Novel supported membranes based on polyvinyl alcohol (PVA) were developed using two strategies: first, by the modification of the PVA network, via so-called bulk modification, with the formation of the selective layer accomplished through the introduction of fullerenol and/or poly(allylamine hydrochloride), and second, by the functionalization of the surface with successive depositions of multilayered films of polyelectrolytes, such as poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate) on the PVA surface. The membrane surface modifications were characterized by scanning electron microscopy and contact angle measurements. The modified PVA membranes were examined for their dehydration transport properties by the pervaporation of isopropyl alcohol-water (80/20% w/w), which was chosen as a model mixture. Compared with the pristine PVA membrane, the main improvement was a marked increase in permeance. It was found that the surface modifications mainly gave rise to a higher global flux but with a strong reduction in selectivity. Only the combination of both bulk and surface modifications with PEL could significantly increase the flux with a high water content in the permeate (over 98%). Lastly, it should be noted that this study developed a green procedure to prepare innovative membrane layers for dehydration, making use of only water as a working medium.

In this work, dense and supported pervaporation polyvinyl alcohol (PVA)-based membranes modified with poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate)(PSS)/PAH top nanolayers were synthesized. Two main points were investigated: the role of the polyelectrolyte PAH on water selectivity of the selective polymer matrix and the impact of the porous substrate based on polyacrylonitrile (PAN) and aromatic polysulfone amide (UPM-20 ® ), used to get supported high-performance membranes. Various methods of analysis (fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), porosity, contact angles, ultrafiltration) were applied to study the developed membranes. Transport characteristics of the developed membranes were studied in isopropanol dehydration by pervaporation. Obtained results are discussed in the light of the structure and physicochemical characteristics of these PVA/PAH membranes and the types of porous substrate. It was shown that the PAN-supported membrane with the selective layer based on PVA/PAH modified by 10 polyelectrolyte PSS/PAH bilayers possessed~4.5 times higher permeation flux with the same high selectivity level (99.9 wt % water in the permeate) for the dehydration of the isopropanol (20 wt % water) at 60 • C compared to the commercial analog PERVAP TM 1201.Polymers 2020, 12, 14 2 of 22 repellents, etc. Yet, for industrial application, the solvent must usually be anhydrous. In addition, this alcohol forms an azeotropic mixture with water (12 wt % water-88 wt % isopropanol) [8], which considerably hinders its dehydration via simple traditional methods of separation that entail a non-environmentally friendly process (addition of a third harmful organic reagent) and a high energy consumption (high temperature or low pressure, expensive equipment). Pervaporation is a promising and perspective technology for this task. Different types of pervaporation membranes (polymeric, inorganic, and composite) were developed for the dehydration of isopropanol [9][10][11][12]. Polymeric membranes find wider applications and are attractive because of the simplicity of their fabrication and lower price compared to inorganic membranes. The most popular polymer materials for dehydration are green water-soluble polymers, such as polyvinyl alcohol (PVA), chitosan (CS), cellulose, and sodium alginate [1,13,14], because these polymers possess high selectivity to water. However, the use of membranes based on these polymer materials requires additional cross-linking that, as a rule, leads to the decrease of permeation flux [12]. To improve the transport characteristics, additional bulk and surface modification methods can to be successfully applied, as previously shown [15][16][17][18][19][20].In this study, the selected material is polyvinyl alcohol, which is widely used for dehydration purposes due to its high water selectivity, good film-forming properties, and economic accessibility [1,4,21,22]. However, p...

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Nowadays, nanofiltration is widely used for water treatment due to its advantages, such as energy-saving, sustainability, high efficiency, and compact equipment. In the present work, novel nanofiltration membranes based on the polymer of intrinsic microporosity PIM-1 modified by metal-organic frameworks (MOFs)—MIL-140A and MIL-125—were developed to increase nanofiltration efficiency for the removal of heavy metal ions and dyes. The structural and physicochemical properties of the developed PIM-1 and PIM-1/MOFs membranes were studied by the spectroscopic technique (FTIR), microscopic methods (SEM and AFM), and contact angle measurement. Transport properties of the developed PIM-1 and PIM-1/MOFs membranes were evaluated in the nanofiltration of the model and real mixtures containing food dyes and heavy metal ions. It was found that the introduction of MOFs (MIL-140A and MIL-125) led to an increase in membrane permeability. It was demonstrated that the membranes could be used to remove and concentrate the food dyes and heavy metal ions from model and real mixtures.