LAUSR

Abstract In recent studies, biopolymers such as chitosan and alginate have been applied as effective inhibitors for acidic-induced corrosion of metals. In this study, polydopamine (PDA) nanoparticles with different water stabilities, sizes, and chemistries were synthesized via three different methods (PDA-1, PDA-2, and PDA-3). The size, morphology, and chemistry of the PDA nanoparticles were investigated by FE-SEM, FT-IR, UV–Visible and zeta potential methods. FE-SEM analysis revealed a significant size difference between the PDA particles obtained from the three methods. Finer particles were obtained for PDA-2 and PDA-3 samples. In addition, PDA-2 particles showed higher hydrophilic natures compared with PDA-1 and 3 due to the presence of large numbers of carboxylic groups in its structure. The inhibition abilities of the PDA-1, PDA-2 and PDA-3 particles against mild steel corrosion in 1 M HCl solution were studied by EIS and polarization methods. Results evidenced 93%, 99%, and 96% inhibition degrees in the solutions containing 5 mg/L PDA-1, PDA-2 and PDA-3 particles, respectively. Polarization test results evidenced that all PDA particles could suppress the steel corrosion via a mixed-type inhibition mechanism with a dominant anodic effect. The generation of a dense film composed of PDA particles on the steel substrates subjected to the HCl solutions was demonstrated by SEM analysis results.