Preparation of Tetraethylene Glycol Dialdehyde Cross-linked Electrospun PVA Nanofiberous Membranes for Use in Water Treatment

The recent increasing use of horizontal hydraulic fracturing and the development of the Alberta tar sands mining have been turning million gallons of fresh water every day into wastewater that contains deadly chemicals including carcinogens, toxins and organic wastes. The development of effective low cost and energy efficient water filtration techniques is required for treating these polluted wastewaters.;The most important part of any water filtration such as reversed osmosis (RO), is the development of the filtration membrane material. The effectiveness of the filtration membranes can be mainly evaluated based on its flux rate and rejection percentage. The majority of the membranes used in the industry and in labs are made of hydrophobic polymer materials. However surface fouling due to organic substances getting stuck on the hydrophobic membrane can really impede the flux rate and decreases the effectiveness of the filtration membrane.;Poly(vinyl alcohol) (PVA) is a cheap polymer material which is commercially available. It can be electrospun into a nanofiberous membrane. However, due to its hydrophilic nature, PVA dissolves easily in an aqueous environment. Adequate cross-linking of PVA is required before it can be applied as a filtration membrane for water treatments. Cross-linked PVA membrane that retains high hydrophilicity can decrease surface fouling caused by hydrophobic attraction between organic contaminates and the membrane.;The optimum condition determined for electrospinning PVA solutions was by using an 8 wt% PVA solution with 0.4 wt% of Triton X-100 surfactant added to the solution, which was then electrospun at 30 µL/ feed rate under 27 kV.;Tetraethylene glycol dialdehyde diethyl acetal was synthesized from tetraethylene glycol and bromoacetaldehyde diethyl acetal and was characterized by 1H and 13C NMR. The acetal functionalities were converted to aldehyde before cross-linking with electrospun PVA membrane in acetone with diluted 0.1 N HCl. The resulting PVA membrane was viewed under scanning electron microscopy (SEM) and adequate cross-linking was confirmed. The hydrophilicity of such cross-linked PVA membrane was compared with glutaraldehyde cross-linked PVA membrane in an attempt to measure their water contact angles.