Adsorption behavior and corrosion inhibitive potential of xanthene on mild steel/sulphuric acid interface

The inhibition of xanthene (XEN) on the corrosion of mild steel in 0.5 M H₂SO₄ was studied by gravimetric and UV–visible spectrophotometric methods at 303–333 K. Results obtained show that XEN act as inhibitor for mild steel in H₂SO₄ solution. The inhibition efficiency was found to increase with increase in XEN concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using Statistical Physics were calculated and discussed. The corrosion process in 0.5 M H₂SO₄ in the absence and presence of XEN follows zero-order kinetics. The UV–visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a XEN–Fe complex. Quantum chemical calculations using DFT were used to calculate some electronic properties of the molecule in order to ascertain any correlation between the inhibitive effect and molecular structure of xanthene.     

Synthesis,characterization and corrosion inhibition efficiency of 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline on mild steel in sulphuric acid

Phenanthroline derivative, 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline (MIP) was synthesized and characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, and single crystal X-ray diffraction study. MIP was evaluated as corrosion inhibitor for mild steel in 0.5 M H₂SO₄ solution using gravimetric and UV–Visible spectrophotometric methods at 303–333 K. Results obtained show that MIP acts as inhibitor for mild steel in H₂SO₄ solution. The inhibition efficiency was found to increase with increase in MIP concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using statistical physics were calculated and discussed. The UV–Visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a MIP-Fe complex.     

Spondias mombin L. as a green corrosion inhibitor for aluminium in sulphuric acid: Correlation between inhibitive effect and electronic properties of extracts major constituents using density functional theory

The inhibition of aluminium in 0.5 M H₂SO₄ by extracts of Spondias mombin L. was investigated using the standard gravimetric technique at 30–60 °C. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition. It was found that the S. mombin L. extract acts as an inhibitor for acid-induced corrosion of aluminium. Inhibition efficiency (%I) of the extract increased with an increase in concentration of the S. mombin L. extract but decreased with temperature. Furthermore, inhibition efficiency (%I) synergistically increased on addition of potassium iodide. Inhibitor adsorption characteristics were approximated by Langmuir adsorption isotherm at all the concentrations and temperatures studied. The mechanism of physical adsorption is proposed from the trend of inhibition efficiency with temperature and from the calculated values of Gibbs free energy, activation energy and heat of adsorption. Quantum chemical calculations were performed using the density functional theory at B3LYP/6-31G (d) level of theory to find out whether a clear link exists between the inhibitive effect of the extract and the electronic properties of its main constituents.     

Benzalkonium chloride/titanium dioxide as an effective corrosion inhibitor for carbon steel in a sulfuric acid solution

In this study, the corrosion performance of carbon steel samples in 0.5 M sulfuric acid by the addition of novel inhibitors, 200 ppm of (25% and 50%) titanium dioxide nanoparticles in benzalkonium chloride, was thoroughly investigated. Gravimetric measurements, cyclic and linear potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and hydrogen collection by water displacement evaluated inhibition performance. Analogously, TiO₂/ILB (50%), TiO₂/ILB (75%), and ILB inhibitors enhanced corrosion protection with over 80% inhibition efficiency in electrochemical tests. In addition, weight loss and hydrogen collection measurements reached comparable results. According to potentiodynamic polarization curves, inhibitors exhibited dual behavior, but cathodic protection was more predominant. Scanning electron microscopy (SEM) was employed to examine the surface morphology before and after immersion using corrosion tests. The correlation between electronic properties and inhibition efficiencies of tilted inhibitors was determined by simple linear regression. Electronic properties were calculated for neutral and protonated forms using a polarizable continuum model by the DFT method at the B3LYP/6-311+G (d, p) level of theory. The active adsorbed sites of HM1-HM3 on the metal surface were determined by analyzing their corresponding electrostatic surface potentials (ESP). Furthermore, molecular dynamics simulations were performed to illustrate the most conceivable adsorption configuration between the inhibitors and metal surfaces.     

Adsorption and inhibition properties of Tephrosia Purpurea as corrosion inhibitor for mild steel in sulphuric acid solution

Abstract

The present study investigated the adsorption and inhibition behavior of leaf extract of Tephrosia Purpurea (T. purpurea) on mild steel corrosion in 1?N H₂SO₄ solution using electrochemical and surface morphological methods. Techniques adopted for electrochemical studies were Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) technique; and surface morphological studies were carried out using Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The leaf extract of T. purpurea was characterized using UV-Visible spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance Spectroscopy (NMR) and Gas Chromatography – Mass Spectrometry (GCMS). The results obtained from electrochemical studies exhibited the potential of T. purpurea as good corrosion inhibitor. And, it was found that, the inhibition efficiency (I.E in %) increases with increase in concentration of the inhibitor molecules, the optimum inhibitor concentration observed was 300?ppm and the inhibition efficiency of 93% was observed at this inhibitor concentration. Above 300?ppm, there was not much changes in inhibition efficiency. Polarization studies provided the information that the inhibition is of mixed type and EIS confirmed that the corrosion process is controlled by single charge transfer mechanism. And, it was obtained that, the adsorption of inhibitor molecules obeys Langmuir adsorption isotherm. The inhibition is mainly by the adsorption of inhibitor molecules on the mild steel electrode surface, which was confirmed by FT-IR, SEM and AFM studies. Through all the experimental results, it can be arrived that, the leaf extract of T. purpurea performed as a good corrosion inhibitor for mild steel in 1?N sulfuric acid medium.     

