A combination of experimental and theoretical methods in evaluating triazole derivatives' mild steel corrosion inhibition ability in an acidic solution

A comprehensive study was conducted, both experimentally and theoretically, to evaluate the corrosion inhibition ability of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol (AT) and 4-amino-5-(pyridine-4-yl)-4H-1,2,4-triazole-3-thiol (AP) on mild steel. The findings show that AT and AP are potential mixed-type inhibitors in hydrochloric acid solution. At 293 K and a concentration of 5 x 10-3 M, AT and AP have efficiencies of 93.33% and 97.33%. When the temperature rises to 323 K, their efficiencies drop to 87.27% and 90.82%. The adsorption behavior of AT and AP on the steel surface conforms to the Langmuir adsorption isotherm. A key finding is the superior inhibition performance of AP over AT, attributed to its higher nitrogen heteroatom content, which enhances the interaction with the mild steel surface. Molecular dynamics simulations and quantum chemical calculations reveal that AP exhibits a notably higher binding energy (pAP-N20: 847.17 kJ mol-1) compared to AT (pAT-S18: 847.17 kJ mol-1). This study established a correlation between molecular structure, adsorption behavior, and corrosion inhibition efficiency, providing new insights into the design of effective corrosion inhibitors for industrial applications.