硫酸溶液中1,1'-硫代羰基二咪唑在碳钢上的吸附及缓蚀影响和碘离子的增强应

The inhibition effect of 1,1'-thiocarbonyldiimidazole (TCDI) on the corrosion behaviors of mild steel impedance spectroscopy(EIS),and linear polarization resistance(LPR)techniques.The effect of immersion time on the inhibition effect of TCDI was also investigated over 72 h.For the long.term tests.hydrogen evolution with immersion time(VH2-t)was measured in addition to the three techniques already mentioned.The thermodynamic parameters.such as adsorption equilibrium constant(Kads) and adsorption free energy(△Gads)values,were calculated and discussed.To clarify inhibition mechanism,the synergistic effect of iodide ion was also investigated.The potential of zero charge (PZC)of the MS was studied by electrochemical impedance spectroscopy method.and a mechanism of adsorption process was proposed.It was demonstrated that inhibition efficiency increased with the increase in TCDI concentration and synergistically increased in the presence of KI.The inhibition efficiency was discussed in terms ofadsorption of inhibitormolecules on the metal surface and protective film formation.     

硫酸溶液中1,1’-硫代羰基二咪唑在碳钢上的吸附及缓蚀影响和碘离子的增强效应

The inhibition effect of 1,1’-thiocarbonyldiimidazole (TCDI) on the corrosion behaviors of mild steel (MS) in 0.5 mol·L -1 H2SO4 solution was studied with the help of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) techniques. The effect of immersion time on the inhibition effect of TCDI was also investigated over 72 h. For the long-term tests, hydrogen evolution with immersion time (VH2-t) was measured in addition to the three techniques already mentioned. The thermodynamic parameters, such as adsorption equilibrium constant (Kads) and adsorption free energy (⊿Gads) values, were calculated and discussed. To clarify inhibition mechanism, the synergistic effect of iodide ion was also investigated. The potential of zero charge (PZC) of the MS was studied by electrochemical impedance spectroscopy method, and a mechanism of adsorption process was proposed. It was demonstrated that inhibition efficiency increased with the increase in TCDI concentration and synergistically increased in the presence of KI. The inhibition efficiency was discussed in terms of adsorption of inhibitor molecules on the metal surface and protective filmformation.     

Extended protection of mild steel in molar HCl using the Garcinia Indica fruit rind extract (GIW) and iodide ions; electrochemical,thermodynamic and kinetic studies

The extended protection of mild steel in hydrochloric acid (HCl) media at four different temperatures using the synergistic interaction of a nontoxic, green corrosion inhibitor Garcinia Indica fruit rind (GIW) and potassium iodide (KI) is discussed in this paper. The investigations are mainly carried out using weight loss and electrochemical studies. The corrosion inhibition property of the aqueous extract is due to the presence cyanidin anthocyanins such as cyanidin 3-glucoside and cyanidin sambubioside and o-hydroxy citric acid. By the addition of 200 ​ppm of KI to 4% GIW extract, the efficiency increased from 89% to 90% at 303K but the increase is appreciable at 333K from 74% to 81%. The results explain the charge transfer controlled reactions of corrosion inhibition and proves the mixed type characteristic of GIW/KI pair. The adsorption process is found to be mainly the physisorption of GIW/KI pair. Monte-Carlo simulations of the constituent molecules reveal an increase in binding energy when GIW adsorbed along with KI.     

柠檬酸中锌防蚀剂（1,3-Dioxolan-2-ylmethyl）三苯基溴化磷和碘离子的协同效应研究

采用称重法、动电位极化法和电化学交流阻抗技术研究了30 ^oC时(1,3-Dioxolan-2-ylmethyl)三苯基溴化磷（DTPB）对0.5 mol·L^-1柠檬酸中锌腐蚀行为的影响. 通过在环保型电解槽中对锌进行酸洗,这在文献中是不常用的. 结果表明,DTPB作为一种有效的防蚀剂,添加浓度仅为3×10^-3 mol·L^-1时,锌在柠檬酸溶液中的防蚀效率可达98.9%. 由于DTPB和碘化钾存在协同效应,两者联用时的防蚀效果要比单独使用DTPB强,防蚀参数为1.2,并随温度升高而减小. 本文提出了碘化钾作为吸附媒介,可使金属表面与DTPB结合的防蚀机制.     

