Manipulation of the loading and size of zero-valent iron nanoparticles immobilized in electrospun polymer nanofibers

A simple approach to controlling the loading percentage and size of zero-valent iron nanoparticles (ZVI NPs) immobilized within polyacrylic acid (PAA)/polyvinyl alcohol (PVA) nanofibrous mats for dye remediation applications is described. A functional "nanoreactor" comprised by electrospun PAA/PVA nanofibers served to bind ferric ions with the carboxyl groups of PAA, prior to their reduction to ZVI NPs. The resulting ZVI NP-immobilized hybrid polymer nanofibers were characterized using scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The morphology of the polymer nanofibers exhibited no appreciable change even after eight cycles of ferric ion binding/reduction, and the loading percentage and size of the ZVI NPs were controlled simply by varying the number of ferric ion binding/reduction cycles. Dye remediation experiments revealed that the decoloration effect of ZVI NPs immobilized within the polymer nanofibers is both size- and loading percentage-dependent. At low loading percentages, smaller ZVI NPs better decoloration efficiency, while at relatively higher loading percentages the permeability of the nanofibers plays an important role in determining ZVI NPs decoloration efficiency. The strategy of controlling loading percentages and sizes of the ZVI NPs within polymer nanofibers may be extendable to other particle systems for various applications in catalysis, sensing, and environmental remediation.