New epoxy resin as a high-performance corrosion inhibitor for steel: experimental and theoretical investigations

초록

In this study, a novel epoxy resin, triglycidyl-dibenzylidene-thiosemicarbazide (TGDBTSC), was firstly synthesized and evaluated as an efficient defensive agent for mild steel in 1 M HCl. Electrochemical studied demonstrated excellent protection performance, with efficiencies reaching 93.2% at a concentration of 10(-)3 M. The corrosion current density exhibited a substantial decline, from 983 to 66 mu A cm(-)2, as measured by Potentiodynamic Polarization (PDP), while the charge transfer resistance underwent an increase from 34.7 to 312.8 Omega cm2, as measured by Electrochemical Impedance Spectroscopy (EIS). Thermodynamic studies revealed an activation energy of 40.57 kJ<middle dot>mol(-)1 and an enthalpy of activation of 37.97 kJ<middle dot>mol(-)1, indicating an endothermic adsorption process. At approximately 328 K, the inhibition efficiency remained high (86.5%), thereby confirming the thermal stability of TGDBTSC. Surface analysis revealed a smooth and compact surface morphology of protected steel, accompanied by inhibitor adsorption. Density Functional Theory (DFT) calculations revealed a smaller energy gap (Delta Egap = 2.965 eV) and higher electron-donating ability (Delta N = 0.450) for the protonated form of TGDBTSC. Monte Carlo (MC) and molecular dynamics (MD) simulations further corroborated the strong adsorption affinity, with adsorption energies of - 180.65 kcal/mol and radial distribution function (RDF) peaks between 1.5 and 3.0 & Aring;, indicative of chemisorption. These findings confirm the potential of TGDBTSC as a highly effective, durable, and thermally stable inhibitor for acid-treated steel corrosion.

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