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

In this study, nanoscale Fe0 was immobilized in and on poly(vinyl alcohol) (PVA) microspheres by the inverse suspension crosslinked method. Two different sizes of Fe0/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 Fe0/PVA microspheres were characterized by environmental scanning electron microscope, energy-dispersive X-ray spectrometry, and X-ray diffraction. Nanoscale Fe0 particles were mostly dispersed over the surface of the microspheres. They were distributed more homogeneously on the surfaces of Fe0/PVA microspheres with diameter of 600-700 μm than those with diameter of 10-12 μm. The nitrobenzene (NB) reduction reactions followed pseudo-first-order kinetics. The normalized surface rate constants (kSA) values were determined to be 0.162 L h-1 m-2 for L-Fe0/PVA microspheres, 0.098 L h-1 m-2 for S-Fe0/PVA microspheres, and 0.023 L h-1 m-2 for nanoscale Fe0 particles. Furthermore, with the analysis of the products by GC/MS, possible reductive pathways of NB by Fe0/PVA microspheres were suggested. The recovery rates of iron in microspheres were determined to be 81.17% for large Fe0/PVA and 60.31% for small Fe0/PVA.