Mössbauer spectroscopy study on the corrosion inhibition of carbon steel in hydrochloric acid solution

The effect of ammonium polymolybdate (APM) on the corrosion of carbon steel in a solution of 1 M HCl was studied by weight loss and Mössbauer spectrometry. Inhibition efficiencies (P) have been obtained from weight measurement. The inhibition efficiencies increased with increase APM concentration. Mössbauer spectrometry shows that a superficial compound is formed on the electrode surface as a result of corrosion.     

N-benzyl-N,N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]amine as corrosion inhibitor of steel in 1 M HCl

The inhibition effect of a new bipyrazole derivative namely N-benzyl-N,N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]amine (BBPA) on the corrosion of steel in 1 M HCl is studied at 308 K. Weight-loss measurements, potentiodynamic polarisation, linear polarisation and impedance spectroscopy (EIS) methods were used. Results show that BBPA is a good inhibitor and inhibition efficiency reaches 87% at 5 · 10^− 4 M. The values of the inhibition efficiency calculated from these techniques are reasonably in good agreement. Polarisation curves revealed that this organic compound acts as a mixed-type inhibitor. The temperature effect on the corrosion behaviour of steel in 1 M HCl with and without BBPA at 5 · 10^− 4 M is studied in the temperature range 308-353 K. The associated activation energy is determined. The adsorption of BBPA on the steel surface obeys to the Langmuir's adsorption isotherm. EIS measurements show that the transfer resistance increases with the inhibitor concentration. Efficiency is explained by the theoretical studies.     

Effects of alcohol-based inhibitors on corrosion of mild steel in hydrochloric acid

The inhibition efficiencies of Octyl alcohol (OCAL) and propargyl alcohol (PRAL) on the corrosion of mild steel in 15% commercial hydrochloric acid have been evaluated by mass loss method, electrochemical techniques and surface analysis techniques with 0–1% inhibitor concentration at 30 °C and 105 °C. Both OCAL and PRAL are excellent inhibitors for the above-mentioned system. OCAL gives 87% and 82% inhibition efficiencies at 30 °C and 105 °C, respectively, for 1% inhibitor concentration whereas PRAL gives 100% and 99% efficiencies at 30 °C and 105 °C, respectively, for 0.6% inhibitor concentration. Polarization studies confirm that OCAL and PRAL are mixed type inhibitors. OCAL and PRAL obey Temkin's adsorption isotherm at both the temperatures. UV-reflectance, FT-IR and SEM studies confirm that the surface of mild steel is not affected at the maximum concentration of OCAL and PRAL.     

Investigation of inhibition effect of rhodanine-N-acetic acid on mild steel corrosion in HCl solution

Corrosion inhibition effect of rhodanine-N-acetic acid (R-NA) on mild steel (MS) corrosion in 0.1 M HCl solution was investigated. For this purpose, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) as well as hydrogen gas evolution (VH₂−t) and the change of open circuit potential as a function of immersion time (E_ocp − t) were used. The MS surfaces exposed to 0.1 M HCl solution in the absence and presence of inhibitor were examined by scanning electron microscopy (SEM). The thermodynamic parameters of adsorption were calculated and discussed. In order to gain more information about the adsorption mechanism, the EIS technique was used to evaluate the potential of zero charge (PZC) and a mechanism of adsorption process was proposed. It was found that, R-NA is a good corrosion inhibitor for the MS corrosion in 0.1 M HCl solution. The inhibition efficiency increased with increasing inhibitor concentration and reached 98% at 1.0 × 10⁻² M R-NA. The high inhibition efficiency was related to adsorption of R-NA on steel surface. Surface SEM images showed a good surface coverage of inhibitor on the metal surface.     

