Anodic Inhibitor Research Articles

Effect of Schiff's bases on corrosion protection of mild steel in hydrochloric acid medium: Electrochemical, quantum chemical and surface characterization studies

Schiff's bases such as (E)-3-(3-hydroxybenzylideneamino)-2-(3-hydroxyphenyl)-2,3-dihydroquinazolin-4(1H)-one (SB-1) and (E)-3-(5‑bromo-2-hydroxybenzylideneamino)-2-(5‑bromo-2-hydroxyphenyl)-2,3-dihydraquinazolin-4(1H)-one (SB-2) were synthesized and investigated to the surface interactions & corrosion protection performance on mild steel (MS) in 2 M HCl medium by means of weight loss, electrochemical polarization and electrochemical impedance spectroscopic (EIS) techniques. Tafel polarization measurements showed that, the synthesized compounds were exhibited as mixed type (cathodic / anodic) inhibitors and the maximum protection efficiencies of 86.44% and 87.36% for SB-1 and SB-2 respectively were observed at optimized concentration. The corrosion control of MS in presence of inhibitors could evaluate through adsorption phenomenon and fitted to Langmuir's adsorption isotherm. Activation energy (Ea) values in absence of the inhibitor is minimum 51.45 kJ mol−1 and higher values of 89.98 kJ mol−1 and 70.09 kJ mol−1 in the presence of SB-1 and SB-2 respectively. Thermodynamic adsorption parameters such as ∆Hads, ∆Gads & ∆Sads were correlated to the corrosion inhibition process. Quantum chemical analysis revealed the nature of chemical interaction established between the inhibitor molecules and metal atoms. The change in surface morphology of mild steel and chemical interactions of inhibitor molecules on specimen surface were evaluated through FT-IR, Scanning electron microscopic linked with EDX, Atomic force spectroscopy and Contact angle techniques. Atomic force microscopic results revealed that, an average roughness of the mild steel surface has been reduced from 443 nm to 11.0 nm and 26.9 nm in presence SB-1 and SB-2 respectively.

Influence of a Show Case Polish Coating on Corrosion Resistance of Mild Steel in Simulated Concrete Pore Solution

Mild steel is relatively less expensive. So in reinforced concrete, mild steel can be used. Mild steel in concrete structures may experience corrosion. To avert corrosion of mild steel, a number of inhibitors are used along with concrete admixtures. In this category of research, saturated calcium hydroxide solution is considered as simulated concrete pore solution (SCPS). Numerous corrosion inhibitors have been utilized in this field along with organic coatings. In the present investigation show case polish coated mild steel has been used in concrete. The corrosion resistance has been calculated by electrochemical studies such as polarization study and AC impedance spectra. When show case polish coated mild steel is immersed in SCPS, the corrosion resistance of mild steel increases. This is long-established by the facts that in presence of show case polish coating , the linear polarization resistance value increases, corrosion current value decreases, charge transfer resistance increases, double layer capacitance decreases, impedance increases, and phase angle increases. The protecting layer functions as anodic inhibitor and controls the anodic reaction primarily. The protective coating offers 99.99% inhibition efficiency. It implies that the show case polish coated mild steel can be used in concrete technology. This will increase the lifetime of the rebars.

Corrosion Inhibition of Low Carbon Steel in Soil Solutions, Using Novel Schiff Base Inhibitor

The investigation of Corrosion inhibition behavior of synthesized amino acid-based Schiff base inhibitor [(E)-5-nitro-N1-((E)-3-phenylallylidene) benzene-1,2-diamine] was carried out. Its adsorption in two types of (5%) soil solutions was studied at room temperature, using potentiodynamic polarization and gravimetric techniques. The inhibition efficiency obtained at the optimum inhibitor concentration (300ppm), were 23% in acidic and 70% in neutral electrolyte. Results illustrated that the inhibitor worked well in less acidic environment in one of the soil solutions which was relatively acidic than the other. Experimental data of potentiodynamic study also indicated that the inhibitor was more inclined to adsorb on the anodic sites of the carbon steel sample, thus the inhibitor can be categorized as the anodic inhibitor due to suppression of more anodic reaction on the carbon steel sample.

