硫酸溶液中聚天冬氨酸对碳钢的吸附缓蚀性能

应用电化学极化曲线和交流阻抗研究聚天冬氨酸(PASP)对碳钢的缓蚀性能,讨论了PASP浓度和温度对缓蚀效果的影响.结果表明:PASP是一种以抑制阳极为主的缓蚀剂.在实验温度范围内,PASP在0.5mol/L硫酸溶液中对碳钢的缓蚀效率随着温度升高而降低,并以10℃时的缓蚀效果最好.在给定温度下,缓蚀率均随PASP浓度的增加而迅速增加,但当PASP质量浓度达到2.5g/L时,缓蚀率的增加趋于平缓,10℃下,缓蚀率的最高值可达80.33%(PASP 6.0g/L),PASP在碳钢表面的吸附基本服从Freund lich吸附等温式,PASP的加入增大了碳钢的腐蚀反应表观活化能.     

Experimental and Theoretical Studies on Extract of Date Palm Seed as a Green Anti-Corrosion Agent in Hydrochloric Acid Solution

Extracts from plant materials have great potential as alternatives to inorganic corrosion inhibitors, which typically have harmful consequences. Experimental and theoretical methodologies studied the effectiveness of agricultural waste, namely, date palm seed extract as a green anti-corrosive agent in 0.5 M hydrochloric acid. Experimental results showed that immersion time and temperature are closely related to the effectivity of date palm seed as a corrosion inhibitor. The inhibition efficiency reduced from 95% to 91% at 1400 ppm when the immersion time was increased from 72 h to 168 h. The experimental results also indicated that the inhibition efficiency decreased as the temperature increased. The presence of a protective layer of organic matter was corroborated by scanning electron microscopy. The adsorption studies indicated that date palm seed obeyed Langmuir adsorption isotherm on the carbon steel surface, and Gibbs free energy values were in the range of −33.45 to −38.41 kJ·mol⁻¹. These results suggested that the date palm seed molecules interacted with the carbon steel surface through mixture adsorption. Theoretical calculations using density functional theory showed that the capability to donate and accept electrons between the alloy surface and the date palm seed inhibitor molecules is critical for adsorption effectiveness. The HOMO and LUMO result indicated that the carboxyl (COOH) group and C=C bond were the most active sites for the electron donation-acceptance type of interaction and most auxiliary to the adsorption process over the Fe surface.     

Comparative study on the inhibitive effect of Sulfadoxine–Pyrimethamine and an industrial inhibitor on the corrosion of pipeline steel in petroleum pipeline water

The corrosion inhibition characteristics of Sulfadoxine plus Pyrimethamine (S&P) was evaluated and compared with the inhibition performance of an industrial corrosion inhibitor (S-Ind) under anaerobic condition. Modified gravimetric and electrochemical techniques were used. The corrosion inhibition efficiencies of both S&P and S-Ind were comparable for all the techniques applied. S&P gave slightly higher inhibition efficiency, while S-Ind gave a more steady corrosion protection. The corrosion inhibition efficiencies increased with increased concentration of both substances. The polarization curves showed mixed inhibition behavior for both S&P and S-Ind. A mechanism of chemisorption was proposed for the adsorption of S&P and S-Ind on pipeline steel surface, while the negative Gibbs free energy of adsorption values indicates a spontaneous adsorption process. The adsorption characteristics of the inhibitors were fitted into Langmuir adsorption isotherm.     

Electrochemical studies of mild steel corrosion inhibition in sulfuric acid chloride by aniline

The corrosion behavior of mild steel in dilute hydrochloric acid under the inhibiting action of various concentrations of aniline was studied using the weight loss and linear polarization resistance technique. The efficiency of the inhibitor increased with the increase in the inhibitor concentration. The results obtained reveal that aniline performed effectively as a corrosion inhibitor. The adsorption mechanism indicates mixed molecular interaction from values of Gibbs free energy. The values of the inhibition efficiency calculated from the two techniques are in reasonably good agreement. The adsorption of the inhibiting compound was found to obey Langmuir, Frumkin and Freudlich adsorption isotherms. The mechanism of inhibition was discussed in the light of the chemical structure of the inhibiting compound and their adsorption on steel surfaces in relation to the potentiodynamic parameters.     

