Optimization of amino acid corrosion inhibitors based on quantum chemistry and molecular simulation

In this study, a multiscale computational approach combining density functional theory calculations with all-atom molecular dynamics (MD) simulations was employed to systematically evaluate the corrosion inhibition performance of 20 amino acids at oil-gas pipeline interfaces. A three-dimensional evaluation system integrating “electronic structure-adsorption behavior-practical inhibition” was established to reveal the highly efficient inhibition mechanism of tryptophan in acidic and asphaltene-containing environments. Quantum chemical calculations show that tryptophan has the lowest molecular orbital energy gap (3.42 eV), with its frontier molecular orbitals highly localized on the aromatic rings and nitrogen-containing heterocyclic rings, endowing it with notable electronic activity.MD simulations reveal a strong negative correlation (R2=0.91) between adsorption energy and energy gap. Tryptophan exhibits the most favorable interfacial binding characteristics under acidic conditions (-944.88 kcal/mol) and during co-adsorption with oleic acid (-1 608.25 kcal/mol). Strong electrostatic interactions between the carboxyl oxygen atoms and the Fe(110) surface (electrostatic potential is -32.06 kcal/mol) form the core adsorption sites. Experimental validation shows that tryptophan achieves a corrosion inhibition efficiency of 92.3% at a concentration of 140 mg/L, with a deviation of less than 5% from theoretical predictions. Overall, the cross-scale computational method developed in this study establishes an accurate linkage between electronic structure and macroscopic performance, providing a theoretical paradigm for molecular design and engineering application of green corrosion inhibitors.