High purity ethanol is one of the most sought-after renewable energy sources. However, standard production methods yield ethanol of insufficient quality. Membrane processes such as pervaporation are recognized as a viable method for upgrading ethanol. Their performance and selectivity depend solely on membrane employed. Hydrophilic polyvinyl alcohol (PVA) membranes are used industrially for this purpose, but there is a trade-off between selectivity and permeability. Among other materials, chemically converted graphene attracts particular attention due to its exceptional water transport properties, however its application is limited by the fabrication of free-standing membranes. In this study, a composite reduced PVA/graphene oxide (rGO) membranes with different rGO content (up to 49 wt%) was synthesized. Polyvinyl alcohol acted as a mediator to improve the mechanical stability of membrane layers by crosslinking rGO flakes with hydrogen bonds. The resulting membranes were fully characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, water contact angle and mechanical tests. Pervaporation tests with water/ethanol mixtures (10/90 wt%) at temperatures between 20 and 50 oC demonstrated an excellent selectivity (over 12 000) of membranes and satisfactory flux, even at high temperatures. The total permeate flux for membranes varied slightly as a function of operating temperature, demonstrating a good thermostability of the reduced graphene oxide-based membranes. The pervaporation separation index (PSI) of synthesized membrane exceed 5000 and surpassed majority of rGO containing membranes reported in the literature. Results indicate that rGO membranes noncovalently strengthened with PVA are a promising material for selective ethanol dehydration via pervaporation.

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.

The use of traditional biocidal products in cultural heritage has suffered a slowdown due to the risks related to human health and the environment. Thus, many studies have been carried out with the aim of testing innovative and environmentally friendly alternatives. In this framework, this review attempts to provide an overview of some novel potential products with biocidal action, tested to counteract the process of degradation of paper and stone materials due to microbial activity, keeping in mind the sustainability criteria. In particular, we have focused our attention on the testing of nanotechnologies, essential oils, DES (deep eutectic solvents) with low toxicity, and colloidal substances for conservation purposes.

Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (?-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages.

The development of polymeric fabrics with photoinduced antibacterial activity is important for different emerging applications, ranging from materials for medical and clinical practices to disinfection of objects for public use. In this work we prepared a series of cellulose acetate membranes, by means of phase inversion technique, introducing different additives in the starting polymeric solution. The loading of 5,10,15,20-tetraphenylporphyrin (TPP), a known photosensitizer, was considered to impart antibacterial photodynamic properties to the produced membranes. Besides, the addition of a surfactant (Pluronic F-127) allowed to modify the morphology of the membranes whereas the use of graphene oxide (GO) enabled further photo-activated antibacterial activity. The three additives were tested in various concentrations and in different combinations in order to carefully explore the effects of their mixing on the final photophysical and photodynamic properties. A complete structural/morphologycal characterization of the produced membranes has been performed, together with a detailed photophysical study of the TPP-containing samples, including absorption and emission features, excited state lifetime, singlet oxygen production, and confocal analysis. Their antibacterial activity has been assessed in vitro against S. aureus and E. coli, and the results demonstrated excellent bacterial inactivation for the membranes containing a combination of the three additives, revealing also a non-innocent role of the membrane porous structure in the final antibacterial capacity.

A new non-invasive method to evaluate the thermal polarization is herein proposed for hollow fiber (HFs) membranes during the Direct Contact Membrane Distillation (DCMD) process. The goal was reached by using a temperature-sensitive phosphorescent molecular probe such as Tris(phenanthroline) ruthenium(II) chloride (Ru(phen)3) and an infrared camera (IR) camera, to map, in-situ, the thermal profile directly at the membrane surface which is in contact with the hot feed water solution. The molecular probe was immobilized, by means of a perfluoropolyether (PFPE)-based coating, on the surface of a polypropylene HF in order to obtain a thermosensitive polymerized coating. The produced HFs were fully characterized in order to demonstrate the successful embodiment of the molecular probe on the surface of the membrane and their suitability, in terms of pore size, hydrophobicity and stability, for DCMD application. The luminescent activity of the immobilized Ru(phen)3 complex was measured by a bifurcated optical fiber, one branch was used to excite the molecular probe and the other branch was able to constantly monitor the molecular emission which was dependent on the temperature along the HF surface. The HFs were tested in DCMD at different feed temperatures (40 oC, 50 oC, 60 oC) and constant conditions of streams flow rate and distillate temperature (Qf = 90 L/h; Qp = 24 L/h; Tp = 13 oC). The obtained results clearly demonstrated the possibility of studying the thermal polarization phenomenon occurring during DCMD, with the temperature profile developed on the HF surface monitored, for the first time, at molecular level using a non-invasive technique. This approach can shed the light on better understanding this phenomenon and the possible strategies for its mitigation and counteraction.

