[en] Nanofiltration is a membrane separation pro where the driving force is the difference of pressure on both sides of the membrane. In membrane separation is input stream separated into permeate (the part of the mixture that passes through the membrane) and retentate (a portion of the mixture retained above the inlet surface of the membrane - concentrate). The model dye Acid blue 80 was selected for this work, which was removed from the aqueous solutions by nanofiltration. It is a blue anthraquinone dye used for dyeing wool and polyamide [1]. During experiments attention was paid to the dependences of permeate flow intensity per time with different concentrations and the overall dependence of the permeate flow on the pressure, from where we could find the ideal pressure for operation, whether rejection is sufficient and whether this process can be affected by pH. (authors)

[en] Vitreous carbon is a material of great use in electrochemistry due to its conducting properties and its stability in the presence of acids and strong bases under a wide range of temperatures. For practical uses, the electrochemically active area needs to be increased with an adequate access of reagents from the dissolution. One way to do this is by creating macropores (≥50 nm in diameter following IUPAC) in the material, which can then be applied to porous electrodes, absorption filters, catalytic bearings, etc. A manufacturing procedure for macroporous vitreous carbon was developed and the resulting product was described. The macroporous vitreous carbon was produced by forming phenol-formol and resorcinol-formol resins, to which macropore creating agents were added. The macroporous resins were carbonized by heating (≤900^oC) in inert atmosphere to form the carbonaceous matrix and to eliminate the pore creating agents. The materials were studied with microscopic techniques, electrochemical characterization (cyclic voltametry, faradaic impedance) and conductivity measures. Of the analysis of the manufacturing procedure and the description of the product obtained we can state that its synthesis and carbonization is relatively easy, the carbon obtained is highly permeable due to its interconnected macropores, and the control and distribution of the pore size was attained by the proper selection of pore forming agents (CW)

No abstract available

[en] Synthesis of nano- and microstructures of materials inside the pores of specific template-track membranes can be used to obtain nano- and microwires or nano- and microtubes. It is important for these applications to know the inner geometry of the pores like sizes, shape and surface morphology. Scanning electron microscopy technique (SEM) was used predominantly for this kind of membrane characterisation. The use of other methods of sample preparation as electron, gamma rays or UV irradiation allows to make them more brittle. In present paper authors describe preliminary results of the tensile measurements of membranes after UV irradiation. Poly(ethylene terephthalate) (PET) membrane 10 μm thick with pore diameter 1.0 μm were prepared t the Joint Institute for Nuclear Research (Dubna, Russia) using the standard procedure. The samples were irradiated with UV light with energy flux 2.8 W/cm² during different periods of time. The tensile measurements of the initial and irradiated materials were carried in the Institute of Nuclear Chemistry and Technology (Warsaw, Poland). In conclusion, authors claim that it is possible to find the dose of UV irradiation that ensures the fracture without elastic deformation. In the case when the time of UV irradiation increases up to 90 h, the PET membrane breaks without distortion of its channel structure

[en] Highlights: • Acylation of CyaA-Hly by CyaC-acyltransferase requires AR-acylation and HP-hydrophobic regions, hence hemolysis activation. • ∼100-kDa AR-containing CyaA-RTX lacking HP cannot be acylated by functional CyaC, thus hemolytically inactive. • ∼70-kDa hemolytically inactive-CyaA-HP/BI containing both AR and HP could interact with co-expressed CyaC. • ∼20-kDa CyaA-HP comprising α1-α5 potentially interacted with CyaC via multiple H-bonding and ionic interactions. • HP is required for not only membrane-pore formation but also CyaC-association, hence toxin acylation. Previously, we demonstrated that the ∼130-kDa CyaA-hemolysin (CyaA-Hly, Met⁴⁸²-Arg¹⁷⁰⁶) from Bordetella pertussis was palmitoylated at Lys⁹⁸³ when co-expressed with CyaC-acyltransferase in Escherichia coli, and thus activated its hemolytic activity. Here, further investigation on a possible requirement of the N-terminal hydrophobic region (HP, Met⁴⁸²-Leu⁷⁵⁰) for toxin acylation was performed. The ∼100-kDa RTX (Repeat-in-ToXin) fragment (CyaA-RTX, Ala⁷⁵¹-Arg¹⁷⁰⁶) containing the Lys⁹⁸³-acylation region (AR, Ala⁷⁵¹-Gln¹⁰⁰⁰), but lacking HP, was co-produced with CyaC in E. coli. Hemolysis assay indicated that CyaA-RTX showed no hemolytic activity. Additionally, MALDI-TOF/MS and LC-MS/MS analyses confirmed that CyaA-RTX was non-acylated, although the co-expressed CyaC-acyltransferase was able to hydrolyze its chromogenic substrate−p-nitrophenyl palmitate and acylate CyaA-Hly to become hemolytically active. Unlike CyaA-RTX, the ∼70-kDa His-tagged CyaA-HP/BI fragment which is hemolytically inactive and contains both HP and AR was constantly co-eluted with CyaC during IMAC-purification as the presence of CyaC was verified by Western blotting. Such potential interactions between the two proteins were also revealed by semi-native PAGE. Moreover, structural analysis via electrostatic potential calculations and molecular docking suggested that CyaA-HP comprising α1-α5 (Leu⁵⁰⁰-Val⁶⁹⁸) can interact with CyaC through several hydrogen and ionic bonds formed between their opposite electrostatic surfaces. Overall, our results demonstrated that the HP region of CyaA-Hly is conceivably required for not only membrane-pore formation but also functional association with CyaC-acyltransferase, and hence effective palmitoylation at Lys⁹⁸³.

