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Abstract: The reuse of iron oxide nanoparticles as a catalyst of organic matter in the H2O2/iron oxide mineralization process was investigated. The particle size and morphology of iron oxide particles obtained from TEM (Transmission Electron Microscopy) images and DLS (Dynamic Light Scattering) measurements, indicate the formation of a rod-like morphology with an average length of 50±10nm. An electron diffraction pattern identified the particles as either α-FeOOH or β-FeOOH. Stability of iron oxide nanoparticles in organic model compound solutions was studied as a function of pH solution and was correlated with average size. The optimal pH for maximum mineralization in the H2O2/iron oxide system was found to be 2.8. Finally, results indicated that at least seven stages of catalytic mineralization-recovery cycles can take place without a reduction in the catalytic properties of the iron oxide nanocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: Sulfate removal from aqueous solutions by hydrous iron oxide freshly prepared in the presence of some heavy metals cations and some anions has been investigated in batch systems by varying the pH and concentrations of various ions. Infrared spectroscopic analyses have been performed to characterize the effect of these ions on the mechanism of sulfate interaction with the surface of the hydrous oxide. The results of macroscopic studies show that in the binary systems, copper and zinc ions inhibit the sulfate removal at pH higher than 5.5. In the presence of oxalate and phosphate ions, significant competitive effects are observed contrary to acetate ions. The IR spectra of the solids obtained show that among the studied ions, only phosphate ions have an effect on the sulfate interaction with the surface of the oxide. In their presence, the formation of outer sphere complex is more probable. [Copyright &y& Elsevier]