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 ?m, respectively. For the ZrSiO4 top-layer, after firing at 1190 °C, a typical average pore size of about 0.3 ?m and a thickness of about 70 ?m 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 membrane-based water purification technology, control of the membrane pore structure is fundamental to defining its performance. The present study investigates the effect of the preparation conditions on the final pore size distribution and on the dye removal efficiency of cellulose acetate membranes. The membranes were fabricated by means of phase inversion (using different speeds of film casting and different thicknesses of the casted solution) and introducing modifications in the preparation conditions, such as the use of a coagulation bath instead of pure water and the addition of a surfactant as a solution additive. Both isotropic and anisotropic membranes could be fabricated, and the membranes' pore size, porosity, and water permeability were found to be greatly influenced by the fabrication conditions. The removal capacity towards different types of water contaminants was investigated, considering, as model dyes, Azure A and Methyl Orange. Azure A was removed with higher efficiency due to its better chemical affinity for cellulose acetate, and for both dyes the uptake could be fitted using a pseudo-second order model, evidencing that the rate-limiting step is chemisorption involving valency forces through the sharing or exchange of electrons between the dye and the membrane.

Membrane processes are employed in a wide variety of industrial applications such as separation of complex mixtures, hydrogen isolation, CO2 removal, wastewater treatment, etc. Their use allows energy savings on the production cost compared to other traditional separation technologies. Nevertheless, the preparation of membranes not always fulfills sustainability obligations, especially when considering the commonly employed solvents, i.e., N-methyl- 2-pyrrolidone and N,N-dimethylformamide, to mention just a few. Dialkyl carbonates (DACs) are well-known green solvents and reagents that have been extensively investigated as safe alternatives to chlorine-based compounds and media such as alkyl halides, phosgene, and chlorinated solvents. Following our recent study on a scale-up procedure to non-commercially available or expensive DACs, herein we report for the first time the application of organic carbonates as green media for membrane preparation. Theoretical thermodynamic studies were first carried out to predict the solubilities in DACs of different polymers commonly employed for membranes preparation. As a result, the use of selected organic carbonates as media for polyvinylidene difluoride membrane preparation was investigated by nonsolvent-induced phase separation (NIPS) and a combination of vapor-induced phase separation (VIPS)-NIPS techniques. Membranes obtained with custom-made DACs displayed greater structural resistances and smaller pore sizes compared to the ones achieved using commercially available cyclic organic carbonates. Data collected showed that it was possible to achieve a wide variety of dense and porous membranes by using a single family of compounds, highlighting once again the great versatility of DACs as green solvents.

This review points out two main variants of MBR aerobic MBR and anaerobic membrane bioreactor (AnMBR) in seafood wastewater treatment. The mechanisms of their biodegradability and membrane characteristics are mentioned. Besides, the influence of salinity on such processes is discussed to have a general correlation of different factors to membrane performance and their fouling behaviours.

Today, the applicability of deep eutectic solvents (DES) in various fields, including membrane science and technology, is extensively investigated. In pioneering works, we have implemented different DES as a component of chitosan (CS)-based flat membranes for pervaporation (PV) separation. Herein, we present a new protonated (by sulphuric acid) 2- Pyrrolidone-5-carboxylic acid: sulfolane DES, as a green additive for its chemical blending and thus study its effect in CS structure. The resultant flat CS-based membranes have been characterized and tested for their ability in separating water molecules from ethanolic mixtures (10 wt% water in ethanol) using PV. Experiments revealed a progressive increase in total permeation along with increase of temperature in the range of 20-50 °C. Simultaneously, the value of separation factor was reduced. The maximum permeation (approximately 0.44 kg m-2 h-1) was observed for the highest experimental temperature, in which water was the main component, while the highest separation factor (approximately 518) was observed for lowest operating temperature. It was confirmed that application of selected DES allowed to improve the permeation rates in comparison with the bare CS membrane. As a perspective, such membranes could be tested for another hydrophilic pervaporation applications for the removal of polar compounds - with high applicability in biorefineries.

Membrane bioreactor (MBR) technology has attracted great attention over the last 3 decades and achieved rapid growth in an increasing number of practical small- and large-scale applications worldwide. However, its application in Sub-Saharan Africa as well as in aquaculture was so far limited. The installation and operation of a pilot membrane bioreactor (MBR) in Kisumu, Kenya, adopts an integrated approach by providing an integral, sustainable, cost-effective, and robust solution for water sanitation, which also meets the demand for clean water in the fish processing industry, aquaculture, and irrigation. The innovative system comprises a pilot MBR coupled with a recirculating aquaculture system (RAS) which is linked to a 14.3 kW photovoltaic (PV) system, including a 30 kWh Li battery storage to supply sustainable energy. The RAS is able to recirculate 90-95% of its water volume; only the water loss through evaporation and drum filter back flushing has to be replaced. To compensate for this water deficit, the MBR treats domestic wastewater for further reuse. Additionally, excess MBR treated water was used for irrigating a variety of local vegetables and could be also used in fish processing plants. The pilot-scale MBR plant with around 6 m2 submerged commercial UF polyethersulfone (PES) membranes provides treated water in basic agreement with Food and Agriculture Organization (FAO) standards for irrigation and aquaculture, showing no adverse effects on tilapia fingerlings production. A novel membrane module with a low-fouling coating technology is operating stably but has not yet shown improved performance compared to the commercial one.

