Corrosion Behavior of S235JR and 304 SS in Amine-Functionalized Ionic Liquid Aqueous Solutions

Amine-functionalized ionic liquid (IL) aqueous systems were recently tested as a CO2 absorber. Nevertheless, equipment corrosion of CO2 capture into IL aqueous solutions is still rarely studied. In the present study, the corrosion behaviors of various concentrated dimethylethylenediamine acetate [DMEDA][CH3COO] aqueous solutions had been investigated by systematically probing the effect of IL concentrations, CO2 loading for typical mild steel S235JR and stainless steel 304 SS. The experimental results indicated that neat [DMEDA][CH3COO] showed negligible corrosivity, while high water contents would accelerate the corrosion rates. The corrosion process was controlled by charge transfer according to Tafel curves. Also, the presence of CO2 slightly altered the corrosion rates, which were quite different from the previous report that CO2-producing hydrogen protons (H+) promoted the dissolution of iron and accelerated the corrosion rates. It was likely that [DMEDA][CH3COO] was attached on the metal surface to resist the H+ attack. The corrosion behaviors suggested that [DMEDA][CH3COO]/water mixtures could be proper candidates for CO2 capture.