Preparation and Characterization of Hydroxyiron-Montmorillonite Complexes

Hydroxy Fe ions react slowly with montmorillonite by intercalation into their interlayer space and adsorption on their surface to form various hydroxyiron montmorillonite complexes. Hydroxyiron montmorillonite complexes are assumed to have the ability to adsorb anions such as H₂PO₄^-, HPO₄^2-, CrO₄^2-, CrO₂^-, H₂AsO₄^-, HAsO₄^2-, AsO₄^3- and F^-, which may come from weathered rocks or waste industrial water, and result in concentration of P, Cr, As and F in soil. In this paper, hydroxy Fe ions including Fe(OH)²⁺, Fe(OH)₂⁺ and Fe₂(OH)₂²⁺ are prepared through hydrolysis of iron in acid solutions with different pH values. Corresponding hydroxyiron montmorillonite complexes are obtained by intercalation and adsorption of these hydroxy Fe ions into the interlayer space and on the surface of montmorillonite. The obtained hydroxyiron montmorillonite complexes are characterized with XRD and DTA, showing that they have similar basal space and thermal stability with Fe montmorillonite.