Novel Corrosion Inhibitor for Carbon Steel in Acidic Solutions Based on α-Aminophosphonate (Chemical, Electrochemical, and Quantum Studies).

Abstract

α-aminophosphonate (α-AP) is used as a novel corrosion inhibitor for carbon steel. The aggressive media applied in this study are HCl and H2SO4 acid solutions. The findings indicate that the morphology of the α-AP compound is cubic, with particles ranging in size from 17 to 23 μm. FT-IR, 1HNMR, 31PNMR, and 13CNMR analysis confirmed the synthesis of the α-AP molecule. It has been discovered that the compound α-AP plays an important role in inhibiting the corrosion of carbon steel in both HCl and H2SO4 acids. This was identifiably inferred from the fact that the addition of α-AP compound decreased the corrosion rate. It is important to report that the maximum inhibition efficiency (92.4% for HCl and 95.7% for H2SO4) was obtained at 180 ppm. The primary factor affecting the rate at which steel specimens corrode in acidic electrolytes is the tendency of α-AP compounds to adsorb on the surface of steel through their heteroatoms (O, N, and P). This was verified by SEM/EDX results. The adsorption actually occurs through physical and chemical mechanisms via different active centers which are matched with the calculated quantum parameters. In addition, the adsorption of α-AP follows the Langmuir isotherm.