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The approach of the present work is based on the use of poly (methylmethacrylate) (PMMA) polymer, which is compatible with PVDF and TiO2 nanoparticles in casting solutions, for the preparation of nano-composites membranes using a safer and more compatible solvent. TiO2 embedded poly (vinylidene fluoride) (PVDF)/PMMA photocatalytic membranes were prepared by phase inversion method. A non-solvent induced phase separation (NIPS) coupled with vapor induced phase separation (VIPS) was used to fabricate flat-sheet membranes using a dope solution consisting of PMMA, PVDF, TiO2, and triethyl phosphate (TEP) as an alternative non-toxic solvent. Membrane morphology was examined by scanning electron microscopy (SEM). Backscatter electron detector (BSD) mapping was used to monitor the inter-dispersion of TiO2 in the membrane surface and matrix. The effects of polymer concentration, evaporation time, additives and catalyst amount on the membrane morphology and properties were investigated. Tests on photocatalytic degradation of methylene blue (MB) were also carried out using the membranes entrapped with different concentrations of TiO2. The results of this study showed that nearly 99% MB removal can be easily achieved by photocatalysis using TiO2 immobilized on the membrane matrix. Moreover, it was observed that the quantity of TiO2 plays a significant role in the dye removal.

This Special Issue aims to provide a collection of recent advancements in the field of membrane science [...].This Special Issue aims to provide a collection of recent advancements in the field of membrane science [...].

Vacuum membrane distillation is foreseen as a membrane unit operation capable of providing access to drinking water in the future, through the saline water desalination. To increase the permeation of standard hydrophobic membranes, such as PVDF, mixed matrix membranes are defined as the next generation of membranes and prepared by adding a filler into the polymer phase. Therefore, the aim of this work was to evaluate the effect of a chabazite zeolite filler (from 0.5 to 4 wt%) into PVDF membranes, which were prepared by a non-solvent induced phase separation, and later tested, for the first time, for water desalination application at different operating temperatures. Chabazite was selected due to its high-water affinity (comparable to zeolite 4 A or 13X) and exceptional hydrothermal stability. To explain the impact of the chabazite, resulting membranes were thoroughly characterized with different analytical techniques, such as scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), nitrogen sorption, gas liquid porometry, water contact angle, and mechanical testing. As part of the outcomes, significant enhancement of the desalination performance was observed upon the addition of the chabazite; with the 4 wt% formulation being the best-performing. The permeate flux at 40 °C increased 2.7 times compared to the pristine PVDF membrane, e.g., 6.133 ± 0.540 and 2.256 ± 0.203 kg m − 2 h − 1 , respectively. Despite different nature of the chabazite (hydrophilic) and PVDF (hydrophobic), the compatibility was sufficient to avoid formation of non-selective gaps and completely reject salt (99.99%). The membrane performed stable, with high salt rejection, for over 16 h before pore wetting was observed. Although, some issues with chabazite aggregation and pore wetting were observed, the chabazite demonstrated promising potential as a filler that enhances water transport.

Electrospinning is an emerging technique for the preparation of electrospun fiber membranes (ENMs), and a very promising one on the basis of the high-yield and the scalability of the process according to a process intensification strategy. Most of the research reported in the literature has been focused on the preparation of poly (vinylidene fluoride) (PVDF) ENMs by using N,N- dimethylformamide (DMF) as a solvent, which is considered a mutagenic and cancerogenic substance. Hence, the possibility of using alternative solvents represents an interesting approach to investigate. In this work, we explored the use of dimethyl sulfoxide (DMSO) as a low toxicity solvent in a mixture with acetone for the preparation of PVDF-ENMs. As a first step, a solubility study of the polymer, PVDF 6012 Solef®, in several DMSO/acetone mixtures was carried out, and then, different operating conditions (e.g., applied voltage and needle to collector plate distance) for the successful electrospinning of the ENMs were evaluated. The study provided evidence of the crucial role of solution conductivity in the electrospinning phase and the thermal post-treatment. The prepared ENMs were characterized by evaluating the morphology (by SEM), pore-size, porosity, surface properties, and performance in terms of water permeability. The obtained results showed the possibility of producing ENMs in a more sustainable way, with a pore size in the range of 0.2–0.8 µm, high porosity (above 80%), and water flux in the range of 11.000–38.000 L/m2·h·bar.

Multilayer ceramic membranes to be used for bacteria removal by filtration were prepared from ceramic materials. They consist of a macro-porous carrier, an intermediate layer and a thin separation layer at the top. Tubular and flat disc supports were prepared from silica sand and calcite (natural raw materials), using extrusion and uniaxial pressing methods, respectively. Making use of the slip casting technique, the silica sand intermediate layer and the zircon top-layer were deposited on the supports, in this order. The particle size and the sintering temperature for each layer were optimized to achieve a suitable pore size for the deposition of the next layer. Morphology, microstructures, pore characteristics, strength and permeability were also studied. Filtration tests were conducted to optimize the permeation performance of the membrane. Experimental results show that the total porosity and average pore size of the porous ceramic supports sintered at different temperatures within the range (1150–1300 °C), and lie in the ranges of 44–52% and 5–30 μm, respectively. For the ZrSiO4 top-layer, after firing at 1190 °C, a typical average pore size of about 0.3 μm and a thickness of about 70 μm were measured, while water permeability is estimated to a value of 440 lh−1m−2bar−1. Finally, the optimized membranes were tested in the sterilization of a culture medium. Filtration results show the efficiency of the zircon-deposited membranes for bacteria removal; indeed, the growth medium was found to be free of all microorganisms.

