Inhibition of mild steel corrosion in groundwater by pyrrole and thienylcarbonyl benzotriazoles

The inhibition efficiency of Zn²⁺, 3-phosphonopropionic acid (3-PPA), benzotriazole (BTA) and two synthesized benzotriazole derivatives namely 1-(2-pyrrole carbonyl) benzotriazole (PCBT) and 1-(2-thienylcarbonyl) benzotriazole (TCBT) were evaluated as inhibitors for the corrosion of mild steel in ground water. The inhibition efficiencies of PCBT and TCBT in combination with Zn²⁺ and 3-PPA were also investigated and the results were compared with BTA. In order to study the corrosion rate and inhibition efficiency we employed potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Further characterization using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) demonstrates the adsorption of inhibitor and the formation of corrosion products on the mild steel surface, respectively. Combination of PCBT along with Zn²⁺ and 3-PPA shows better corrosion inhibition efficiency than other inhibitor combinations and the individual inhibitors.     

Investigation on the inhibition effect of aspartic acid and Zn2+ ions on carbon steel surface in aqueous solution

A protective film has been formed on the surface of carbon steel in aqueous environment using a synergistic mixture of an environment-friendly inhibitor, aspartic acid, and Zn²⁺. The synergistic effect of aspartic acid (AS) in controlling corrosion of carbon steel has been investigated by gravimetric studies in the presence of Zn²⁺. The formulation consisting of AS and Zn²⁺ has an excellent inhibition efficiency. The results of potentiodynamic polarization revealed that the formulations are of mixed-type inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. X-ray photoelectron spectroscopic analysis of the protective film showed the presence of the elements iron, nitrogen, oxygen, carbon, and zinc. The spectra of these elements in the surface film showed the presence of oxides/hydroxides of iron(III), Zn(OH)₂, and [Fe(III)/Fe(II)–Zn(II)-AS] complex. Further, surface characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy are used to ascertain the nature of the protective film formed on the carbon steel surface.     

Synergistic effect of polyethylene glycol 600 and polysorbate 20 on corrosion inhibition of zinc anode in alkaline batteries

Polyethylene glycol 600 (PEG 600) and polysorbate 20 (Tween 20) were used as a composite corrosion inhibitor of zinc in alkaline solution for the first time. The effects of the composite and individual inhibitors on corrosion inhibition of zinc were evaluated by weight-loss analysis and electrochemical methods including potentiodynamic, potentiostatic, and electrochemical impedance spectroscopic measurements. It was found that there was a synergistic effect between PEG 600 and Tween 20 on corrosion inhibition of zinc. The corrosion inhibition efficiency of the composite inhibitor, 500 ppm PEG 600 + 500 ppm Tween 20, was 89%, much higher than that of the individual inhibitor, 1000 ppm Tween 20 (71%) or 1000 ppm PEG 600 (55%). The battery (Zn/MnO₂) discharge performance tests showed that the composite inhibitor reduced the self-discharge of zinc anode more effectively than the individual inhibitor. The synergistic mechanism between PEG 600 and Tween 20 was discussed.     

Electrochemical Behaviour of Al, Al—In and Al–Ga–In Alloys in Chloride Solutions Containing Zinc Ions

The electrochemical behaviour of Al, Al—In and Al–Ga–In alloys in 0.6 m NaCl solutions with and without Zn²⁺ was investigated. The study was performed by means of open circuit potential, potentiodynamic polarization, potentiostatic current-time and electrochemical impedance spectroscopy measurements as well as by SEM-EDAX examination. It was found that the Al—In alloy exhibits the highest negative open circuit potential in 0.6 m NaCl and the corrosion resistance of the tested electrodes decreases in the following order: Al > Al–Ga–In > Al—In. The greater activity of the Al—In alloy was interpreted on the basis of the autocatalytic attack by indium. The potentiostatic current–time measurements in Zn²⁺ containing electrolyte at potentials above the pitting potential revealed that Zn²⁺ has an insignificant influence on the Al electrode, while it enhances the corrosion of the Al–Ga–In alloy and improves the attack morphology of the Al—In alloy. Furthermore, the impedance spectra recorded under open circuit conditions showed a decrease in the polarization resistance of Al—In and Al–Ga–In alloys in presence of Zn²⁺ indicating the activating effect of Zn²⁺ ions.     

