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.     

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.     

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.     

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.     

Inhibition of mild steel corrosion in sulfuric acid solution by thiadiazoles

Four heterocyclic compounds namely 2-amino-1,3,4-thiadiazoles (AT), 5-Methyl-2-amino-1,3,4-thiadiazoles (MAT), 5-Ethyl-2-amino-1,3,4-thiadiazoles (EAT) and 5-Propyl-2-amino-1,3,4-thiadiazoles (PAT) were synthesized and their influence on the inhibition of corrosion of mild steel (MS) in 0.5 M H₂S0₄ was investigated by weight loss and potentiodynamic polarization techniques. The values of activation energy, free energy of adsorption, heat of adsorption, enthalpy of activation and entropy of activation were also calculated to investigate the mechanism of corrosion inhibition. Potentiodynamic polarization studies were carried out at room temperature, and showed that all the compounds studied are 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 the sulfuric acid solution. The adsorption of the compounds on mild steel for sulfuric acid was found to obey Langmuir’s adsorption isotherm. FT–IR spectroscopic studies were also used to investigate the purity of compounds synthesized.     

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.     

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     

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.     

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.     

Experimental and theoretical study on amino acid derivatives as eco-friendly corrosion inhibitor on mild steel in hydrochloric acid solution

Amino acid derivatives, namely, 2-(2-oxo-2-phenothiazin-10-yl)ethylamino)-3-mercaptopropanoic acid (OPEM) and 2-(2-oxo-2-phenothiazin-10-yl)ethylamino)acetic acid (OPEA) were synthesized and investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss, polarization, and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency of both the inhibitors increased with increasing the temperature and concentration of inhibitor. The inhibitors OPEM and OPEA show corrosion inhibition efficiency of 97.5 and 95.8%, respectively, in 200?ppm concentration, at 333?K. Polarization studies showed that both studied inhibitors were of mixed type in nature. The adsorption of inhibitors on the mild steel surface obeys Langmuir adsorption isotherm and the surface of inhibited and uninhibited specimens were analyzed by scanning electron microscopy (SEM). The semiempirical AM1 method was employed for theoretical calculations and the obtained results were found to be consistent with the experimental findings.     

Ceftriaxone: a novel corrosion inhibitor for mild steel in hydrochloric acid

Corrosion inhibition of mild steel in 1 N HCl by Ceftriaxone was studied by polarization resistance, Tafel polarization, EIS, and weight loss measurement. The inhibitor showed more than 90% inhibition efficiency at optimum concentration of 400 ppm. Results obtained revealed that inhibition occurs through adsorption of the drug on the metal surface without a modification of the mechanism of the corrosion process. Potentiodynamic polarization suggests that this is a mixed type of inhibitor. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition. Thermodynamic parameters such as E _a, ΔH, ΔS, ΔG and Q were calculated to investigate the mechanism of inhibition. All the investigations suggested that the compound follows the Langmuir adsorption isotherm.     

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.     

Fatty acid oxadiazoles as corrosion inhibitors for mild steel in formic acid

Selected oxadiazoles of fatty acids; namely 2-hepta decene-5-mercapto-1-oxa-3,4-diazole (HMOD); 2-undecane-5-mercapto-1-oxa-3,4-diazole (UMOD); and 2-decene-5-mercapto-1-oxa-3,4-diazole (DMOD), were synthesized. Their influence on the inhibition of corrosion of mild steel in 20% formic acid (HCOOH) was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of the compounds was found to vary with concentration, immersion time and temperature. All the compounds showed good inhibition efficiency (e _IE) in formic acid solution. Adsorption on mild steel obeyed the Langmuir adsorption isotherm. Potentiodynamic polarization revealed that all three inhibitors, HMOD, UMOD, and DMOD are mixed inhibitors. Electrochemical impedance spectroscopy was also used to investigate the inhibition mechanism.     

Inhibition of mild steel corrosion in acidic medium using starch and surfactants additives

The corrosion inhibition of mild steel in 0.1M H₂SO₄ in presence of starch (polysaccharide) was studied using weight loss and potentiodynamic polarization measurements in the temperature range of 30–60°C. Starch inhibits the corrosion rates of mild steel to a considerable extent; the maximum inhibition efficiency (%IE) being 66.21% at 30^oC in presence of starch concentration of 200 ppm. The effect of the addition of very small concentration of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide on the corrosion inhibition behavior of starch was also studied. The IE of starch significantly improved in presence of both the surfactants. The effect of surfactants on the corrosion inhibition behavior of starch appears to be synergistic in nature. Starch alone and in combination with surfactants is found to obey Langmuir adsorption isotherm from the fit of the experimental data of all concentration and temperature studied. Phenomenon of physical adsorption is proposed from the trend of IE with temperature and also the values E_a, ΔG_ads, and Q_ads obtained. The results obtained by potentiodynamic polarization measurements are consistent with the results of the weight loss measurement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

Non-toxic organic zinc corrosion inhibitors in hydrochloric acid

The efficiency of some substituted N-arylpyrroles as zinc corrosion inhibitors in hydrochloric acid was examined by electrochemical (d.c. and a.c.) and gravimetric methods. The influence of the structure and composition of a molecule on the inhibition characteristics was observed by investigation of the action of the functional group located on the pyrrole ring (-CHO) and at the ortho position of the benzene ring (-H, -Cl, -CH₃). The results have shown that all the organic compounds investigated possess good inhibiting properties. In contrast to most commercial acid corrosion inhibitors, which are highly toxic and very hazardous products, substituted N-arylpyrroles are nontoxic compounds with good environmental characteristics.     

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.     

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.     

钼酸盐和钨酸盐在HCl中对冷轧钢的缓蚀作用

用失重法和动电位极化曲线法研究了在0．2mol／L HCl介质中,钼酸钠（Na2MoO4）、钨酸钠（Na2WO4）对冷轧钢片的吸附及其缓蚀作用。实验结果表明,在酸性溶液中,钼酸盐、钨酸盐均对冷轧钢片具有较好的缓蚀作用,而且用量很低。缓蚀剂在钢表面的吸附符合Langmuir吸附方程。在相同条件下,对比了钼酸钠、钨酸钠对冷轧钢的缓蚀作用,发现缓蚀率取决于缓蚀剂的质量浓度,当缓蚀剂浓度极低时缓蚀率排序为：钼酸钠〈钨酸钠,但在较大缓蚀剂质量浓度范围内钼酸钠表现出优越的缓蚀性能。动电位极化曲线表明,钼酸盐、钨酸盐在HCl中为混合抑制型缓蚀剂。     

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.