Adsorption and Corrosion Inhibition Effect of 1,1′-Thiocarbonyldiimidazole on Mild Steel in H2SO4 Solution and Synergistic Effect of Iodide Ion

The inhibition effect of 1,1′-thiocarbonyldiimidazole (TCDI) on the corrosion behaviors of mild steel (MS) in 0.5 mol·L⁻¹ H₂SO₄ solution was studied with the help of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) techniques. The effect of immersion time on the inhibition effect of TCDI was also investigated over 72 h. For the long-term tests, hydrogen evolution with immersion time (V_H2-t) was measured in addition to the three techniques already mentioned. The thermodynamic parameters, such as adsorption equilibrium constant (K_ads) and adsorption free energy (ΔG_ads) values, were calculated and discussed. To clarify inhibition mechanism, the synergistic effect of iodide ion was also investigated. The potential of zero charge (PZC) of the MS was studied by electrochemical impedance spectroscopy method, and a mechanism of adsorption process was proposed. It was demonstrated that inhibition efficiency increased with the increase in TCDI concentration and synergistically increased in the presence of KI. The inhibition efficiency was discussed in terms of adsorption of inhibitor molecules on the metal surface and protective film formation.     

Synergistic effect of AM-4VP-9 copolymer and iodide ion on corrosion inhibition of mild steel in 1 M H2SO4

The effect of iodide ions on the corrosion inhibition of mild steel in 1 M sulfuric acid in the presence of poly(acrylamide-co-4-vinylpyridine) copolymer abbreviated by (AM-4VP-9) was studied by weight loss measurements and electrochemical techniques (impedance spectroscopy and polarisation curves) at 18 °C. The results obtained showed that the inhibition efficiency increased with increasing copolymer concentration. It was also found that the inhibition efficiency increased with the addition of potassium iodide (KI) to the copolymer. A synergistic effect was observed between the AM-4VP-9 copolymer and KI. On the other hand, it was found that the inhibiting effect of the system (AM-4VP-9 + KI) increased with increasing immersion time. Polarisation curves indicate that (AM-4VP-9) copolymer act as mixed inhibitors. EIS measurements show an increase of the transfer resistance with the inhibitor concentration.     

药物莫西沙星对Q235钢在盐酸溶液中的缓蚀作用

为了探寻新的环境友好型缓蚀剂,采用电化学方法、失重法和量子化学计算研究了莫西沙星在1 mol/L HCl溶液中对Q235钢的缓蚀性能和缓蚀机理。结果表明,莫西沙星对Q235钢在盐酸溶液中是一种良好的以抑制阴极为主的混合抑制型缓蚀剂,缓蚀效率随其浓度的增加而增大,但随温度增加而减小,35℃下,在其浓度为200 mg/L时,缓蚀效率达90%;莫西沙星在Q235钢表面的吸附为自发过程,且符合Langmuir和El-Awady等温方程,同时,计算和讨论了相关的热力学和动力学参数。此外,采用量子化学计算对莫西沙星的缓蚀机理进行了进一步的分析,结果发现,莫西沙星的缓蚀作用由物理吸附和化学吸附共同产生。     

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.     

MMI作为铜的盐酸酸洗缓蚀剂作用机理的研究

用失重法研究了N-甲基-2-巯基咪唑（MMI）在5％盐酸中对铜的酸洗缓蚀性能.探讨了温度和MMI浓度对缓蚀效果的影响，从中得出了MMI在铜表面的吸附等温式，计算了吸附热及MMI的加入对铜在盐酸中腐蚀反应活化能的影响，进而探讨了MMI对铜缓蚀作用的机理.结果表明， 30 ℃下，在5％盐酸中，当MMI的浓度在3 mmol•L－1和8 mmol•L－1之间时,缓蚀率随MMI浓度的增加而迅速增加，当浓度达到8 mmol•L－1时，缓蚀率趋于定值，而当浓度小于3 mmol•L－1时， MMI的加入会加速铜的腐蚀；吸附在铜表面的MMI分子间的作用力整体表现为引力； MMI在铜表面的吸附是吸热反应； MMI的加入降低了铜的腐蚀反应活化能.     