Inhibition of cold rolled steel corrosion in sulphuric acid solution by 2-mercapto-1-methylimidazole: Time and temperature effects treatments

2-Mercapto-1-methylimidazole (MMI) has been evaluated as a corrosion inhibitor for cold rolled steel in aerated 2 M H₂SO₄ by gravimetric method. The effect of MMI on the corrosion rate was determined at various immersions time and concentrations. The effect of the temperature on the corrosion behaviour with addition of different concentrations of MMI was studied in the temperature range 30–60 °C. The MMI acts as an effective corrosion inhibitor for cold rolled in sulphuric acid medium. The inhibition process is attributed to the formation of an adsorbed film of MMI on the metal surface which protects the metal against corrosion. The protection efficiency increased with increase in inhibitor concentration at various immersions time and decreased with increase in temperature. Adsorption of MMI on the cold rolled steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined.     

Corrosion prevention of mild steel in acidic medium by 2-Pyrrolidin-1-yl-1,3-thiazole-5-carboxylic acid: Theoretical and experimental approach

The inhibition efficiency of 2-Pyrrolidin-1-yl-1,3-thiazole-5-carboxylic acid (PTCA) against mild steel (MS) corrosion was investigated in acidic solution by using quantum chemical calculations based on Density Functional Theory (DFT) method and electrochemical measurements. The electrochemical impedance spectroscopy (EIS), potentiodynamic, potential zero charge (pzc) analysis and electrochemical noise (EN) measurements at various concentrations (from 0.1 to 10 mM) and immersion times were utilized in experimental part. The surface analysis was achieved scanning electron microscope (SEM) and contact angle measurements in the absence and presence of 10 mM PTCA. According to DFT results, PTCA exhibited 3.737 eV band gap and 8.130 Debye dipole moment which were a signal of potentially convenient corrosion inhibitor properties. PTCA has a remarkable corrosion inhibition capability to mild steel, which inhibited both anodic and cathodic corrosion rates, relying on it's physically adsorption on the metal solution interface and protection ability was increased with increasing PTCA concentration. The obtained adsorption equilibrium constant was 11.11 × 10³ M^-1 and calculated standard free energy of adsorption was ?33.03 kJ mol^?1. The determined activation energy values were 55.58 kJ mol^?1 and 96.86 kJ mol^?1 in 0.5 M HCl in the absence and presence of 10 mM PTCA, respectively. PTCA demonstrated a strong inhibition efficiency of 98.3%, after 168 h immersion, according to the EIS results. As a consequently, we recommend that PTCA is a convenient inhibitor in 0.1 M HCl for mild steel protection against corrosion.     

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.     

4-phenyl-decahydro-1H-1,5-benzodiazepin-2-one as novel and effective corrosion inhibitor for carbon steel in 1 M HCl solution: A combined experimental and empirical studies

The heterocyclic system, namely 4-phenyl-decahydro-1H-1,5-benzodiazepin-2-one (POBZ) was inspected as a corrosion inhibitor of carbon steel (CS) in a 1 M HCl medium through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP), and scanning electron microscopy (SEM). The experimental data indicate that the inhibiting action augments with augmenting POBZ amount and reduces with augmenting temperature. The inhibiting action efficiency of 90.98% is obtained with 0.001 M at 303 K. The potentiodynamic polarization (PDP) results mentioned that the POBZ is of mixed type. The adsorption of POBZ on the CS followed Langmuir isotherm. SEM exams affirmed that the steel surface is smooth in presence of POBZ. In light of the calculations of density functional theory (DFT) and molecular dynamics simulation, the mechanism of POBZ inhibitory activity was addressed.     

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...     

Utilization of biowaste as an eco-friendly biodegradable corrosion inhibitor for mild steel in 1 mol/L HCl solution

This report focuses on the application of a biodegradable biowaste [human hair-(HHR)], to produce a mild steel corrosion inhibitor. The performance of HHR extract in inhibiting metallic corrosion in 1 mol/L HCl was investigated. The analysis of the metal corrosion behavior using electrochemical and weight loss techniques revealed that HHR exhibits an efficient corrosion-mitigating effect via adsorption on the metal surface following a Langmuir isotherm. Tafel-plot results revealed the mixed-mode corrosion protection behavior of HHR. Surface analysis using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and Fourier transform infrared (FT-IR) spectroscopy provided evidence for the precipitation of a protective HHR film on the metal surface.     

