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.     

Inhibition of mild steel corrosion in hydrochloric acid medium by polymeric inhibitors containing residues of essential amino acid methionine

Ethyl ester hydrochloride of amino acid l-methionine 1 was converted to cationic monomers N,N-diallyl methionine ethyl ester hydrochloride 2 and hydrochloride salt of N,N-diallylmethionine 3. Cationic monomers 2 and 3 underwent alternate copolymerization with SO₂ in dimethyl sulfoxide to give terpolymers 4 and 5, respectively, both having?≈?1:1 ratio of sulfide and sulfoxide motifs owing to O transfer from dimethyl sulfoxide to the S. The sulfide groups in 5 have been oxidized with H₂O₂ to give polymer sulfoxide 6. In the presence of a small concentration of 35.2 µM (~?11?±?1 ppm) of each of the polymers 4, 5 and 6, the inhibition efficiency against mild steel corrosion in 1.0 M HCl at 60 °C was determined to be 90.8, 98.7 and 93.0%, respectively. The inhibition efficiency obtained from gravimetric weight loss was corroborated by the findings of potentiodynamic polarization and electrochemical impedance spectroscopy methods. Adsorption of polymer compounds onto the mild steel surface followed a mixture of chemisorption and physisorption processes and obeyed Langmuir, Temkin and Freundlich adsorption isotherms. The X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques further confirmed that the synthesized compounds formed a protective film onto the metal surface and prove it against further corrosion attack.     

Investigation of triazole derived Schiff bases as corrosion inhibitors for mild steel in hydrochloric acid medium

3,5-Diamino-1,2,4-triazole Schiff base derivatives and their inhibition efficiency, based on the effect of changing functional groups, were reported to establish a relationship between inhibitor efficiency and molecular structure using weight loss method, electrochemical and Fourier transform infrared spectral techniques. It was found that the molecules containing more electron donating groups have higher inhibition efficiency than the corresponding compounds with low electron donating groups. The results indicate that the order of inhibition efficiency of the triazole and its Schiff bases in solution and the extent of their tendency to adsorb on mild steel surfaces are as follows: vanilidine 3,5-diamino-1,2,4-triazole > furfuraldine 3,5-diamino-1,2,4-triazole > anisalidine 3,5-diamino-1,2,4-triazole > 3,5-diamino-1,2,4-triazole.     

Substitutional inhibition mechanism of mild steel hydrochloric acid corrosion by hexylamine and dodecylamine

Hexylamine and dodecylamine were investigated as inhibitors of mild steel hydrochloric acid corrosion, in concentrations from 1 × 10^–6 to 1.0 M, at a temperature of 298 K. For a given inhibitor concentration, dodecylamine showed higher effectiveness than hexylamine. The inhibitor mechanism was treated as a substitutional adsorption process according to Flory–Huggins (FH), Dhar–Flory–Huggins (DFH) and Bockris–Swinkels (BS) isotherms. The best approach was obtained using FH and DFH isotherms, with one molecule of inhibitor replacing three molecules of water. A structural parameter, the projected molecular area of these two inhibitors, was calculated to elucidate inhibitor orientation in the adsorption process.     

Adsorption properties and inhibition of mild steel corrosion in hydrochloric acid solution by ceftobiprole

The inhibition effect of ceftobiprole against the corrosion of mild steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and atomic force microscopy techniques. Inhibition efficiency increased with inhibitor concentration where as decreased with acid concentration. Data obtained from EIS studies were analyzed to model the corrosion inhibition process through appropriate equivalent circuit models. The adsorption of ceftobiprole obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters were calculated and discussed. Polarization curves indicated that they are mixed type of inhibitors. Polarization curves showed that ceftobiprole act as mixed-type inhibitor. The results obtained from weight loss, EIS and Potentiodynamic polarization are in good agreement.     

盐酸介质中聚醚改性七甲基三硅氧烷对碳钢的缓蚀研究

本文研究了三种聚醚改性七甲基三硅氧烷(分别简称为TEO-13、TEO-23和TEO-29)的缓蚀性能.通过静态失重筛选出缓蚀效果较好的聚醚硅氧烷,利用动电位扫描极化曲线及SEM考察了最优化的聚醚硅氧烷在1.0mol· L-1盐酸中对20#碳钢的缓蚀效果,并对缓蚀机理进行了探讨.结果表明:合成的聚醚改性七甲基三硅氧烷对碳钢在HCl介质中表现出优异的缓蚀效果,其中TEO-23的缓蚀效果最好,当达到0.9g·L-1的浓度时,腐蚀速度降为5.9g· (m2·h)-1,缓蚀效率为94.1％.扫描电镜显示TEO-23可在碳钢表面形成致密完整的吸附保护膜,阻碍碳钢的腐蚀.极化曲线表明,该表面活性剂属于阴极型缓蚀剂.     

