Adenosine as corrosion inhibitor for mild steel in hydrochloric acid solution

Research on Chemical Intermediates - (2R,3R,4S,5R)-2-(6-amino-9H-purin-9-yl)-5-(hydroxymethyl)oxolane-3,4-diol (adenosine) is an identified component present in agarwood leaf extract. The corrosion...     

Inhibitive effect of chloroquine towards corrosion of mild steel in hydrochloric acid solution

Corrosion inhibition of mild steel (MS) by chloroquine (CQ) in 1 M HCl was investigated using weight loss, polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical techniques. The inhibitor showed 99 % inhibition efficiency at concentration of 3.1 × 10^?4 M. Polarization studies showed that CQ is a mixed-type inhibitor. Adsorption of inhibitor molecules on the MS surface showed Langmuir adsorption isotherm. Thermodynamic parameters led to the conclusion that adsorption is predominantly chemisorption. Quantum chemical calculations were carried out to investigate the corrosion-inhibiting property of CQ. Various parameters such as energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), softness of molecule, Mullikan charges on various atoms and number of electrons transferred from inhibitor molecule to metal were calculated and correlated with the inhibiting property of CQ.     

Experimental and theoretical investigation on adsorption and corrosion inhibition properties of imidazopyridine derivatives on mild steel in hydrochloric acid solution

Imidazopyridine derivatives, namely 4‐methoxy‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3‐yl)methylene)benzenamine (MMPIPB) and 4‐chloro‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3yl)methylene)benzenamine (CMPIPB), were investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss and electrochemical techniques. According to electrochemical impedance spectroscopy studies, MMPIPB and CMPIPB show corrosion inhibition efficiency of 84.8 and 77.2% at 10‐ppm concentration and 98.1 and 94.8% at 80‐ppm concentration, respectively at 303 K. The corrosion inhibition efficiency of both inhibitors increased with increasing inhibitor concentration and decreased with increasing temperature. The adsorption of both inhibitor molecules on the surface of mild steel obeys Langmuir adsorption isotherm. Polarization studies showed that both studied inhibitors were of mixed type in nature. Electrochemical impedance spectroscopy studies showed that for both inhibitors, the value of charge transfer resistance increased and double‐layer capacitance decreased on increasing the concentration of inhibitors. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy (EDX), and atomic force microscopy were performed for surface study. The density functional theory was employed for theoretical calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Avogadro natural oil on the corrosion inhibition of mild steel in hydrochloric acid solution

The inhibition action of Avogadro natural oil on corrosion of mild steel in one molar hydrochloric acid solution was investigated by gravimetric and potentiodynamic polarization techniques. The surface morphology of as-corroded samples was assessed with high resolution scanning transmission electron microscopy equipped with energy dispersive spectroscopy (HR-STEM/EDS). From the results, the presence of Avogadro natural oil in the metal–acidic interface decreased the corrosion rate with all the exposure times. The inhibition efficiency (%IE) increases with the concentration of the inhibitor considered. Results obtained from gravimetric measurements indicate that the natural oil exhibited higher efficiencies of 93.26 % after 384 h of exposure time and 98.26 % recorded in the potentiodynamic polarization method, both at 4.5 g/v inhibitor addition. Equally, results from the linear polarization indicated higher potential value with an increase in the polarization resistance (R _p) and lower current density for the inhibited samples than the uninhibited mild steel sample. The inhibitive effect of this oil was explained in view of adsorption on the metal surface. The adsorption process follows the Langmuir adsorption isotherm.     

Adsorption and corrosion inhibition of mild steel in hydrochloric acid solution by verbena essential oil

The inhibitive action of verbena essential oil (VEO) on the corrosion of mild Steel in 1 M HCl solutions in the temperature range 298 to 328 K was measured by use of the weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results showed that VEO inhibited corrosion of C38 steel in 1 M HCl solution and that inhibition efficiency increased with increasing concentration of inhibitor but decreased proportionally with temperature. Potentiodynamic polarization studies suggested VEO is a mixed-type inhibitor, with the anodic type predominating. Nyquist plots were depressed semicircles with their centre below the real axis. Adsorption of VEO by the C38 steel surface followed the Langmuir adsorption isotherm. Kinetic data for dissolution were investigated.     