[en] Highlights: • Proposal for a new type of anisotropically nanoporous graphyne membrane. • Analysis of the water desalination performance of the proposed membrane. • Investigation of possible ways to increase the water flow while blocking the ions. In this paper, the molecular dynamics simulation method is applied to investigate the possibility of using anisotropically nanoporous graphyne membranes (ANGMs) in water desalination. In the simulations, four ANGMs and three γ-graphyne membranes (graphyne-3,-4,-5) in the pressure range of 50 to 250 MPa are used to analyze the effect of pressure and membrane pore size on system performance. The reason for using γ-graphyne membranes is to compare their permeability and ion rejection with the proposed ANGMs to get a better insight into the performance of ANGMs. The results reveal that ANGMs, in addition to having high permeability (7.98–47.14 L/cm²/day/MPa), can block a high percentage of ions thanks to the properly engineered shapes of their nanopores, and also, some of them have more efficient performance than γ-graphyne membranes. Furthermore, the mechanism of high ion-rejection of ANGMs and the effects of their pore shapes on their desalination performance are investigated, in detail. Overall, it can be concluded that, due to the high permeability (about 2–3 orders of magnitude larger than reverse osmosis membrane) and high ion rejection, some of the ANGMs can be considered as promising membranes with high potential for water desalination to solve current problems of global water shortage in the future.

[en] Dead-end filtration equipment was operated to evaluate the performance of polyethersulfone (PES-2) and polyamide (NF-1 and NF-2) membranes in terms of rejection and permeate flux for treatment of high-concentration uranium solutions under a variety of operational conditions. The optimum pH for uranium rejection using PES-2 was determined 6 while the rejection increased significantly in polyamide membranes with increase of pH. The permeate flux of all membranes increased as the pressure increased from 5 to 20 bar while the uranium rejection by these membranes changed differently. As the feed concentration increased from 7.5 to 238 mg/l, the uranium rejection by PES-2 decreased. On the contrary, the rejection by NF-1 and NF-2 increased from 57 to 79% and 62 to 98%, respectively. Also, the permeate flux of PES-2 was relatively constant whereas the permeate flux of polyamide membranes declined due to a decrease in the effective membrane pore size and an increase in osmotic pressure. The results showed that the nanofiltration process can be effectively employed for uranium removal from aqueous solutions.

No abstract available

[en] Covalent Organic Frameworks (COFs) represent a new class of highly porous, crystalline polymers with uniformly arranged ordered pore channels. Even though COFs have been used for storage of a wide variety of molecular species like gases, nanoparticles, enzymes and drugs; the benefits of their ordered pore channels for molecular separation is hardly extracted. The key issue behind this problem is the difficulty of fabricating COF particles into a self-standing, stable membrane form. Apart from the processability, the other formidable obstacle that prevents utilization of COFs in real life applications are i) chemical stability, ii) difficult synthetic procedures, and iii) scalability. In this context, we have successfully overcome the chemical stability problem of COFs, by synthesizing β-ketoenamine based frameworks. Irreversible enol to keto tautomerism resulted in phenomenal stability within the frameworks

[en] Highlights: • TiO₂ nanoparticles were immobilized on PVDF-TrFE for photocatalytic degradation of tartrazine. • A solar photoreactor was used for the photocatalytic experiments. • The dependence of tartrazine concentration on photocatalysis efficiency was addressed. • The light intensity and the reusability of the of the TiO₂/PVDF-TrFE membranes was tested. - Abstract: Recalcitrant dyes present in effluents constitute a major environmental concern due to their hazardous properties that may cause deleterious effects on aquatic organisms. Tartrazine is a widely-used dye, and it is known to be resistant to biological and chemical degradation processes and by its carcinogenic and mutagenic nature. This study presents the use of TiO₂ (P25) nanoparticles immobilized into a poly(vinylidenefluoride–trifluoroethylene) (P(VDF–TrFE)) membrane to assess the photocatalytic degradation of this dye in a solar photoreactor. The nanocomposite morphological properties were analyzed, confirming an interconnected porous microstructure and the homogeneous distribution of the TiO₂ nanoparticles within the membrane pores. It is shown that the nanocomposite with 8 wt% TiO₂ exhibits a remarkable sunlight photocatalytic activity over five hours, with 78% of the pollutant being degraded. It was also demonstrated that the degradation follows pseudo-first-order kinetics model at low initial tartrazine concentration. Finally, the effective reusability of the produced nanocomposite was also assessed.