Corrosion Inhibition of Mild Steel in Aqueous Solution Containing H2S by some Thiosemicarbozone Compounds

The Electrochemical behavior of mild steel in 3% NaCl is still the objective of many studies which include the investigations of natural and synthetic compounds as inhibitors. In this paper, some derivatives of thiosemicarbazone compound were investigated as inhibitors in medium of 3% NaCl for the mild steel samples. The galvanostatic technique was used in this study to characterize both cathodic and anodic behaviour of mild steel. the percent of inhibition P.I. was calculated for each of thiosemicarbazone compounds in order to determine the effectiveness of these undertesting compounds. As estimated the P.I. was increased with the concentration of each of undertesting compound. In addition the mild steel was tested in 3% NaCl in presence of H₂S. So the synergistic effect of each inhibitor manifests itself for the tested compounds. It was found that the change of the methoxy group position has an active role in the inhibition effect of the tested compound. From others side the introduction of chloro group has also a beneficial inhibition effect.     

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.     

Corrosion of mild steel in acid solutions containing thiourea and thiosemicarbazide

Cathodic polarization curves for mild steel in 1.0 N H₂SO₄ and 1.0N HCl, containing various concentrations of thiourea (TU) (1–25 mM) and thiosemicarbazide (TSC) (0.2–25 mM), were measured in the temperature range 20–50 °C. The apparent activation energy for corrosion (ΔE*) was calculated from I_cor vs 1/T and R_p/T vs 1/T relations. ΔE* is virtually constant by changing TU concentrations (55–57 KJ/mole in H₂SO₄). An interpretation for the loss of inhibition efficiency of TU in acid solution is given. This is based on the decomposition of TU to ammonium thiocyanate.     

Inhibition of mild steel corrosion in sulfuric acid by some newly synthesized organic compounds

The corrosion inhibition of mild steel in 0.5 M sulfuric acid solutions by some new synthesized organic compounds namely (E)-2-acetyl-3-(butyl amino)-N-phenyl buten-2-thioamide (compound A), (E)-3-(4-(dimethyl amino) phenyl amino)-2-acetyl-N-phenyl buten-2-thioamide (compound B) and (E)-3-(2,3-dimethyl phenyl amino)-2-acetyl-N-phenyl buten-2-thioamide (compound C) was investigated using weight loss and potentiostatic polarization techniques. These measurements reveal that the inhibition efficiency obtained by these compounds increased by increasing their concentration. The inhibition efficiency follows the order A > B > C. Polarization studies show that these compounds are of the mixed-type but dominantly act as an anodic inhibitors for steel in 0.5 M H₂SO₄ solutions. These inhibitors function through adsorption following Langmuir isotherm. Activation energy and Gibbs free energy for adsorption of inhibitors are calculated. Molecular modeling has been conducted to correlate the corrosion inhibition properties with the calculated quantum chemical parameters.     

Corrosion Inhibition of iron in 2M hydrochloric acid solution

The effect of some hydrazone oxime derivatives on the corrosion of iron in 2M HCl have been studied by polarization and weight-loss techniques. It was found that the compounds under consideration are adsorbed on the iron surface according toe the Temkin isotherm. The Tafel slope is approximately constant independent of the concentration of the inhibitor. The results of polarization indicate that all compounds tested were of a mixed type, but the cathodic is more preferenially polarized. The inhibition efficiency was found to follow the order:I>III>IV>VI>II.     

Corrosion inhibition of nickel in H2SO4 solution by alanine

The effect of alanine, as a safe inhibitor, was studied by measuring the corrosion of Ni in aerated and stagnant 1 M H₂SO₄ solution (pH ～0.2). Measurements were performed under various conditions using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and the new electrochemical frequency modulation (EFM) methods. The obtained results showed that the addition of alanine alone gives a moderate inhibition and acts as an anodic-type inhibitor. The inhibition is due to physical adsorption of alanine on the metal surface. The inhibition efficiency enhances with increasing alanine concentration and immersion time but decreases with rise in temperature. The apparent activation energy, E_a, is higher in the presence than in the absence of alanine. Addition of I^? ions greatly improves the inhibition efficiency of alanine. The synergistic effect is due to enhanced adsorption of alanine cations by chemisorbed I^? anions on the metal surface. The results obtained from polarization, EIS and EFM techniques are in good agreement indicating that EFM method can be used successfully for monitoring corrosion rate of Ni in H₂SO₄ solution with and without alanine.     

Acoustic emission characterization of steel in H2S solution subjected to tensile load

Abstract

This paper investigates the characteristics of acoustic emission (AE) signals generated from hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC) for a medium strength steel in hydrogen sulfide (H₂S) solution. The experiments performed in this study include the constant load test (CLT) and the constant extension rate test (CERT).

From the results of the CLT, the AE count rate caused by SSCC was found to be much higher than that resulted from the HIC; and the increase of the AE count rate was observed to be approximately proportional to the increase of the applied loading. In addition, the AE frequency distribution diagrams obtained from these tests were found to contain potential information for distinguishing the mechanisms of HIC and SSCC. From the results of CERT, the AE signals detected from the specimens tested in the H₂S solution were compared with those obtained from the specimens tested in the air. In addition, the AE count rate detected from the tensile specimens was studied according to the different deformation stages of the specimens. From this study, the variation of the AE count rate in each deformation stage was described.     

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.     

Corrosion of mild steel under diesel oil by sulphate-reducing bacteria

A laboratory investigation has been carried out on the corrosion of mild steel under oil storage conditions by $\text{Desulfovibrio desulfuricans}$. This shows the anaerobic sulphate-reducing bacterium to be more active in corrosion than suggested by the amount of sulphide it generates. Sulphate increases bacterial action, and in the presence of this nutrient borax is unable to exert its normal bactericidal properties.The sulphide present in the bacterially active water layer below the oil was monitored with a sulphide ion-selective electrode following sampling, under oxygen-free conditions, into sodium hydroxide containing ascorbic acid as anti-oxidant.     