Adsorption and inhibition effect of curcumin on mild steel corrosion in hydrochloric acid

The inhibition effect of curcumin on the corrosion of mild steel in 1.0 M HCl solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The experimental results suggest that this compound is an efficient corrosion inhibitor and the inhibition efficiency increases with the increase in inhibitor concentration. Adsorption of this compound on mild steel surface obeys Langmuir isotherm. Also the objective of this work is to attempt to find relationships between electronic structure and inhibition efficiency. The structural parameters, such as the frontier molecular orbital energies (E _HOMO and E _LUMO), gap of energy ΔE, from the molecule to iron as well as electronic parameters such as Mulliken atomic populations were calculated and discussed using the Density Functional Theory method (DFT).     

Study of the corrosion products formed on carbon steel surface in hydrochloric acid solution

Effect of an antibacterial drug, sulfacetamide, IUPAC name N-[(4-aminophenyl) sulfonyl] acetamide (APSA), on the corrosion products formed on carbon steel surface in 1.0?mol?L^?1 HCl solution has been investigated using mass loss, X-ray photoelectron spectroscopy (XPS), and simultaneous thermal and differential scanning calorimetry/differential thermal analysis (TG/DSC/DTA). Mass loss measurements reveal that the corrosion rate of carbon steel is retarded by APSA and that the inhibition efficiency of this inhibitor increases with increasing the concentration. XPS analysis shows that, at this stage, the main product of corrosion is a non-stoichiometric Fe³⁺ oxyhydroxide, consisting of a mixture of FeO(OH) in anhydrous or hydrated forms, containing Cl^? inclusions and adsorbed APSA molecules. The mechanism of inhibition was discussed in light of the chemical structure of the investigated inhibitor. The corrosion products were analyzed using TG/DSC/DTA technique.     

Schiff’s bases as inhibitors of mild steel corrosion in hydrochloric acid

Mass loss and thermometric methods are used to study the inhibition of corrosion of mild steel in hydrochloric acid by Schiff’s bases N-(furfurlidine)-4-methoxy aniline, N-(furfurlidine)-4-methylaniline, N-(salicylidine)-4-methoxy aniline, N-(cinnamalidine)-4-methoxy aniline, and N-(cinnamalidine)-2-methylaniline. Results of inhibition efficiency yielded by the two methods are in good agreement and depend on the inhibitor and acid concentration. Maximum inhibition efficiency is 98%. The efficiency increases with the inhibitor concentration and acid strength. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 2, pp. 252–256. The text was submitted by the authors in English.     

Corrosion inhibition performance of tannins for mild steel in hydrochloric acid solution

Research on Chemical Intermediates - The corrosion inhibition behavior of commercial hydrolysable tannin (tara tannin), condensed tannin (black wattle tannin) and complex tannin (bayberry tannin)...     

The effect of 2-aminoquinoline-6-carboxylic acid on the corrosion behavior of mild steel in hydrochloric acid

The inhibitive effect of 2-aminoquinoline-6-carboxylic acid (AQC) against mild steel corrosion in 1?M HCl solutions was investigated using conventional weight loss, potentiodynamic polarization, linear polarization and electrochemical impedance spectroscopy methods. The weight loss results showed that AQC is an excellent corrosion inhibitor since its efficiency increased with the concentration to attain 91.8?% at 500?mg?l^?1. Electrochemical polarization measurements revealed that AQC acted as a mixed-type inhibitor and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the inhibitor is due to the adsorption of the molecule leading to the formation of a protective layer on the surface of mild steel. The adsorption was assumed to occur on the steel surface through the active centers of the molecule. The inhibition action of AQC was discussed in view of Langmuir adsorption isotherm. Density functional theory calculations of quantum parameters were used to explain efficiency in relation with molecular structure.     

Phenyl semicarbazide derivatives as corrosion inhibitors for aluminium in hydrochloric acid solution

Summary Measurements of the corrosion rate of aluminium in 2N HCl at 27°C with and without addition of phenyl semicarbazide derivatives (10^–3–10^–5 mol/l) were performed. The adsorption of these compounds was elucidated. Results show that phenyl semicarbazide derivatives are adsorbed on the aluminium surface according to the Frumkin isotherm. From the adsorption isotherm some thermodynamic data for the adsorption process (G° _ads . andf) are calculated and discussed.

