Investigation into the adsorption and inhibition properties of sodium octanoate against CO2 corrosion of C1018 carbon steel under static and hydrodynamic conditions

Sodium octanoate (Na-oct), a simple, naturally-abundant, cheap and low-toxic organic molecule has been investigated for its adsorption and inhibition properties against the CO2 corrosion of C1018 carbon steel in 3.5 % NaCl under static (0 rpm) and hydrodynamic conditions (10 0 0 rpm). At open circuit potential (OCP) under static condition, a Langmuir-type adsorption of Na-oct modified the dielectric property of the steel-solution interface by lowering double layer capacitance and increasing resistance to charge transfer, based on electrochemical impedance spectroscopy (EIS) analysis. Under this condition, potentio-dynamic polarization (PDP) analysis showed that Na-oct adsorbed more preferentially on anodic sites of steel surface and impacted-96 % inhibition efficiency. Hydrodynamic con-dition at 10 0 0 rpm caused a Langmuir and Temkin adsorption mechanism and diminished the Na-oct efficiency to-86 %. FTIR characterization revealed that the inhibitor adsorption was enabled by its COO- functional group. Computational modeling, using DFT and MDS, confirmed the experimental findings.(c) 2023 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )