Carbon Steel In Sulfuric Acid Research Articles

Studies on preparing and corrosion inhibition behaviour of quaternized polyethyleneimine for low carbon steel in sulfuric acid

Quaternized polyethyleneimine (QPEI) was prepared via two procedures of macromolecular reactions, tertiary amination reaction and quaterisation, and its chemical structure was characterized with infrared and UV spectra. In this paper, the corrosion inhibition property of QPEI for low carbon steel (A 3 steel) in H 2SO 4 solution was mainly investigated by using weight loss method, electrochemical technique (potentiodynamic polarization curves) and scanning electron microscopy (SEM) investigation. Meanwhile, the corrosion inhibition mechanism of QPEI was also fully explored. The experiment results show that as a polymeric quaternary ammonium salt, QPEI is quite an excellent corrosive inhibitor, it possesses outstanding inhibition action for low carbon steel, and only with 5 mg L −1 of QPEI concentration, the inhibition efficiency of A 3 steel can reach to 92% in 0.5 M H 2SO 4 solution for 72 h of immersing time. The inhibition efficiency increases with the increase of QPEI concentration, and the inhibition efficiency also increases with the enhancement of the cationic degree (quaternized agree) of QPEI. QPEI acted as a mixed type inhibitor with anodic predominance. QPEI possesses functions of double filming, adsorption filming and polymer filming, so with the cooperation of the two filming effects, QPEI can form a compact barrier film on A 3 steel surface, and prevent metal dissolution and retard H + discharging. The adsorption of QPEI on A 3 steel surface was found to follow the Langmuir isotherm equation.

Influence of 1‐methyl 2‐mercapto imidazole on corrosion inhibition of carbon steel in 0.5 M H2SO4

PurposeTo evaluate the inhibition efficiency of 1‐methyl 2‐mercapto imidazole (MMI) in controlling the corrosion of carbon steel in sulphuric acid and to study its action mechanism.Design/methodology/approachThe effect of concentration, immersion time and temperature on the behaviour of this inhibitor has been studied using weight loss, d.c. polarisation and a.c. polarisation techniques.FindingsThe results show that MMI is a mixed type inhibitor. Changes in impedance parameters (charge transfer resistance, Rt; and double layer capacitance, Cdl) were indicative of adsorption of MMI on the metal surface, leading to the formation of a protective film that grew with the increasing exposure time. Adsorption of MMI on the carbon steel is found to obey the Langmuir adsorption isotherm. The inhibition efficiency of MMI is temperature‐independent and its addition leads to a small increase in activation corrosion energy.Research limitations/implicationsSurface analytical techniques such as X‐ray photoelectron spectroscopy and Auger spectroscopy can enlighten more on the mechanism of corrosion inhibition.Originality/valueA survey of literature has shown that no work using electrochemical techniques has yet been done on MMI as corrosion inhibitor for carbon steel in sulfuric acid.

The effect of isomers of some organic compounds as inhibitors for the corrosion of carbon steel in sulfuric acid

PurposeTo study the effects of isomers of organic compounds such as phenylenediamine, toluidine and nitroaniline as inhibitors for the corrosion of carbon steel in sulfuric acid.Design/methodology/approachStandard methods have been adopted in this study such as weight loss, polarization tests, impedance measurements and hydrogen permeation studies to find out the corrosion behavior of carbon steel in sulfuric acid with and without inhibitors.FindingsAll the selected isomers inhibited the corrosion. The best performance was found in ortho‐phenylenediamine when compared with other inhibitors under study.Originality/valueIt clearly shows the effect of isomers of phenylenediamine, toluidine and nitroaniline. The method of study may be applicable to find out the performance of other isomers of organic compounds. As these isomers behave as good inhibitors in sulfuric acid, these may be tried as inhibitors in other acids. Hence, this study is useful to academics and researchers in the field of corrosion science and engineering.

Corrosion inhibition of carbon steel in sulfuric acid by bicyclic isoxazolidines

The cycloaddition of cyclic nitrone1‐pyrroline‐1‐oxide with 1‐dodecene and 1‐hexadecene afford a bicyclic (isoxazolidines). These isoxazolidines were tested for corrosion inhibition of carbon steel in 1N H2SO4 in the 30‐60°C temperature range by gravimetric and electrochemical methods. The compound isoxazolidines exhibited excellent inhibition efficiency in the acidic corrosion environment. The presence of heteroatoms such as N and O induce greater adsorption of the inhibitor molecules onto the surface of carbon steel and the long hydrocarbon chains ensure coverage of the metal surface. The values of activation energy and free energy of adsorption indicated the physical nature of the adsorption on the surface of the carbon steel. Thermodynamic parameters were determined for the adsorption process (ΔGadso, ΔHadso, ΔSadso), and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction in the presence of the isoxazolidines. The adsorption of inhibitors on the metal surface was found to obey the Langmuir adsorption isotherm. The isoxazolidines were found to be mixed‐type inhibitors. The isoxazolidine which had a tetradecyl hydrophobe was found to be a better inhibitor than was the decyl analogue.

Effect of Microstructure on Anodic Polarization of Carbon Steel in Sulfuric Acid

Abstract Previous work on anodic polarization and anodic protection of carbon steel in sulfuric acid has neglected to consider the possible effect of differences in steel microstructure on polarization behavior. If such differences do affect anodic-polarization behavior of the steel, it would be important to recognize this fact when, for example, anodic protection is applied to a welded steel vessel containing heat-affected zones of varying microstructure. In the present work, anodic polarization curves were determined in three concentrations of sulfuric acid for samples of carbon steel that had been heat-treated to produce various microstructures. In general, results showed that microstructural differences, had only a minor effect on polarization behavior. Therefore, when anodic protection is applied to carbon steel in sulfuric acid, micro-structural differences resulting from heat treatment of steel should not be a critical factor. Test results also indicated that carbon content of the steel had little ...

硫酸中における炭素鋼の陽極防食

硫酸中における炭素鋼の陽極防食

Anodic Protection of Carbon Steel in Sulfuric Acid

Abstract Anodic polarization curves and the corrosion rates of unprotected and anodically protected 1020 mild steel coupons were determined in sulfuric acid at 80 F in concentrations ranging from 45 to 105 percent. Additional data were determined at temperatures of 120, 200 and 535 F. The effectiveness of anodic protection and the current density requirements for maintaining protection were found to be dependent on acid concentration and temperature. Field performance of anodic protection systems in carbon steel-sulfuric acid vessels is in agreement with laboratory current requirement and corrosion data.