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Phenylsemicarbazide als Korrosionsinhibitoren für Aluminium in salzsauren Lösungen

Zusammenfassung Es wurden Messungen der Korrosionsgeschwindigkeit von Aluminium in 2N HCl bei 27°C mit und ohne Zusatz von Phenylsemicarbaziden (10^–3–10^–5 mol/l) durchgeführt. Es wurde die Adsorption dieser Verbindungen untersucht, wobei sich zeigte, daß die Adsorption der Phenylsemicarbazidderivate der Frumkin-Isotherme gehorcht. Aus der Isotherme wurden einige thermodynamische Parameter des Adsorptionsprozesses (G° _ads. ,f) berechnet.

     

Comparative inhibition study of mild steel corrosion in hydrochloric acid by new class synthesised quinoxaline derivatives: part I

7-Cchloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (CMOSQ) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (CMOPTQ) have been investigated for mild steel corrosion in 1 M HCl at different concentrations using weight loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. Generally, inhibition efficiency of the investigated compounds was found to depend on inhibitor concentration and their structures. Comparitive results showed that CMOPTQ was the best inhibitor and the inhibition efficiency increased with increasing the concentration and attained 86 and 87 % at 10^?3 M of CMOPTQ and 10^?3 M of CMOSQ, respectively. Potentiodynamic polarization studies clearly reveal that these inhibitors act essentially as cathodic-type inhibitors. The inhibition efficiency increases with immersion time and reaches 95 % CMOPTQ at 24 h. The electrochemical impedance spectroscopy result showed that these compounds act by formation of film.     

Inhibition effect of environmentally benign Karanj (Pongamia pinnata) seed extract on corrosion of mild steel in hydrochloric acid solution

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the seed extract of Karanj (Pongamia pinnata) has been studied using weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization, and linear polarization techniques. Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in 1 M HCl with addition of extract was also studied. The adsorption of the extract on the mild steel surface obeyed the Langmuir adsorption isotherm. Values of inhibition efficiency calculated from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy are in good agreement. Polarization curves showed that Karanj (P. pinnata) seed extract behaves as a mixed-type inhibitor in hydrochloric acid. The activation energy as well as other thermodynamic parameters for the inhibition process was calculated. The adsorbed film on mild steel surface containing Karanj (P. pinnata) seed extract inhibitor was also measured by Fourier transform infrared spectroscopy. The results obtained showed that the seed extract of Karanj (P. pinnata) could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.     

Effect of temperature on adsorption and corrosion inhibition characteristics of gelatin on mild steel in hydrochloric acid medium

Research on Chemical Intermediates - Adsorption characteristics of a water-soluble bio-polymer, gelatin, on mild steel in 1-M hydrochloric acid (HCl) together with its potential corrosion resistive...     

Indole‐3‐acetic acid and N‐acetyltryptophan corrosion inhibition effects on mild steel in 1 M hydrochloric acid solution

Corrosion inhibition of indole‐3‐acetic acid and N‐acetyl tryptophan on carbon steel was investigated using polarization and electrochemical impedance spectroscopy (EIS). Polarization results revealed that corrosion inhibitors could reduce the rate of cathodic and anodic reactions on metal surface. EIS analysis showed inhibition efficiency of indoles increases by increasing the inhibitor concentration. The maximum inhibition efficiency was 97% and 80% in solutions containing 10 mM indole‐3‐acetic acid and 10 mM N‐acetyl tryptophan, respectively. The adsorption of inhibitors was found to follow Langmuir isotherm. Adsorption and film formation of inhibitors on the metal substrate were confirmed by calculating thermodynamic adsorption parameter (ΔG⁰_ads) and characterization of exposed metals' surface through contact angle measurements. Copyright © 2014 John Wiley & Sons, Ltd.     

Nile Blue and Indigo Carmine organic dyes as corrosion inhibitor of mild steel in hydrochloric acid

The inhibiting behavior of Nile Blue and Indigo Carmine organic dyes on mild steel corrosion was evaluated in 1 M HCl solution, separately, by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques. Results show that the inhibition efficiency (%IE) increases with the increasing concentration of Indigo Carmine up to 9.65 × 10⁻⁰⁵ M (%IE ~ 98) and Nile Blue up to 1.08 × 10⁻⁰⁴ (%IE ~ 75–80). Good agreement was found between the results obtained from the different techniques used. Polarization curves indicate that the inhibition of the both inhibitors is of a mixed anodic–cathodic nature, and Langmuir isotherm is found to be an accurate isotherm describing the adsorption behavior. The inhibition mechanism of the inhibitors involves chemisorption interaction between the inhibitor and the mild steel. The inhibition efficiency for both inhibitors decreased by the rising temperature in the range of 25–55 °C, and these results verified the chemisorption behavior of both the inhibitors.     