Nicotinic acid as a novel inhibitor for alkaline cobalt CMP: Experiment and molecular simulation

Cobalt (Co) is the interconnect metal of integrated circuits with the feature size of 10 nm and below, and Co corrosion is the main problem in cobalt interconnect chemical mechanical polishing (CMP). The introduction of inhibitors is one of the most ideal approaches to reduce corrosion. In this work, useful insights into the corrosion inhibition performance of nicotinic acid (NA), a green inhibitor, on cobalt film in alkaline medium were investigated via electrochemical characterization, surface analysis, quantum chemical calculation, and molecular dynamics (MD) simulation, as well as the adsorption mechanism at atomic level was explored. NA belongs to anodic erosion inhibitor and its inhibition efficiency reached a maximum of 86.65 % at the concentration of 80 mM pH 10, which was identified by the contact angle and potentiodynamic polarization (PDP) test. The electrochemical impedance spectra (EIS) suggested that the surface resistance was enhanced to prevent corrosion. Free energy obtained from the Langmuir model indicates that NA molecules are physically and spontaneously adsorbed on cobalt surface. XPS results further confirmed this point, which reveals that NA exists in the form of Nic2− in alkaline solution and forms a Co(OH)2(Nic2-) molecule group (Co(II)-NA) on Co surface. Additionally, quantum chemical calculations based on density function theory (DFT) have approved that CN bond and carboxyl group are the active sites of NA molecule and form the most significant electrostatic adsorption force with cobalt atoms. Moreover, it can be inferred from MD simulations that NA molecules are spontaneously and physically adsorbed on the cobalt surface at a certain angle. In a word, NA manifests its effectiveness in corrosion inhibition of cobalt and will become a potential cobalt CMP inhibitor. The research methods and results of this paper are beneficial to the study of the adsorption characteristics and inhibition mechanism of inhibitors on the metal surface, and provide a theoretical basis for optimizing the composition of Co CMP slurry.

Effect of Aloe Vera Extract as Green Corrosion Inhibitor on Medium Carbon Steel in Sulphuric Acid Environment

Medium carbon steel is widely consumed by various industrial sectors due to its attractive set of mechanical properties and low cost, but it experiences deterioration when exposed to a corrosive environment. In the present study, Aloe Vera plant extract was studied as a green corrosion inhibitor for medium carbon steel in an acidic medium. The presence of inhibitive compounds in Aloe Vera plant extract was determined by FTIR. Moreover, the inhibition efficiency was determined through gravimetric analysis and electrochemical analysis. The results show that the Aloe Vera plant extract provided inhibition efficiency of more than 90% in both gravimetric and electrochemical analyses. Furthermore, the shift in polarization curves depicts that this plant extract is a mixed type inhibitor acting as an anodic and cathodic inhibitor. Overall, Aloe Vera plant extract provides excellent corrosion inhibition to medium carbon steel in the H2SO4 environment and can be used as a green corrosion inhibitor for mitigating internal corrosion of pipelines and storage tanks.

Electrochemical Evaluation of 5-aminosalicylic Acid as an Inhibitor for Under Deposit Corrosion of X60 Pipeline Steel in Marine Environments

Inhibition effects of 5-aminosalicylic acid (5-ASA) on the under deposit corrosion of X60 steel in 3.5 % NaCl solution saturated with CO2 have been investigated by the techniques of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The sand-covered electrode was prepared by covering the X60 steel electrode with a layer of silica sand. The increase of 5-ASA concentration up to 600 ppm led to increasing the inhibition efficiency of X60 steel against under deposit corrosion in the brine solution. The Langmuir isotherm can describe the adsorption behavior of 5-ASA on the surface of the steel. Measurements of potentiodynamic polarization indicated that 5-ASA is an anodic inhibitor. The effects of temperature on the under deposit corrosion behavior of carbon steel were studied both in the absence and presence of 600 ppm 5-ASA. The enthalpy of the 5-ASA adsorption was obtained from the temperature dependence of the corrosion inhibition process. A reasonable agreement was observed between the IE values resulted from the Tafel and the EIS techniques. The electronic properties of 5-ASA were calculated in both the gas phase and the aqueous phase by a density functional theory (DFT) approach to establish the relationship between the inhibitive effect and molecular structure of 5-ASA.