聚苯胺&聚氨基酚纳米材料的制备及防腐性能

分别以苯胺(AN)和间氨基酚(m AP)为单体、乙酸(Ac OH)与对甲氧基苯乙酸(MOPAc)为掺杂酸、Fenton(Fe~(2+)/H_2O_2)试剂为引发剂,合成了Ac OH-PANI、AcOH-PmAP、MOPAc-PmAP、MOPAc-PANI防腐纳米材料。采用FTIR、UV-Vis、XRD、SEM及粒度分布对聚合物防腐材料的形貌、结构进行了表征。结果表明:以对甲氧基苯乙酸为掺杂酸制备出的聚合物粒径分布均匀且溶解度好。电化学测试表明:该聚合物为阴极为主的混合型缓蚀剂,且缓蚀效率遵循:MOPAc-PmAPAcOH-PmAPMOPAc-PANIAcOH-PANI。MOPAc-PmAP、Ac OH-PmAP分别与吐温80(Tween80)复配的电化学测试结果表明:当缓蚀剂质量浓度为100mg/L,吐温80质量浓度为50 mg/L时,MOPAc-Pm AP-Tween80体系防腐效果最佳,相比未添加Tween80的样品(71.04%)缓蚀效率高达94.66%。说明MOPAc-PmAP与吐温80表现出了优异的协同作用。     

The spatial distribution of Zn during galvanic corrosion of a Zn/steel couple

The spatial distribution of Zn²⁺ during galvanic corrosion of a model Zn/steel couple in 0.01 M NaCl was investigated using a scanning zinc disk electrode. The couple had a coplanar arrangement of a steel substrate with an electroplated zinc layer at the center. During galvanic corrosion, the marked changes in the Zn²⁺ concentration were confined to a thin solution layer ca. 1.0 mm thick above the couple surface. In this thin solution layer above the zinc layer, a higher concentration region of Zn²⁺ in the range of 5-18 mM extended around the zinc layer in the solution during galvanic corrosion. Conversely, above the steel surface distant from the zinc layer, the surface concentration of Zn²⁺ was almost zero during galvanic corrosion. On this surface, the precipitation of zinc corrosion products due to the hydrolysis reaction of Zn²⁺ was observed. The distribution of the Zn²⁺ concentration supported that Zn²⁺ acted as a buffer that suppressed the increased pH due to the cathodic reaction on the steel surface near the zinc layer and almost no corrosion products formed there. The spatial distribution of Zn²⁺ is discussed in relation to the distributions of potential and pH and the surface morphology of the galvanic couple.     

Enhanced corrosion inhibition behavior of carbon steel in aqueous solution by Phosphoserine-Zn2+ system

The corrosion inhibition effect of carbon steel in aqueous solution was using a synergistic mixture of an environmentally friendly inhibitor system phosphoserine (PS) and Zn²⁺ using gravimetric studies, potentiodynamic polarization, and electrochemical impedance studies. Potentiodynamic polarization studies showed that the inhibitor system is a mixed type inhibitor. Electrochemical impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous solution. X-ray photoelectron spectroscopic analysis of the protective film exhibited the presence of the elements viz., iron, phosphorus, nitrogen, oxygen, carbon, and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron, Zn(OH)₂, and [Fe(II)/(III)-Zn(II)-PS] complex. Further, the surface examination techniques viz., FTIR, SEM, and AFM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on the results obtained, a suitable mechanism of corrosion inhibition is presented.     

Corrosion and scale processes and their inhibition in simulated cooling water systems by monosaccharides derivatives: Part I: EIS study

A study of the ordinary mild steel/cooling water interface, with and without inhibitor, was carried out using electrochemical impedance spectroscopy (EIS). EIS spectra in uninhibited medium reveal that a layer of corrosion and scale products is formed naturally and evolves with the immersion time. Monosaccharides derivatives were used as corrosion inhibitors. Most of them exhibit good behaviour against corrosion of ordinary steel in simulated water systems. Their inhibiting efficiency increases with concentration rise and depends on molecular structure especially -OH groups' position on two adjacent carbons and their number. In addition, the effect of MoO₄²⁻ on the corrosion inhibition in the presence of the best inhibitor was also studied by EIS. The addition of MoO₄²⁻ enhanced the inhibition efficiency.     

