Corrosion inhibition investigations of 3-acetylpyridine semicarbazone on carbon steel in hydrochloric acid medium

Synthesis, Cyclic Voltammetric, Electrochemical, and Gravimetric Corrosion Inhibition Investigations of Schiff Base Derived from 5,5-Dimethyl-1,3-cyclohexanedione and 2-Aminophenol on Mild Steel in 1 M HCl and 0.5 M H2SO4

Schiff base 2,2’-(5,5-dimethylcyclohexane-1,3-diylidene)bis(azan-1-yl-1-ylidene) diphenol (DmChDp) was synthesized and characterized using spectroscopic methods (IR, UV, NMR, and Mass) and cyclic voltammetric (CV) studies. The corrosion inhibition potency of (DmChDp) on mild steel (MS) in 1M HCl and 0.5M H2SO4 was investigated. The corrosion monitoring techniques employed for this purpose are gravimetric and electrochemical methods (EIS and potentiodynamic polarization studies). The study reveals that the Schiff base, DmChDp, acts as excellent corrosion inhibitor on mild steel in 1M HCl. DmChDp obeys Langmuir adsorption isotherm both in 1M HCl and 0.5M H2SO4 on MS. Polarization studies show that DmChDp behaves as a mixed type inhibitor in both media. Scanning electron microscopic analysis established the protective nature of DmChDp on mild steel surface. The impact of temperature on the corrosion of MS was also evaluated using gravimetric method.

Monitoring the Interaction of Two Heterocyclic Compounds on Carbon Steel by Electrochemical Polarization, Noise, and Quantum Chemical Studies

A heterocyclic phenylhydrazone 2-[(E)-(2-phenylhydrazinylidene)methyl]pyridine (P2APH) and its reduced form 2-[(2-phenylhydrazinyl)methyl]pyridine (RP2APH) were synthesized, characterized, and subjected to corrosion inhibition investigation on carbon steel (CS) in 1 M HCl using gravimetric, polarization, electrochemical noise, quantum chemical, and surface studies. P2APH showed more inhibition capacity than RP2PPH. But RP2PPH was very stable in acid medium and showed pronounced corrosion inhibition efficacy for days. Energy of HOMO and LUMO, their difference, number of electrons transferred, electronegativity, chemical hardness, and so forth were evaluated by quantum chemical studies. Agreeable correlation was observed between the results of quantum chemical calculations and other corrosion monitoring techniques.