Abstract
Experimental insights into the synergistic effect of 1-acetyl-3-thiosemicarbazide (AST) and iodide ions on the corrosion of C1018 carbon steel in 1 M HCl solution were investigated using open-circuit potential (OCP), linear polarization resistance (LPR), electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP) measurements and electrochemical impedance spectroscopy (EIS). Theoretical studies were further undertaken using ACD/LABS Percepta software, density functional theory (DFT) calculations and Monte Carlo simulation to understand the mechanism of the corrosion inhibition process and interpret the experimental results at the atomic and molecular levels. The electrochemical results obtained showed that AST alone inhibited the acid-induced corrosion of C1018 carbon steel. The inhibition efficiency increases with a concentration reaching up to 72.27% at 750 ppm of AST. The addition of 5 mM KI to 250 ppm of AST improved the inhibition efficiency to 81.64%. The solubility and protonated state results predicted using the ACD/LABS Percepta software showed that AST was highly soluble in the aqueous acidic medium and approximately 95% of AST exists in the neutral form in 1 M HCl (pH = 0). DFT calculations and a Monte Carlo simulation were utilized to predict the active reactivity sites of AST and calculate the lowest adsorption energy and configuration of AST alone and AST + iodide on/Fe (110)/water interface.
Highlights
Carbon steel, such as cylindrical sample of grade UNS G10180 (C1018), are widely used in industries as construction materials for engineering applications due to their low cost and ease of fabrication
In order to further improve the performance of thiosemicarbazide as a corrosion inhibitor, we investigated the corrosion inhibition efficiency of a new thiosemicarbazide, AST, alone and in the presence of potassium iodide for C1018 carbon steel corrosion in 1 M HCl
The carbon steel sample used in this study was a cylindrical sample of grade UNS G10180 (C1018) with the following chemical composition: C = 0.16, Mn = 0.7, S = 0.05, P = 0.04 and Fe balance
Summary
Carbon steel, such as C1018, are widely used in industries as construction materials for engineering applications due to their low cost and ease of fabrication. Several efforts were recently made to develop technologies to mitigate the adverse effect of acid corrosion of carbon steel These methods include protective coatings, cathodic protection, corrosion-resistant materials and corrosion inhibitors. Organic compounds successfully applied as corrosion inhibitors are compounds possessing heteroatoms such as N, O, P, S and cyclic rings in their molecules In this regard, nitrogen-containing structures such as benzimidazole [5,6], imidazole [7,8], tetrazole [9,10] and triazole [11,12] have been extensively studied as carbon steel corrosion inhibitors in acid media. Compounds containing nitrogen and sulfur atoms in the same structures have been shown to possess even higher corrosion inhibition efficiency for carbon steel than those containing only nitrogen In this regard, we can cite some. Theoretical studies were undertaken using ACD/LABS Percepta software, DFT calculations and a Monte Carlo simulation to elucidate atomistic information on the corrosion inhibition action of AST on the C1018 surface
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