Corrosion Inhibition Performance and Mechanism of a Phosphorus-Free, Nitrogen-Free Polymer for Q235 Carbon Steel in Artificial Seawater

In this study, a novel ternary copolymer containing ether, sulfonic, and carboxylic acid groups was synthesized through a free radical polymerization using itaconic acid (IA), α-allyl glycerol ether (AG), and sodium methyl allyl sulfonate (SMAS). The corrosion inhibitive performance of the IA-AG-SMAS on Q235 carbon steel in artificial seawater was assessed by the weight loss experiment, morphology evaluation as well as electrochemical analysis at different temperatures by varying inhibitor dosage. Experimental results showed that IA-AG-SMAS achieved a maximum 89.58% corrosion inhibition efficiency at 400 mg/L for 30°C as a mixed-type inhibitor. The adsorption behavior of IA-AG-SMAS on Q235 steel surface obeys the Langmuir isotherm with a physisorption mechanism. According to potentiodynamic polarization and electrochemical impedance spectroscopy measurement, the inhibition performance was significantly improved, while the anticorrosion mechanism was not affected by increasing the concentration of inhibitors. Moreover, the dispersion test confirmed that IA-AG-SMAS efficiently prevented Fe2O3 from deposition on a metal surface, which further retarded corrosion. At a concentration of 16 mg/L, IA-AG-SMAS exhibited an Fe2O3 solubility of 97.90% with complete sediment disappearance. Molecular dynamics simulation was employed to investigate the affinity of IA-AG-SMAS inhibitor on Fe(110) surface in the ASW environment. Theoretical results aligned with the experiments and confirmed the promising anticorrosion ability of IA-AG-SMAS by adopting a parallel adsorption configuration on an Fe(110) surface, thus inhibiting the corrosion.