Green approach to corrosion inhibition of mild steel in hydrochloric acid and sulphuric acid solutions by the extract of Murraya koenigii leaves

The inhibition of the corrosion of mild steel in hydrochloric acid and sulphuric acid solutions by the extract of Murraya koenigii leaves has been studied using weight loss, electrochemical impedance spectroscopy (EIS), linear polarization and potentiodynamic polarization techniques. Inhibition was found to increase with increasing concentration of the leaves extract. The effect of temperature, immersion time and acid concentration on the corrosion behavior of mild steel in 1 M HCl and 0.5 M H₂SO₄ with addition of extract was also studied. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the metal surface. The adsorption of the extract on the mild steel surface obeys the Langmuir adsorption isotherm. The activation energy as well as other thermodynamic parameters (Q, ΔH^*, and ΔS^*) for the inhibition process was calculated. These thermodynamic parameters show strong interaction between inhibitor and mild steel surface. The results obtained show that the extract of the leaves of M. koenigii could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric and sulphuric acid media.     

Green approach to corrosion inhibition of mild steel in two acidic solutions by the extract of Punica granatum peel and main constituents

The effect of the extract of Punica granatum (PG) and their main constituents involve ellagic acid (EA) and tannic acid (TA), as mild steel corrosion inhibitor in 2 M HCl and 1 M H₂SO₄ solutions was investigated by weight loss measurements. The results obtained from the weight loss measurements show that the inhibition efficiency of TA even in high concentration is very low. Thus, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) investigations were used for different concentrations of PG and EA and best concentration of TA. Potentiodynamic polarization curves indicated that PG and EA behave as mixed-type inhibitors. EIS measurements show an increase of the transfer resistance with increasing inhibitor concentration. The temperature effect on the corrosion behavior of steel without and with the PG extract was studied. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm.     

The inhibition of mild steel corrosion in hydrochloric acid media by two Schiff base compounds

Schiff bases of 2-({-1-methyl-3-[(2-sulfanylphenyl)imino]butylidene}-amino)-1-benzenethiol and 2-({-1,2-diphenyl-2-[(2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenthiol are investigated as corrosion inhibitors in acid solution. Polarization, electrochemical impedance spectroscopy, and weight loss measurements were performed on mild steel in 15% HCl with and without the inhibitors. A significant decrease in the corrosion rate of mild steel was observed in the presence of investigated inhibitors. Polarization curves indicate that both compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. The adsorption of inhibitors on mild steel surface in 15% HCl was found to follow Langmuir adsorption isotherm. Thermodynamic adsorption parameters (K _ads, ∆G _ads) of studied Schiff bases were calculated using the Langmuir adsorption isotherm. Activation parameters of the corrosion process such as activation energies, E _a, activation enthalpies, ∆H*, and activation entropies, ∆S*, were calculated by the obtained corrosion currents at different temperatures.     

盐酸介质中几种表面活性剂对钢的缓蚀作用

采用失重法和电化学方法研究了在HCl介质中阳离子表面活性剂十六烷基三甲基溴化铵(CTAB,C19H42BrN)阴离子表面活性剂十二烷基磺酸钠(DSASS,C12H25SO3Na)及非离子表面活性剂聚乙二醇辛基苯基醚(OP)对钢的缓蚀作用.应用吸附理论讨论缓蚀作用产生的原因.结果表明,在同一浓度下,三种表面活性剂对钢在HCl介质中的缓蚀效率的顺序如下CTAB＞OP＞DSASS.     

Cefalexin drug: A new and efficient corrosion inhibitor for mild steel in hydrochloric acid solution

Corrosion inhibition of mild steel in 1N HCl by cefalexin has been studied by electrochemical and weight loss measurements. The inhibitor showed increase in inhibition efficiency with increase in inhibitor concentration up to optimum concentration 400 ppm. Potentiodynamic polarization suggests that it is a mixed type of inhibitor. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition. Thermodynamic parameters were calculated to investigate mechanism of inhibition. AFM is used to investigate the surface morphology of the uninhibited and inhibited mild steel.     

