Microbial-induced stable iron mineral production for corrosion mitigation application in reinforced concrete

Abstract

This study aims to mitigate corrosion in reinforced concrete and other iron-based materials by microbial-induced production of siderite (ferrous carbonate) and vivianite (ferrous phosphate), as stable forms of iron compounds. The capability of iron-reducing bacteria, including Shewanella loihica (PV-4), Shewanella oneidensis (MR-1), and Tessaracoccus lapidicaptus (IPBSL-7), to reduce ferric iron (Fe 3+ ) as the electron acceptor and consequently, to produce stable iron minerals was investigated in both solution-based (soluble source of ferric iron) and solid-based (insoluble source of ferric iron) matrices. While the bacterial-induced reduction of iron, and consequently, the biogenic production of stable iron minerals was confirmed using X-ray diffraction (XRD), results indicated that the quantity of biogenic ferrous minerals produced is greatly influenced by the type of electron donor and environmental oxygen levels. For instance, using sodium lactate as the electron donor under hypoxic conditions resulted in the highest biogenic siderite ratio (34 %). IPBSL-7 exhibited the highest siderite-to-total precipitate ratio after treatment (50 %) compared to the other two bacterial species. Additionally, examining the microstructure of the biogenic layer precipitated on corroded iron coupons using scanning electron microscopy (SEM) supported the formation of ferrous minerals after bacterial treatment in the form of spherical as well as flat microcrystals. Gravimetry analysis of the biogenic precipitate suggests that it can potentially function as a comparatively dense (with a mass over surface area of 12 mg/cm 2 ) protective layer against further corrosion. This study provides insights into optimizing conditions for microbial-induced biomineralization and its potential applications in corrosion mitigation in reinforced concrete.

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