Luffa aegyptiaca leaves extract as corrosion inhibitor for mild steel in hydrochloric acid medium

The performance of methanol extract of Luffa aegyptiaca leaves (MLA) as corrosion inhibitor for mild steel (MS) in 1 M HCl was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. Polarization measurements showed that the MLA acts as a mixed inhibitor. It was found that the percentage inhibition efficiency increased with MLA concentration and decreased with temperature. Thermodynamic parameters indicate the spontaneous adsorption of MLA on MS surface. In addition, it has been established that the adsorption process obeyed Langmuir isotherm. Additions of halide ions considerably increase the inhibition efficiency. Synergistic parameters confirm the synergistic effect of halide ions. The adsorption of the chemical constituents of MLA on MS surface was confirmed by Fourier transform infrared spectroscopy and atomic force microscopy.     

Eco friendly inhibitor for corrosion inhibition of mild steel in phosphoric acid medium

The inhibition effect of Zenthoxylum alatum plant extract on the corrosion of mild steel in 20, 50 and 88% aqueous orthophosphoric acid has been investigated by weight loss and electrochemical impedance spectroscopy (EIS). Plant extract is able to reduce the corrosion of steel more effectively in 88% phosphoric acid than in 20% phosphoric acid. The effect of temperature on the corrosion behaviour of mild steel in 20, 50 and 88% phosphoric acid with addition of plant extract was studied in the temperature range 50-80 °C. Results on corrosion rate and inhibition efficiency have indicated that this extract is effective up to 70 °C in 88% phosphoric acid medium. Surface analysis (XPS and FT-IR) was also carried out to establish the mechanism of corrosion inhibition of mild steel in phosphoric acid medium.     

Hector bases – a new class of heterocyclic corrosion inhibitors for mild steel in acid solutions

Three heterocyclic compounds namely 3-anilino-5-imino-4-phenyl-1, 2,4-thiadiazoline (AIPT), 3-anilino-5-imino-4-tolyl-1, 2,4-thiadiazoline (AITT), and 3-anilino-5-imino-4-chlorophenyl-1, 2,4-thiadiazoline (AICT) were synthesized and their influence on the inhibition of corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ was investigated by weight loss and potentiodynamic polarization techniques. The values of activation energy and free energy of adsorption of these compounds were also calculated. Potentiodynamic polarization studies were carried out at room temperature, and showed that all the compounds were mixed type inhibitors causing blocking of active sites on the metal. The inhibition efficiency of the compounds was found to vary with concentration, temperature and immersion time. Good inhibition efficiency was evidenced in both acid solutions. The adsorption of the compounds on mild steel for both acids was found to obey the Langmuir adsorption isotherm. Electrochemical impedance spectroscopy was also used to investigate the mechanism of corrosion inhibition.     

Inhibition of mild steel corrosion in the presence of fatty acid triazoles

The influence of some fatty acid triazoles namely, 4-Phenyl-5-undecyl-4H- [1,2,4] triazole-3-thiol (PUTT), 5-Heptadec-8-enyl-4-phenyl-4H- [1,2,4] triazole-3-thiol (HPTT), and 5-Dec-9-enyl-4-phenyl-4H- [1,2,4] triazole-3-thiol (DPTT) on the corrosion of mild steel in 1 M hydrochloric acid (HCl) and 0.5 M sulfuric acid (H₂SO₄) was studied by weight loss and potentiodynamic polarization methods. The values of activation energy and free energy of adsorption of all the triazoles were calculated to investigate the mechanism of corrosion inhibition. The potentiodynamic polarization studies were carried out at room temperature, according to which all the compounds were mixed type inhibitors and inhibit the corrosion of mild steel by blocking the active sites of the metal. The adsorption of all the triazoles on mild steel surface in both the acid solutions was found to obey the Langmuir adsorption isotherm. All the compounds showed good inhibition efficiency in both acids. The inhibition efficiency of the compounds was found to vary with their nature and concentration, solution temperature and immersion time. Electrochemical impedance spectroscopy was also used to investigate the mechanism of the corrosion inhibition.     