聚环氧琥珀酸与氨基三甲叉膦酸复配阻垢缓蚀性能研究

为了提高聚环氧琥珀酸(PESA)的缓蚀阻垢性能,将其与氨基三甲叉膦酸(ATMP)进行复配,研制了一种适合酸性条件新型缓蚀阻垢剂。通过静态阻垢实验、、塔菲尔极化曲线法、交流阻抗法及静态失重法研究了该缓蚀阻垢剂在酸性介质中的阻垢和缓蚀性能。实验结果表明;该缓蚀阻垢剂属于混合型缓蚀剂,在酸性介质中表现出了较好的阻垢和缓蚀效果。     

Impedance study on calcium nitrite as a penetrating corrosion inhibitor for steel in concrete

Penetrating corrosion inhibitors are thought to be able to penetrate through the capillary structure of concrete to reinforcing steel and to reduce the already initiated corrosion of steel. In this work the ability of calcium nitrite to inhibit the chloride induced corrosion of steel was studied. The test protocol was adjusted to simulate the performance of penetrating corrosion inhibitors in concrete structures. Steel samples were first prepassivated in saturated solution of Ca(OH)₂ and then exposed to the same solution with 1% NaCl addition, simulating pore liquid in chloride contaminated concrete. After the initiation of steel corrosion, the first dose of calcium nitrite was added, and then its concentration was gradually increased and the inhibition effect was related to the molar ratio of chloride to nitrite ions [Cl⁻]/[NO₂⁻]. Different rates of the increase in the inhibitor concentration were applied.Electrochemical impedance spectroscopy was used to follow the behaviour of steel at different stages of the corrosion process. The evolution of acquired spectra reflected the initiation of localized corrosion of steel and then the gradual inhibition with increasing concentration of the inhibitor. It was found, that calcium nitrite is able to inhibit the initiated corrosion (pitting) of steel and the optimum inhibitor efficiency was observed for the [Cl⁻]/[NO₂⁻] ratio below 1. The inhibition efficiency was larger, when this value of the [Cl⁻]/[NO₂⁻] ratio was reached in early stages of the corrosion development. Calcium nitrite can be effective as a penetrating corrosion inhibitor for steel in concrete, if it will be present in the sufficient concentration at the steel surface in early stages of the corrosion development.     

Effect of Co2+, Ni2+, Cu2+, or Zn2+ on properties of polyaniline nanoparticles

Uniform polyaniline (PANI) nanoparticles with typical sizes of about 50 nm were electropolymerized on indium tin oxide surfaces in the presence of Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺. According to shaping theory, we first suggest the reason forming PANI spherical particles. Their conductivity, UV‐vis spectra, FTIR spectra, X‐ray diffraction, and thermogravimetric analysis were investigated. The conductivities and crystallinity of PANI doped with these ions are higher than those of PANI doped with HCl (PANI/HCl). Both UV‐vis absorption spectra and FTIR spectra indicate the interactions between Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ and PANI chains. TG analysis also shows that the thermal stability of PANI doped by Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ is lower than that of PANI/HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis, Surface Properties, Synergism Parameter and Inhibitive Performance of Novel Cationic Gemini Surfactant on Carbon Steel Corrosion in 1 M HCl Solution

Electrochemical and gravimetric measurements were performed to investigate the effectiveness of a synthesized cationic gemini surfactant as corrosion inhibitor for carbon steel in 1 M HCl solution. The inhibition efficiency obtained from all methods are in good agreement. Potentiodynamic polarization measurements showed that, the prepared surfactant hinders both anodic and cathodic processes, i.e. acted as mixed-type inhibitor. It was found that the adsorption of the synthesized inhibitor followed the Langmuir adsorption isotherm and showed a mixed physical and chemical adsorption. Kinetic parameters were calculated and discussed. The inhibitor exhibited a synergistic effect with Sn²⁺ more than with Cu²⁺. The synthesized cationic gemini surfactant exhibited good surface properties.     

Extremely high corrosion resistance of ZnxNi1–xCr2O4 spinel as sidewalls in the aluminum electrolyte

The sidewall material is a key component in new electrolytic cell with an inert electrode for the aluminum electrolysis industry. The continuous development of novel sidewall materials with excellent corrosion resistance in molten salts electrolyte is an important topic. Herein, a new system of sidewall material, spinel structured Zn_xNi_1–xCr₂O₄ (x = 0 – 1), is prepared by solid-phase reaction and the corrosion-resistance enhancement is investigated. The results prove that Zn²⁺ plays two roles in the Zn_xNi_1–xCr₂O₄ spinels. Firstly, Zn²⁺ tunes the surface energies of spinels resulting in the octahedral grains, which suppresses the cation diffusion in the corrosion process. Secondly, Zn²⁺ stabilizes the Cr³⁺ in the spinels. As a result, the Zn_0.5Ni_0.5Cr₂O₄ spinel displays an extremely low corrosion rate ～0.007 cm·a^–1 in NaF-KF-AlF₃ bath at 800 °C comparing with other sidewall materials. The as-obtained spinel shows great potential as a novel sidewall material for the new electrolytic cell.     

