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1.
The inhibition behaviour of 2-undecyl-1-ethylamino-1-methylbenzyl quaternary imidazoline (2UMQI) and KI on mild steel in 1.0 M H2SO4 solutions was investigated at 25 °C using electrochemical methods. The results indicated that 2UMQI inhibited the corrosion of mild steel and the extent of inhibition increased with 2UMQI concentrations. The inhibition action in the presence of 2UMQI is due to physical adsorption of 2UMQI. A mixed-inhibition mechanism is proposed for the inhibitive effects of 2UMQI. Inhibition efficiency of 2UMQI was enhanced by the addition of iodide ions. In the presence of KI, the potentials of unpolarization, Eu was observed and increased with KI concentration.  相似文献   

2.
The corrosion inhibition of mild steel in 0.5 M H2SO4 and 1.0 M HCl by 2-amino-5-phenyl-1,3,4-thiadiazole (APT) has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the inhibition efficiency increases with the increase of APT concentration in both acids, and the higher inhibition efficiency is obtained in 0.5 M H2SO4. The adsorption of APT molecules on the steel surface obeys Langmuir adsorption isotherm in both acids, and occurs spontaneously. The molecular dynamics method has also been used to simulate the adsorption of ATP molecule and solvent ions on the iron surface. The results show that with the adsorption of sulfate ions the Fe + anion + APT system has the higher negative interaction energy comparing to the case of the adsorption of chloride ions.  相似文献   

3.
The effect of 1-methyl-3-pyridin-2-yl-thiourea on the corrosion resistance of mild steel in H2SO4 solution was investigated by different techniques. The results show that the inhibition efficiency increases with the increase of inhibitor concentration. This compound affects both the anodic dissolution of steel and the hydrogen evolution reaction in 0.5 M H2SO4. The adsorption of this inhibitor is also found to obey the Langmuir adsorption isotherm. From the adsorption isotherm, value of the ΔGads for the adsorption process was calculated. From the corrosion rate obtained at 25-45 ± 1 °C Ea, ΔHa and possible mechanism have been proposed.  相似文献   

4.
Butyl triphenyl phosphonium bromide (BuTPPB) has been evaluated as a corrosion inhibitor for mild steel in 0.5 M H2SO4 solutions using galvanostatic polarisation and potentiostatic polarisation measurements. The study was also complemented by infra red (IR) spectroscopy, scanning electron microscopy (SEM) and quantum chemical calculations. Galvanostatic polarisation measurements showed that the presence of BuTPPB in aerated 0.5 M H2SO4 solutions decreases corrosion currents to a great extent and the corrosion rate decreases with increasing inhibitor concentration at a constant temperature. At 298K, inhibition efficiency was found to be 94.5% for 10−7 M BuTPPB which increased to about 99% for the BuTPPB concentration of 10−2 M. The effect of temperature on the corrosion behaviour of mild steel was studied at five different temperatures ranging from 298 to 338K. The polarisation curves clearly indicate that BuTPPB acts as a mixed type inhibitor. Adsorption of BuTPPB on the mild steel surface follows the Langmuir isotherm.Potentiostatic polarisation measurements showed that passivation was observed only for lower BuTPPB concentrations (10−5 and 10−7 mol l−1) for the mild steel in 0.5 M H2SO4. IR and SEM investigations also confirmed the adsorption of BuTPPB on the mild steel surface in 0.5 M H2SO4 solutions. The molecular parameters obtained using PM3 semi-empirical method, were correlated with the experimentally measured inhibitor efficiencies.  相似文献   

5.
The corrosion inhibition of mild steel in a 2.5 M H2SO4 solution by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT) was studied at different temperatures, utilising open circuit potential, potentiodynamic and impedance measurements. The results indicate that APTT performed as an excellent mixed-type inhibitor for mild steel corrosion in a 2.5 M H2SO4 solution and that the inhibition efficiencies increased with the inhibitor concentration but decreased proportionally with temperature. The kinetic and thermodynamic parameters for adsorption of APTT on the mild steel surface were calculated. A chemisorption mechanism of APTT molecules on the mild steel surface was proposed based on the thermodynamic adsorption parameters.  相似文献   

6.
A newly synthesized oxadiazol-triazole derivative (TOMP), was investigated as corrosion inhibitor of mild steel in 0.5 M H2SO4 solution using weight loss measurements, polarization and electrochemical impedance spectroscopy (EIS) methods. Results obtained revealed that TOMP is effective corrosion inhibitor for mild steel in sulphuric acid and its efficiency attains more than 97.6% at 298 K. The number of water molecules (X) replaced by a molecule of organic adsorbate was determined from the substitutional adsorption isotherms applied to the data obtained from the weight loss experiments performed on mild steel specimen in acidic solution in the 298-333 K range.  相似文献   

