Multidimensional insights into the corrosion inhibition of 3,3-dithiodipropionic acid on Q235 steel in H₂SO₄ medium: A combined experimental and in silico investigation

3,3-Dithiodipropionic acid (DDA) as a potential corrosion inhibitor for Q235 steel in 0.5 M H₂SO₄ solution was examined. A variety of research approaches including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), atomic force microscopy (AFM), and computational techniques were employed. The toxicity and solubility of DAA were reasonably assessed. Its inhibition efficiency can reach approximately 93% when the optimal concentration is 5 mM. The results of PDP curves manifest that DDA is a mixed type corrosion inhibitor. EIS data indicate that the charge transfer resistance increases with increasing concentration of DDA. Gibbs free energy obtained from the Langmuir isotherm model suggests that DDA molecules hinder the acid attack mainly by chemisorption. Surface topography analysis strongly confirmed the electrochemical findings. Moreover, the simulation results based on density functional theory (DFT) calculation and molecular dynamics (MD) simulations supported the successful interfacial adsorption of DDA on Fe(1 1 0) surface.