K. Babić‐Samardžija, K.F. Khaled and N. Hackerman
Work reported in the present paper investigated the inhibiting properties of a number of N‐heterocyclic amines in 0.1 mol/l HClO4. An attempt also was made to correlate some…
Abstract
Purpose
Work reported in the present paper investigated the inhibiting properties of a number of N‐heterocyclic amines in 0.1 mol/l HClO4. An attempt also was made to correlate some molecular parameters of these compounds with their corrosion inhibitor efficiency.
Design/methodology/approach
The test series included piperidine (pip), 2‐methylpiperidine (2mp), 3‐methylpiperidine (3mp), cis‐2,6‐dimethylpiperidine (26dp), 3,5‐dimethylpiperidine (35dp), 3‐hydroxy piperidine (3hp), 4‐hydroxypiperidine (4hp), 4‐aminopiperidine (4ap), piperazine (pz), 2‐methylpiperazine (2mpz) and cis‐2,6‐dimethylpiperazine (26dpz). The inhibiting effect was investigated in 0.1& mol/L HClO4 by potentiodynamic polarization (DC) and electrochemical impedance spectroscopy (EIS).
Findings
The results show that these compounds suppressed both cathodic and anodic processes of iron corrosion in 0.1 mol/l HClO4 by adsorption on the surface, which followed a Langmuir adsorption isotherm. Experimental observations indicated that basic piperidine and piperazine were better corrosion inhibitors than were their derivatives. The inhibition properties of N‐heterocyclic amines were found to be related to the charge on the nitrogen atom and the sum of the net charge of the all six atoms from the cyclic ring.
Originality/value
This paper provides useful information relative to corrosion inhibition efficiency of the group of N‐heterocyclic amines. It is concerned with a theoretical explanation between electronic and structural characteristics of these compounds and their inhibitor efficiency.
Details
Keywords
Z. AHMAD, M. GHAFELEHBASHI and S. NATEGH
Introduction The degree of adsorption of organic inhibitors on a metal surface in presence of halide anion is predominantly influenced by the synergistic effect. The synergistic…
Abstract
Introduction The degree of adsorption of organic inhibitors on a metal surface in presence of halide anion is predominantly influenced by the synergistic effect. The synergistic effect brings about an improvement in inhibition as a result of chemisorption or physical adsorption depending on the nature of the interaction between the halide and the cation of the inhibitor. This effect is partly attributed to the stabilization of the adsorbed anion layer by an organic cation through a possible covalent linkage. The degree of availability of electrons influences the mode of adsorption. Investigations on ferric ion corrosion have shown that the synergistic inhibition effects the corrosion processes by primarily increasing the polarization of the cathodic reaction. The adsorption of quinoline on 18–8 steel in the presence of halider ions is predominantly influenced by the synergistic effect. It has been found that the addition of smaller concentration of quinoline inhibits the cathodic reaction and higher concentrations of quinoline inhibit the anodic reaction as well. According to Iofa the formation of an adsorbed layer of positively charged ion retards the transfer of cation through a binary layer and lowers the transfer rate. Work on amines has shown that tertiary and secondary amines are stronger than the primary amines as a result of increase of dipole moment of the doublet, increase of ionisation energy and increase of polarizability. Basicity and stearic effects, both are important. The high effectiveness of cyclic amines with more than seven carbon atoms appears to be correlated with the character of the free electron. It has been shown that whereas the organic compounds of cationic type were weakly absorbed on the iron surface in H2SO4 the addition of halides produced a considerable increase in the adsorption. Cavallaro and others have shown that several nitrogen molecules inhibit both the anodic and cathodic reactions.
J.A. Von Fraunhofer and G.A. Pickup
In the study of a corrosion phenomenon, corrosion product analysis can only be regarded as a part, albeit essential, of the whole investigation. The content to which any corrosion…
Abstract
In the study of a corrosion phenomenon, corrosion product analysis can only be regarded as a part, albeit essential, of the whole investigation. The content to which any corrosion process, and its manifestations, is studied is governed by several factors, which include the information required, the motive behind the investigation (research or industrial), the relevance of laboratory tests with respect to service conditions and the cost of the work. The ad hoc solutions of a plant engineer are often satisfactory over an indefinite period but they can only rarely be regarded as the complete answer to a particular corrosion problem although they will permit the plant to carry on in operation. The corrosion engineer must be able to justify his proposed research or fundamental investigations into a corrosion process from a cost and time standpoint.
S. Muralidharan, P. Chandrakumari, K. Madhavan, T. Vasudevan and S. Venkatakrishna Iyer
Introduction Amines have been known for a number of years as effective corrosion inhibitors. Their efficiency is attributed to the presence of the nitrogen atom acting as the…
Abstract
Introduction Amines have been known for a number of years as effective corrosion inhibitors. Their efficiency is attributed to the presence of the nitrogen atom acting as the active centre for the adsorption of organic molecules on the metal surface. Several aliphatic and aromatic amines have been reported to serve as effective corrosion inhibitors for iron and steel in acidic solutions. The nitrogen‐containing corrosion inhibitor exhibited a very good performance in hydrochloric acid, but very little effect in sulphuric acid. Hence a study of the mechanism by which the corrosion rate is reduced when these organic compounds are added to solutions is of interest. In this study the inhibition of corrosion of mild steel in HCl and H2SO4 has been studied using different electrochemical techniques. Results are reported and discussed.
