Synergistic effect and mechanism of copper corrosion inhibition using cinnamaldehyde and vanillin in HCl solution: An experimental and theoretical approach

Corrosion of copper has gained substantial attention due to its significant impact on the performance and reliability of metal in various applications. The process also makes the application of metal capital-intensive. In this work, a new approach was achieved by mixing two biologically extracted corrosion inhibitors (Cinnamaldehyde (C9H8O) and Vanillin (C8H8O3)) in acid solution to protect copper surface from corrosion. The inhibitors are environmentally friendly and can cover up to 98.36% of the metal's surface, thus significantly reducing the corrosion rate. Molecular dynamic simulation on inhibitor films shows that the synergistic inhibitory effect is enhanced due to the reasons that: (1) the new inhibitor films are denser at the surface due to the filling of C8H8O3 into the voids of C9H8O and (2) the new inhibitor films are more stable and the diffusion coefficients of inhibitor molecules approximately are 1-2 x 10(-4) cm(2) s(-1). The results from this study could contribute to better understanding of the synergistic mechanism of the two corrosion inhibitors, which could in turn help in developing novel inhibitors in future.