In recent decades, membrane technologies have attracted a lot of interest in operations for highly selective separations. Particularly, pervaporation (PV), vapour permeation (VP) and membrane distillation (MD) represent three membrane processes well-studied and applied at the research level and with a great potential of exploitation in different industrial sectors. [...].

This study explores the development of chitosan-based membranes blended with three distinct deep eutectic solvents (DESs) for the pervaporation separation of methanol and methyl tert-butyl ether. DESs were selected for their eco-friendly properties and their potential to enhance membrane performance. The chitosan (CS) membranes, both crosslinked and non-crosslinked, were characterized in terms of morphology, chemical composition, wettability, mechanical resistance, and solvent uptake. Pervaporation tests revealed that incorporating DESs significantly enhanced the membranes’ selective permeability toward methanol, with up to a threefold increase in separation efficiency compared to pristine CS membranes. The membranes demonstrated a strong dependence on feed temperature, with higher temperatures improving permeation flux but reducing separation factor. Crosslinking with glutaraldehyde further increased membrane selectivity by reducing free volume into the polymer matrix. These findings underscore the potential of DESs as green additives for improving the performance of biopolymer membranes, making them promising candidates for efficient and eco-friendly organic–organic separations.

A microporous carboxylate metal-organic framework MIL-100 Fe was prepared as submicron particles by microwave-assisted hydrothermal synthesis (Fe-MOF-MW). This product was explored, for the first time, for the preparation of polylactic acid (PLA) mixed matrix membranes. The produced MOF was characterised by powder X-ray diffraction (PXRD), environmental scanning electron microscopy (ESEM) as well as by thermogravimetric analysis (TGA) and nitrogen adsorption/desorption. The effect of different Fe-MOF-MW concentrations (0.1 and 0.5 wt%) on the membrane properties and performance were evaluated. These membranes were used in the pervaporation process for the separation of methanol/methyl tert-butyl-ether mixtures at the azeotropic point. The influence of the feed temperature and vacuum pressure on the membrane performance was evaluated and the results were compared with PLA pristine membranes. Moreover, the produced membranes have been characterised in terms of morphology, MOF dispersion in the polymeric membrane matrix, wettability, thickness, mechanical resistance and swelling propensity. The presence of Fe-MOF-MW was found to have a beneficial effect in improving the selectivity of mixed matrix membranes towards methanol at both concentrations. The highest selectivity was obtained for the PLA membranes embedded with 0.5 wt% of Fe-MOF-MW and tested at the temperature of 25 °C and vacuum pressure of 0.09 mbar.

The low-fouling propensity of commercially available polyethersulfone (PES) membranes was studied after modification of the membrane surface via coating with polymerizable bicontinuous microemulsion (PBM) materials. The PBM coating was polymerized within 1 min using ultraviolet (UV) light exposure. It was detected on the PES membrane surface via attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The PBM coating led to an average 10% increase in the hydrophilicity of the PES membrane surface and an increase in total organic content (TOC) removal by more than 15%. Flux-step tests were conducted with model foulant comprising 100 mg L−1 humic acid (HA) solution to detect the onset of critical fouling, characterized by a rapid and substantial increase in TMP, and to compare the fouling propensity of commercially available PES membranes with PBM-coated membranes. The critical flux was found to be about 40% higher for PBM spray-coated membrane and 20% lower for PBM casting-coated membrane than the commercial PES membrane. This demonstrates the performance advantages of the thin PBM layer spray-coated on PES membrane compared to the thick casting-coated PBM layer. The study showcases the potential of PBM spray-coated membranes over commercial PES membranes for use in membrane bioreactors (MBR) for wastewater treatment systems with reduced maintenance over longer operation periods.

We investigate the use of lemon CytroCell nanocellulose as a new biobased filler for Nafion‐based proton exchange membranes. Pristine and composite membranes are prepared via casting and solvent evaporation technique. CytroCell is added up to 20 wt.% with respect to the polymer in a hydroalcoholic solution of Nafion perfluorosulfonic acid ionomer. Composite CytroCell@Nafion membranes are homogeneous on a molecular scale and showed enhanced proton conductivity with optimal performance for the composite membrane embedding 10 wt.% CytroCell. The composite membranes also showed improved flexibility and ductility compared to Nafion pristine membranes. Should stability of the new membranes be confirmed during prolonged PEM electrolyzer or H2 fuel cell operation, these findings open the route to the development of enhanced PEM membranes of broad applicability. A 10 wt.% amount of lemon CytroCell nanocellulose added to Nafion results in homogeneous composite CytroCell@Nafion membranes showing substantially higher proton conductivity, flexibility, and ductility than pristine Nafion membranes prepared via the same casting method and membrane post‐treatment. Should stability of the new membranes be confirmed during prolonged PEM electrolyzer or H2 fuel cell operation, these findings open the route to the development of enhanced PEM membranes of broad applicability.