Tannic acid reinforced sol-gel silica coatings for corrosion protection of zinc substrates

Silica (SiO2) coatings are a widely discussed inorganic coating alternative, offering a feasible and simple method of passive corrosion protection, with the option of enhancement by incorporating different inhibitors into the matrix. The novelty of the present study lies in the reinforcement of the sol-gel SiO2 coating system, by the addition of different tannic acid (TA) amounts in the sol phase and producing nano scale coatings by dip-coating technique, on Zn. Tannic acid is a non-toxic substance, which acts as anodic corrosion inhibitor. Long term corrosion measurements were carried out to check the durability and corrosion resistance of the thin coatings. They were characterized by Electrochemical Impedance Spectroscopy and Potentiodynamic polarization curves, as well as by physical methods (SEM, contact angle and adhesion measurements). The pseudo-porosity of the coatings was also evaluated. It has been concluded that SiO2 coatings containing TA in an optimal concentration show lower corrosion current densities than simple SiO2 coatings, good adhesion to the zinc substrate, and lower porosity. The interactions occurring between the SiO2 and TA put in evidence by FT-IR, Raman spectroscopy offer an explanation of the better corrosion behavior of the SiO2+TA coating compared to the pure SiO2.

Effect of rust inhibitor on the composition of steel passive film in carbonized concrete

The composition and characteristics of the passive film formed in the simulated carbonation solution with the concentration of 1.0% and 2.0% rust inhibitor were studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The formation mechanism of steel passive film under the action of rust inhibitor was expounded. The results showed that the anticorrosion performance was the best and stable passive film was formed on the steel surface when the content of rust inhibitor was 2.0%; under the action of rust inhibitor, the main compositions of passive film on the steel surface were Fe2O3 and FeOOH. Among anodic rust inhibitors, Na2MoO4 was more effective than Na2CrO4. Between cathodic rust inhibitors, the anticorrosion performance of benzotriazole (BTA) was better than N-N dimethyl ethanolamine (DMEA). Among the composite rust inhibitors, the corrosion resistance of Na2MoO4 + BTA group was superior, and the corrosion resistance of Na2MoO4 + DMEA group was the worst. The composite rust inhibitor was better than the single rust inhibitor, and the inhibition efficiency was the highest when Na2MoO4 and BTA were mixed together.

Synthesis, structure, and corrosion inhibiting properties of REIII 3-thiophenecarboxylate complexes

Two series of Rare Earth (RE) 3-thiophencarboxylate (3TPC) complexes have been synthesized by reactions between a RE salt and Na(3TPC). Based on weight loss measurements and potentiodynamic polarization measurements, the compounds show good corrosion inhibitory properties and act mainly as anodic inhibitors.

Uticaj tiouree na otpornost na koroziju mekog čelika uronjenog u simulirani rastvor betonskih pora

The corrosion resistance of mild steel in simulated concrete pore solution (SCPS) in the absence and presence of thiourea has been investigated by polarization study and AC impedance spectra. Polarisation study reveals that thiourea system functions as anodic inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. When mild steel is used as rebar, thiourea may be mixed with concrete. Thus the mild steel will be protected from corrosion. The protective film consists of iron-thiourea complex formed on metal surface. In the presence of thiourea the linear polarisation resistance increases, corrosion current decreases, charge transfer resistance (Rt) increases, impedance increases, phase angle increases and double layer capacitance (Cdl) value decreases. This formulation may find application in concrete technology.

