Azo ligand as new corrosion inhibitor for copper metal: Spectral, thermal studies and electrical conductivity of its novel transition metal complexes

The acid corrosion inhibition process of copper metal in 1.0 M HCl by a novel azo ligand (L) Bis-(1,5 dimethyl-4-[(E)-(3Methyl phenyl)diazenyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) was detected by potentiodynamic polarization and electro chemical impedance spectroscopy (ES). Azo ligand (L) and its metal complexes (Fe(III), Cr(III), Ru(III) Hf(IV) and Zr(IV)) were synthesized and their structural features were demonstrated and confirmed using elemental analysis, spectroscopic techniques (FT-IR, UV-Vis, H-1 NMR, mass), magnetic moment and thermal analysis. Potentiodynamic polarization studies indicate that azo ligand (L) acts as a mixed-type inhibitor. The inhibition efficiency increases as the concentration of inhibitor increased and attains its maximum of 87.1% at 5 x 10(-4) ppm. Electro chemical impedance spectroscopy (ES) measurements indicated that the corrosion mechanism of copper metal in presence of azo ligand (L) were controlled not only by the charge transfer reaction but also, diffusion process. The electrical conductivity measurements proved that the metal complexes are shown higher conductivity values than that of the free ligand (L). The electrical conductivities of the studied metal complexes at room temperature increase in the following order: Cr (III) < Zr (IV) < Ru (III) < Hf (IV) < Fe (III). The synthesized compounds azo ligand and its metal complexes exhibited semiconducting nature. EDX and SEM analysis proved that, the azo ligand (L) has good inhibition effect to retard the corrosion rate. These compounds can be used in industrial applications such as production of wires, tube, electronic devices and as corrosion inhibitor for copper metal. (C) 2020 Elsevier B.V. All rights reserved.