M.N. Desai and S.M. Desai
Mann, Antonucci, Nathan, Hackerman and Antropov investigated aniline and N — substituted methyl and ethylamines as corrosion inhibitors for iron in acidic media. The present study…
Abstract
Mann, Antonucci, Nathan, Hackerman and Antropov investigated aniline and N — substituted methyl and ethylamines as corrosion inhibitors for iron in acidic media. The present study was therefore undertaken to investigate the retardation of corrosion of aluminium 65S in hydrochloric acid.
M.N. Desai, G.H. Thanki and M.H. Gandhi
Organic compounds containing sulphur, nitrogen and oxygen atoms are capable of retarding metallic corrosion. As the thiourea molecule contains one sulphur and two nitrogen atoms…
Abstract
Organic compounds containing sulphur, nitrogen and oxygen atoms are capable of retarding metallic corrosion. As the thiourea molecule contains one sulphur and two nitrogen atoms, thiourea and its derivatives are potential corrosion inhibitors. While extensive investigations have been carried out on inhibitor properties of thiourea, due attention has not yet been paid to a systematic study of inhibitor action of thiourea derivatives. However, several substituted thioureas have been investigated as corrosion inhibitors. The applications of thiourea and its derivatives as corrosion inhibitors reported in literature up to 1967 are narrated in this article.
S. Muralidharan, S. Syed Azim, L. John Berchmans and S.V.K. Iyer
The synergistic influence caused by iodide ions on the inhibition of corrosion of mild steel in 0.5M H2SO4 in the presence of n‐hexyl amine (n‐HA) has been studied using…
Abstract
The synergistic influence caused by iodide ions on the inhibition of corrosion of mild steel in 0.5M H2SO4 in the presence of n‐hexyl amine (n‐HA) has been studied using potentiodynamic polarization, linear polarization and a.c impedance technique. n‐HA accelerates the corrosion of mild steel at lower concentrations but inhibits the corrosion at higher concentrations. The addition of iodide ions enhances the inhibition efficiency to a considerable extent. The adsorption of this compound is found to obey Temkin’s adsorption isotherm. The increase in surface coverage in the presence of iodide ions indicates that iodide ions enhance the adsorption of n‐HA on the metal surface. Defines and evaluates synergism parameter (SI). Values of the parameter which are more than unity indicate the fact that the enhanced inhibition efficiency in the presence of iodide ions is only due to synergism and there is a definite contribution from the inhibitor molecule. n‐HA is then adsorbed by coulombic interaction on the metal surface, where iodide ions are already adsorbed, and thus reduces the corrosion rate.
M.N. DESAI, V.K. SHAH and M.H. GANDHI
Due to the constituent nitrogen atom of the amino group, amines have been extensively used as inhibitors of metallic corrosion. This article reviews the reported uses of aniline…
Abstract
Due to the constituent nitrogen atom of the amino group, amines have been extensively used as inhibitors of metallic corrosion. This article reviews the reported uses of aniline and related aromatic amines as corrosion inhibitors.
D.L. Burns, R.L. Hildebrand and P.D. Thomas
Presented herein is information developed by a panel of the Sub‐Committee on Corrosion of the American Institute of Petroleum concerned with the mechanism of corrosion inhibition…
Abstract
Presented herein is information developed by a panel of the Sub‐Committee on Corrosion of the American Institute of Petroleum concerned with the mechanism of corrosion inhibition, temperature limitations, detergent action and chemical composition of the high‐molecular‐weight organic inhibitors commonly used in process streams. Included is a literature survey on the mechanism of corrosion inhibition; refinery experiences with inhibitors as developed by a questionnaire; and information contributed by manufacturers of inhibitors. Other data pertinent to corrosion and inhibitor problems are discussed.
A.S. Fouda, S.S Elkaabi and A.K. Mohamed
The inhibitive effect of some substituted phenyl n‐phenylcarbamates on corrosion of iron in 2N HCI have been studied using gaivanostatic polarization measurement. Studies carried…
Abstract
The inhibitive effect of some substituted phenyl n‐phenylcarbamates on corrosion of iron in 2N HCI have been studied using gaivanostatic polarization measurement. Studies carried out with different concentrations of the inhibitor indicated that the compounds act as a mixed inhibitor. The results indicate that the additives reduce the corrosion rate by way of adsorption through the oxygen atom of phenoxy group and nitrogen atom of NH group. The inhibitory character of the compounds depends upon the concentration of the inhibitor, as well as its chemical composition. The results of electrocapillary measurements are consistent with the electrochemical measurements. Thermodynamic parameters for absorption of inhibitors have been calculated and discussed.