The inhibition of 4-(2′-amino-5′-methylphenylazo) antipyrine on corrosion of mild steel in HCl solution

The effect of 4-(2′-amino-5′-methylphenylazo) antipyrine (AMPA) on the corrosion of mild steel in a 2 M HCl solution was studied using weight loss and potentiodynamic polarization techniques. All of the data reveal that AMPA acts as an inhibitor in the acid environment; furthermore, polarization data show that the compound behaves as a mixed-type inhibitor. It was found that the inhibition efficiency increases with an increase in AMPA concentration but decreases with an increase in temperature. Flory–Huggins adsorption isotherm and El Awady thermodynamic–kinetic model fit the experimental data of the studied compound. Thermodynamic parameters for corrosion and adsorption processes were obtained from experimental data of the temperature studies.     

The corrosion inhibition and adsorption behavior of Uncaria gambir extract on mild steel in 1 M HCl

The inhibitive effect of the ethyl acetate extract of Uncaria gambir on the corrosion of mild steel in 1 M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of this catechin-containing extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 303–333 K. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1000 ppm. Surface analyses via scanning electron microscope (SEM) shows a significant improvement on the surface morphology of the mild steel plate. Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface.     

Experimental and theoretical investigations on the inhibition of mild steel corrosion in the ground water medium using newly synthesised bipodal and tripodal imidazole derivatives

Two new imidazole derivatives, namely 1,4-bis(N-imidazolylmethyl)-2-5-dimethoxybenzene (BIDM) and 1,3,5-tris(N-imidazolylmethyl)-2,4,6-trimethoxybenzene (TITM), were synthesised and their effects on the inhibition of mild steel corrosion in ground water medium are reported. The study was carried out using gravimetric and electrochemical techniques in order to determine the corrosion inhibition efficiencies of the bipodal and tripodal structured imidazoles. Further, the quantum chemical calculations using density functional theory (DFT) gave a profound insight into the inhibitory action mechanism of BIDM and TITM and their calculation parameters, such as E_HOMO, E_LUMO and ΔE were in good agreement with the results of the experimental studies. BIDM and TITM exhibited lowest corrosion current densities of circa 7.5 μA cm⁻² and 4.1 μAcm⁻² at the optimum concentrations of 0.67 and 0.49 mM, respectively. All measurements thus confirmed that both BIDM and TITM behaved as good inhibitors for mild steel corrosion in ground water medium.     

Adsorption and corrosion inhibition effect of 2-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)phenol Schiff base on mild steel

In this study, the inhibition effect of 2-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)phenol Schiff base (MTMP) on mild steel corrosion in 0.5 M HCl solution was studied. For this aim, electrochemical techniques such as potentiodynamic polarization curves, weight loss (WL), electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) were used. It was shown that, the MTMP Schiff base has remarkable inhibition efficiency on the corrosion of mild steel in 0.5 M HCl solution. Polarization measurements indicated that, the studied inhibitor acts as mixed type corrosion inhibitor with predominantly control of cathodic reaction. The inhibition efficiency depends on the concentration of inhibitor and reaches 97% at 1.0 mM MTMP. The remarkable inhibition efficiency of MTMP was discussed in terms of blocking of electrode surface by adsorption of inhibitor molecules through active centers. The adsorption of MTMP molecules on the mild steel surface obeys Langmuir adsorption isotherm.     

Inhibitory mechanism of mild steel corrosion in 2 M sulphuric acid solution by methylene blue dye

Methylene blue dye (MB) was investigated as a corrosion inhibitor for mild steel in 2 M sulphuric acid solution using gravimetric and thermometric techniques. The inhibition efficiency of MB increased with concentration and synergistically increased in the presence of the halide additives, namely KCl, KBr and KI. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface at lower concentration (0.01–0.5 mM), and chemically adsorbed at higher concentration (1.0–5.0 mM). These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data at the temperatures studied. MB was found to obey Langmuir and Frumkin adsorption isotherms in the concentration range investigated.     