Inhibitive effect of imidazopyridine derivative towards corrosion of C38 steel in hydrochloric acid solution

The effect of adding 2-phenylimidazo[1,2-a]pyridine-3-carbaldehyde derivative named (P2), newly synthesized on the electrochemical behavior of C38 steel in molar hydrochloric acid was investigated by using the weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. EIS results show that the transfer resistance increases with the increase of concentration of P2 and it also had an inhibiting effect on C38 steel corrosion in HCl solutions. Weight-loss essays confirm that the corrosion rate decreases as the P2 concentration increases. The inhibition efficiency for this compound studied increased with the increase in the inhibitor concentrations to attain 91.7 % at the 10^?3 M of P2. The potentiodynamic polarization curves indicated that P2 acted as a mixed-type inhibitor in hydrochloric acid.     

Influence of bis-(2-benzothiazolyl)-disulfide on corrosion inhibition of mild steel in hydrochloric acid media

The inhibiting behavior of bis-(2-benzothiazolyl)-disulfide on mild steel corrosion was evaluated in 1?M HCl solution. Weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques were used in this study. In EIS technique, by performing Kramers–Kronig transformations, the experimental results validated, before fitting any theoretical model on them. The obtained results showed that the inhibition efficiency (%IE) increases by increasing the concentration of bis-(2-benzothiazolyl)-disulfide up to 2.02?×??0^???M (%IE?～??2??8). Between the results obtained from various used techniques, a good agreement was found. Polarization curves indicate that the inhibition of the inhibitor is a mixed anodic–cathodic nature and Langmuir isotherm is found as an accurate isotherm describing the adsorption behavior. It also found that its inhibition mechanism of bis-(2-benzothiazolyl)-disulfide is at the interval of physical adsorption and chemical binding. The inhibition efficiency of the inhibitor decreased by rising of temperature in the range of 25??5?°C and these results, verified adsorption behavior of the inhibitor.     

Adsorption and corrosion inhibitive properties of piperidine derivatives on mild steel in phosphoric acid medium

The present study describes the inhibition effect of 4-benzyl piperidine (P1), 1,6-bis(4-benzylpiperidine-1-carboxamide)hexane (P2) and bis(4-benzylpiperidine)thiuram disulfide (P3) towards the corrosion of mild steel in 5.5 M H₃PO₄ solution using weight loss measurements and polarization technique. The influence of inhibitor concentration and temperature on the inhibitory behavior of P2 and P3 was investigated. Meanwhile, the inhibition efficiency (IE) was found to depend on the molecule structure and the concentration of piperidine derivatives. The IE for 10^?3 M P2 and P2 in 5.5 M H₃PO₄ is around 90 %. Polarization studies clearly revealed that all the compounds used act as mixed-type inhibitors. Adsorption isotherms were fitted by the Langmuir isotherm. Adsorption energies ( $ \Updelta {\text{G}}^\circ_{\text{ads}} $ and $ \Updelta {\text{H}}^\circ_{\text{ads}} $ ) and kinetic parameters were evaluated. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that the variation of inhibition with structure of the inhibitor may be explained in terms of electronic properties.     

5-Naphthylazo-8-hydroxyquinoline (5NA8HQ) as a novel corrosion inhibitor for mild steel in hydrochloric acid solution

In this study, 5-naphthylazo-8-hydroxyquinoline (5NA8HQ) was synthesized, characterized, and tested as a corrosion inhibitor for mild steel in 1 M HCl solution in the temperature range 20 to 50 °C. Weight-loss and potentiodynamic polarization measurements were used to analyse the corrosion behaviour of the metal in the absence and presence of different concentrations of the inhibitor. Analyses of surface film and inhibited solutions by FT-IR and UV–visible spectroscopy enabled us to clarify aspects of the inhibition mechanism. Further examination using X-ray diffraction confirmed the action of 5NA8HQ as an effective inhibitor of corrosion of mild steel in acidic media. The results obtained showed that this compound was a good inhibitor of corrosion. The inhibition is of mixed anodic–cathodic nature with predominance of anodic character. The Langmuir isotherm was found to accurately describe the adsorption behaviour of 5NA8HQ. Spectrophotometric analysis showed the formation of a layer at the surface of the corroded sample; this was interpreted as formation of complexes between 5NA8HQ and metal cations present in the steel structure.