Immobilization of nanoscale Fe0 in and on PVA microspheres for nitrobenzene reduction

In this study, nanoscale Fe-0 was immobilized in and on poly(vinyl alcohol) (PVA) microspheres by the inverse suspension crosslinked method. Two different sizes of Fe-0/PVA microspheres were synthesized in the presence and absence of dispersant. The chelating action between Fe2+ and PVA was identified by Fourier transform infrared and X-ray photoelectron spectroscopy. The morphology and distribution of the obtained Fe-0/PVA microspheres were characterized by environmental scanning electron microscope, energy-dispersive X-ray spectrometry, and X-ray diffraction. Nanoscale Fe-0 particles were mostly dispersed over the surface of the microspheres. They were distributed more homogeneously on the surfaces of Fe-0/PVA microspheres with diameter of 600-700 mu m than those with diameter of 10-12 mu m. The nitrobenzene (NB) reduction reactions followed pseudo-first-order kinetics. The normalized surface rate constants (k(SA)) values were determined to be 0.162 L h(-1) m(-2) for L-Fe-0/PVA microspheres, 0.098 L h(-1) m(-2) for S-Fe-0/PVA microspheres, and 0.023 Lh(-1) m(-2) for nanoscale Fe-0 particles. Furthermore, with the analysis of the products by GC/MS, possible reductive pathways of NB by Fe-0/PVA microspheres were suggested. The recovery rates of iron in microspheres were determined to be 81.17% for large Fe-0/PVA and 60.31% for small Fe-0/PVA. (C) 2009 Elsevier B.V. All rights reserved.