of a uniform and defect-free top polyamide (PA) layer. Effects of NaCl content in the coagulation bath on the morphology and intrinsic properties of resulting PAN substrates, the formed PA layer, as well as the morphology and FO performance of resulting TFC membranes, are investigated systematically. Moreover, an extended study on cellulose acetate (CA) substrate is also conducted to study the universality of this salt induction method to fabricate high-performance TFC membranes. Compared to the control TFC membrane, modified TFC membranes show much lower S parameters and superior separation performance with the higher water flux (324% increment) and lower reverse salt flux (58% reduction). Image 1 • Substrates with low ICP were fabricated using salt-containing coagulation bath. • Modified substrates exhibit higher porosity, smaller thickness and large pore size. • TFC membranes with a modified substrate have rougher and thicker PA layers. • Modified TFC membrane possesses much higher water flux and lower reverse salt flux. • Modified TFC membrane has significantly lower structural parameter. [ABSTRACT FROM AUTHOR]