Experimental and theoretical studies of Schiff bases as corrosion inhibitors

Abstract

BackgroundRelatively inexpensive, stable Schiff bases, namely 3-((4-hydroxybenzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ3) and 3-((4-(dimethylamino)benzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ4), were employed as highly efficient inhibitors of mild steel corrosion by corrosive acid.FindingsThe inhibition efficiencies were estimated based on weight loss method. Moreover, scanning electron microscopy was used to investigate the inhibition mechanism. The synthesized Schiff bases were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and micro-elemental analysis. The inhibition efficiency depends on three factors: the amount of nitrogen in the inhibitor, the inhibitor concentration and the inhibitor molecular weight.ConclusionsInhibition efficiencies of 96 and 92% were achieved with BZ4 and BZ3, respectively, at the maximum tested concentration. Density functional theory calculations of BZ3 and BZ4 were performed to compare the effects of hydroxyl and N,N-dimethylamino substituents on the inhibition efficiency, providing insight for designing new molecular structures that exhibit enhanced inhibition efficiencies.

Experimental and Quantum Chemical Studies on the Corrosion Inhibition of Mild Steel By 2-((Thiophen-2-Ylmethylene) Amino)Benzenethio in 1M HCl

“…Density function theorem (DFT) was employed to elucidate optimization texture tested inhibitor and quantum parameters "EHOMO and ELUMO (Energy of highest occupied molecular orbital and Energy of lowest unoccupied molecular orbital), dipole moment/μ, chemical hardness/η, chemical softness/σ and Electrophilicity index/ω" at the function DFT-B3LYP with the basis set 6-31G. The mechanism of inhibiton of the investigated inhibitor depending on quantum parameters were figured as in Equations 3-7 (14).…”

“…Mild steel coupons texture of C (0.21%), Si (0.38%), Mn (0.05%), P (0.09%), Al (0.01%), and Fe (99.21%) were utilized for weight loss investigations. The coupons were cleaned according to the standard procedure to be specific ASTM G1-03 (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). In a typical methodology, coupons were suspended volume 200 mL of a corrosive solution (in duplicate) to try or not of 2-((thiophen-2-ylmethylene) amino) benzenethiol.…”

Novel ecofriendly corrosion inhibition of mild steel in strong acid environment: Adsorption studies and thermal effects

“…Coupons of mild steel which have the chemical composition of Fe, 99.21; C, 0.21; Si, 0.38; P, 0.09; S, 0.05; Mn, 0.05; and Al, 0.01; and it had an effective surface area of 4.5 cm 2 were used for gravimetric and surface analysis. Initially the coupons were polished then washed with distilled water, acetone and dry at room temperature [31][32][33]. Hydrochloric acid solutions of 1 M were used and the concentrations of inhibitor were varied from 0.1 mM to 0.5 mM.…”

Effect of Santolina pectinata (Lag.) Essential Oil to protect against the corrosion of Mild steel in 1.0 M HCl: Experimental and quantum chemical studies

“…Almost all inhibitors of corrosion are synthetic organic compounds 4 . Owing to the high cost, toxicity, and dangerous effects of synthesized corrosion inhibitor 5,6 , the search for green alternatives that are eco-friendly and non-toxic to protect health and ensure human security is at present attractive [7][8][9][10][11][12][13] . In our laboratory, a great deal of research has been carried out to study inhibitive effect using plant extract on the corrosion of steel in acidic media.…”