Synergistic effect of polyaspartic acid and iodide ion on corrosion inhibition of mild steel in H2SO4

The inhibition effect of polyaspartic acid (PASP) and its synergistic effect with KI on mild steel corrosion in 0.5 M H₂SO₄ solution are studied by weight loss and electrochemical methods. The inhibition efficiency increases with the concentration of PASP and increases further with the presence of 1 mM KI. Result of the zero charge potential measurement shows that iodide ion promotes the film formation of PASP greatly. The mild steel surfaces after immersion test were analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. An adsorption model is proposed to elucidate the synergistic mechanism of synergistic effect.     

Synergistic effect of potassium iodide with phthalazone on the corrosion inhibition of mild steel in 1.0 M HCl

The effects of phthalazone (PTO) and its synergistic effect with KI on the corrosion of mild steel in 1.0 M HCl solution were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The inhibition efficiency increases with the concentration of the inhibitor and increased further with the presence of 6.02 mM KI. The synergistic effect of 6.02 mM KI at different concentrations of PTO was determined by calculating the synergism parameters, which showed that a cooperative mechanism exists between the iodide anion and PTO cations.     

Investigation of corrosion inhibition mechanism and stability of Vitamin B1 on mild steel in 0.5 M HCl solution

The corrosion inhibition mechanism and the stability of Vitamin B1 (VitB1) on mild steel in 0.5 M HCl solution were investigated. Surface of the steel after exposing to test solutions were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectroscopy (EDX). The stability of the inhibitor film was investigated by electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and cyclic voltammetry (CV) techniques. It was found that VitB1 acts by adsorption on mild steel via physical and chemical interactions and a protective film formation. The inhibitor film evenly distributes over the steel surface and is stable.     

Enhancing the inhibition action of cationic surfactant with sodium halides for mild steel in 0.5 M H2SO4

The synergistic effect of N-hexadecylpyridinium bromide (PyC₁₆Br) and different sodium halides on the corrosion of mild steel in 0.5 M H₂SO₄ solution has been investigated using electrochemical methods, X-ray diffraction (XRD) and scanning electron microscope (SEM). Experimental results showed that the protection efficiency (P_icor) of PyC₁₆Br improved at either considerable high concentration near its critical micelle concentration (CMC) or in the presence of the different halides with different extents. The synergism parameter (S_θ) is found to be greater than unity indicating high P_icor. Corrosion products phases and surface morphology were studied using XRD and SEM, respectively.     

Synergistic effect of sulfate-reducing bacteria and elastic stress on corrosion of X80 steel in soil solution

In this paper, the individual and simultaneous effects of stress and sulfate-reducing bacteria on corrosion of X80 steel were conducted by electrochemical impedance spectroscopy, scanning electron microscope and X-ray photoelectron spectroscopy. Both elastic stress and activity of SRB enhance corrosion of the steel and, furthermore, they have synergistic effects on corrosion behavior of the steel. The activities of SRB give rise to the initiation of pits, and the applied elastic stress keeps and promotes the growth of pits. The activities of SRB and the applied elastic stress induce tiny secondary corrosion pitting at the bottom of the primary pitting.     

Schiff bases of increasing complexity as mild steel corrosion inhibitors in 2 M HCl

The effect of three Schiff base compounds with increasing number of coordination sites, namely, 2-{(E)-[(2-hydroxyethyl)imino]methyl} phenol (I), 2-[(E)-({2-[(2-hydroxyethyl)amino]ethyl}imino)methyl]phenol (II) and 2,2′-{iminobis[ethane-2,1-diylnitrilo(E)methylylidene]}diphenol (III) have been investigated at 298 K by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The inhibition efficiencies obtained from all methods employed are in good agreement. Results show compound III to be the best inhibitor with a mean efficiency of 93% at 10⁻² M additive concentration. Studies showed all three compounds to act as mixed type inhibitors.     

Investigation of the inhibition effect of 5-((E)-4-phenylbuta-1,3-dienylideneamino)-1,3,4-thiadiazole-2-thiol Schiff base on mild steel corrosion in hydrochloric acid

The inhibition effect of 5-((E)-4-phenylbuta-1,3-dienylideneamino)-1,3,4-thiadiazole-2-thiol (PDTT) Schiff base on mild steel corrosion in 0.5 M HCl was studied for both short and long immersion time. For this purpose, potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization resistance, hydrogen gas evolution, the change of open circuit potential as a function of immersion time, SEM and AFM techniques were utilized. The PDTT Schiff base has shown remarkable inhibition on the corrosion of mild steel in 0.5 M HCl solution. The high inhibition efficiency was attributed to the blocking of active sites by adsorption of inhibitor molecules on the steel surface.     