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.     

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).     

Butyl substituents in n-butylamine and their influence on mild steel corrosion inhibition in hydrochloric acid

This paper describes a study of the influence of the butyl group as substituent in n-butylamine used as a mild steel corrosion inhibitor in hydrochloric acid solution. An inhibition mechanism is proposed. n-Butylamine, dibutylamine and tributylamine were studied in concentrations from 10–4 to 1 m and in the temperature range 278–308K using electrochemical, gravimetric and surface roughness techniques. The three inhibitors adsorbed on the mild steel according to a Frumkin isotherm.     

Fatty acid derivatives as corrosion inhibitors for mild steel and oil-well tubular steel in 15% boiling hydrochloric acid

Selected hydrazides and thiosemicarbazides of fatty acids with 11, 12, and 18 carbon atoms were synthesized and evaluated as corrosion inhibitors on mild steel and oil-well steel (N-80) in boiling 15% hydrochloric acid solution, by weight loss method. Potentiodynamic polarization studies carried out on mild steel and N-80 steel at room temperature showed that all the tested compounds are of mixed type. Adsorption studies showed that all the investigated compounds followed Temkin's adsorption isotherm.     

Corrosion inhibition of mild steel by alkylimidazolium ionic liquids in hydrochloric acid

The acid corrosion inhibition process of mild steel in 1 M HCl by 1-butyl-3-methylimidazolium chlorides (BMIC) and 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO₄) has been investigated using electrochemical impedance, potentiodynamic polarization and weight loss measurements. Potentiodynamic polarization studies indicate the studied inhibitors are mixed type inhibitors. For both inhibitors, the inhibition efficiency increased with increase in the concentration of the inhibitor and the effectiveness of the two inhibitors are in the order [BMIM]HSO₄ > BMIC. The adsorption of the inhibitors on mild steel surface obeyed the Langmuir's adsorption isotherm. The effect of temperature on the corrosion behavior in the presence of 5 × 10⁻³ M of inhibitors was studied in the temperature range of 303-333 K. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy of activation (ΔH), entropy of activation (ΔS), adsorption equilibrium constant (K_ads) and standard free energy of adsorption (ΔG_ads) were calculated to elaborate the mechanism of corrosion inhibition.     

Investigation of some oleochemicals as green inhibitors on mild steel corrosion in sulfuric acid

The inhibitive effect of four oleo chemicals (namely; 2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI)), regarded as green inhibitors, were studied for the corrosion protection of mild steel in 0.5 M H₂SO₄. The methods employed were weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy (SEM) was carried out on the inhibited and uninhibited metal samples to characterize the surface. The purity of synthesized inhibitors was checked by FT-IR and NMR studies. The inhibition efficiency increased with increase in inhibitor concentration, immersion time and decreased with increase in solution temperature. No significant change in IE values was observed with increase in acid concentration. The best performance was obtained for UDI possessing 96.2% inhibition efficiency at 500 ppm concentration. The adsorption of the compounds on the mild steel surface in the presence of sulfuric acid obeyed Langmuir’s adsorption isotherm. The values obtained for free energy of adsorption and heats of adsorption suggest physical adsorption. The addition of inhibitor decreased the entropy of activation suggesting that the inhibitors are more orderly arranged along the mild steel surface. The potentiodynamic polarization data indicate mixed control. The electrochemical impedance study further confirms the formation of a protective layer on the mild steel surface through the inhibitor adsorption.     

Corrosion inhibition of carbon steel in hydrochloric acid by furan derivatives

The efficiency of three furan derivatives (2-methylfuran, furfuryl alcohol and furfurylamine), as corrosion inhibitors for carbon steel in 1 M HCl, has been determined by gravimetric and electrochemical measurements. These compounds inhibit corrosion even at very low concentrations, and furfuryl alcohol is the best inhibitor. Polarization curves indicate that all compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of furan derivatives on the carbon steel surface is in agreement with the Langmuir adsorption isotherm model, and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. The structural and electronic properties of these inhibitors, obtained using AM1, PM3, MNDO and MINDO/3 semi-empirical self-consistence field methods, are correlated with their experimental efficiencies.     

