Sulfate removal from aqueous solutions by hydrous iron oxide macroscopic, thermal and spectroscopic analyses

A series of hydrous iron oxide samples were prepared by homogeneous precipitation from FeCl3 solution in the presence of SO42− ions. Experiments were conducted to study the removal of sulfate ions by varying pH, SO42−/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.