Synthesis and Electrochemical, Thermodynamic, and Surface and Quantum Chemistry Studies to Evaluate Corrosion Inhibition Effect of Polyepichlorohydrin Modified with 3-Nitro-1,2,4-triazole-5-one Sulfur Group for Mild Steel in Hydrochloric Acid Solution

This paper replaced 3-nitro-1,2,4-triazole-5-one (NTO) with the chlorine branches of the polyepichlorohydrin (PECH) compound and analyzed the inhibitory efficiency of this compound for the steel immersed in a (1-M) solution of hydrochloric acid. The synthesis of this compound was confirmed by the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), elemental analysis (CHN), thermal analysis (TGA), and visible-ultraviolet (UV-Vis) spectroscopy. Moreover, the inhibitor corrosion properties of this compound in the acidic solution were analyzed through the electrochemical impedance spectroscopy (EIS), polarization, and quantum chemistry tests. According to the results, the sample containing NTO and SO(OH) had the highest rate of inhibition corrosion. Its efficiency was enhanced by increasing the concentration of inhibitors in the acidic solution, something which indicated the dominant role of the adsorption mechanism in improving the inhibitory properties of the system. Furthermore, the results of the polarization test depicted that the inhibitors acted as mixed inhibitors in an acidic medium and affected both anodic and cathodic reactions of corrosion through adsorption on the surface of the steel immersed in a corrosive medium.