脂肪酰胺类缓蚀剂对碳钢缓蚀作用的电化学研究

开发了一种新型环境友好型N-烷基-N-脂肪酰基氨基脂肪酸盐(TS-417)无磷缓蚀剂。采用极化曲线和电化学阻抗谱方法研究了TS-417对低碳钢在模拟中碱中硬循环冷却水中的缓蚀作用。结果表明:TS-417缓蚀剂对碳钢具有良好的缓蚀作用,属于阳极抑制型缓蚀剂;其缓蚀效率随着缓蚀剂浓度的增大而增大,当添加浓度为100 mg/L时,缓蚀剂效率即可达到90%。     

复合型缓蚀剂对珠海海水中的碳钢缓蚀研究

针对珠海海水进行水样分析后,选择钨酸钠、钼酸钠、柠檬酸钠三种缓蚀剂按不同比例组合,建立复合缓蚀剂方案,并配制一系列缓蚀剂,通过静态失重法、极化曲线发法测定其在珠海海水中对碳钢的缓蚀效果,试验条件下,缓蚀剂复合配方钨酸钠、钼酸钠、柠檬酸钠最佳配比为9∶8∶3。     

有机膦酸对碳钢缓蚀性能及机理研究

采用失重法评定了氨基三亚甲基膦酸（ATMP）、羟基乙叉二膦酸（HEDP）、乙二胺四亚甲基膦酸（EDTMP）、二乙烯三胺五甲叉膦酸（DTPMP）、羟基膦酰基乙酸（HPAA）及2-磷酸丁烷-1,2,4-三羧酸（PBTC）在酸性条件下对碳钢的缓蚀性能,并结合电化学极化曲线研究了有机膦酸的缓蚀机理。结果表明：DTPMP、HEDP、ATMP、PBTC及HPAA为阳极型缓蚀剂,其缓蚀效率由大到小为：DTPMP〉EDTMP〉HEDP〉ATMP〉PBTC〉HPAA。     

咪唑啉曼尼希碱缓蚀剂对碳钢的缓蚀性能研究

利用动态失重法、电化学测试技术以及SEM-EDS测试方法,研究了在含1 mol/L HCl溶液中分别添加不同浓度的IMDD和IMDDM对10#钢的缓蚀行为的影响。结果表明,60℃动态下1 mol/L HCl溶液的腐蚀介质对10#钢造成严重的局部腐蚀及均匀腐蚀;两种缓蚀剂均属于混合型缓蚀剂,添加缓蚀剂后有效地抑制了10#钢的腐蚀,IMDDM的缓蚀效果高于IMDD。两者均在金属表面发生致密的化学吸附并遵循Langmuir等温吸附方程。     

酸性介质中苯甲醛缩苯胺对A3碳钢的缓蚀作用

采用失重法及电化学法研究了苯甲醛缩苯胺在不同浓度盐酸介质和温度中对A3碳钢的缓蚀行为。结果表明,该缓蚀剂对盐酸介质中的A3碳钢有明显的缓蚀作用;加入缓蚀剂后,腐蚀反应活化能由52.23 k J/mol升高到103.85 k J/mol,随着温度的升高这种缓蚀剂能在一定程度上抑制温度对腐蚀速率的影响。随着缓蚀剂浓度的提高,腐蚀速率显著降低,缓蚀率显著提高,但最终会随着缓蚀剂用量加大,腐蚀速率和缓蚀率趋于平缓。     

2-羟基-4-甲氧基苯乙酮席夫碱化合物的合成

以2-羟基-4-甲氧基苯乙酮与3-硝基苯胺为原料，在一定条件下，通过加成-脱水反应制备2-羟基-4-甲氧基苯乙酮席夫碱，探讨了合成反应的影响因素，利用元素分析、红外光谱确定其结构，产品的收率为84％。     

硫脲/硫氰酸钾复合缓蚀剂对20碳钢的缓蚀性能研究

借助静态腐蚀失重法研究了硫脲/硫氰酸钾缓蚀剂的最佳配方及在5%盐酸、5%硫酸、5%硝酸中对20碳钢的缓蚀性能。结果表明,在5%盐酸中,只需加入0.2%的复合缓蚀剂(硫脲∶硫氰酸钾=7∶3),20碳钢材质的缓蚀率可以达到85.1%;在5%硫酸介质中,缓蚀率在复合缓蚀剂(硫脲∶硫氰酸钾=5∶5)为0.2%时达到最大,为87.3%;在5%硝酸溶液中,当复合缓蚀剂(硫脲∶硫氰酸钾=7∶3)的加入量为0.15%时,20碳钢的缓蚀率可达到99%。     