Self-assembly of corrosion inhibitors-intercalated layered double hydroxides (LDHs) in cementitious systems

This work investigates the self-assembly of corrosion inhibitor-intercalated layered double hydroxides (LDHs) in cementitious systems. The impacts of inorganic and organic corrosion inhibitors (i.e., sodium nitrite, sodium benzoate, and sodium molybdate) on the intercalation chemistry and chloride-induced transformation of LDHs in ordinary Portland cement (OPC) and limestone calcined clay cement (LC3) pastes are revealed. The results show that direct admixing of inorganic or organic inhibitors results in spontaneous formation of inhibitors-intercalated LDHs (i.e., NO2-AFm, C6H5COO-AFm, and MoO4-AFm), regardless of binder chemistry. The sequestrated anodic inhibitors in cementitious systems are released upon exposure to chloride, accompanied by simultaneous formation of Friedel's salts (Cl-AFm). The incorporation of anodic inhibitors has little influence on the chloride binding capacity of OPC and LC3 pastes, but impacts their chloride resistance via pore structure modification. This research advances our understanding of the physicochemical roles of admixed anodic inhibitors in cementitious systems.

An integral non-intrusive electrochemical and in-situ optical technique for the study of the effectiveness of corrosion inhibition

This work investigates an integrated analysis of in-situ optical data and time-frequency information from electrochemical potential noise (EPN) data to study the effectiveness and durability of an anodic and cathodic corrosion inhibitor. Two different corrosion inhibiting species, cerium(III) (Ce(III)) and phytic acid (PHA), are tested on aluminum alloy AA2024-T3. Corrosion of AA2024-T3 serves as a negative reference. Time-frequency analysis of EPN data provides a direct insight in the kinetics of the electrochemical processes related to different types of corrosion and/or inhibitor activity over time. The simultaneous, in-situ optical technique allows visualizing and quantifying the surface changes associated with the electrochemical signals. Both Ce(III) and PHA were not capable to inhibit corrosion to a large extent, as re-immersion led to electrochemical (corrosion) activity for both inhibitors. Time-variant changes between corrosion, inhibitor activity, inhibited state and re-activation can effectively be discriminated from each other.

Corrosion Inhibition Mechanism of Steel Reinforcements in Mortar Using Soluble Phosphates: A Critical Review.

The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (Na2PO3F) (MFP), disodium hydrogen phosphate (Na2HPO4) (DHP) and trisodium phosphate (Na3PO4) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, H2PO4− ions being stable in the pH range of 3–6, the HPO42− in the pH range of 8–12, while the PO43− ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP.

Experimental and theoretical assessment of benzopyran compounds as inhibitors to steel corrosion in aggressive acid solution

The present work introduces an environmentally friendly synthesis of two heterocyclic α,β-unsaturated carbonyl group benzopyran compounds (4-[(2E)-3-(1H-indol-3-yl)prop‑2-enoyl]-2H-1-benzopyran-2-one, and 4-(6-(1H-3-indolyl)-2,3-dihydropyrimidin-2(1H)thione-4-yl)-2-benzopyranone) referred to as Ch-I and Ch-II and explores their corrosion inhibition against API steel type in 15% hydrochloric solution. FTIR, 1H NMR, mass spectroscopy, and elemental analysis were used to characterize the synthesized benzopyran derivatives. Gravimetrical, morphological, and electrochemical techniques were used to investigate the inhibition properties of these two derivatives. The surface morphology analysis was studied using scanning electron microscope associated with energy dispersive x-ray (SEM/EDX), and atomic force microscopy (AFM) techniques. The experimental results showed inhibition efficiencies of 79.9% and 95.8% for Ch-I and Ch-II, respectively at concentrations 1 × 10−3 M. The electrochemical techniques show that the two benzopyran derivatives act as an anodic and cathodic inhibitor. SEM and AFM results are compatible with the electrochemical measurements. Theoretical and molecular dynamic simulations studies were applied to elucidate the effect of the chemical structure of Ch-I and Ch-II on their inhibition efficiencies, and further to clarify their adsorption process on the carbon steel substrate. The obtained experimental results were in line with the calculated theoretical parameters.

