Anticorrosion Agents for Carbon Steel in Acidic Environments: Synthesis and Quantum Chemical Analysis of New Schiff Base Compounds with Benzylidene

Hamdy Khamees Thabet; Jwaher M AlGhamdi; Hoda A Mohammed; Mahmoud A M Elsaid; Ashraf M Ashmawy

doi:10.1021/acsomega.3c05790

Anticorrosion Agents for Carbon Steel in Acidic Environments: Synthesis and Quantum Chemical Analysis of New Schiff Base Compounds with Benzylidene

ACS Omega. 2023 Oct 12;8(42):39770-39782. doi: 10.1021/acsomega.3c05790. eCollection 2023 Oct 24.

Authors

Hamdy Khamees Thabet¹, Jwaher M AlGhamdi², Hoda A Mohammed³, Mahmoud A M Elsaid⁴, Ashraf M Ashmawy⁵

Affiliations

¹ Chemistry Department, Faculty of Arts and Science, Northern Border University, PO 840, Rafha 91911, Saudi Arabia.
² Department of Chemistry, College of Science, Imam Abdulrahman Bin Faisal University, 31451 Dammam, Saudi Arabia.
³ Analysis and evaluation department, Egyptian Petroleum Research institute (EPRI), Cairo 11727, Egypt.
⁴ Metallurgy Department, Nuclear Research Center (NRC), Egyptian Atomic Energy Authority (EAEA) Cairo 0202, Egypt.
⁵ Chemistry Department, Faculty of Science (boys), Al-Azhar University, Nasr City 11884, Egypt.

Abstract

Novel Schiff bases (SBs), namely, N₁,N₂-bis(2-(((E)-4-chlorobenzylidene)amino)ethyl)ethane-1,2-diamine (I), N₁,N₂-bis(2-(((E)-4-(dimethylamino)benzylidene)amino)ethyl)ethane-1,2-diamine (II), and N₁,N'₁-(ethane-1,2-diyl)bis(N₂-((((Z)-4-dimethylamino)benzylidene) amino)methylethane-1,2-diamine) (III), were prepared and characterized by using elemental analysis, IR, and ¹H NMR spectroscopy. For assessing carbon steel in diverse settings, with and without inhibitors at varying concentrations, electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) techniques were employed. The results showed that the synthesized inhibitors effectively decreased the corrosion rate of carbon steel in acidic media and the inhibition efficiency reached up to 93% for compound III at a concentration of 250 ppm. In addition, all prepared compounds were successful as anticorrosion agents, and the inhibition mechanism followed chemisorption from the Langmuir isotherm. The data obtained from the theoretical analysis show that the efficiency of the prepared compounds was in the order III < II < I. Furthermore, quantum chemical calculations were performed to gain insight into the electronic structure of the compounds. The analysis of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) showed that compound III had the highest surface coverage due to its specific molecular structure and spacer. This observation agreed well with the Langmuir adsorption data.