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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]

Abstract: A series of hydrous iron oxide samples were prepared by homogeneous precipitation from FeCl3 solution in the presence of SO4 2− ions. Experiments were conducted to study the removal of sulfate ions by varying pH, SO4 2−/Fe3+ molar ratio and the nature of the associated cation. Conventional methods including Infrared Spectroscopy, X-ray Diffraction and Thermal Analyses were used for the characterization of sulfate ions interactions with the hydrous iron surface. The results of macroscopic studies show that the removal of sulfate is highly pH dependent, it is greater at pH range [3–4] and it decreases as the molar ratio enhances. Thermal and IR analyses demonstrate strong interactions of sulfate ions with the hydrous iron oxide. In the pH range studied, the results are consistent with innersphere surface complexes. [Copyright &y& Elsevier]