环丙沙星、诺氟沙星、氧氟沙星在1 mol·L~(-1) HCl中对碳钢的缓蚀性能及机理研究(英文)

The inhibiting effect of ciprofloxacin,norfloxacin and ofloxacin on the corrosion of mild steel in 1 mol·L-1 HCl and the mechanism were studied at different temperatures using mass loss measurement,electrochemical method,and X-ray photoelectron spectroscopy(XPS) .Effective inhibition was shown by mass loss,potentiodynamic polarization and impedance spectroscopy measurement.The corrosion rate of the metal in the mass loss measurement,and the corrosion reaction on cathode and anode in the electrochemical measurement were accelerated when temperature was increased.XPS results showed that the inhibitors adsorbed effectively on the metal surface.     

Synergistic inhibition between the gemini surfactant and bromide ion for steel corrosion in sulphuric acid

The inhibitive synergistic effect between a cationic gemini surfactant, 1,3-propane-bis(dimethyl dodecylammonium bromide) (12-3-12), and bromide ion for the corrosion inhibition of cold rolled steel in 0.5 mol L⁻¹ H₂SO₄ was investigated by weight loss, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The inhibition system composed by 12-3-12 and bromide ion is efficient. The adsorption mechanism of the 12-3-12 and bromide ion on steel in acidic medium is discussed on the basis of experimental data and an adsorption model is proposed. Adsorption of inhibitor system on the mild steel surface in acidic medium obeys Langmuir’s adsorption isotherm. In addition, potentiodynamic polarization studies show that the system acts as a mixed-type inhibitor. Electrochemical impedance spectroscopy also suggests the formation of a protective layer on the steel surface by the adsorption of surfactant molecules and bromide ions.     

Inhibitive effect of FA derivatives on mild steel corrosion in the presence of formic acid

The influence of selected long-chain FA hydrazides and thiosemicarbazides on the corrosion inhibition of mild steel in the presence of 20% formic acid was studied. The inhibition efficiency of these compounds varied with concentration, temperature, and immersion time. All the FA derivatives in the formic acid solution followed Temkin's adsorption isotherm. The activation energies and free energies of adsorption of all the hydrazides and thiosemicarbazides also were calculated. Potentiodynamic polarization studies indicated that all the tested compounds were of mixed type. Electrochemical impedance spectroscopy was also used to investigate the mechanism of corrosion inhibition.     

硫酸中Q235钢缓蚀剂的电化学研究

采用塔菲尔极化曲线和电化学阻抗谱(EIS)测量方法,研究了5%(质量分数)硫酸溶液中N,N'-二苯基硫脲(DPH-TU)和十二烷基磺酸钠(SDS)对Q235钢的协同缓蚀效应及其机理.实验表明,添加十二烷基磺酸钠时N,N'-二苯基硫脲的缓蚀效果有促进作用.当N,N'-二苯基硫脲和十二烷基磺酸钠的浓度比为1:1时,其协同缓...     

Eco friendly corrosion inhibitors: Inhibitive action of quinine for corrosion of low carbon steel in 1 m HCl

Quinine, a natural product, was investigated as a corrosion inhibitor for low carbon steel in 1.0 m HCl solution. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to study the inhibition action in the temperature range 20–50 °C. The corrosion of steel was controlled by a charge transfer process at the prevailing conditions. The electrochemical results showed that quinine is an efficient inhibitor for low carbon steel and an efficiency up to 96% was obtained at 20 °C. The inhibition efficiency increases with inhibitor concentration and reaches a near constant value in the concentration range 0.48 mM and above. Application of the Langmuir adsorption isotherm enabled a study of the extent and the mode of adsorption.     

An exploration of corrosion inhibition of mild steel in sulphuric acid solution through experimental study and Monte Carlo simulations

Abstract

4-[4-(1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (ITBP) and 4[4-(1H-1,2,4-triazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (TTBP) are synthesized as new heterocyclic compounds of the triazole derivative family and tested successfully as potential inhibitors for MS in 1?M H₂SO₄ corrosive medium by using gravimetric analysis, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive X-ray spectroscopy (EDX). Polarization curves show that the tested inhibitors are mixed-type inhibitors. Scanning electron microscopy (SEM) affirmed the existence of an adsorbed film on the steel surface. Monte Carlo simulations were in excellent agreement with the experimental tests.