硫脲/硫氰酸钾复合缓蚀剂对20碳钢的缓蚀性能研究

借助静态腐蚀失重法研究了硫脲/硫氰酸钾缓蚀剂的最佳配方及在5%盐酸、5%硫酸、5%硝酸中对20碳钢的缓蚀性能。结果表明,在5%盐酸中,只需加入0.2%的复合缓蚀剂(硫脲∶硫氰酸钾=7∶3),20碳钢材质的缓蚀率可以达到85.1%;在5%硫酸介质中,缓蚀率在复合缓蚀剂(硫脲∶硫氰酸钾=5∶5)为0.2%时达到最大,为87.3%;在5%硝酸溶液中,当复合缓蚀剂(硫脲∶硫氰酸钾=7∶3)的加入量为0.15%时,20碳钢的缓蚀率可达到99%。     

阻垢缓蚀剂对不锈钢管缓蚀效果的评定方法

用点蚀电位法和失重法评价了七种阻垢缓蚀剂在不同冷却水样中对不锈钢的缓蚀效果。用腐蚀失重法评价阻垢缓蚀剂对不锈钢的缓蚀效果，既不合理也很难测准。点蚀电位法是评价阻垢缓蚀剂对不锈钢缓蚀效果的有效方法，但要选择合适的空白水样。     

Inhibitive effect of 4-amino-N-benzylidene-benzamide Schiff base on mild steel corrosion in HCl solution

Abstract

A newly Schiff base, 4-amino-N-benzylidene-benzamide (4-BAB) protection ability was synthesised from a condensation reaction of 4-aminobenzamide (4-AB) and benzaldehyde (BA). Adsorption and corrosion inhibition effect of this compound on mild steel (MS) in 1.0?M HCl solution were studied. The data obtained from measurments of this compound were compared with that of 4-AB and BA using many electrochemical, microscopic and hydrogen gas evolution techniques to clarify superiority of the Schiff base. Some thermodynamic parameters were calculated from experimental results and discussed. The value of ΔG_ads showed that adsorption of 4-BAB on MS from acidic solution obeys the Langmuir adsorption isotherm model. Surface SEM images of the MS specimens which were exposed to 1.0?M HCl solution in the absence and presence of the inhibitors showed that a homogeneous and protective inhibitor film forms on the metal surface, which hinder corrosive attack. It was concluded that synthesising the Schiff base improves protection ability with respect to related amine and aldehyde and the inhibitive action is in the order of 4-BAB > 4-AB?>?BA.

• Highlights

• 4-Amino-N-benzylidene-benzamide (4-BAB) is synthesized by condensation reaction between 4-aminobenzamide (4-AB) and benzaldehyde (BA)

• The inhibitor efficiencies calculated from all the applied methods are in agreement and are found to be in the order: 4-BAB >4-AB?>?BA

• The adsorption process of inhibitors on mild steel surface obeys the Langmuir adsorption isotherm

     

油酸咪唑啉类缓蚀剂对不锈钢的缓蚀性能研究

利用静态失重法、Tafel极化曲线研究了油酸咪唑啉类缓蚀剂在不同酸介质中对不锈钢的缓蚀性能,并尝试了油酸咪唑啉缓蚀剂与KI的复配实验。结果表明,油酸咪唑啉类缓蚀剂在10%盐酸中和10%硫酸中对不锈钢有很好的缓蚀作用。在10%盐酸介质中,只需加入0.3%的油酸咪唑啉缓蚀剂,不锈钢材质的缓蚀率就能达到98%;在10%硫酸介质中,缓蚀率在油酸咪唑啉缓蚀剂添加量为0.5%时最大,达到94%。与KI的复配结果表明,咪唑啉与KI之间有一定的缓蚀协同效应,复合使用可以达到降低成本和保持高缓蚀率的作用。     

Corrosion inhibition of mild steel by Calotropis procera leaves extract in a CO2 saturated sodium chloride solution

The Calotropis procera leaves extract (CPLE) was investigated as a corrosion inhibitor for mild steel in a CO₂-saturated 3.5 wt% NaCl solution using various electrochemical techniques. The results show that the CPLE is an effective inhibitor with inhibition efficiency of 80% using 50 ppm. Polarization studies show that the CPLE acts as a mixed inhibitor, and the adsorption of CPLE follows Langmuir adsorption isotherm. Molecular dynamics simulations reveal that the presence of N, O in the CPLE as well as π-electron systems coupled with high adsorption energies of interaction of the CPLE with steel are responsible for corrosion inhibition performance.     

Extraction and experimental studies of Citrus aurantifolia as an economical and green corrosion inhibitor for mild steel in acidic media

The Citrus aurantifolia leaves extract was tested for corrosion inhibition on the mild steel in a 0.5?M sulfuric acid solution using weight loss, Tafel and EIS. The state of mixed adsorption with the potentiodynamic polarization effect is shown. Citrus aurantifolia showed the strongest corrosion inhibition of 96.46% at a concentration of 250?mg/L. SEM and AFM are used to verify the formation of a protective layer on the surface of mild steel. The adsorption phenomenon was verified using UV-Vis. spectroscopic technique, whereas FT-IR confirmed the presence of several functional groups containing heteroatoms. Adsorption of the inhibitory molecules on the mild steel surface followed the Langmuir adsorption isotherm. All obtained results ensure that C. aurantifolia leaves extract can form an effective blocking layer and control the corrosion process.     