Kinetic investigation of C38 steel corrosion in concentrated perchloric acid solutions

The corrosion behaviour of steel at various concentrations of perchloric acid was studied by weight loss method in temperature range from 298 to 323 K. Results obtained show that corrosiveness of acid increases with its concentration and temperature. The logarithm of corrosion rate was plotted against the acid concentration and values of Hammett H_o and Strehlow R_o(H) acidity functions. The activation energies, enthalpies and entropies of the corrosion process of steel were also determined and fitted against R_o(H).     

Corrosion inhibition of mild steel in hydrochloric acid solution by methylene blue dye

The corrosion inhibition of mild steel in hydrochloric acid solution by methylene blue dye (MB) was investigated by gravimetric techniques at 30 and 60 °C as well as thermometric technique. MB was shown to be an inhibitor in the acidic corrodent. Inhibition efficiency increased with MB concentration but decreased with rise in temperature, with maximum value of 94–95% obtained for 5.0 mM MB at 30 °C. Corrosion inhibition is attributed to the adsorption of MB on the mild steel surface via a physical adsorption mechanism. These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data.     

Synthesis and corrosion inhibition of α-amino acids alkylamides for mild steel in acidic environment

New compounds of alkylamides derived from α-amino acids were tested as corrosion inhibitors for carbon steel in an aqueous solution of hydrochloric acid. The chemical synthesis of these amides performed by aminolysis of α-amino acid methyl esters resulted in good yields. Electrochemical testing was carried out using polarization scans and weight loss measurements. Polarization scans indicated that compounds act as mixed corrosion inhibitors with an efficiency of 80–90% when dissolved in the testing solution at ≥50 ppm, whereas gravimetric results displayed a similar tendency. Microtox testing indicated a correlation with the molecular structure of inhibitors. Apparently, a long aliphatic chain (C > 12) promoted not only higher corrosion efficiency, but also a higher toxicity. The higher efficiency of dodecyl amine of tyrosine was apparently derived from its longer aliphatic chain, with some contribution from its phenyl ring, which reinforces the molecular interactions of π type bonding to the d orbital metal favouring film formation.     

The corrosion behaviours of polyaniline coated stainless steel in acidic solutions

Polyaniline (PANI) coating on stainless steel (SS) using oxalic acid as supporting electrolyte was obtained by using cyclic voltammetry technique. The corrosion performances of these PANI coated electrodes (SS/PANI) were determined in 0.05 M sulphuric acid and in 0.1 M hydrochloric acid solutions with electrochemical impedance spectroscopy and anodic polarization curves. The results clearly showed that SS/PANI immersed in sulphuric acid appeared to have better protective effect on the corrosion of SS than that of hydrochloric acid. The PANI coating was found to be stable and protective for extended immersion period in 0.05 M H₂SO₄.     

Poly(o-phenylenediamine) as an inhibitor of mild steel corrosion in HCl solution

The inhibition properties of the electro-prepared P(o-phenylenediamine), P(oPD), on the corrosion rate of mild steel (MS) in HCl solutions have been investigated under different experimental conditions using weight loss and potentiodynamic polarization techniques. The data obtained from the two techniques are comparable and showed that the presence of P(oPD) in the acid solutions suppresses the corrosion rate of MS indicating that the polymer acts as corrosion inhibitor. The inhibition efficiency (IE%) of the polymer enhances with increasing its concentration and decreases with an increase in temperature. The inhibition occurs through adsorption and formation of barrier film on the metal surface which separates the metal from direct contact with the corrosive medium and hence protects the metal against the corrosion. Langmuir isotherm fits well with the experimental data. Thermodynamic parameters for both dissolution and adsorption processes were determined.     

工业盐酸中微量氟的测定

样品分离氯离子后,在弱酸性介质中,用氟离子选择性电极、已知量添加法测定工业盐酸中微量氟。本方法标准偏差为5×10~(-5)％,变异系数<6％。回收率在91.8～104.0％。方法简便、数据准确。