Corrosion inhibition of mild steel by highly stable polydentate schiff base derived from 1,3- propanediamine in aqueous acidic solution

Recently, the hydrolysis of Schiff bases under experimental conditions gives suspicion for their corrosion inhibition performance. The current study employs a stable Schiff base namely, 2,2′-{propane-1,3-diylbis[azanylylidene (E) methanylylidene]}bis(6-methoxyphenol) (LPD) as corrosion inhibitor for mild steel (MS) in 1 M HCl solution. The presence of the characteristic peak of the imine group in UV-visible spectra was taken as an indicator for LPD stability in acidic media. The inhibition action was examined using electrochemical techniques including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) besides gravimetric measurement. The inhibition efficiency reached 95.93 % for 0.75 mM LPD after 24 h of immersion at 25 °C. This high efficiency is owing to the presence of the characteristic imine group and other heteroatoms and π- electrons of the aromatic benzene rings. The mechanism of inhibition depends on adsorption phenomena on mild steel surface which obeys Langmuir isotherm model. The calculated values of adsorption equilibrium constant (K_ads), adsorption free energy ΔG_ads, adsorption enthalpy ΔH_ads and adsorption entropy ΔS_ads indicated spontaneous exothermic adsorption process of both physical and chemical nature. By rising temperature, the inhibition efficiency of LPD was decreased. The calculated activation energy was increased as the concentration of LPD increased. LPD was considered as a mixed-type inhibitor as indicated from PDP measurements. The obtained surface morphology and composition analysis using SEM/EDS, AFM and FTIR techniques ensures the high efficiency of LPD as corrosion inhibitor.     

曲唑酮的两步法制备及对碳钢的缓蚀机理

以3-氯苯胺、N-氯丙基二乙醇胺和吡啶三唑酮为原料，两步法制备出曲唑酮（TZD）.通过动态失重、极化曲线与电化学阻抗谱研究了TZD在0.5 mol/L盐酸溶液中对20#钢的缓蚀性能；借助扫描电子显微镜、原子力显微镜、衰减全反射红外光谱与吸附活化参数分析研究了TZD在碳钢表面的作用机理.结果表明，TZD可显著降低碳钢在盐酸溶液中的腐蚀速率，缓蚀率随TZD添加浓度的增加而增大，随温度升高而降低；298 K下，添加6 mmol/L TZD时，缓蚀率达95.8%；TZD可自发吸附组装于碳钢表面，同时抑制腐蚀反应的阴、阳极过程，显著增加界面极化阻抗；吸附为放热过程，符合Langmuir等温式.理论计算结果显示，TZD倾向以平行取向组装于碳钢表面.     

Sildenafil citrate (Viagra) as a corrosion inhibitor for carbon steel in hydrochloric acid solutions

Abstract  

The inhibition effect of sildenafil citrate (Viagra) on the corrosion of carbon steel in 1 M HCl was studied by weight loss, polarization, electrochemical impedance spectroscopy, and UV–Vis spectrophotometry. The results showed that sildenafil citrate is a good corrosion inhibitor for carbon steel in acidic media and acts as mixed type (cathodic/anodic) inhibitor. The adsorption of the inhibitor was well described by the Langmuir adsorption isotherm. Some thermodynamic parameters such as adsorption heat, adsorption entropy, and adsorption free energy were calculated. Kinetic parameters such as the apparent activation energy and pre-exponential factor were calculated and discussed.     

