Influence of phosphate species on green rust I transformation and local structure and morphology of γ-FeOOH

To clarify the role of phosphate in the formation of corrosion products, the transformation of GRI(CI-) with the addition of phosphate was characterized through XRD, TEM, and solution analysis. Electrochemical analysis showed that the transformation of GRI(CI-) was delayed and the size of the final products, i.e., gamma-FeOOH was reduced in the phosphate added case. X-ray absorption spectroscopy indicated that the neighboring Fe-Fe coordination number of FeO6 octahedral unit in gamma-FeOOH was decreased. These effects of phosphate are attributed to its adsorption on GRI(CI-) and nucleated gamma-FeOOH that prevented particle growth during oxidation process. (C) 2011 Elsevier Ltd. All rights reserved.