Inhibition of Silver Corrosion in Nitric Acid by Some Aliphatic Amines

The inhibition of silver corrosion in dilute nitric acid (0.01 M) was studied using electrochemical polarization technique in the presence of different concentrations of methylamine, ethylamine, n-propylamine, and n-butylamine. It was found that the inhibition efficiency obtained from Tafel plots improved when the inhibitor concentration and the length of the alkyl chain were increased. The inhibition efficiency increased markedly with increase the additive concentrations according to the following order: methylamine < ethylamine < n-propylamine < n-butylamine. The inhibition action of such compounds occurred by simple blocking of amines on the electrode surface through adsorption process according to Temkin adsorption isotherm. The nearly constant values of the anodic Tafel slopes indicated that the presence of such amines do not affect the mechanism of metal dissolution.     

Some aromatic hydrazone derivatives as inhibitors for the corrosion of C-steel in phosphoric acid solution

The effect of furfural benzoylhydrazone and its derivatives (I-VII) as corrosion inhibitors for C-steel in 1M phosphoric acid solution has been studied by weight-loss and galvanostatic polarization techniques. A significant decrease in the corrosion rate of C-steel was observed in the presence of the investigated inhibitors. This study revealed that, the inhibition efficiency increases with increasing the inhibitor concentration, and the addition of iodide ions enhances it to a considerable extent. The effect of temperature on the inhibition efficiency of these compounds was studied using weight-loss method. Activation energy (E(a)*) and other thermodynamic parameters for the corrosion process were calculated and discussed. The galvanostatic polarization data indicated that, the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The adsorption of these compounds on C-steel surface has been found to obey Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.     

Exploration of the potentials of imidazole-based inhibitor package for heat exchanger-type stainless steel during acid cleaning operation

Protecting heat exchanger alloys from corrosion during acid cleaning is sacrosanct and necessitates the development and application of highly–efficient environmentally–friendly corrosion inhibitors. In the present work, gravimetry, electrochemical impedance spectroscopy (EIS), cyclic potentiodynamic polarization (CPDP), cyclic voltammetry and scanning electron microscopy-energy dispersive x-ray spectrophotometry (SEM-EDX) have been employed to investigate the potential of 1–benzylimidazole and its mixture with potassium iodide (KI) for the mitigation of stainless steel (SS316L) corrosion in 1 M HCl solution at 60 °C. After short immersion time, 1–benzylimidazole is found to decrease the weight loss and corrosion rate of the substrate and impacts an inhibition efficiency of ≈ 65% at 2000 ppm dosage. The inhibitor adsorption followed the Freundlich isotherm. The synergism significantly lowers the rate of anodic half–reactions involving Fe and Cr oxidation which, in turn, boosts the inhibitor efficiency to > 80% through a competitive synergism. SEM-EDX characterization confirm that the passive layer formed in the presence of 1–benzylimidazole + KI significantly mitigated against the propagation of localized pitting corrosion. Prolonged immersion time, up to 72 h, lowers the inhibition efficiency of 1–benzylimidazole + KI mixture to 74 %.     

Synergistic and antagonistic effects between halide ions and carboxymethyl cellulose for the corrosion inhibition of mild steel in sulphuric acid solution

The corrosion and corrosion inhibition effect of carboxymethyl cellulose (CMC) for mild steel in sulphuric acid medium was investigated using chemical (weight loss and hydrogen evolution) techniques at 30–60 °C. The effect of addition of halide ions (Cl⁻, Br⁻, and I⁻) was also studied. It was found that CMC functions as an inhibitor for acid induced corrosion for mild steel. Inhibition efficiency increases with increase in immersion time but decreases with increase in temperature. Addition of halide ions reveals that chloride ions (Cl⁻) antagonize the inhibition process whereas iodide ions (I⁻) exert synergistic effect on the corrosion inhibition by CMC. Corrosion inhibitive effect was afforded by adsorption of CMC molecules onto the mild steel surface both in the absence and presence of halide ions which was found to follow Langmuir adsorption isotherm model. The phenomenon of physical adsorption is proposed from decrease in inhibition efficiency with increase in temperature. The inhibition mechanism was further corroborated by the values of thermodynamic and kinetic parameters obtained from the experimental data.     

