Adsorption of a new urea-based organic inhibitor “UI” on corrosion of brass in 1 M HCl: Electrochemical and DFT study

• M. Benhlal¹, M. Ouakki^1,2, E. Ech-chihbi³ and M. Cherkaoui^1,2

¹ Laboratory of Organic Chemistry, catalysis and Environment, Faculty of Sciences, Ibn Tofaïl University, PO Box 133, 14000, Kenitra, Morocco
² Ingénierie, Durabilité et Innovation, National Higher School of Chemistry (NHSC), University Ibn Tofail BP. 133-14000, Kenitra, Morocco
³ Laboratory of Physics and Chemistry of Inorganic and Organic Materials, Materials Science Research Centre, Higher Normal School, Mohammed V University, Rabat, Morocco

Abstract: The effectiveness of the urea-based inhibitor, namely 1-ethyl-3-hydroxy-5-(3-methylbenzyl)-6,13-dioxa-9,10-diaza-1,5(1,2),3(1,3)-tribenzenacyclotridecaphane-8,11-dione (UI), in preventing brass corrosion was evaluated using electrochemical methods and DFT modeling. The new aromatic compound UI was tested for corrosion protection in 1 M hydrochloric acid (HCl) at concentrations ranging from 25 to 150 ppm and at temperatures from 298 to 328 K. Electrochemical studies using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the inhibition efficiency increases with the inhibitor concentration. The results also indicate that the compound acts as a mixed-type inhibitor. At 150 ppm, the maximum inhibition efficiency reached 87.6%. Polarization curves confirmed that brass corrodes more slowly in the presence of the UI, especially at higher concentrations. However, the inhibition efficiency decreased slightly with increasing temperature. The Langmuir adsorption isotherm model confirmed that molecules from UI adsorb effectively on the brass surface. Additionally, quantum chemical simulations based on density functional theory (DFT) supported the observed inhibitory behavior. Fourier-transform infrared spectroscopy (FT-IR) and SEM analysis confirmed the formation of a protective layer due to the adsorption of the UI through its amino groups.

Keywords: corrosion inhibition, brass, urea-family inhibitor, adsorption, hydrochloric acid

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1622-1648
doi: 10.17675/2305-6894-2025-14-3-30

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