Influence de l'antimoine et du cuivre sur la cementation du cobalt par le zinc

Zinc sulphate solution (160g/l Zn²⁺) used for zinc electrowinning is purified for cobalt by cementation with metallic zinc powder. Industrial practice shows that considerable acceleration of this operation is achieved by the presence of trace impurities in solution. Eventually, CuSO₄ and Sb₂O₃ are deliberately added to the solution. The aim of this work is to elucidate the mechanism of action of those impurities.Zn²⁺ ions present in the solution are responsible for the slow speed of cobalt deposition (160g/l Zn²⁺; 10 mg/l Co²⁺).The cathodic part of the cementation reaction was simulated on a flat electrode through potentiostatic deposits at ?730 mV/ENH (potential at zero current of metallic zinc in the solution). The deposits were studied by anodic dissolution, radioactive tracers, X-ray diffraction and fluorescence, atomic absorption spectrophotometry, optical and electronic microscopy (transmission and scanning). The results were compared with cementation on zinc plate and zinc powder.Antimony and copper are deposited together with cobalt and form alloys with reduced cobalt activity. Total voltage available to overcome the inhibitor effect of zinc ions is thus increased and the reduction of cobalt ions accelerated. Antimony, copper and cobalt triple alloys resist particularly well to corrosion with hydrogen evolution. Copper has a higher accelerating effect on cobalt cementation than antimony, but the latter stabilizes the deposit very effectively.The electrochemical methods used and the knowledge of the mechanism of action of the impurities open new trends for industrial practice.     

复合阻垢剂PASP-ATMP的协同效应及影响因素研究

采用静态阻垢法,研究了聚天冬氨酸(PASP)与氨基三甲叉膦酸(ATMP)复配体系的协同效应,考察阻垢剂添加量、温度、pH值、Ca2+浓度、HCO3-浓度对阻垢性能的影响。结果表明,复配体系的阻垢性能较单一阻垢剂好,PASP/ATMP质量比在2∶3时,阻垢性能最优,当复合阻垢剂PASP-ATMP投加量为5 mg/L时,阻垢率高达93.04%。复配体系阻垢性能随温度、pH值、Ca2+浓度、HCO3-的增加虽然有所下降,但仍表现出一定钙容忍度及适合高pH值、高HCO3-环境使用等特性。     

Some environmentally friendly formulations as inhibitors for mild steel corrosion in sulfuric acid solution

The corrosion resistance of mild steel in 1 M H₂SO₄ solution was evaluated after addition of Sn²⁺ and Zn²⁺, N-acetylcystein (ACC) and S-benzylcystein (BzC) as a function of concentration (5–1000 μM) and solution temperature (35–50°C). Eight blends were also investigated. Both polarization resistance (R _p) and electrochemical impedance spectroscopy (EIS) were employed. For single additives, Zn²⁺ ions acted as accelerator for mild steel corrosion while the other additives showed good performance. The most effective additive was Sn²⁺. Adsorption of Sn²⁺, ACC and BzC obeyed the Temkin adsorption isotherm and had a very high negative value of free energy of adsorption (−ΔG°_ads). All blends provided good inhibition which increased with rise in temperature. Corrosion kinetic parameters such as activation energy (E _a) and the pre-exponential factor (λ) were calculated and discussed. EIS revealed that the interface of the uninhibited and inhibited systems can be represented by the simple equivalent circuit R _e(R _ct Q _dl).     

Study of the inhibition of certain trophic levels by the presence of metal cations in water

Bioassays and biological tools have been developed for the evaluation of the toxicity of water. A protocol of short-term tests allowed the examination of the influence of temperature, salinity, hardness and effect of complexation on the toxicity of Cd²⁺, Cu²⁺, Ni²⁺ and Zn²⁺ by means of a test daphnia (Daphnia magna). The development of an experimental installation functioning continuously, where the trophic level is represented by the daphnia, led to the development of a system of bio-indication. The survival of the daphnia is examined under conditions of disturbances produced by Cd²⁺, Cu²⁺, Ni²⁺ and Zn²⁺. The application of the chronic test (21 d) allowed the folow-up of the inhibition of the survival and the reproduction of D. magna by Cd²⁺, Cu²⁺ and Ni²⁺. A methodology with the help of the phototactic effect of D. magna was proposed. This one aims at developing a phototactic biosensor subjected to the toxicity of cadmium. Bioassays, using the purifying activity of the activated sludge, were considered and enabled understanding of the phenomena of inhibition and adaptation of these muds in the presence of trivalent chromium. In addition, two watery freshwater plants, Lemna minor and Salvinia natans, were exposed to Cd²⁺, Cu²⁺ and Zn²⁺ in order to test their sensitivity. We consequently carried out a histological study on leaves of S. natans contaminated by metal toxicity independently of the test.     

