Interpenetrating Nanofibrous Composite Membranes for Water Purification

Free-standing interpenetrating nanofibrous composite membranes were fabricated by the two-nozzle electrospinning approach, where poly­(vinyl alcohol) (PVA) and polyacrylonitrile (PAN) nanofibers were integrated. The membrane contained two components: PVA nanofibers with thicker diameter as the skeleton scaffold and PAN nanofibers with thinner diameter as the functional scaffold. The geometrical characteristics of the composite membrane were determined in terms of fiber diameter, pore size, and their distributions, which were affected by electrospinning parameters. The mechanical properties and durability of the composite membrane, containing cross-linked PVA skeleton (with glutaraldehyde (GA)) and interpenetrating ultrafine PAN scaffold, were drastically enhanced as compared to the single-component membrane. A model of interpenetrating nanofibrous networks was proposed to describe the structural feature of the composite membrane. The resulting composite membrane exhibited high water permeability as well as high adsorption of chromium­(VI) from contaminated water after functionalization of the PAN component by surface grafting of positively charged species.