Experimental and theoretical studies for mild steel corrosion inhibition in 1 M HCl by two new benzothiazine derivatives

The inhibition effect of new heterocyclic compounds, namely 2-aryl-benzothiazin-3-one (P1) and 3-aryl-benzothiazin-2-one (P2) on mild steel corrosion in 1 M HCl was investigated using electrochemical measurements. The results indicated that the inhibition efficiency depends on concentration and molecular structure of the investigated compounds. It is also found that the inhibition of P1 is greater than P2. The molecular structure effect on the corrosion inhibition efficiency was investigated using DFT calculations. The structural and electronic parameters were calculated and discussed. The obtained results show that the experimental and theoretical studies agree well and confirm that P1 is the better inhibitor.     

Synergistic effect of halide ions on improving corrosion inhibition behaviour of benzisothiozole-3-piperizine hydrochloride on mild steel in 0.5 M H2SO4 medium

The synergistic effect of iodide ions and benzisothiozole-3-piperizine hydrochloride (BITP) on corrosion inhibition of mild steel in 0.5 M H₂SO₄ solution has been studied by both chemical and electrochemical methods. The corrosion performance of BITP in 1.0 M HCl and 0.5 M H₂SO₄ media was examined and compared. The adsorption of BITP and its combination with iodide ions on mild steel surface followed Langmuir adsorption isotherm via chemisorption mechanism. The calculated values of synergism parameter (S_θ) were found to be greater than unity. This result clearly showed the existence of synergism between iodide ions and BITP molecules.     

Evaluation of corrosion inhibition at sand-deposited carbon steel in CO2-saturated brine

The adsorption of four CO₂ corrosion inhibitors on silica sand and their subsequent inhibition activity at sand-deposited steel has been investigated. The presence of a sand deposit affects the performance of inhibitors at carbon steel due to their competitive adsorption on sand. Sulfur-containing organic compounds show minimal adsorption on sand compared to pyridinium surfactants and provide the highest inhibition efficiency at the sand-deposited steel. The extent of inhibitor adsorption onto sand is discussed in relation to their chemical structures. The significance of determining the adsorption affinity to sand in the selection of inhibitors to mitigate under-deposit corrosion is demonstrated.     

N-Aminorhodanine as an effective corrosion inhibitor for mild steel in 0.5 M H2SO4

The corrosion inhibition effect of N-aminorhodanine (N-AR) on mild steel (MS) in 0.5 M H₂SO₄ was studied in both short and long immersion duration using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), chronoamperometry and hydrogen gas evolution. The surface morphology of MS was examined with scanning electron microscopy (SEM) in absence and presence inhibitor. The inhibitor adsorption process on MS surfaces obeys the Langmuir adsorption isotherm. The results show that NAR is a good inhibitor for MS in the acidic medium. The inhibition efficiency obtained from potentiodynamic polarization, EIS and LPR up to 98% is determined.     

Effectiveness of some diquaternary ammonium surfactants as corrosion inhibitors for carbon steel in 0.5 M HCl solution

Four Gemini surfactants were synthesized and characterized using elemental analysis, FTIR and ¹H NMR spectroscopy. The synthesized compounds were evaluated as corrosion inhibitors for carbon steel in 0.5 M HCl solution. The inhibition efficiencies of the tested inhibitors were depended on the hydrophobic chain length and the used doses of the inhibitors. The polarization measurements showed that these inhibitors are acting as mixed inhibitors for both anodic and cathodic reactions. The results showed that the inhibition efficiencies were increased by increasing the inhibitor doses and the hydrophobic chain length and reached the maximum at 500 ppm by weight for stearyl derivative. The efficiencies obtained from the impedance measurements were in good agreement with those obtained from the gravimetrical and polarization techniques which prove the validity of these tolls in the measurements of the tested inhibitors.     

The investigation of synergistic inhibition effect of rhodanine and iodide ion on the corrosion of copper in sulphuric acid solution

The synergistic inhibition effect of rhodanine (Rdn) and iodide ion on the corrosion of copper in 0.5 M H₂SO₄ solution was studied using electrochemical techniques. The surface morphologies of the substrates were examined by scanning electron microscopy (SEM). Elemental analysis of electrode surface exposed to test solution was determined by energy dispersive X-ray spectroscopy (EDX). It was found that Rdn provided satisfactory inhibition on the corrosion of copper. Moreover, its inhibition efficiency further increased in the presence of iodide ions due to synergistic effect. Finally, a mechanism of inhibition is proposed and discussed.     

Electrochemical characterization and computational fluid dynamics simulation of flow-accelerated corrosion of X65 steel in a CO2-saturated oilfield formation water