Effects of Sr2+/Zn2+ co-substitution on crystal structure and properties of nano-β-tricalcium phosphate

The incorporation of therapeutic ions like Sr²⁺, Si⁴⁺, Zn²⁺ and Li⁺ into biomaterials has become a promising approach to promote bone regeneration. However, the effects of Sr²⁺ and Zn²⁺ co-substitution on the crystal structure and properties of β-tricalcium phosphate (β-TCP) have not been elucidated well. In this study, Sr²⁺/Zn²⁺ co-substituted β-tricalcium phosphate (SrZnTCP) nano-powders with different extents of substitution (0–4.8 mol%) were synthesized by poly(ethylene glycol)-assisted co-precipitation and subsequent heat treatment. The as-synthesized SrZnTCP nano-powders were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, Rietveld refinement and differential scanning calorimetry. The results showed that the conversion of calcium-deficient apatite to β-TCP was achieved after heat-treatment above 800 °C. The a-axis and c-axis lattice parameters gradually decreased with increasing level of Sr²⁺/Zn²⁺ co-substitution in β-TCP lattice. Sr²⁺ and Zn²⁺ preferentially occupied the ninefold coordinated Ca (4) sites and the sixfold coordinated Ca (5) sites, respectively. The co-substitution of Sr²⁺ and Zn²⁺ for Ca²⁺ significantly improved the thermal stability of β-TCP. The release rate of Zn²⁺ from SrZnTCP depended on Ca²⁺ concentration over 63-day immersion in PBS solution while that of Sr²⁺ was not affected by Ca²⁺ concentration. The amount of Sr²⁺ released increased with increasing Sr²⁺ content in SrZnTCP. Collectively, SrZnTCP showed great promise as a Sr²⁺/Zn²⁺-releasing biomaterial for bone repair, although no obvious mineralization was observed on β-TCP and SrZnTCP disc samples during 56 days of immersion in simulated body fluid.     

Corrosion of brass in natural and artificial seawater

The corrosion of brass in artificial seawater, (ASW), and in natural seawater, (NSW), collected at the beach of Ericeira, Portugal, was studied. The weight gains and the corresponding average corrosion rates of brass samples, immersed in both media, during periods of 1 week, 1, 3 and 6 months were determined. The concentrations of Cu²⁺ and Zn²⁺ ions in solution, produced by the corrosion of brass, were determined by atomic absorption spectrometry. The concentration of dissolved oxygen was also determined. The morphology of the corroded surfaces, with and without the corrosion products, was analyzed by visual observation and by scanning electron microscopy. The hydrated basic zinc chloro-sulfate compound, Zn₁₂(OH)₁₅Cl₃(SO₄)₃⋅5H₂O, was identified by X-ray powder diffraction as the predominant compound in all the samples, particularly in those with longer exposure to NSW. It was concluded that the corrosion of brass in natural seawater is much higher than in artificial seawater.     

Competent inhibitor for the corrosion of zinc in hydrochloric acid based on 2,6-bis-[1-(2-phenylhydrazono)ethyl]pyridine

A novel compound, 2,6-bis-[1-(2-phenylhydrazono)ethyl]pyridine (BPEP), was synthesized and confirmed by NMR and IR spectroscopy. BPEP was examined as an inhibitor for the corrosion of zinc electrode in 1.0 M HCl. The inhibition efficiency of BPEP was assessed through various techniques such as hydrogen evolution, galvanostatic polarization, potentiodynamic anodic polarization, and electrochemical impedance spectroscopy. The inhibiting action of BPEP was explained in terms of the formation of a stable complex between zinc ions and BPEP and then adsorbed onto the zinc surface. The formation of the complex was established by FT-IR spectroscopy. A conductometric titration indicated that the stoichiometry of Zn⁺²:BPEP (metal:ligand) is 1:1. The adsorption follows the Langmuir isotherm. The Galvanostatic polarization measurements have shown that the BPEP molecule acts as a mixed-type inhibitor. The pitting potential shifted in the noble direction, indicating that the inhibition of pitting corrosion of zinc in the presence of BPEP.The activation energy and themodyanamic parameters of the adsorption process were calculated and have been explained.