Inhibition of aluminium and mild steel corrosion in acidic medium using Gum Arabic

The corrosion behaviour of mild steel and aluminium exposed to H₂SO₄ solution and their inhibition in H₂SO₄ containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature. Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69% at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel.     

Sebacic acid as corrosion inhibitor for hot-dip galvanized (HDG) steel in 0.1 M NaCl

The potential of sebacic acid as a corrosion inhibitor for hot-dip galvanized steel in 0.1 M NaCl solution has been investigated. Different concentrations of the organic acid have been tested in order to understand the inhibition mechanism of the compound. The electrochemical test revealed a competitive mechanism between the dissolution of the metal in the acidified solution and the inhibition provided by the dicarboxylic species. The formation of a whitish layer consisting of zinc carboxylates and corrosion products was proved by means of scanning electron microscopy (SEM) investigation combined with Fourier transform infrared (FT-IR) analysis. A bidentate bridging coordination between the Zn(II) and the carboxylic species is suggested.     

Ceforanide: a new and efficient corrosion inhibitor for mild steel in HCl solution

The corrosion inhibition properties of ceforanide for mild steel in HCl solution were analyzed by electrochemical impedance spectroscopy, potentiodynamic polarization, and gravimetric methods. The increase in inhibitor concentration and immersion time showed a positive effect on inhibition efficiency. The experimental data showed a frequency distribution and therefore a modeling element with frequency dispersion behavior and a constant phase element have been used. In aqueous acid solution, mild steel reacts by evolution of hydrogen. Visual observations showed that the hydrogen evolution decreased (i.e., corrosion inhibition effect increased) with increasing concentration of ceforanide. Potentiodynamic polarization study revealed that ceforanide acted as a mixed type of inhibitor. The results obtained from different methods are in good agreement. The adsorption behavior of ceforanide is experimentally investigated by contact angle measurement on metal surface. The contact angle of metal surface to the acid solution increased with inhibitor concentration; thereby confirming the increased hydrophobic nature of metal surface to the acid solution having inhibitors.     

Inhibitive action of ethanol extracts from Nauclea latifolia on the corrosion of mild steel in H2SO4 solutions and their adsorption characteristics

The inhibitive action of ethanol extracts from leaves (LV), bark (BK) and roots (RT) of Nauclea latifolia on mild steel corrosion in H₂SO₄ solutions at 30–60 °C was studied using weight loss and gasometric techniques. The extracts were found to inhibit the corrosion of mild steel in H₂SO₄ solutions and the inhibition efficiencies of the extracts follow the trend: RT > LV > BK. The inhibition efficiency increased with the extracts concentration but decreased with temperature rise. Physical adsorption of the phytochemical components of the plant on the metal surface is proposed as the mechanism of inhibition. The adsorption characteristics of the inhibitor were approximated by the thermodynamic-kinetic model of El-Awady et al.     

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Density functional theory (DFT) at the B3LYP/6‐31G (d,p) and BP86/CEP‐31G* basis set levels and ab initio calculations using the RHF/6‐31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely E_HOMO (highest occupied molecular orbital energy), E_LUMO (lowest unoccupied molecular orbital energy), the energy gap (ΔE), the Mulliken charges on the C, O, N, S atoms, hardness (η), softness (S), polarizability (α), dipole moment (μ), total energy change (ΔE_T), electrophilicity (ω), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), and the fraction of electrons transferred (ΔN). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the E_HOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Effect of acetic acid on CO2 corrosion of carbon steel in NaCl solution

Potentiodynamic sweep and electrochemical impedance spectroscopy measurements were applied to investigate the effects of both temperature and acetic acid (HAc) on the anodic and cathodic reactions in CO₂ corrosion of P110 steel in 3.5% NaCl solution. The temperatures were controlled at 30 and 60 °C. The concentrations of HAc were controlled at 0, 1000, 3000 and 5000 ppm. In this work, the corrosion parameters of polarization curves, such as corrosion potential (E_corr), corrosion current density (i_corr), and anodic and cathodic branch slopes (b_a and b_c), are presented and discussed in detail. In addition, the equivalent circuit models and ZsimpWin software were utilized to discuss the Nyquist plots. The plots showed that the E_corr values shifted in the positive direction as the HAc concentration increased. The i_corr values increased with the increase in HAc concentration, indicating that HAc could accelerate the corrosion. The impedance spectra measured at 30 and 60 °C have different time constants and characterization. The coverage fraction θ and the thickness L of corrosion film are two most important controlled variables that influence and control the CO₂ corrosion mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.