Degradation of bisphenol A in aqueous solution by H2O2-assisted photoelectrocatalytic oxidation

A series of titanium dioxide (TiO(2)/Ti) film electrodes were prepared from titanium (Ti) metal mesh by an improved anodic oxidation process and were further modified by photochemically depositing gold (Au) on the TiO(2) film surface as Au-TiO(2)/Ti film electrodes. The morphological characteristics, crystal structure and photoelectroreactivity of both the TiO(2)/Ti and Au-TiO(2)/Ti electrodes were studied. The experiments confirmed that the gold modification of TiO(2) film could enhance the efficiency of e(-)/h(+) separation on the TiO(2) conduction band and resulted in the higher photocatalytic (PC) and photoelectrocatalytic (PEC) activity under UV or visible illumination. To further enhance the TiO(2) PEC reaction, a reticulated vitreous carbon (RVC) electrode was applied in the same reaction system as the cathode to electrically generate H(2)O(2) in the aqueous solution. The experiments demonstrated that such a H(2)O(2)-assisted TiO(2) PEC reaction system could achieve a much better performance of BPA degradation in aqueous solution due to an interactive effect among TiO(2), Au, and H(2)O(2). It may have good potential for application in water and wastewater treatment in the future.     

2A12铝合金在含Cl~-环境中的腐蚀行为和规律研究

通过室内浸泡模拟实验方法,研究了2A12铝合金在含Cl-典型环境中的腐蚀行为与电化学规律.采用扫描电镜观察了试样的组织和腐蚀产物的微观形貌,并用能量色散谱(EDS)分析了腐蚀产物元素组成.采用失重法分析了2A12铝合金腐蚀动力学规律,并采用电化学阻抗技术分析了2A12铝合金腐蚀后的电化学行为规律.实验结果表明,浸泡480 h后,2A12铝合金发生了明显的点蚀和小片状剥蚀,Cl-和第二相是促进点蚀形成和发展的主要原因;浸泡480 h后的动力学规律遵从幂指数规律;电化学阻抗谱中的Nyquist曲线由压缩的双容抗弧组成,随浸泡时间的延长,点蚀不断生成并发展,与腐蚀产物的产生与剥落综合作用,使电化学阻抗模值呈先减小后增大再减小的动态变化.     

Effect of some ethoxylated fatty acids on the corrosion behaviour of mild steel in sulphuric acid solution

The inhibition of the corrosion of mild steel in 1.0 M sulphuric acid solution by some ethoxylated fatty acids OL[EO]₂₀, OL[EO]₄₀ and OL[EO]₈₀ has been studied in relation to the concentration of the inhibitors as well as the temperature using chemical (weight loss) and electrochemical (potentiodynamic polarization) techniques. The inhibition efficiency increases with increasing the concentration and the chain length of the inhibitor but decreases with temperature. The inhibition was assumed to occur via adsorption of the fatty acid molecules on the metal surface. The thermodynamic functions of dissolution and adsorption processes were calculated.     

吐温-60对钢在H2SO4中的缓蚀性能

用失重法研究了非离子表面活性剂吐温-60对冷轧钢在0.5-7.0 mol/L H2SO4溶液中的缓蚀作用。结果表明：吐温-60对冷轧钢在1.0 mol/L H2SO4溶液中具有良好的缓蚀作用,且在钢表面的吸附符合校正的Langmuir吸附模型。缓蚀率随缓蚀剂浓度的增加而增大,但随温度和硫酸浓度的增加而减小。求出了相应的吸附热力学（吸附自由能ΔG^0, 吸附焓ΔH^0, 吸附熵ΔS^0）和动力学参数（腐蚀速率常数k, 腐蚀动力学常数B）,并根据这些参数讨论了缓蚀作用机理。     

The Inhibition Behaviour of some 1,2-azole derivatives for the corrosion of mild steel in sulphuric acid solutions

The corrosion inhibition of mild steel in sulphuric acid solutions by two series of 1,2-azole derivatives was studies by using weight loss, polarization and capacitance measurements. Series 1 derivatives were 3-methy1-5-amino-1,2-azoles (azole = pyrazole, isoxazole and isothiazole) and series 2 derivatives were 3(5)-amino-5(3)[4′-X-phenyl]pyrazoles (X = H-, Cl?, NO^2?, Me? and MeO?). The effect of inhibitor concentration, temperature, acidity and chloride ion concentration on the inhibition efficiency was also investigated. The inhibition was found to increase with increase of the inhibitor concentration and decrease of temperature, acidity and chloride ion concentration. Generally, the inhibition efficiency was found to increase with increase of the azole basisity and the electron density on the azole ring. The inhibition occurs through adsorption of the inhibitor molecules onto the metal surface following Temkin isotherm. The nature of the inhibitive species and the modes of adsorption were discussed.     

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.     

硫化氢介质条件下换热器管束钢的腐蚀行为

采用腐蚀失重及慢应变速率拉伸试验(SSRT)方法,对20钢和08Cr2AlMo钢在饱和H2S水溶液中的腐蚀行为进行了研究.结果表明,08Cr2AlMo钢在饱和H2S水溶液中的耐腐蚀能力优于20钢,但存在比较明显的点蚀倾向;在饱和H2S水溶液中两种钢都具有硫化氢应力腐蚀开裂(SSCC)敏感性,应力腐蚀开裂大多发生在塑性变形区,应力水平要求比较高,20钢的断口属于韧脆混合型断口,08Cr2AlMo钢断口则属于典型的准解理脆性断口.