Corrosion inhibitors part 31 : quantum chemical studies on the efficiencies of some aromatic hydrazides and Schiff bases as corrosion inhibitors of steel in acidic medium

Abstract

A quantum chemical study of the efficiency of some o-, m-, and p-substituted benzohydrazides, cinnamohydrazide, and Schiff bases derived from salcylaldehyde with o-substituted anilines, psubstituted benzaldehydes with 2-aminopyridine and 2-aminopyrimidine, benzaldehyde and cinnamaldehyde with p-phenylenediamine as corrosion inhibitors of steel in the presence of 1M HCl is presented. The AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods were used. A possible correlation between corrosion inhibition efficiencies and structural properties was searched to reduce the number of compounds to be selected for testing from a library of compounds. Quantum parameters, total negative charge (TNC) on the molecule, energy of highest occupied molecular orbital (E HOMO ), energy of lowest unoccupied molecular orbital (E LUMO ), dipole moment (µ), total energy (TE), and linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (π*) were correlated to corrosion inhibition efficiency of the studied compounds. The results were used to predict the corrosion inhibition of some related aromatic hydrazide derivatives with correlation coefficient r > 0.96.

Water-Soluble Polyaniline–Polyacrylic Acid Composites as Efficient Corrosion Inhibitors for 316SS

“…11,12 PANI is the most promising corrosion inhibitor at very low concentrations because its molecular structure exhibits the extensive delocalization of π electrons. 13,14 The organic inhibitors containing the heteroatoms such as N, P, and S, 15−17 unsaturated bonds and conjugated systems with aromatic cycles 18,19 ensure their adsorption on the metal's surface. These inhibitors can therefore interact with the metal to form a protective film that hinders the physical contact of aggressive species with the metal surface in the acidic medium.…”

“…Among organic inhibitors, conducting polymer attracts much attention because of its ability to protect metals in aggressive environment. , As a conducting polymer, polyaniline (PANI) is considered an appropriate candidate because of its facile synthesis, environmental stability, redox reversible activity, and controllable electrical conductivity by chemical doping. , PANI is the most promising corrosion inhibitor at very low concentrations because its molecular structure exhibits the extensive delocalization of π electrons. , The organic inhibitors containing the heteroatoms such as N, P, and S, − unsaturated bonds and conjugated systems with aromatic cycles , ensure their adsorption on the metal’s surface. These inhibitors can therefore interact with the metal to form a protective film that hinders the physical contact of aggressive species with the metal surface in the acidic medium .…”

Effect of 1-Acetyl-1H-Benzotriazole on Corrosion of Mild Steel in 1M HCl

“…Adsorption isotherms are often used to demonstrate the performance of organic adsorbent type inhibitors and are essential in determining the mechanisms of organic electrochemical reactions. The most frequently used adsorption isotherms are Langmuir, Temkin, and Frumkin isotherms, describing the relation between surface coverage θ and bulk concentration (C) [11]. The values of surface coverage θ were evaluated using the value of % IE, resulted from the weight loss experiment in 1M HCl.…”

Ethanol extract of Camphor tree bark as green corrosion inhibitor of LCS in 0.5 M H2SO4 with and without synergistic effect

“…The majority of inhibitor defense is based on the adsorption of inhibitor molecules on metal surfaces, followed by the creation of a protective layer [25,26]. Quantitative structure activity relationship have been studied and the relation between chemistry structure of compounds and their inhibition e ciencies toward corrosion of different metal surfaces were reported [27][28][29][30][31][32][33]. The large number of the corrosion inhibitors used in operation were natural products derived from plant parts such as roots, bark, seeds, stems, leaves, owers, and fruits [34][35][36][37].…”