Molecular dynamics simulation and DFT calculation of “green” scale and corrosion inhibitor

Abstract The environmental-friendly scale and corrosion inhibitors have been a hot topic in research. Four carboxylic acid type scale and corrosion inhibitors are introduced in this study, including polyaspartic acid (PASP), polyepoxysuccinic acid (PESA), oxidized starch (OS), and carboxymethyl cellulose (CMC). The scale and corrosion inhibition performance of PASP, PESA, OS, and CMC were investigated by molecular dynamics (MD) simulation and density functional theory (DFT) calculation. The interaction between the inhibitor and the surface of CaCO3 (1 1 0), CaCO3 (1 0 4), CaSO4 (0 2 0), and Fe (1 1 0) was explored with and without water, respectively. The results indicate that the binding energy of the inhibitor onto the surface of CaCO3 (1 1 0), CaCO3 (1 0 4), and CaSO4 (0 2 0) is as follows: PESA > PASP > OS > CMC. The binding energy onto the Fe (1 1 0) surface is: PASP > OS > CMC > PESA. It is worth noting that the influence of water molecules cannot be ignored. Besides, the global reactivity parameters of four inhibitors were also calculated to further explain the corrosion inhibition performance and mechanism, such as EHOMO, ELUMO, ΔE, χ.