7.
The synergism between red tetrazolium (RT) and uracil (Ur) on the corrosion of cold rolled steel (CRS) in H2SO4 solution is first investigated by weight loss, potentiodynamic polarization, and atomic force microscope (AFM). Effects of inhibitor concentration (25-500 mg l−1), temperature (20-50 °C), and acid concentration (1.0-5.0 M) on synergism are discussed systematically. The results reveal that RT has a moderate inhibitive effect, and its adsorption obeys the Freundlich adsorption isotherm. For Ur, it has a poor effect. However, incorporation of RT with Ur significantly improves the inhibition performance, and produces synergistic inhibition effect.  相似文献   

8.
Three ferrocene derivatives, namely 1,1′-diacetylferrocene (Diacetyl Fc), 1,1′-diformylferrocene (Diformyl Fc) and 2-benzimidazolythioacetylferrocene (BIM Fc) were synthesized and their inhibitive effects against mild steel corrosion in aerated 0.5 M H2SO4 and 1 M HCl solutions were evaluated. Corrosion measurements based on polarization resistance (Rp), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) indicate that Diacetyl Fc, in most cases, accelerates mild steel corrosion in HCl while Diformyl Fc and BIM Fc act as weak inhibitors. In H2SO4 solution, ferrocene derivatives show good inhibition performance. The efficiency of the inhibitors follows the order: BIM Fc > Diformyl Fc ? Diacetyl Fc. Adsorption of both Diacetyl Fc and Diformyl Fc obey Langmuir adsorption isotherm with very low value of free energy of adsorption ΔG° for the Diformyl Fc (physisorption) while adsorption of BIM Fc follows that of Frumkin with high negative value of ΔG° (chemisorption). Both Diformyl Fc and BIM Fc act as mixed-type inhibitors with predominant effect on the anodic dissolution of iron. Analysis of the polarization curves and impedance spectra indicates that charge transfer process mainly controls mild steel corrosion in H2SO4 solution without and with ferrocene compounds. The mechanism of corrosion inhibition or acceleration by ferrocene derivatives was discussed in the light of the molecular structure of the additives.  相似文献   

9.
The inhibition effect of 6-benzylaminopurine (BAP) on the corrosion of cold rolled steel (CRS) in 1.0-7.0 M H2SO4 at 25-50 °C was studied by weight loss and potentiodynamic polarization methods. Fourier transform infrared spectroscopy (FTIR) and atomic force microscope (AFM) were used to characterize the CRS surface. The results showed that BAP was a good inhibitor in 1.0 M H2SO4, and the adsorption of BAP obeyed the Temkin adsorption isotherm. Polarization curves showed that BAP acted as a mixed-type inhibitor in sulfuric acid. Depending on the results, the inhibitive mechanism was proposed.  相似文献   

10.
Ziprasidone is composed of the benzisothiozole-3-piperizine (BITP) and an indole moiety. The inhibition potential of ziprasidone for the corrosion of steel in 1.0 M HCl and 0.5 M H2SO4 was assessed by weight loss, polarisation, electrochemical impedance spectroscopy and quantum methods. The results showed that nearly 10 times lower concentration of ziprasidone showed the same efficiency that was rendered by BITP. This is related to the planarity of ziprasidone molecule, potential adsorption sites and the extensive distribution of LUMO orbitals on indole moiety which cause larger back donation. Ziprasidone follow Langmuir adsorption isotherm.  相似文献   

11.
2,2′ benzothiazolyl disulfide (BTDS) has been synthesised and their inhibiting action on mild steel corrosion in 1 M HCl and 0.5 M H2SO4 at 308 K has been investigated using weight loss, EIS, polarization and SEM study. BTDS showed better efficiency in 0.5 M H2SO4 compared to 1 M HCl. Polarization studies revealed that BTDS is a mixed type inhibitor in both acids predominantly cathodic in 1 M HCl where as predominantly anodic in 0.5 M H2SO4. Thermodynamic parameters i.e. free energy of adsorption, enthalpy, entropy and activation energy were calculated, the values of these parameters showed good interaction.  相似文献   

12.
The efficiency, as steel corrosion inhibitors in 0.5 M H2SO4, of two thiadiazole derivatives, 2-amino-5-(3-pyridyl)-1,3,4-thiadiazole (3-APTD) and 2-amino-5-(4-pyridyl)-1,3,4-thiadiazole (4-APTD), was investigated by polarization and electrochemical impedance spectroscopy. The protection efficiency increases with increasing inhibitors concentration, but the temperature has hardly effect on the inhibition efficiency of APTD. The adsorption of APTD on iron surface obeys the Langmuir isotherm. The experimental results show that the inhibition efficiency of 4-APTD is higher than that of 3-APTD, and the molecular dynamics (MD) simulations show that the adsorption of 4-APTD on iron surface has the higher binding energy than that of 3-APTD.  相似文献   