Abbreviation: PDP: Potentiodynamic Polarization; EIS: Electrochemical impedance spectroscopy; DFT: Density functional theory; MC: Monte Carlo     

Effect of sodium molybdate on the corrosion behavior of cold rolled steel in peracetic acid solution

The effect of sodium molybdate (Na₂MoO₄) on the corrosion of cold rolled steel (CRS) in peracetic acid (PAA) solution was investigated by gravimetric measurements, Tafel polarization curves, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All the data indicate that Na₂MoO₄ acts as a very good inhibitor in PAA solution. The inhibition efficiency increases with increasing concentration of Na₂MoO₄ and immersion time. The inhibition efficiencies, calculated from gravimetric measurements, Tafel polarization curves and electrochemical impedance spectroscopy, are in reasonably good agreement and are very similar in the three cases. Furthermore, polarization data show that Na₂MoO₄ behaves as an anodic passive type inhibitor. Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used to characterize the corrosion surface. A probable mechanism is presented to explain the experimental results.     

Synergistic inhibition effect of polyethylene glycol–polyvinyl pyrrolidone blends for mild steel corrosion in sulphuric acid medium

The corrosion inhibition of mild steel in sulphuric acid solution in the presence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), and their blends was investigated using weight loss and hydrogen evolution techniques at temperature range of 30–60°C. It was found that inhibition efficiency (η%) increases with increase in concentration of the homopolymers and decreases with increase in temperature. Inhibition efficiency was found to be synergistically enhanced on blending the two polymers with highest inhibition efficiency obtained for (PEG : PVP) blending ratio of 1 : 3. The experimental data obtained fitted well into Temkin adsorption isotherm model. Physical adsorption mechanism is proposed from the trend of inhibition efficiency with temperature. The proposed mechanism is also corroborated by kinetic and thermodynamic parameters obtained. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

An investigation of mild carbon steel corrosion inhibition in hydrochloric acid medium by environment friendly green inhibitors

Inhibition effect of Brugmansia suaveolens (BS) and Cassia roxburghii (CR) on mild carbon steel in 1.0 M HCl solution was studied. Inhibition efficiency of plant extracts were carried out by using chemical (weight loss method) and electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy). The effect of temperature on the corrosion behavior of mild carbon steel in 1.0 M HCl with addition of plant extracts was studied in the temperature range of 300–320 ± 1 K. Inhibition efficiencies up to 94.69 for BS and 93.22 for CR can be obtained. The adsorption mechanism of inhibition was supported by FT-IR, surface analysis (SEM–EDS), and adsorption isotherms. The thermodynamic parameter values of free energy of adsorption (∆G _ads) reveal that inhibitor was adsorbed on the mild carbon steel surface via both physisorption and chemisorption mechanisms.     

An environmentally friendly coating for corrosion protection of aluminum and copper in sodium chloride solutions

Triacetoxyvinylsilane (TAVS) has been used as precursor to prepare sol-gel under aqueous conditions for the surface treatment of aluminum and copper metals. The corrosion behavior of the sol-gel-treated metals has been investigated with cyclic voltammetry, potentiodyamic polarization and electrochemical impedance spectroscopy. Results from the electrochemical measurements have shown that the TAVS sol-gel-coated metal provided a better corrosion protection than the triethoxysilane (TES) sol-gel-coated metal due to the hydrophobic nature of vinyl group. Contact angle measurements have been conducted and the results have been applied to explain the degree of the corrosion protection of the coating film.     

