Inhibitive effects of a novel efficient Schiff base on mild steel in hydrochloric acid environment

• A.J.M. Eltmimi¹, A. Alamiery², A.J. Allami³, R.M. Yusop⁴, A.H. Kadhum^2,3 and T. Allami²

¹ Pharmacy Department AlRasheed University College, Baghdad, Iraq
² Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
³ University of Al-Ameed, Karbala, Iraq
⁴ Faculty of Science and Technology – FST, Universiti Kebangsaan Malaysia, 43000, Bangi, Selangor, Malaysia

Abstract: The corrosion inhibition performance of a novel Schiff base, namely 5-((4-fluoro-benzylidene)amino)-1,3,4-thiadiazole-2-thiol (FATT), on mild steel in 1.0 M hydrochloric acid environment has been studied by the weight loss method and scanning electron microscope (SEM). The inhibition efficiencies and the adsorption characteristics were determined from the gravimetrical results. The inhibition effectiveness increases with an increase in the concentration of the studied inhibitor but decreases with rising solution temperature. The inhibitor molecules are adsorbed on the coupon (mild steel) surface and obey the Langmuir adsorption isotherm. Scanning electron spectroscopy (SEM) was utilized to test the coupon surface morphology without and with the inhibitor at a concentration of 0.5 mM at 303 K. SEM implies the formation of a protective layer of FATT molecules on the coupon surface in the hydrochloric acid solution at 303 K. Quantum chemical calculations using density functional theory (DFT) were employed to identify the relationship between the electronic structure parameters of the FATT molecule and the inhibition efficiency. The quantum chemical parameters such as HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), ΔE (energy gap), μ (dipole moment), χ (electronegativity), η (global chemical hardness), σ (softness), and ΔN (fraction of electrons transferred) were calculated. The quantum chemical parameters by calculated the DFT method for the tested inhibitor agree with the experimental inhibition efficiency.

Keywords: fluorobenzylidene, mild steel, FATT, inhibitor, weight loss, scanning electron spectroscopy

Int. J. Corros. Scale Inhib., 2021, 10, no. 2, 634-648 PDF (527 K)
doi: 10.17675/2305-6894-2021-10-2-10

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