Abstract
In the present work, the novel dense and supported membranes based on polyvinyl alcohol (PVA) with improved transport properties were developed by bulk and surface modifications. Bulk modification included the blending of PVA with chitosan (CS) and the creation of a mixed-matrix membrane by introduction of fullerenol. This significantly altered the internal structure of PVA membrane, which led to an increase in permeability with high selectivity to water. Surface modification of the developed modified dense membranes, based on composites PVA-CS and PVA-fullerenol-CS, was performed through (i) making of a supported membrane with a thin selective composite layer and (ii) applying of the layer-by-layer assembly (LbL) method for coating of nano-sized polyelectrolyte (PEL) layers to increase the membrane productivity. The nature of polyelectrolyte type—(poly(allylamine hydrochloride) (PAH), poly(sodium 4-styrenesulfonate) (PSS), poly(acrylic acid) (PAA), CS), and number of PEL bilayers (2–10)—were studied. The structure of the composite membranes was investigated by FTIR, X-ray diffraction, and SEM. Transport properties were studied during the pervaporation separation of 80% isopropanol–20% water mixture. It was shown that supported membrane consisting of hybrid layer of PVA-fullerenol (5%)–chitosan (20%) with five polyelectrolyte bilayers (PSS, CS) deposited on it had the best transport properties.
Highlights
Polymers are widely used materials in different fields owing to their good mechanical and physicochemical properties as well as their economic accessibility [1,2,3]
These dense membranes based on composites polyvinyl alcohol (PVA)-chitosan and PVA–fullerenol–chitosan were created for the investigation of the modifier impact on the transport characteristics of PVA-based membranes, due to the fact that in the study of dense membranes, the influence of the support and defects of the selective layer can be excluded
To improve transport properties by reducing the thickness of the hybrid membranes, it was decided to develop a supported membrane with a thin selective layer based on PVA composites casting on a commercial ultrafiltration support UPM-20, which did not affect the mass transfer of the components through the membrane (1st possibility of the surface modification)
Summary
Polymers are widely used materials in different fields owing to their good mechanical and physicochemical properties as well as their economic accessibility [1,2,3]. The use of polymers for membrane production for applying in different membrane processes enables highly effective separation of liquid and gas mixtures. There are a large number of commercial polymer membranes that have undergone the necessary series of studies and found their application in membrane processes in industry due to their low cost, good film-formability, and mechanical strength. Polymers 2018, 10, 571 and productivity for existing processes. In this regard, the development of new membranes is a highly important task
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