Inhibitive effect of salicylidene‐N‐N′‐dimorpholine towards corrosion of zinc in hydrochloric acid

Abstract

PurposeThe purpose of this paper is to describe the behavior of salicylidene‐N‐N′‐dimorpholine as a corrosion inhibitor for zinc in hydrochloric acid and the mechanism of its action.Design/methodology/approachThe effects of various parameters on the behavior of this inhibitor have been studied using weight loss, galvanostatic polarization, and cathodic protection methods. Thermodynamic parameters and adsorption data also were utilized.FindingsThe inhibitor showed excellent corrosion inhibition (>99 percent) at effective concentration. It appeared from thermodynamic parameters that an efficient inhibitor is characterized by a relatively greater decrease (i.e. more negative) in free energy of adsorption (ΔGA°), positive values of entropy of adsorption (ΔSA°), and lower heat of adsorption (QA). Galvanostatic polarization data indicate that this is a “mixed” type inhibitor with predominant effect on the cathode. The inhibitor followed Langmuir adsorption isotherm behavior. The cathodic protection indicated that the conjoint action of the inhibitor and the cathodic current was either synergistic or additive.Originality/valueVery few inhibitors exhibit such excellent inhibitive effect on zinc in aggressive corrosive media as is shown in this paper.

Improvement in Corrosion Protection of Zinc by A Natural Inhibitor Incorporated with Zinc Oxide Nanoparticles in an Acidic Medium Evaluated using Gravimetric Measurement, Electrochemical Method and Atomic Force Microscopy

“…The specimens were mechanically abraded with 150, 300 and P518 grade emery papers and then polished to a mirror finish using jeweler's rouge, leaving a working area of 3 cm × 3 cm × 0.12 cm dimensions for weight loss measurements. The working surface was subsequently ground with acetone followed by double-distilled water, dried in warm air and then stored in moisture-free desiccators before immersion in a corrosive medium 8 . For the electrochemical impedance measurements, metal specimens of a circular design of apparent surface area 6.156 cm 2 were used as the working electrode.…”

Corrosion Inhibition of Aa6061 and Aa6063 Alloy in Hydrochloric Acid Media by Schiff Base Compounds

“…Assuming that the inhibitors adsorbed on the alloy surface decrease the surface available for cathodic and anodic reactions to take place. The nitrogen atoms of the Schiff bases act as the reaction centers (polar function) because of its higher electron density resulting in the formation of a monolayer on the metal surface [22,23] . It is generally assumed that the adsorption of the inhibitors on the metal surface is an essential step in the inhibition mechanism [24] .…”

Evaluation of Impedance Measurements on Al-Pure Corrosion in 1.0 M HCl in the Presence of Organic Schiff

“…The polar unit is regarded as the reaction centre for the establishment of the adsorption process and the adsorption bond strength is determined by the electron density on the atom, acting as the reaction centre and by the polarisability of the fundamental unit [32]. Amine-type inhibitors have electron-donating ability and their action is attributed to the adsorption of the molecule on the metal surface through an unshared pair of electrons belonging to the nitrogen atom [31]. The inhibitor molecules are adsorbed chemically on the surface of the bulk metal, M, forming a charge transfer complex between the polar atom/atoms and the metal,…”

“…So it is very important to clarify the interactions between the inhibitor molecules and metal surfaces in order to search new and efficient corrosion inhibitors [26]. In earlier work the inhibition of corrosion of zinc in sulphuric acid and aluminium in hydrochloric acid by Schiff bases of ethylenediamine [27], orthosubstituted aniline-N-salicylidenes [28], ortho-, meta-, and para-aminophenol-Nsalicylidenes [29], meta-substituted aniline-N-salicylidenes [30], salicylidine-N,N′-dimorpholine [31] and aniline-N-benzylidene [32] has been reported. In the present work, the inhibitive effectiveness of (A) and (B) Schiff bases have been studied in retarding corrosion of Al-Pure in 1.0 M HCl.…”