脱氢枞胺水杨醛类Schiff碱对铜的缓蚀性能研究

以脱氢枞胺为原料,采用直接缩合法合成了5种脱氢枞胺水杨醛类Schiff碱,用IR、¹H NMR确证其结构,并用静态失重法研究了它们在酸性介质中对铜的缓蚀性能。结果表明:它们对铜的缓蚀率随着Schiff碱处理浓度的增大、成膜时间的延长、腐蚀时间的缩短而增大。脱氢枞胺(5,6-二羟基)水杨醛Schiff碱对铜的缓蚀性能最强。     

Corrosion inhibition performance of 2-mercaptobenzimidazole and 2-mercaptobenzoxazole compounds for protection of mild steel in hydrochloric acid solution

The effect of some mercapto functional azole compounds on the corrosion of mild steel in 1 M hydrochloric acid solution was studied by polarization and electrochemical impedance spectroscopy (EIS). Polarization studies showed depression of cathodic and anodic polarization curves in the presence of mercapto functional azole compounds, indicating mixed type corrosion inhibition of the compounds. Double layer capacitance and charge transfer resistance values were derived from EIS results. Changes in impedance parameters are indicative of adsorption of these compounds on the metal surface. Surface analysis SEM/EDX showing presence of sulfur on the surface confirmed the adsorption of the azole compounds on the mild steel surface as showed by electrochemical methods. Both compounds contain a pyridine-like nitrogen atom and a sulfur atom in their molecular structure, while they differ in only one heteroatom: oxygen in the oxazole ring and pyrrole-like nitrogen in the imidazole ring. The results of the electrochemical techniques revealed that changing the pyrrole like nitrogen atom to oxygen atom in the azole ring results in a decrease of corrosion inhibition performance in hydrochloric acid solution, which could be related to more negative charge on pyrrole-like nitrogen atom in comparison to oxygen atom as depicted by quantum chemical calculations.     

Thiazoles as corrosion inhibitors for mild steel in formic and acetic acid solutions

2-(N,N-dimethylamino) benzylidene imino-4-(4-methyl phenyl)-1,3-thiazole (DIMPT), 2-benzylidene imino-4-(4-methyl phenyl)-1,3-thiazole (BIMPT), 2-salicylidene imino-4-(4-methyl phenyl)-1,3-thiazole (SIMPT) and 2-cinnamylidene imino-4-(4-methyl phenyl)-1,3-thiazole (CIMPT) were synthesized in the laboratory and their influence on the inhibition of corrosion of mild steel in 20 formic acid and 20 acetic acid was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of these compounds was found to vary with their nature and concentration, temperature, immersion time and acid concentration. The values of activation energy and free energy of adsorption of the thiazoles were calculated to investigate the mechanism of corrosion inhibition. The adsorption of all the thiazoles on mild steel surface was found to obey Langmuir adsorption isotherm. The potentiodynamic polarization result revealed that the compounds studied are mixed type inhibitors. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition.     

Corrosion inhibition effect of pyrazole derivatives on mild steel in hydrochloric acid solution

Synthesized compounds, namely methyl 5-(4-Chlorobenzoyloxy)-1-phenyl-1H-pyrazole-3-carboxylate (MCPPC) and 5-(4-methoxyphenyl)-3-(4-methylphenyl)4,5-dihydro-1H-pyrazol-1-yl-(pyridin-4-yl)methanone (MMDPPM) were investigated as corrosion inhibitor for mild steel (MS) in 15% HCl solution using weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. Inhibition efficiency was found concentration-dependent and increased by increasing the concentration of MCPPC and MMDPPM. Both of inhibitors were efficient even at a very low concentration of 25 ppm. The inhibitors MCPPC and MMDPPM showed inhibition efficiency of 67.1 and 76.8%, respectively, at 25 ppm, whereas it was 92.0 and 95.9%, respectively, at 250 ppm concentration at 303 K. The potentiodynamic polarization curves showed that MCPPC and MMDPPM act as mixed-type inhibitor in 15% HCl solution. The Nyquist plots showed that charge transfer resistance increased and double-layer capacitance decreased on increasing the concentration of studied inhibitors due to adsorption of inhibitor molecules on MS surface. The adsorption of each inhibitor on MS surface obeys Langmuir adsorption isotherm. On the basis of thermodynamic adsorption parameters, mixed-type adsorption (physisorption and chemisorption) for the studied inhibitors on MS surface was suggested. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM) analyses confirmed the existence of a protective film of the inhibitor on MS surface. The density functional theory was employed for theoretical calculations, and the obtained results were found to be consistent with the experimental findings.