In order to design a systematic synthesis of iron oxide nanoparticles, preparation and characterization of iron oxide nanoparticles using zeolite-NaY as a host material have been performed, and photocatalytic activity of the oxide has also been examined by using phenol photodegradation as a model. Preparation was conducted by introducing Fe@) ions in the solution into the zeolite pores by ion exchange method, followed by dehydration and calcination. In the preparation, the influences of solution pH, temperature, Fe(lI) concentration, and calcinations temperature on the ion exchange efficiency presented by the amount of the iron uptake and relative crystallinity of the zeolite have been evaluated. The amount of the iron uptake by zeolite was determined by atomic absorption spectroscopy ( U S ) and relative crystallinity of the zeolite was detected by X-ray diffraction XRD method. The iron oxide resulted can be distributed in the zeolite cages and on the external surface, which was determined by dissolution method in EDTA solution accompanied by AAS. The correlation of the iron oxide distribution idon the zeolite structure to their types, size, and characters was also verified. The types of the iron species formed were identified by electron spin resonance (ESR) spectroscopy, the size and character as a photocatalyst (presented as band gap energy, Eg) were determined by diffise reflectance UV-Visible @RUV-Visible) spectroscopy. The photocatalysis phenol degradation was carried out by batch system in a closed reactor equipped with UV lamp. In photocatalytic study, the correlation of the iron oxide distribution and the photocatalytic activity was investigated. The research results indicated that increasing solution pH, temperature, and the introduced Fe(II) concentration can increase the iron uptake by zeolite, while decreasing solution pH, elevating temperature, and increasing F e O concentration and calcinations temperature led to an increase in the zeolite structural damage. The highest efficiency of the ion exchange was obtained when the process was carried out in pH solution = 7 maintained by borax buffer, at room temperature (about 30°C) for 45 min, and the iron loaded zeolite was calcined at temperature lower than 400°C. The preparation has successfully resulted in the iron oxide nanoparticles, which were distributed on the zeolite external surface and encapsulated in the zeolite cages. The correlation of the iron oxide distribution to its characters and activity has been well addressed. The iron oxide encapsulated in the cages that existed as iron-oxo clusters and superclusters exhibited smaller size and larger Eg than the oxide located on the zeolite external that was present as larger fine particles of FeOOH and/or Fe203. Furthermore, photocatalytic activity of the iron encapsulated in the zeolite cages was higher than that of located on the external surface. The increase of the iron loaded in the zeolites has improved the phenol photodegradation efficiency, but hrther increase led to a decrease in the efficiency. A decrease in the relative crystallinity of the iron-loaded zeolites has reduced the efficiency of the phenol photodegradation. Further studies regarding the inclusion ways of Fe(I1) ions into the zeolite cages, the states of the iron oxide formed, the role of OH radicals on the phenol degradation, the identification of the photoproduct compounds, and the mechanism of the phenol photodegradation, are suggested.

Kata Kunci : IRON OXIDE, NANOPARTICLES, ZEOLITE-NaY