The flow-accelerated corrosion (FAC) of an X65 pipeline steel was investigated in a CO₂-saturated formation water by electrochemical measurements and computational fluid dynamics (CFD) simulation on micro-electrodes installed on an impingement jet system. The surface morphology of the electrodes after corrosion test was characterized by scanning electron microscopy. Results demonstrated that the role of fluid hydrodynamics in FAC of the steel depends on its effect on the carbonate corrosion scale formed on the electrode surface. An increasing flow velocity and shear stress would thinner, degrade or even remove completely the scale, increasing corrosion of the steel. An oblique impact of fluid would generally result in a high corrosion rate of the steel. The effect of impact angle on corrosion of the steel is attributed to the distribution of fluid flow field and shear stress on the electrode surface. At the normal impact, a low flow velocity and shear stress and thus a low mass transfer rate would be generated at the centric region. Consequently, a compact corrosion scale can be formed on the electrode surface to protect the steel from corrosion. The highest corrosion rate is observed on micro-electrodes that are adjacent to the center, with the highest flow velocity and shear stress. At the oblique impact angles, the fluid flow velocity and shear stress, and the corrosion rate of the micro-electrodes are higher at the side far away from the nozzle than those at the side close to nozzle. The corrosion activity of the steel electrode located at the center of the sample holder generally increases with the decreasing impact angle due to the enhancing shear effect on the corrosion scale.     

Electrochemical and quantum chemical studies of some azomethine compounds as corrosion inhibitors for mild steel in 1 M hydrochloric acid

The corrosion inhibition effect of new azomethine compounds: PhNNC (COCH₃)NC₆H₄Y {Y = OCH₃ (SB₁), CH₃ (SB₂), H (SB₃), Br (SB₄) and Y = Cl (SB₅)} on mild steel in 1 M HCl, was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemistry analysis. It has been found that the inhibition efficiency increased with increasing inhibitor concentration. The polarization curves showed that these Schiff bases function as mixed inhibitors. The adsorption of studied compounds on mild steel surface was found to follow the Langmuir isotherm. Molecular modeling was used to correlate corrosion inhibition properties and calculated quantum chemical parameters.     

Synergistic inhibition effect of 6-benzylaminopurine and iodide ion on the corrosion of cold rolled steel in H3PO4 solution

The synergistic inhibition effect of 6-benzylaminopurine (BAP) and iodide ion (I⁻) on the corrosion of cold rolled steel (CRS) in 1.0 M H₃PO₄ solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that BAP has a moderate inhibitive effect. However, incorporation of BAP with I⁻ improves the inhibition performance significantly. The adsorption of BAP in the absence and presence of I⁻ obeys Langmuir adsorption isotherm. BAP and BAP/I⁻ mixture act as mixed-type inhibitors. A probable synergism mechanism is proposed.     

Electrochemical impedance spectroscopy and electrochemical noise measurements as tools to evaluate corrosion inhibition of azole compounds on stainless steel in acidic media

The corrosion inhibition function of two azole derivatives namely benzotriazole (BTR) and benzothiazole (BNS) on stainless steel in 1 M HCl was investigated using electrochemical techniques and SEM surface analysis as well. In consistency with the data obtained from EIS and polarization curves, electrochemical current noise transient analysis, noise resistance and characteristic charge from shot noise theory indicated effectiveness of the inhibitors. The corrosion damage mitigation was also confirmed through SEM in the presence of BNS. To remove the DC trend from noise data, the appropriate p value was proposed based on the correlation with polarization and EIS data.     

Synergistic inhibition behaviour of methylbenzyl quaternary imidazoline derivative and iodide ions on mild steel in H2SO4 solutions

The inhibition behaviour of 2-undecyl-1-ethylamino-1-methylbenzyl quaternary imidazoline (2UMQI) and KI on mild steel in 1.0 M H₂SO₄ solutions was investigated at 25 °C using electrochemical methods. The results indicated that 2UMQI inhibited the corrosion of mild steel and the extent of inhibition increased with 2UMQI concentrations. The inhibition action in the presence of 2UMQI is due to physical adsorption of 2UMQI. A mixed-inhibition mechanism is proposed for the inhibitive effects of 2UMQI. Inhibition efficiency of 2UMQI was enhanced by the addition of iodide ions. In the presence of KI, the potentials of unpolarization, E_u was observed and increased with KI concentration.     

Investigation on some Schiff bases as corrosion inhibitors for mild steel

In the present work, the effect of some newly synthesized Schiff bases containing sulphur nitrogen as heteroatom was investigated on mild steel corrosion in acidic media. Electrochemical studies of the mild steel samples were performed in an aerated solution of 0.1 M HCl + dimethyl sulphoxide (DMS) as co-solvent. DMS is also behaving as a corrosion inhibitor for mild steel. At low inhibitor concentration and short immersion time one can see only the inhibitive effect of DMS as anodic inhibitor for mild steel. At high concentration and long immersion time inhibition efficiencies are increased and cathodic inhibition is observed.     

Corrosion inhibition of mild steel in hydrochloric acid solution by some double Schiff bases

The inhibition effect of four double Schiff bases on the corrosion of mild steel in 2 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The inhibitors were adsorbed on the steel surface according to the Langmuir adsorption isotherm model. From the adsorption isotherm, some thermodynamic data for the adsorption process were calculated and discussed. Kinetic parameters activation such as E_a, ΔH∗, ΔS∗ were evaluated from the effect of temperature on corrosion and inhibition processes. Quantum chemical calculations have been performed and several quantum chemical indices were calculated and correlated with the corresponding inhibition efficiencies.