Inhibition of cold rolled steel corrosion by Tween-20 in sulfuric acid: weight loss, electrochemical and AFM approaches

The inhibiting action of a nonionic surfactant of Tween-20 on the corrosion of cold rolled steel (CRS) in 0.5-7.0 M sulfuric acid (H(2)SO(4)) was studied by weight loss and potentiodynamic polarization methods. Atomic force microscope (AFM) provided the surface conditions. The results show that inhibition efficiency increases with the inhibitor concentration, while it decreases with the sulfuric acid concentration. The adsorption of inhibitor on the cold rolled steel surface obeys the Langmuir adsorption isotherm equation. Effect of immersion time was studied and discussed. The effect of temperature on the corrosion behavior of cold rolled steel was also studied at four temperatures ranging from 30 to 60 degrees C, the thermodynamic parameters such as adsorption heat, adsorption free energy, and adsorption entropy were calculated. The results revealed that the adsorption was physisorption mechanism. A kinetic study of cold rolled steel in uninhibited and inhibited acid was also discussed. The kinetic parameters such as apparent activation energy, pre-exponential factor, rate constant, and reaction constant were calculated for the reactions of corrosion. The inhibition effect is satisfactorily explained by both thermodynamic and kinetic models. Polarization curves show that Tween-20 is a cathodic-type inhibitor in sulfuric acid. The results obtained from weight loss and potentiodynamic polarization are in good agreement, and the Tween-20 inhibition action could also be evidenced by surface AFM images.     

辛烷基二甲基苄基季铵盐离子液体对Q235钢的缓蚀性能

利用失重分析、 极化曲线、 电化学阻抗谱和扫描电子显微镜等研究了辛烷基二甲基苄基季铵盐离子液体(ODBA)对1 mol/L盐酸溶液中Q235钢的缓蚀性能, 并分析了其在Q235钢表面的吸附行为. 失重分析结果表明, 随着ODBA浓度的增加, 缓蚀效率逐渐提高, 在ODBA质量浓度为0.2 g/L、 温度为30 ℃时, 缓蚀效率可达95.53%; 电化学测试结果与失重分析结果一致; 热力学研究结果表明, ODBA在碳钢表面的吸附是放热过程, 且遵循Langmuir吸附等温线, 是以化学吸附为主的混合型吸附; 同步热分析测试表明ODBA具有良好的热稳定性.     

Thermokinetics on the reaction of formation of Dy[(C<Subscript>5</Subscript>H<Subscript>8</Subscript>NS<Subscript>2</Subscript>)<Subscript>3</Subscript>(C<Subscript>12</Subscript>H<Subscript>8</Subscript>N<Subscript>2</Subscript>)]

The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen?H₂O) in absolute ethanol at 298.15 K has been determined as (-16.12 ± 0.05) kJ?mol^-1 by a microcalormeter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29) kJ?mol^t-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.     

Electroanalytical studies of the corrosion-protection properties of 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) on mild steel in 0.5?N sulfuric acid

Inhibition of the corrosion of mild steel in aerated 0.5?N H₂SO₄ solution by 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) was investigated by use of potentiodynamic polarization (Tafel), electrochemical impedance spectroscopy, adsorption, and surface morphological studies. The effects on the rate of corrosion of inhibitor concentration, temperature, extent of surface coverage, adsorption kinetics, and surface morphology were investigated. Inhibition efficiency increased markedly with increasing ATD concentration and decreased slightly with increasing temperature. The presence of ATD reduced the capacitance of the double layer and increased the charge-transfer resistance. Values of the activation energy (E _a) and of the thermodynamic data adsorption equilibrium constant (K _ads) and free energy of adsorption (??G _ads) were computed from the temperature dependence of the corrosion current. The inhibitor molecule first became adsorbed on the mild steel surface, obeying the Langmuir adsorption isotherm, and substantially reduced the rate of corrosion. Results of electroanalytical studies revealed that ATD acts as a mixed-type inhibitor.     

Poly (vinyl alcohol – aniline) water soluble composite as corrosion inhibitor for mild steel in 1 M HCl

Poly (vinyl alcohol – aniline) PVAA composite was tested for its performance in protecting mild steel MS against corrosion in 1 M HCl. The inhibitive parameters were evaluated by means of weight loss, electrochemical polarization and impedance methods. Results indicated that the addition of PVAA to the acid reduces the corrosion of the metal. Inhibition efficiency increases with increase in inhibitor concentration. The results further revealed that PVAA at a concentration of 2000 ppm furnishes a maximum of 92% inhibition efficiency. Thermodynamic parameters such as free energy of adsorption, heat of adsorption, etc., had been evaluated from temperature studies. The adsorption of PVAA followed Langmuir and Temkin adsorption isotherms. Polarization curves revealed that PVAA is a mixed inhibitor.     