13.
14.
Corrosion inhibition of iron in H2SO4 by polyacrylic acid (PAA) was investigated using electrochemical techniques at 30 °C. Results obtained indicate that PAA inhibited the corrosion of iron in the acid medium. Inhibition efficiency increases with increase in PAA concentration and synergistically enhanced on addition of iodide ions. Potentiodynamic polarization results suggest that PAA functions as a modest cathodic inhibitor. The adsorption of PAA onto the iron surface followed Temkin adsorption isotherm. FTIR analysis revealed that the synergistic effect due to co-adsorption of iodide ions and PAA is co-operative in nature.  相似文献   

15.
The corrosion behavior of cold isostatically pressed (CIP) high purity alumina ceramics in aqueous HCl and H2SO4 solutions with various concentrations has been studied simultaneously at room temperature (25 °C). Corrosion tests were also performed with 0.65 mol/l HCl and 0.37 mol/l H2SO4 solutions at 40, 55 and 70 °C for 48 h. Chemical stability was monitored by determining the amount of Al3+, Mg2+, Ca2+, Na+ Si4+ and Fe3+ ions eluted in different concentrations of HCl and H2SO4 solutions by means of atomic absorption spectrometry (AAS). By increasing the concentration from 0.37 to 6.5 mol/l, it was notified that the corrosion susceptibility in HCl and H2SO4 solutions for the CIP alumina specimens at room temperature decreases.  相似文献   

16.
The inhibition effect of alizarin violet 3B (AV3B) on the corrosion of cold rolled steel (CRS) in 1.0 M HCl and 0.5 M H2SO4 solutions was investigated for the first time by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that AV3B is a good inhibitor, and exhibits more efficient in 1.0 M HCl than 0.5 M H2SO4. The adsorption of AV3B on CRS surface obeys Langmuir adsorption isotherm in both acids. Polarization curves reveal that AV3B acts as a mixed-type inhibitor.  相似文献   

17.
The inhibition effect of triazolyl blue tetrazolium bromide (TBTB) on the corrosion of cold rolled steel (CRS) in 1.0 M HCl and 0.5 M H2SO4 solution was investigated for the first time by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results show that TBTB is a very good inhibitor, and is more efficiency in 1.0 M HCl than 0.5 M H2SO4. The adsorption of TBTB on CRS surface obeys Langmuir adsorption isotherm. Polarization curves reveal that TBTB acts as a mixed-type inhibitor in both acids.  相似文献   

18.
The cycloaddition reactions of the cyclic nitrones 1-pyrroline 1-oxide and 3,4,5,6-tetrahydropyridine 1-oxide with alkenes, 11-phenoxy-1-undecene and 11-p-methoxyphenoxy-1-undecene, afforded cycloaddition products (bicyclic isoxazolidines) in excellent yields. One of the cycloadducts on reaction with propargyl chloride and ring opening with zinc in acetic acid afforded quaternary ammonium salt and aminoalcohol, respectively. All the new inhibitor molecules in the presence of 400 ppm at 60 °C achieved inhibition efficiencies, determined by gravimetric method, in the range 99-99.6% and 85-99% for mild steel in 1 M HCl and 0.5 M H2SO4, respectively. Comparable results were obtained by the electrochemical methods using Tafel plots and electrochemical impedance spectroscopy for the synthesized compounds. The isoxazolidine derivatives were also found to be good inhibitors of mold steel corrosion in synthetic brine. Negative values of in the acidic media ensured the spontaneity of the adsorption process. While the corrosion inhibition by these molecules was predominantly under cathodic control in 1 M HCl, the inhibition in 0.5 M H2SO4 was found to be under anodic control. The isoxazolidines and their derivatives were found to be among a rare class of molecules, which provide suitable inhibition mechanism for the corrosion inhibition in HCl as well as in H2SO4 media.  相似文献   

19.
The corrosion inhibitive efficiencies of two crown type polyethers, namely dibenzo-bis-imino crown ether (C-1) and dibenzo-diaza crown ether (C-2), which are macrocyclic Schiff base and its reduced form (macrocyclic amine), respectively, for the steel in 1 M H2SO4 have been investigated by Tafel extrapolation and linear polarization methods. Corrosion and adsorption isotherm parameters were determined from current-potential curves. The studies show that C-1 and C-2 inhibit the corrosion of the steel in H2SO4 solution. Semiempirical AM1 method was used for theoretical calculations. The obtained results of these calculations for the compounds were found to be consistent with the experimental findings.  相似文献   

20.
Corrosion inhibition of mild steel in 2 M HCl and 1 M H2SO4 by extracts of selected plants was investigated using a gasometric technique at temperatures of 30 and 60 °C. The studied plants materials include leaf extracts Occimum viridis (OV), Telferia occidentalis (TO), Azadirachta indica (AI) and Hibiscus sabdariffa (HS) as well as extracts from the seeds of Garcinia kola (GK). The results indicate that all the extracts inhibited the corrosion process in both acid media by virtue of adsorption and inhibition efficiency improved with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms were deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. Comparative analysis of the inhibitor adsorption behaviour in 2 M HCl and 1 M H2SO4 as well as the effects of temperature and halide additives suggest that both protonated and molecular species could be responsible for the inhibiting action of the extracts.  相似文献   

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