Electrospinning of chitosan/PVA nanofiberous membrane for efficient removal of acid dyes from waste water

Chitosan is N-deacetylated form of chitin that is obtained by alkaline treatment of chitin (50% of aqueous NaOH) at high temperature[1]. Chitosan has a repeated structure of (1,4)-linked β-D-glucosamine and an apparent pK of 6.5. Commercial products are traditionally composed of 80% β-D-glucosamine and 20% N-acetyl-β-D-glucosamine [2]. Chitosan is a cationic polymer. It’s key properties are biocompatibility, non-toxicity (its degradation products arenatural metabolites) and solubility in moderated acidic aqueous solutions. Chitosan has been widely used in food, cosmetic, biomedical, treatment of wastewater, chromatographic support and pharmaceutical applications[3]. A large variety of useful forms, including beads, films,sponges, tubes, powders, and fibers, can be obtained from chitosan [4]. Electrospinning is a versatile technique for producingmultifunctional nanofibers from various polymers, polymer blends and composites[5] Electrospinning applies high voltages to a capillary droplet of polymer solution or a meltto overcome liquid surface tension and thus enables the formation of much finer fibers than conventional fiber spinning methods.[6] Electrospinning nanofibers have many unique properties such as high surface area-to-volume, pore size within a nano range, high porosity and flexibility for chemical/physical functionalization [7]. Therefore, it has been shown that the very fascinating properties of these electrospun nanofibersmake them applicable in numerous areas, including biotechnology membranes/filters, electroanalysis, power source, and so on[8]. Poly (vinyl alcohol) (PVA) is a nontoxic, water-soluble, biocompatible, and biodegradable synthetic polymer, which is widely used in biomedical field.PVA has better fiberforming and highly hydrophilic properties, and its fibers have been commercialized since the 1950s[9].