关键词: 氨基酸, 缓蚀剂, 量子化学, 分子动力学, 吸附

Abstract: 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 = ?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.

Key words: amino acid, corrosion inhibitor, quantum chemistry, molecular simulation, adsorption