Corrosion inhibition of mild steel in 1.0 M hydrochloric acid medium by new photo-cross-linkable polymers

Photo-cross-linkable polymers namely, poly((E)-(1-(5-(4-(3-(4-chlorophenyl)-3-oxoprop-1-enyl)phenoxy)pentyl)-1H-1,2,3-triazol-4-yl)methyl acrylate) (Cl-5) and poly((E)-(1-(5-(4-(3-(4-chlorophenyl)-3-oxoprop-1-enyl)phenoxy)decyl)-1H-1,2,3-triazol-4-yl)methyl acrylate) (Cl-10) were synthesized by click-chemistry. The polymers were characterized by using various spectroscopic techniques and the rate of cross-linking was evaluated by absorption spectroscopy. The inhibitory action of the photo-cross-linkable polymers was evaluated for mild steel (MS) corrosion in 1.0 M hydrochloric acid solution (HCl) by means of electrochemical impedance spectroscopy, potentiodynamic polarization measurements, adsorption isotherms and surface analysis. To the best of our knowledge, these are the most efficient inhibitors (Cl-5 and C-10) for the corrosion of MS in HCl reported so far. Tafel polarization measurements showed that the polymers act as mixed type inhibitors and the adsorption of the inhibitors onto the MS surface followed the Langmuir adsorption isotherm. The values of the Gibbs free energy of adsorption (ΔG_ads) strongly supported spontaneous physicochemical adsorption of inhibitor molecules on the MS surface. The SEM-EDX results confirmed that the cross-linked polymers inhibited the corrosion to a greater extent than the intact polymer.     

Effect of some substituted anilines‐formaldehyde polymers on mild steel corrosion in hydrochloric acid medium

The influence of linear copolymer of amines and formaldehyde namely poly(aniline‐formaldehyde) (Inh1), poly(o‐toluidene‐formaldehyde) (Inh2), and poly(p‐chloroaniline‐formaldehyde) (Inh3) on corrosion of mild steel in hydrochloric acid was evaluated by weight loss measurements, linear polarization, Tafel polarization, and electrochemical impedance spectroscopy. These polymers showed very high inhibition efficiency at very low concentrations. Results obtained showed that all inhibitors are mixed inhibitors and participate in reaction probably in the form of metal inhibitor complex on metal surface. Atomic force microscopic studies reveal that the surface of metal is quite unaffected after use of inhibitor in hydrochloric acid solution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Hyperbranched poly(cyanurateamine): A new corrosion inhibitor for mild steel in hydrochloric acid medium

Hyperbranched poly(cyanurateamine) (POCYAM) was tested as a novel corrosion inhibitor for mild steel in 0.5–3 M HCl using chemical and electrochemical techniques at 25–70 °C. The results show that this compound has good corrosion inhibiting properties for mild steel in HCl at very low concentrations. Corrosion inhibition efficiency rises with POCYAM concentration. The adsorption of the POCYAM onto the mild steel surface obeys Langmuir adsorption isotherm model. The inhibition mechanism was further corroborated by the values of thermodynamic parameters obtained from the experimental data.     

Quantum chemical studies on corrosion inhibition for series of thio compounds on mild steel in hydrochloric acid

Quantum chemical calculations were performed on ten thio compounds using semi-empirical method PM3 within program package of Material Studio 5.5. The effect of molecular structure on the corrosion inhibition efficiency was investigated using the quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, (LUMO–HOMO) energy gap, dipole moment (λ) and fraction of electron transfer (ΔN) were calculated and discussed. A relationship between the corrosion inhibition efficiency and several quantum parameters was established with coefficient correlation (R²) of 0.8894.     

Corrosion inhibition of carbon steel in hydrochloric acid by some polyethylene glycols

The inhibition effect of some PEGs on carbon steel corrosion at 25 °C in 0.5N hydrochloric acid as corroding solution was evaluated by weight loss method and polarization and electrochemical impedance spectroscopy (EIS) techniques. In order to study the effect of polyethylene glycols’ structure on the inhibition efficiency, different molecular weights (400, 1000, 4000, and 10,000 g mol⁻¹) were selected. This work has demonstrated that polyethylene glycols have inhibition effect on corrosion process and their inhibition efficiencies are between 50 and 90%. The inhibition efficiencies are increased by increase of the inhibitors’ concentration and molecular weight.     

盐酸介质中碳钢缓蚀剂最新研究进展

碳钢是工业应用最广用途最大的一种钢材,在对它的表面处理中,盐酸的使用最多。本文从酸洗清洁生产的角度出发,对近几年研究的在盐酸介质中所使用的碳钢缓蚀剂进行了分类总结,并提出了现阶段研究中还需要重点考虑的问题,最后对缓蚀剂的研发做出了展望。