We report a facile and economic approach to fabricating catalytic active palladium (Pd) nanoparticle (NP)-immobilized electrospun polyethyleneimine (
PEI)/polyvinyl alcohol (PVA) nanofibers for catalytic reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). In this study, PEI/PVA nanofibrous mats were first electrospun from homogeneous mixture solution of PEI and PVA, followed by cross-linking with glutaraldehyde vapor to render the fibers with good water stability. The nanofibrous mats were then alternatively soa
ked in potassium tetrachloropallidate (K
2PdCl
4) and sodium borohydride solution, and the PdCl
42- anions complexed with the free amine groups of PEI were able to be reduced to form zero-valent Pd NPs. The formed Pd NP-containing PEI/PVA nanofibers were characterized by different techniques. We show that the immobilization of Pd NPs does not significantly change the morphology of the PEI/PVA nanofibers; instead the mechanical durability of the fibers is significantly improved. The formed Pd NPs with a mean diameter of 2.6 nm are quite uniformly distributed within the fibers with a small portion of particles having a denser distribution at the outer surface of the fibers. The catalytic activity and reusability of the fabricated Pd NP-containing fibrous mats were evaluated by transformation of Cr(VI) to Cr(III) in aqueous solution in the presence of a reducing agent. Our results reveal that the Pd NP-containing nanofibrous mats display an excellent catalytic activity and reusability for the reduction of Cr(VI) to Cr(III). The facile approach to fabricating metal NP-immobilized polymer nanofibers with a high surface area to volume ratio, enhanced mechanical durability, and uniform NP distribution may be extended to prepare different NP-immobilized fibrous systems for various applications in catalysis, sensing, environmental sciences, and biomedicine.
Keywords:
electrospun PEI/PVA nanofibers; palladium nanoparticles; hexavalent chromium reduction; environmental remediation; reusable catalyst