Abstract
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 PERVAPTM 1201.
Highlights
Membrane-based separation technologies are known to be efficient for molecular separations, and they are already considered as alternative processes to traditional methods at the industrial scale, especially for the separation and purification of azeotropic liquid mixtures and for components having close boiling points
For industrial application, the solvent must usually be anhydrous. 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 and a high energy consumption
The aim of this work was to study dense and supported pervaporation polyvinyl alcohol (PVA)-based membranes modified with poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS)/PAH top nanolayers
Summary
Membrane-based separation technologies are known to be efficient for molecular separations, and they are already considered as alternative processes to traditional methods (absorption, distillation, extractive rectification) at the industrial scale, especially for the separation and purification of azeotropic liquid mixtures and for components having close boiling points. For industrial application, the solvent must usually be anhydrous 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). 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]
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