Impact of ethylene glycol on ions influencing corrosion in pores between iron oxide and calcium carbonate

R Olsen and B Kvamme, MOLECULAR SIMULATION, 49, 664-677 (2023).

DOI: 10.1080/08927022.2023.2184298

Injection wells for carbon capture and storage are made of iron casings supported by cement. Cement can transform into calcium carbonate and iron into iron oxide. Thus, these wells are subject to corrosion. Monoethylene glycol (MEG), used for hydrate prevention and natural gas dehydration, can adsorb both to calcium carbonate and iron oxide. As a first step towards an atomistic understanding of effects caused by adsorbed MEG, molecular dynamics simulations were applied to estimate free energy changes to hydronium and bicarbonate as MEG was adsorbed to the surface. We found that the global free energy minimum of both hydronium and bicarbonate was moved closer to the surfaces, due to adsorbed MEG, which may be caused by MEG replacing water molecules within the first water layers. This could have an effect on chemical reactions involving hydronium and bicarbonate. Minima in the free energy profiles other than the global one was found to originate from adsorbed water combined with interactions from the surfaces.

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