Electrochemical analysis and microstructure of value-added functional Zn-ZnO-rice husk ash composite coating of mild steel

Electro-deposition method was used to incorporate rice husk ash (RHA) into the Zn-ZnO- XRHA composite coatingfor mild steel pipeline exterior coating from a chloride-based bath. Zn-ZnO- XRHA composite coatings were obtained for x = 0 g, 10 g and 20 g at a constant bath temperature of 75 °C, constant stirring rate of 400 rpm, 1.4 A current and 15 min deposition span. Scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS), X-ray diffractometry (XRD) and atomic force microscopy (AFM) were used to study the coated surface. Coatings suitability on exposure to adverse environment was assessed in 3.5% NaCl in situ solution using CHI604E electrochemical analyzer. The result showed corrosion protection of the substrate owing to the decline in corrosion rate from 3.2571 mm/yr to 0.1254 mm/yr. The higher positive value of the E corr of the coatings relative to the substrate inclines the developed coatings to the class of anodic inhibitors.

Free fatty acid influenced corrosion inhibition mechanisms of some inedible plants seeds oils on low alloyed medium-carbon steel in H2SO4

PurposeThe purpose of this paper is to investigate the mechanisms of low alloyed medium-carbon steel (LAMCS) corrosion in 0.5 M H2SO4 inhibited by seeds oils of rubber (SOR), Neem (SON) and Jatropha (SOJ) containing varying degree of free fatty acid (FFA).Design/methodology/approachSpecific gravity, acid values and FFA compositions of oils were determined. Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) are techniques used to investigate the corrosion inhibition mechanisms with evaluated Gibbs free energy of adsorption.FindingsCorrosion inhibition efficiencies of oils reached values >99% as obtained from PDP and EIS. Protective oxide layer was formed on LAMCS consequent on containment of carbonyl and hydroxyl groups in the FFA of SOR, SON and SOJ, respectively. The SOR and SOJ are found to be mixed inhibitors, whereas SON behaved as anodic inhibitor. Mechanism of adsorption of SOR was synergistic between physisorption and chemisorption, while SON and SOJ exhibited physisorption. SEM micrographs images showed that uninhibited sample exhibited thicker mass of corrosion products. Formation of protective oxide layer was confirmed by XRD diffractograms.Practical implicationsThis study has shown that the need for modification of vegetable seed oils containing FFA is unnecessary as the hydroxyl and carbonyl groups of the FFA contained in the respective oil were found to be the center of adsorption of the oils on the steel surface. Hence, cost and by-products associated with modification of oils used as corrosion inhibitors are eliminated.Originality/valueSOR, which has the highest percentage FFA, was found to be the most influential on the corrosion inhibition mechanism of LAMCS, specifically within 0.01–0.02 g/mL concentration. FFA contained in the respective seed oil aided formation of protective oxide layer at interface between H2SO4 and LAMCS, relative to amount composed.

Anti-Corrosive Effect of Jordanian-Bay- Leaves Aqueous Extract on Mild Steel in 1.0 M Hydrochloric Acid Solution

Natural inhibitors are the most crucial manner to lessen the corrosion price of various business metals. There are several strategies being used with corrosion inhibitors. One technique being used is the Electrochemical strategies. The gain with this technique is their brief size time and mechanistic information. It is beneficial in the corrosion's layout safety techniques besides the layout of the brand new inhibitors, there are 3 styles of corrosion inhibitors as anodic inhibitors, cathodic inhibitors, over one inhibitor. The corrosion inhibition of slight metallic in 1.0 M HCl solution with the aid of using Jordanian -Bay- leaves extract has been studied with the use of potentiodynamic polarization technique. Results received a display that Bay- leaves aqueous extract behaves as an anodic inhibitor for slight metallic in 1.0 M HCl solution. The inhibitor capabilities thru adsorption following Temkin adsorption isotherm. The impact of parameters like temperature and inhibitor awareness at the corrosion of slight metallic has additionally been studied.

