Mechanistic study of polyepoxy succinic acid (PESA) as green corrosion inhibitor on carbon steel in aerated NaCl Solution

The inhibition mechanism of mild steel corrosion in aerated aqueous 3% NaCl medium was studied using Polyepoxy succinic acid (PESA) as a green inhibitor. The study utilized electrochemical, thermodynamic, and surface microscopic techniques. Computational methods supported the empirical results of the inhibition mechanism at the molecular level. Results showed inhibition efficiency of PESA exceeding 60% at 2 g/l at 25 °C through the formation of a protection layer on mild steel surface. An addition of 2 mg/l of zinc cations to 2 g/l of PESA at 25 °C enhanced the inhibition efficiency reaching 90%. SEM and AFM scans revealed an efficient coverage of an adsorbed layer on mild steel surface. Quantum chemical, Monte Carlo computation and simulation provided mechanistic insights of the reactivity sites and PESA's adsorption strength on metal surface.