Effect of pH Value on the Adsorption Behavior and Inhibition Mechanism of Dodecylamine on Carbon Steel

The effect of pH value on the adsorption behavior and inhibition mechanism of dodecylamine for carbon dioxide corrosion of carbon steel was investigated by electrochemical methods and scanning electron microscopy (SEM). The results indicated that the pH value of the solution played the crucial role to the adsorption behavior and inhibition mechanism of dodecylamine. The inhibition performance of dodecylamine on carbon steel was dependent on the pH value and the inhibition efficiency increased with the increase of pH value. At pH 4.9, dodecylamine mainly inhibited the cathode process of the corrosion. The adsorption energy of dodecylamine on the metal surface was lower. The adsorption of dodecylamine on the metal surface was not stable and an anode desorption phenomenon could be observed. Hence, dodecylamine did not provide effective inhibition to the corrosion. While at pH 6.9, it had much higher adsorption energy. Dodecylamine adsorbed on the metal surface tightly and formed the effective diffusion barrier which inhibited both the cathode and anode processes effectively.     

pH值对十二胺在碳钢表面的吸附行为及缓蚀机理的影响

采用电化学方法和扫描电镜技术, 研究了pH值对十二胺在碳钢表面的吸附以及对碳钢CO2腐蚀缓蚀机理的影响. 研究结果表明, 溶液的pH值对十二胺的吸附和缓蚀机理起决定性作用. 十二胺对碳钢的缓蚀作用随溶液pH值的增加而增强. pH值为4.9时, 十二胺主要抑制腐蚀的阴极过程. 缓蚀剂分子在金属表面上的吸附能比较低, 缓蚀剂容易发生脱附, 因此不能有效抑制腐蚀反应的进行. pH值为6.9时, 缓蚀剂的吸附能较高, 能够牢固地吸附在金属表面, 形成有效的扩散阻挡层, 同时抑制腐蚀的阴、阳极过程, 从而有效地抑制腐蚀反应的进行.     

Inhibition of aluminium and mild steel corrosion in acidic medium using Gum Arabic

The corrosion behaviour of mild steel and aluminium exposed to H₂SO₄ solution and their inhibition in H₂SO₄ containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature. Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69% at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel.     

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.     

红茶提取液在盐酸中对碳钢的缓蚀作用

采用动电位极化曲线和交流阻抗（EIS）研究了红茶提取液（BLE）在盐酸介质中对碳钢的缓蚀性能和缓蚀机理。 研究结果表明,采用索氏提取法从红茶茶叶中提取的缓蚀剂,对碳钢在1.0 mol/L盐酸溶液中具有良好的缓蚀性能,随着提取物浓度的增加,缓蚀效率增大。 红茶提取液中的有效缓蚀成分为抑制阴阳极反应的混合型缓蚀剂,在碳钢表面的吸附符合Langmuir等温式,属于单分子层吸附。     

双苯并咪唑衍生物对N80钢的缓蚀效果

选用1,3-双(2-苯并咪唑基)丙烷(BBP),1,3-双(2-苯并咪唑基)-2-氧杂丙烷(DMDB),N,N-双(2-苯并咪唑亚甲基)胺(IDB),1,3-双(2-苯并咪唑基)-2-硫代丙烷(BBMS)4种结构相似的双苯并咪唑衍生物作为N80油管钢缓蚀剂。采用失重法和电化学极化测试分别考察了不同缓蚀剂的缓蚀性能及其与KI复配后在pH=4.5的饱和CO2溶液中对N80钢的缓蚀效果。结果表明,此系列双苯并咪唑衍生物在投加量较小的情况下即对N80钢均具有较好的缓蚀效果,且此系列缓蚀剂既抑制了阳极过程,又抑制了阴极过程,为混合型缓蚀剂。当1,3-双(2-苯并咪唑基)-2-硫代丙烷(BBMS)与KI复配后,缓蚀机理没有发生改变,且缓蚀率明显提高,其浓度均为2mmol/L时,缓蚀率高达95.09%。     

Inhibition of acid corrosion of carbon steel using aqueous extract of olive leaves

The inhibitive action of the aqueous extract of olive (Olea europaea L.) leaves toward the corrosion of C-steel in 2 M HCl solution was investigated using weight loss measurements, Tafel polarization, and cyclic voltammetry. It was found that the extract acts as a good corrosion inhibitor for the tested system. The inhibition efficiency increases with increasing extract concentration. The inhibitive action of the extract is discussed with a view to adsorption of its components onto the steel surface, making a barrier to mass and charge transfer. The adsorption of extract components onto the steel surface was found to be a spontaneous process and to follow the Langmuir adsorption isotherm. It was found also that such adsorption increases the activation energy of the corrosion process. The results of cyclic voltammetry showed that the presence of olive extract decreases the charge density in the transpassive region. The inhibition efficiency is greatly reduced as the temperature is increased.