Anaerobic electrochemical corrosion of mild steel in the presence of extracellular polymeric substances produced by a culture enriched in sulfate-reducing bacteria

Kwong Yu Chan, Lichong Xu, Herbert H P Fang

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Abstract

The corrosion of mild steel in a seawater medium containing extracellular polymeric substances (EPS) produced by sulfate-reducing bacteria (SRB) was studied by electrochemical experiments and atomic force microscopy (AFM). Under anaerobic conditions, the corrosion of mild steel increased up to 5-fold in the presence of a 1% (w/w) EPS solution but in the absence of SRB. The enhanced corrosion is mainly due to the oxidizing power of EPS with a reduction potential of E1/2 at -0.54 V (saturated calomel electrode), which is 0.4 V above that of hydrogen reduction. The electrochemical reduction of EPS provides a couple to iron oxidation, as demonstrated by H-shaped cell experiments in which the steel sample and EPS are not in physical contact but are ionically connected via the solution and electronically connected through an external wire. Fourier transformation infrared spectroscopy and X-ray photoelectron spectroscopy showed that EPS derived from SRB are comprised of 60% proteins, 37% polysaccharides, and 3% hydrocarbons. The XPS results showed that, upon corrosion, polysaccharide components were mostly converted to hydrocarbons.

Original languageEnglish (US)
Pages (from-to)1720-1727
Number of pages8
JournalEnvironmental Science and Technology
Volume36
Issue number8
DOIs
StatePublished - Apr 15 2002

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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