Pivotal Role of Heteroatoms in Improving the Corrosion Inhibition Ability of Thiourea Derivatives

Dinh Quy Huong; Nguyen Thi Lan Huong; Tran Thi Anh Nguyet; Tran Duong; Dinh Tuan; Nguyen Minh Thong; Pham Cam Nam

doi:10.1021/acsomega.0c04241

Pivotal Role of Heteroatoms in Improving the Corrosion Inhibition Ability of Thiourea Derivatives

ACS Omega. 2020 Oct 14;5(42):27655-27666. doi: 10.1021/acsomega.0c04241. eCollection 2020 Oct 27.

Authors

Dinh Quy Huong¹, Nguyen Thi Lan Huong¹, Tran Thi Anh Nguyet¹, Tran Duong¹, Dinh Tuan², Nguyen Minh Thong³, Pham Cam Nam⁴

Affiliations

¹ Department of Chemistry, University of Education, Hue University, Hue City 530000, Viet Nam.
² Department of Chemistry, University of Sciences, Hue University, Hue City 530000, Viet Nam.
³ The University of Danang, Campus in Kon Tum, Kontum City 580000, Viet Nam.
⁴ Department of Chemistry, The University of Danang-University of Science and Technology, Danang City 550000, Vietnam.

Abstract

1,3-Diphenyl-2-thiourea (DPTU) and 1-phenyl-3-(2-pyridyl)-2-thiourea (PPTU) were selected as the researched subject for investigating the effect of heteroatoms on the low carbon steel corrosion inhibition ability. Results from the potentiodynamic polarization measurements (PPM) indicate that the addition of a nitrogen atom in the benzene ring increases the corrosion inhibition efficiency of PPTU (97.2%), being higher than that of DPTU (93.1%) at the same condition of 2.0 × 10^-4 M at 30 °C. The Nyquist diagrams show that increasing the concentrations of both DPTU and PPTU will enhance the charge-transfer resistance and reduce the double-layer capacitance. The obtained data based on PPM and electrochemical impedance spectroscopy methods are in accordance to the analysis based on the scanning electrochemical microscopy images. Besides, results from quantum chemical calculations prove that the heteroatoms in the inhibitor molecules are the adsorption centers, and the benzene rings increase the electrostatic interaction between the inhibitor molecules and the steel surface. Results from Monte Carlo and molecular dynamics simulation have clarified the adsorption mechanism of DPTU and PPTU on the steel surface. Adsorption energies confirm that PPTU displays the higher inhibition ability as compared with DPTU.