The study of m-pentadecylphenol on the inhibition of mild steel corrosion in 1 M HCl solution

The acidic fluids used in the acidification of oil wells provoke corrosion of metallic materials unenviably. As a consequence, corrosion inhibitors are needed to mitigate or retard the corrosion process. Herein, we report m-pentadecylphenol as an eco-friendly corrosion inhibitor in acidic media developed from cashew nut shell liquid (CNSL), which is a low-cost and sustainable source. The inhibitor was evaluated as corrosion inhibitor for mild in 1 M HCl corrosive solution by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), weight loss, Fourier transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM), and energy-dispersive X-ray fluorescence (EDX-RF) spectrometry methods. The results showed that the inhibition efficiency of m-pentadecylphenol was at least 95% at an optimal concentration (300 ppm). The inhibition efficiency was found to increase as the inhibitor concentration increments from 100 to 300 ppm. Further studies revealed the inhibition performance of m-pentadecylphenol to be marginally reliant on temperature as the temperature rises from 303 to 333 K. At 333 K, the inhibition performance of the inhibitor was still promising (about 85%) when the concentration was 300 ppm. The adsorption studies revealed the spontaneous aptitude of m-pentadecylphenol to inhibit corrosion by forming a non-conductive inhibitive layer on the mild steel surface mainly through the chemisorption mechanism. The chemisorption adsorption was satisfactorily described by the Langmuir adsorption isotherm model. Besides, the potentiodynamic polarization measurements revealed m-pentadecylphenol to act as an anodic inhibitor. The overall findings revealed that m-pentadecylphenol to be an effective corrosion inhibitor in harsh corrosive vicinities with the added advantages of being eco-friendly and relatively cheaper. Thus, it can replace the use of non-green and expensive corrosion inhibitors in the industry.

Effectiveness of henna leaves extract and its derivatives as green corrosion inhibitors of reinforcement steel exposed to chlorides

In this work, Henna leaves extract (HLE) and its principal derivatives of Lawsone and Gallic acid are examined as green corrosion inhibitors. Our contribution is to quantify the effectiveness of HLE, Lawsone and Gallic acid on the corrosion inhibition of steel in simulated concrete pore solution (SCPS) containing 0.5 M NaCl, using electrochemical methods as open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, environmental scanning electron microscopy, coupled to the energy dispersive X-ray microanalysis, was performed to investigate the morphology of the steel surface immersed in SCPS containing green inhibitors. Results highlight a synergistic effect with the formation of a protective layer on the steel surface by forming inhibitor-metal complexes. The HLE and Gallic acid act as anodic corrosion inhibitors and Lawsone behaves as a mixed type. These inhibitors are adsorbed on the steel surface by chemisorption according to the adsorption isotherm of Langmuir. The maximal inhibition efficiency is about 93% obtained at 0.2 g/L of HLE, which represents the higher effectiveness compared to Lawsone and Gallic acid.

Combining experiment and theory researches to insight into anti-corrosion nature of a novel thiazole derivatives

The propensity of acid corrosion for X65 steel substrate leads to application restrictions. In this research, we develop an efficient and new corrosion inhibitor, S-(benzo[d]thiazol-2-yl) (E)-2-(2-aminothiazol-4-yl)-2-(methoxyimino)ethanethioate (BTAE), as a first example of a sulfuric acid medium additive containing both benzothiazole and aminothiazole with multiple anchoring centers, which can inhibit the X65 corrosion in the sulfuric acid medium. The electrochemical experiment test shows that BTAE can effectually control the anodic reaction of X65 steel and belongs to the anodic type corrosion inhibitor. The corrosion inhibition efficiency of BTAE can still be maintained above 97% within a certain temperature range. The surface topography analysis and electrochemical test results are highly consistent. The adsorption of BTAE onto the interface of X65 steel conforms to the Langmuir model. Quantum chemistry and molecular dynamics simulation results have proved that BTAE is an excellent corrosion inhibitor.