Some new triazole derivatives as inhibitors for mild steel corrosion in acidic medium

Two triazole derivatives, 3,4-dichloro-acetophenone-O-1′-(1′,3′,4′-triazolyl)-methaneoxime (4-DTM) and 2,5-dichloro-acetophenone-O-1′-(1′,3′,4′-triazolyl)-methaneoxime (5-DTM) were synthesized, and the inhibition effects for mild steel in 1 M HCl solutions were investigated by weight loss measurements, electrochemical tests and scanning electronic microscopy (SEM). The weight loss measurements showed that these compounds have excellent inhibiting effect at a concentration of 1.0 × 10⁻³ M. The potentiodynamic polarization experiment revealed that the triazole derivatives are inhibitors of mixed-type and electrochemical impedance spectroscopy (EIS) confirmed that changes in the impedance parameters (R _ct and C _dl) are due to surface adsorption. The inhibition efficiencies obtained from weight loss measurements and electrochemical tests were in good agreement. Adsorption followed the Langmuir isotherm with negative values of the free energy of adsorption . The thermodynamic parameters of adsorption were determined and are discussed. Results show that both 4-DTM and 5-DTM are good inhibitors for mild steel in acid media.     

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).     

Acetyl thiourea chitosan as an eco-friendly inhibitor for mild steel in sulphuric acid medium

Acetyl thiourea chitosan polymer (ATUCS) has been synthesized and evaluated as corrosion inhibitor. The electrochemical behavior of mild steel in naturally aerated 0.5 M H₂SO₄ acid containing different concentrations of ATUCS has been studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The results of EIS showed that the resistance (R_t) increases slightly with increasing immersion time indicating a slight decrease in corrosion rate of the steel with time. Also, the corrosion rate increases with either increasing temperature or decreasing the polymer concentration as observed by polarization technique. Electrochemical impedance spectroscopy measurements under open-circuit conditions confirmed well polarization results. ATUCS has shown very good inhibition efficiency (IE) in 0.5 M sulphuric acid solution reaches to 94.5% for 0.76 mM concentration. IE of this compound has been found to vary with the concentration of the polymer solution, immersion time and temperature.     

Effect of ethylenediamine tetraacetic acid disodium on the corrosion of cold rolled steel in the presence of benzotriazole in hydrochloric acid

The inhibition behavior of cold rolled steel in 0.1 M hydrochloric acid (HCl) by ethylenediamine tetraacetic acid disodium (EDTA) in the absence and presence of benzotriazole (BTA) was investigated with Tafel polarization curve and electrochemical impedance spectroscopy (EIS). The polarization curve results show that the single EDTA acts as an anodic type inhibitor while the combination of EDTA and BTA acts as mixed type inhibitor and mainly inhibits anodic reaction. All impedance spectra in EIS tests exhibit one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. Inhibition efficiencies obtained from Tafel polarization, charge transfer resistance (R_t) are consistent. The corrosion of cold rolled steel in 0.1 M HCl is obviously reduced by EDTA in combination with lower concentrations of BTA. Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used to characterize the corrosion surface of cold rolled steel. Probable mechanisms are present to explain the experimental results.     

A new smart coating of polyaniline–SiO2 composite for protection of mild steel against corrosion in strong acidic medium

Organic coating approaches for corrosion protection with inherently conducting polymers have become important because of restriction on the use of heavy metals and chromates in coatings due to their environmental problems. The present work is directed towards the synthesis of polyaniline (PANI) and polyaniline–SiO₂ composites (PSCs) by chemical oxidation polymerization in the presence of phosphoric acid and evaluation of synthesized PANI and PSCs for protection of mild steel from corrosion in a strong aggressive medium (i.e. 1.0 mol L^–1 HCl). A suitable coating with PSC was formed on mild steel using epoxy resin by the powder coating technique. A comparative study of the corrosion protection efficiency of mild steel coated with PANI and PSC in 1.0 mol L^–1 HCl solution was evaluated using the Tafel extrapolation, chrono‐amperometry and weight loss methods. The PSC coating showed that a significant reduction in the corrosion current density reflects the better protection of mild steel in an acidic environment. Higher protection efficiency up to 99% was achieved by using PSC‐coated mild steel at 6.0 wt% loading of PSC in epoxy resin. The coating performance and corrosion rate of mild steel were investigated by using immersion of polymer‐coated mild steel in 1.0 mol L^–1 HCl for 60 days and indicated that PSC‐coated mild steel showed better performance from corrosion than PANI in an acidic medium.© 2012 Society of Chemical Industry