Some diazepinone analogs as corrosion inhibitors for carbon steel in a hydrochloric acid medium: An integrated theoretical and practical study
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Original research


Corrosion is not just an undesirable phenomenon but a global economic challenge. With the help of current state-of-the-art research facilities, this work proposes the inhibition activity of two diazepinone analogs, namely 4-Phenyl-5a, 6, 7, 8, 9,9a-hexahydro-1 H-1,5-benzodiazepin- 2(5 H)-one (POBD) and 7-phenyl-1,4-diazepin-5-one (PTDZ) for carbon steel (CS) corrosion in 1 M hydrochloric acid using chemical and electrochemical corrosion analysis, especially electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface analysis (SEM & UV-vis), and modeling techniques. Results showed that chemical structure and concentration had an impact on the diazepinone analogs capacity to inhibit. POBD and PTDZ functioned in mixed mode, according to PDP data. Due to the inhibitor molecules' adsorption on the CS surface, the Nyquist plots showed that when the concentration of POBD and PTDZ was raised, polarization resistance increased and double-layer capacitance decreased. The POBD and PTDZ were adsorbed on the metal surface, which followed the Langmuir adsorption isotherm model. The proposed mixed-type adsorption of the examined diazepinone compounds on the CS surface was based on thermodynamic adsorption and activation characteristics. The steel was shown to be shielded from acidic ions by an adsorbed layer of inhibitor molecules by surface examination via scanning electron microscopy (SEM). The interactions between diazepam and the CS surface have been clarified and linked using MDS and DFT.

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