氯化硝基四氮唑蓝对钢在盐酸溶液中的缓蚀作用

采用失重法、动电位极化曲线、电化学阻抗谱(EIS)和扫描电子显微镜(SEM)研究了氯化硝基四氮唑蓝(NTBC)在1.0-5.0mo·lL-1HCl溶液中对冷轧钢(CRS)的缓蚀作用.结果表明:NTBC在1.0mo·lL-1HCl溶液中对冷轧钢具有良好的缓蚀作用,且在钢表面的吸附符合Langmuir吸附等温式.缓蚀率随缓蚀剂浓度的增加而增大,但随盐酸浓度和温度的增加而减小.求出了相应的吸附热力学(吸附自由能ΔG0,吸附焓ΔH0,吸附熵ΔS0)和腐蚀动力学参数(腐蚀速率常数k,动力学常数B),并根据这些参数讨论了缓蚀作用机理.动电位极化曲线表明:NTBC为混合抑制型缓蚀剂;EIS谱在高频区呈容抗弧,在低频区出现感抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大.SEM再次表明NTBC对钢在盐酸介质中的腐蚀产生了明显的抑制作用.     

An investigation of carbon steel corrosion inhibition in hydrochloric acid medium by an environmentally friendly green inhibitor

The inhibition effect of polyphenols extracted from olive mill wastewater (PP) on carbon steel in 1.0 M HCl solution was studied. Inhibition efficiency of PP was carried out by using chemical (weight loss method) and electrochemical techniques [potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)]. The effect of temperature and immersion time on the corrosion behavior of carbon steel in 1.0 M HCl with addition of an extract was also studied. The results show that PP acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of PP and decreases with rising temperature. Polarization curves show that PP behaves as a mixed-type inhibitor in hydrochloric acid. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model; a constant phase element has been used. EIS shows that charge-transfer resistance increases and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The activation energy as well as other thermodynamic parameters for the inhibition process were calculated. The adsorption of PP obeys the Langmuir adsorption isotherm.     

Viscous Flow of Concentrated Aqueous Solutions of NiCl<Subscript>2</Subscript> + FeCl<Subscript>2</Subscript>

The dynamic viscosity, apparent molar volume, enthalpy, and Gibbs energy of activation of a viscous flow of concentrated aqueous solutions of NiCl₂ + FeCl₂ were calculated. The concentration dependences of these parameters were analyzed in terms of structural transformations. A polynomial approximation of the concentration dependences of the dynamic viscosity of the solutions under study was performed using MATLAB 6.1 software package.     

酸性介质中羧甲基纤维素钠在低碳钢表面的吸附和缓蚀作用

The effect of sodiumcarboxymethyl cellulose (Na-CMC) on the corrosion behavior of mild steel in 1.0 mol·L-1 HCl solution has been investigated by using weight loss (WL) measurement, potentiodynamic polarization, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) methods. These results showed that the inhibition efficiency of Na-CMC increased with increasing the inhibitor concentration. Potentiodynamic polarization studies revealed that the Na-CMC was a mixed type inhibitor in 1.0 mol·L-1 HCl. The adsorption of the inhibitor on mild steel surface has been found to obey the Langmuir isotherm. The effect of temperature on the corrosion behavior of mild steel in 1.0 mol·L -1 HCl with addition of 0.04% of Na-CMC has been studied in the temperature range of 298-328 K. The associated apparent activation energy (E*a) of corrosion reaction has been determined. Scanning electron microscopy (SEM) has been applied to investigate the surface morphology of mild steel in the absence and presence of the inhibitor molecules.     

