Enhancement corrosion resistance of mild steel in 15% HCl solution by a novel bio-based polyurethane for oil well acidizing.

[Display omitted] • Citric acid and glucose were used to develop a novel thermally stable corrosion inhibitor. • No dramatic reduction in inhibition efficiency of CAGCI was observed up to 363 K. • CAGCI changed the hydrophobicity of mild steel surface. • The formation of protective film and Fe²⁺-CAGCI complex on mild steel was detected. A novel thermally stable inhibitor was developed based on citric acid and glucose (CAGCI) to inhibit the corrosion of mild steel (MS) in simulated acidic oilfield water for oil well acidizing. All electrochemical measurements were performed in a temperature range of 293–363 K to evaluate the inhibition power of CAGCI. The results of electrochemical tests clearly revealed that CAGCI effectively inhibited MS corrosion via a mixed-type mechanism and 77 × 10⁻⁴ M of the inhibitor provided the highest inhibition efficiency of 90%, 93.6%, 93.7%, and 89.9% at 293 K, 313 K, 333 K, and 363 K, respectively. In addition, CAGCI provided a total polarization resistance of 416.7 Ω cm² for MS at 293 K and decreased the corrosion rate of the metal 7.6 times compared to blank at 363 K. Moreover, the UV–visible results demonstrated the formation of the Fe²⁺-CAGCI complex and the results of the surface analysis confirmed the presence of a protective film of CAGCI molecules on the MS surface. Finally, the experimental outcomes were well complemented by results obtained from density-functional study and molecular dynamics (MD) simulation. According to quantum calculations, citric acid and aromatic rings in the structure of CAGCI played the main role in electron exchanges with the MS surface. The results of the MD simulation were also confirmed that a hydrophobic barrier can be formed by CAGCI molecules on the MS surface with a parallel adsorption configuration. [ABSTRACT FROM AUTHOR]