Insights into Corrosion Inhibition Behavior of a 5-Mercapto-1, 2, 4-triazole Derivative for Mild Steel in Hydrochloric Acid Solution: Experimental and DFT Studies

Israa Abd Alkadir Aziz,Iman Adnan Annon,Wan Nor Roslam Wan Isahak,Mohd S Takriff,Lina M Shaker,Mohammed H Alkaabi,Mahdi M Hanoon,Ahmed A Alamiery,Makarim H Abdulkareem

doi:10.3390/lubricants9120122

Abstract

A triazole heterocyclic compound namely 3-(4-ethyl-5-mercapto-1, 2, 4-triazol-3-yl)-1-phenylpropanone (EMTP) was examined for its corrosion protection of mild steel (MS) against 1 M hydrochloric acid medium using gravimetric techniques. EMTP exhibited excellent corrosion protection performance at low and high concentrations towards MS in HCl solution. Comparison of corrosion protection performance of EMTP and its parent triazole and temperature effects of on inhibition efficacy were also studied. EMTP has potential corrosion inhibitor for mild steel in 1.0 M hydrochloric acid solution with the highest protection efficacy of 97% at 303 K. The weight loss findings implied that EMTP protects the metal surface corrosion through the creation of a protective layer at the surface mild steel–corrosive solution interface. The inhibitive efficacy increases with the increase of inhibitor concentration and decreases with increased temperature. The adsorption of EMTP on the surface of MS follows Langmuir’s adsorption isotherm process. DFT method was conducted on EMTP molecule to calculate the quantum chemical parameters and to determine the relationship between the molecular structure of EMTP and protection performance. The molecular parameters, such as energy gap and frontier molecular orbital (highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)), and the absolute electronegativity (χ) value from inhibitor molecules to unoccupied d-orbital of iron atoms on the mild steel surface were also determined and correlated with protection efficiency. The theoretical findings revealed that the protection performance of EMTP increased with the increase in HOMO energy, and the nitrogen, oxygen and sulfur atoms are most probable positions for bonding through giving electrons to the d-orbital of iron atoms on the mild steel surface.

Highlights

Several five-membered heterocycles were in the recent decade, and five-membered were examined in thehave recent decade, and analysis hasperforshown has shown that heterocycles the large percentage of triazoles good corrosion protection that the percentage of triazoles good corrosion protection performance for mance forlarge shielding a variety of alloys have and metals
The corrosion protection performance was evaluated at 303 K and various immersion periods [28,29]
The increased inhibiting efficacy can be attributed to the increased surface coverage owing to the adsorption of inhibitor molecules on the surface of mild steel [30,31]

Summary

Introduction

The widespread use of hydrochloric acid for pickling, rescaling, and cleaning mild steel (MS) surfaces causes’ severe corrosion concerns. Inhibitors can prevent the corrosion creativecommons.org/licenses/by/ 4.0/). Lubricants 2021, 9, 122 sion of metallic materials by limiting metal solubility and consumption. Organic moleof metallic materials by limiting metal solubility and consumption. N-heterocyclic compounds pounds with polar groups and/or p-electrons, are the mostascommon acid inhibitors [1]. With polar groups and/or p-electrons, are examined the most common acid inhibitors [1].analysis Several. Several five-membered heterocycles were in the recent decade, and five-membered were examined in thehave recent decade, and analysis hasperforshown has shown that heterocycles the large percentage of triazoles good corrosion protection that the percentage of triazoles good corrosion protection performance for mance forlarge shielding a variety of alloys have and metals ( mild steel). Various shielding a variety of alloys and metals [2,3]

Methods

Results

Conclusion