Investigation of Sulfonium-Iodide-Based Ionic Liquids to Inhibit Corrosion of API 5L X52 Steel in Different Flow Regimes in Acid Medium

Abstract

The present work deals with the corrosion inhibition mechanism of API 5L X52 steel in 1 M H2SO4 employing the ionic liquid (IL) decyl(dimethyl)sulfonium iodide [DDMS+I–]. Such a mechanism was elicited by the polarization resistance (R p), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques, both in stationary and dynamic states. The electrochemical results indicated that the corrosion inhibition was controlled by a charge transfer process and that the IL behaved as a mixed-type corrosion inhibitor (CI) with anodic preference. The experimental results revealed maximal inhibition efficiency (IE) rates up to 93% at 150 ppm in the stationary state, whereas in turbulent flow, the IE fell to 65% due to the formation of microvortexes that promoted higher desorption of IL molecules from the surface. The Gibbs free energy of adsorption (ΔG°ads) value of −34.89 kJ mol–1, obtained through the Langmuir isotherm, indicated the formation of an IL monolayer on the metal surface by combining physisorption and chemisorption. The surface analysis techniques confirmed the presence of Fe x O y , FeOOH, and IL on the surface and showed that corrosion damage diminished in the presence of IL. Furthermore, the quantum chemistry calculations (DFT) indicated that the iodide anion hosted most of the highest occupied molecular orbital (HOMO), which eased its adsorption on the anodic sites, preventing the deposition of sulfate ions on the electrode surface.

Synthesis of Ammonium-Based ILs with Different Lengths of Aliphatic Chains and Organic Halogen-Free Anions as Corrosion Inhibitors of API X52 Steel

“…For [ − AI], the carboxylic groups yielded similar conformations to those described for some acids comparable to those employed during the synthesis [61]. As for the anion [ − AD], the alkyl chain presented the linearconformation characteristic of C > 10 chains [62,63]. In the case of cations, the alkyl chains showed the common conformation of ammonium groups that has been reported in other studies [63][64][65].…”

Temperature Effect on the Corrosion Inhibition of Carbon Steel by Polymeric Ionic Liquids in Acid Medium

“…The τ dl values were higher in the presence of PILs with the increasing C INH ( Table 4 ), revealing that the electric charge and discharge process occurring in the metal-solution interface is slower due to the presence of a higher number of macromolecules adsorbed on the metallic surface [ 46 , 48 ]. However, the number of these molecules falls with the increasing temperature, for it reduces the necessary time for their right orientation; as the temperature rises, the molecular thermal movement increases and τ dl goes on diminishing, which negatively affects the migration of PIL inhibiting species toward the metallic surface [ 49 ].…”

Corrosion protection of mild-steel in 1M HCl using nanocomposite from Triumfetta rhomboidei

“…It is evident that the inclusion of TiTR in the corrosive medium appreciably reduced the current density of the process in relation to the current density of the uninhibited solution. Since higher current densities are indications of more serious surface damage to the metal surface, the reduction in the current density with respect to the blank is as a result of the TiTR film adsorbed on the steel surface through transfer of charges, thereby displacing water molecules and aggressive ions [50]. Results also show that the reduction in the corrosion current is a function of inhibitor concentration which consequently translates to an increase in the efficiency of inhibition efficiency of TiTR with increased concentration.…”