Experimental and theoretical investigation on adsorption and corrosion inhibition properties of imidazopyridine derivatives on mild steel in hydrochloric acid solution

Imidazopyridine derivatives, namely 4‐methoxy‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3‐yl)methylene)benzenamine (MMPIPB) and 4‐chloro‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3yl)methylene)benzenamine (CMPIPB), were investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss and electrochemical techniques. According to electrochemical impedance spectroscopy studies, MMPIPB and CMPIPB show corrosion inhibition efficiency of 84.8 and 77.2% at 10‐ppm concentration and 98.1 and 94.8% at 80‐ppm concentration, respectively at 303 K. The corrosion inhibition efficiency of both inhibitors increased with increasing inhibitor concentration and decreased with increasing temperature. The adsorption of both inhibitor molecules on the surface of mild steel obeys Langmuir adsorption isotherm. Polarization studies showed that both studied inhibitors were of mixed type in nature. Electrochemical impedance spectroscopy studies showed that for both inhibitors, the value of charge transfer resistance increased and double‐layer capacitance decreased on increasing the concentration of inhibitors. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy (EDX), and atomic force microscopy were performed for surface study. The density functional theory was employed for theoretical calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

Anticorrosive property of Spiraea Cantoniensisis extract as an eco-friendly inhibitor on mild steel surface in acid medium

Abstract

The inhibitive performance of methanolic extract of eco-friendly green inhibitor Spiraea cantoniensis (S. cantoniensis) on inhibiting corrosion of mild steel (MS) in 1?M HCl was studied by weight loss, AC-impedance, Fourier transform infrared spectroscopy (FT-IR), Raman, x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), atomic absorption spectroscopy (AAS), and scanning electron microscopy (SEM) analysis. The results showed that the corrosion rate significantly decreased in the presence of the S. cantoniensis inhibitor with a gradual increase in inhibition efficiency at an increased inhibitor concentration. The temperature studies were conducted which included activation energy (E_a), change in enthalpy (ΔH°_ads), change in entropy (ΔS°_ads), change in free energy (ΔG°_ads) and heat of adsorption (Q_ads). These calculations were helpful to determine the reaction mechanism and proved it as a physisorption type following the Langmuir adsorption isotherm. The analysis of the protective film using FT-IR, Raman, XRD, and SEM analysis clearly showed the potentiality of S. cantoniensis in blocking the MS surface to prevent corrosion by 1?M HCl. The solution analysis via AAS and UV-Vis showed the inhibitive effect of the inhibitor (S. cantoniensis) in both inhibitive and the uninhibitive solution exhibiting the adsorption of the phytochemical molecules on the MS surface.     

Surface morphological and impedance spectroscopic studies on the interaction of polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) with mild steel in acid solutions

The inhibition of mild steel corrosion in aerated acid mixture of 0.5 N H₂SO₄ and 0.5 N HCl solution was investigated using potentiodynamic polarization studies, linear polarization studies, electrochemical impedance spectroscopy, adsorption, and surface morphological studies. The effect of inhibitor concentration on corrosion rate, degree of surface coverage, adsorption kinetics, and surface morphology is investigated. The inhibition efficiency increased markedly with increase in additive concentration. The presence of PEG and PVP decreases the double-layer capacitance and increases the charge-transfer resistance. The inhibitor molecules first adsorb on the metal surface following a Langmuir adsorption isotherm. Both PEG and PVP offer good inhibition properties for mild steel and act as mixed-type inhibitors. Surface analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that PVP offers better protection than PEG.     

Corrosion inhibition of carbon steel in hydrochloric acid 0.5 M by hexa methylene diamine tetramethyl-phosphonic acid

The efficiency of hexa methylene diamine tetra methyl-phosphonic acid (HMDTMP), as corrosion inhibitor for carbon steel in 0.5 M HCl, has been determined by gravimetric and electrochemical measurements. Polarization curves indicate that the compound is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. Adsorption of HMDTMP derivatives on the carbon steel surface is in agreement with the Langmuir adsorption isotherm model, and the calculated Gibbs free energy value confirms the chemical nature of the adsorption. EIS results show that the charge in the impedance parameters (R_t and C_dl) with concentrations of HMDTMP is indicative. The adsorption of this molecule leads to the formation of a protective layer on carbon steel surface. The electrochemical results have also been supplemented by surface morphological studies.