Co and Mn decrease chemical and biological reduction rate of iron oxyhydroxides

Very few studies related to the solubilization of Fe (III) oxides substituted by Mn and Co, whereas such oxides are frequent in natural environment. In this present work, goethites substituted for various Mn and Co rates were synthesized and subjected to the reducing action, first, by chemical treatment, with a the dithionite-citratebicarbonate (CBD) reagent, and secondly, by biological treatment with Clostridium butyricum a fermentative Fe (III). The comparison of two processes showed that the dissolution rates of iron decreased with substitution. The study of the bacterial fermentative balance shows that substitution, its rate and its nature, does not influence the bacterial fermentative balance (total activity and number of electron produced were unchanged). However, it decreases the percentage of electrons engaged in the reduction process. This result demonstrates the control of the bacterial reduction of iron oxides by the cristallo-chemical characteristics of the latter.