Nanofibers represent a consolidated technology in different sectors where they are experiencing rapid growth. The progress made in nanofibers, however, is recently opening new horizons in other fields of application. This chapter offers a perspective on the new advancements of nanofibers, produced by the electrospinning technique, in different innovative applications ranging from the medical field to the production of sensitive materials able to respond to external stimuli, to the development of materials showing peculiar and original properties

This chapter focuses on electrospun membranes produced by the electrospinning process for air filtration applications. Air pollution, above all in metropolitan and highly populated cities, can be characterized by particulate (PM2.5 and PM0.1) or gaseous pollutants that can be captured by different mechanisms employing electrospun membranes. The filtration efficiency can be influenced by their properties. Electrospun membranes are characterized by different advantages such as uniform and controllable structure, tunable porosity, and high surface area. Electrospinning is the most employed technique for the production of nanofiber membranes used in air filtration. The materials that can be employed for their production have been well investigated and most of them rely on polymers and biopolymers that are fundamental for determining the overall membrane performance. The presence of additives is often crucial for giving specific properties to the final membrane. Individual protection devices and uses for environmental remediation are the two main areas where electrospun membranes find application in the air filtration sector. © 2023 Elsevier Inc. All rights reserved.

Biodegradation is among the most common issues affecting Cultural Heritage stone materials in outdoor environments. In recent years, the application of chemical agents with biocidal activity has been the most usual practice when dealing with biofilm removal. In outdoor environments, the use of these biocides is not effective enough, since the materials are constantly exposed to environmental agents and atmospheric pollutants. Thus, it becomes necessary to protect the surface of Cultural Heritage works with antimicrobial coatings to either prevent or at least limit future colonization. In this study, innovative biocides--both natural and synthetic--were applied on a Roman mosaic located in the Archaeological Park of Ostia Antica to compare their effectiveness in removing the biological degradation affecting it. In addition, an antimicrobial coating called "SI-QUAT" was applied and analyzed in situ. SI-QUAT has recently entered the market for its prevention activity against biocolonization. The biocidal activity of these products was tested and monitored using different analytical portable instruments, such as the multispectral system, the spectrocolorimeter, and the bioluminometer. The analyses showed that promising results can be obtained using the combination of the biocide and the protective effect of Preventol® RI50 and SI-QUAT

Air pollution is one of the major environmental concerns in most highly populated cities, which is typically caused by particulate (PM2.5 and PM0.1) or gaseous pollutants. In this framework, membranes produced by the electrospinning technique are attracting more and more interest thanks to their peculiar properties such as interconnected pore structure, tunable porosity and fiber dimension, high surface area to volume ratio and controllable morphology. This review aims to provide an exhaustive overview on the electrospun membranes applied in air filtration introducing the key principles and fundamentals of the separation mechanisms and discussing the influence of membrane properties (e.g., morphology and charge) on their filtration efficiency. The materials generally employed for the fabrication of electrospun membranes (polymers, solvents) and their combination with additives with defined properties are reviewed also in light of the new environmentally friendly approaches which are increasingly adopted in membrane fabrication. Finally, the practical use of electrospun membranes in several application fields such as individual protection devices, environmental remediation, recovery of volatile organic compounds (VOCs), and ventilation and climate control aspects is widely discussed providing also an outlook on the upscaling potential of electrospun membranes and future directions.

Newsletter reporting the activity of the Institute on Membrane Technology in the first six months of the year 2022. In particular, the focus is on: 1) Highlights on Research (top articles published); 2) Projects and Updates; 3) Events, Meetings, Seminars & Courses; 4) Awards & Recognitions; 5) Staff News; 6) Guests Visits & Research Mobility; 7) Recent Publications.

Hollow fibers display unique properties, which make them highly attractive in many industrial fields. This chapter introduces the reader to the world of hollow fibers with a brief and general introduction to membranes. Hollow fibers have played a significant role in the field of membranes from the moment of the development of the first module to the present day, in various fields of application. They have totally revolutionized the world of membranes, thanks to the new technological breakthroughs and innovative materials discovered.

Polymeric hollow fibers are one of the preferred choices of membranes at the industrial level. This chapter illustrates the different techniques employed, both at small and large scale, for their preparation with particular emphasis on the phase-inversion spinning techniques. Hollow fibers, as their flat sheet counterpart, can be prepared by employing traditional phase-inversion techniques even if their preparation can result more challenging. Numerous factors are involved during their preparation process, which affect their final morphology and properties in different ways. The spinning process, employed for the preparation of hollow fibers, consists in five steps: dope solution preparation; dope solution extrusion through the spinneret; possible passage of the nascent fiber into an air-gap region; coagulation; and post-treatment processes. Hollow fibers can be prepared following different methods of spinning, which include melt spinning, dry spinning, wet spinning, and dry/wet spinning. Polymer concentration is undoubtedly one of the most critical parameters that have to be carefully taken into consideration before preparing hollow fibers.