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

Corrosion inhibition on mild steel in 1 M HCl solution byCryptocarya nigraextracts and three of its constituents (alkaloids)

Corrosion inhibition effect of the crude extracts (hexane, dichloromethane, methanol) from the bark of Cryptocarya nigra and three alkaloids named N-methylisococlaurine 1, N-methyllaurotetanine 2 and atherosperminine 3 isolated from the Cryptocarya nigra dichloromethane extract (CNDE) were investigated for mild steel corrosion in 1 M HCl solution. An electrochemical impedance study showed that CNDE and 2 reduced the corrosion significantly through a charge transfer mechanism with inhibition efficiency of 91.05% and 88.05%, respectively. Potentiodynamic polarization data indicated that CNDE acted through anodic type inhibition while 2 was a mixed type inhibitor with predominant anodic effectiveness. ΔG_ads values calculated from the Langmuir adsorption isotherm plots for CNDE (−28.2 kJ mol⁻¹) and 2 (−13.2 kJ mol⁻¹) suggested that they adsorbed on the mild steel surface via a physisorption mechanism. Scanning electron microscopy micrographs and elemental composition studies confirmed the formation of a protective film over the metal surface. Wastewater quality parameters of all the inhibitors demonstrated good biodegradability as their values were within the permissible limits to discharge for irrigation and horticultural uses.

Staggered and systematic arrangement of N-methyllaurotetanine 2 on the MS surface.

Analyses of New Electrochemical Techniques to Study the Behavior of Some Corrosion Mitigating Polymers on N80 Tubing Steel

Two synthesized polymers were studied as potential corrosion inhibitors for N80 Steel in a sweet corrosive environment. Poly-2-(methacryloyloxy)ethyltrimethyl ammonium chloride (PDMC), or P1, and poly-2-(methacryloyloxy)ethyltrimethyl ammonium chloride-co-N-vinyl-2-pyrrolidone P(DMC-co-NVP), or P2, were investigated using electrochemical impedance spectroscopy, polarization technique, scanning electrochemical microscopy (SECM), scanning Kelvin probe (SKP), and scanning vibrating electrode technique (SVET). The surface was examined using contact angle, scanning electron microscopy, and atomic force microscopy methods. Analyses of electrochemical and polarization techniques revealed a PDMC polymer with a better inhibition efficiency. The SECM, SKP, and SVET methods showed the insulating ability of the polymers that formed a protective coating on the metal surface.

Adsorption characteristics and inhibition effect of two Schiff base compounds on corrosion of mild steel in 0.5 M HCl solution: experimental, DFT studies, and Monte Carlo simulation

In this work, we report the synthesis of two Schiff bases of substituted gallic acid derivatives via amidation reaction and their characterization using ¹H-NMR spectroscopy to study their inhibition performance on the aggressive attack of HCl on mild steel (MS). The inhibitive performance was examined using chemical (weight loss) and electrochemical (Tafel and EIS) test methods. The results indicate that these derivatives significantly suppress the dissolution rate of mild steel via adsorption phenomena, which correlates to the Langmuir adsorption model. Tafel data display the mixed-type properties of these compounds and EIS results show that increasing Schiff base concentration not only leads to delaying the charge transfer (R_ct) of iron from 26.4 ohm cm⁻² to 227.7 ohm cm⁻² but also decreases the capacitance of the adsorbed double layer (C_dl) from 8.58 (F cm⁻²) × 10⁻⁵ to 2.55 (F cm⁻²) × 10⁻⁵. The inhibition efficiency percentage reaches the peak (90%) at optimum concentration of 250 ppm. The Monte Carlo simulations confirm the adsorption ability of the as-prepared compounds on the Fe (1 1 0) crystal. The SEM/EDX results revealed the presence of a protective film on the mild steel sample.

Structures of the synthesized Schiff bases inhibitor.

Application of Unsaturated Fatty Acid Molecules Derived from Microalgae toward Mild Steel Corrosion Inhibition in HCl Solution: A Novel Approach for Metal-Inhibitor Association

Fatty acid molecules 9,12,15-octadecatrienoic acid (C18:3), 9,12-octadecadienoic acid (C18:2), and hexadecanoic acid (C16:0) possessing active functional groups with the capability of fast electron transfer have been established for effective corrosion inhibition of mild steel. In this regard, a microalga Scenedesmus sp. is isolated and its fatty acids have been studied to corroborate the adsorption behavior, attributing the anticorrosion efficacy on mild steel in 1 M HCl solution by forming metal-inhibitor framework. Electrochemical analysis has been used to ascertain the surpassing corrosion inhibition efficiency at an optimal concentration of 36 ppm with maximum 95.1% inhibitive performance. The results of metallography with or without the inhibitor molecules have indicated significant changes in surface morphology of mild steel specimen for gradual enhancement in immersion time (72 h). Hydrogen evolution reaction has been emphasized to observe the tendency of significant decrease in the bubble formation in the presence of inhibitor compared to 1 M HCl solution only. Surface morphometric studies (scanning electron microscopy and atomic force microscopy) have also revealed the excellent adsorption capacity of Scenedesmus fatty acids on metal surface. Quantum chemical calculations, performed by density functional theory, determined significant adsorption effectiveness, based on the donor-acceptor capability between metallic surface and inhibitor molecules.

Corrosion Performance of Nano-ZrO₂ Modified Coatings in Hot Mixed Acid Solutions

A nano-ZrO₂ modified coating system was prepared by incorporation of nano-ZrO₂ concentrates into phenolic-epoxy resin. The corrosion performance of the coatings was evaluated in hot mixed acid solution, using electrochemical methods combined with surface characterization, and the effects of nano-ZrO₂ content were specially focused on. The results showed that 1% and 3% nano-ZrO₂ addition enhanced the corrosion resistance of the coatings, while 5% nano-ZrO₂ addition declined it. The coating with 3% nano-ZrO₂ presented the minimum amount of species diffusion, the lowest average roughness (5.94 nm), and the highest C/O ratio (4.55) and coating resistance, and it demonstrated the best corrosion performance among the coating specimens.

SECM/SKP and SVET studies on mitigation of N80 steel corrosion by some polymers

Three polymers, namely PAMPS (P1), P(AMPS-co-NVP) (P2) and P(AMPS-co-DMC) (P3), synthesized by common solution polymerization were investigated as corrosion inhibitors for N80 steel in 3.5 wt% NaCl flooded with CO₂.

Theoretical, thermodynamic and electrochemical analysis of biotin drug as an impending corrosion inhibitor for mild steel in 15% hydrochloric acid

The corrosion mitigation efficiency of biotin drug for mild steel in 15% hydrochloric acid was thoroughly investigated by weight loss and electrochemical methods. The surface morphology was studied by the contact angle, scanning electrochemical microscopy, atomic force microscopy and scanning electron microscopy methods. Quantum chemical calculation and Fukui analysis were done to correlate the experimental and theoretical data. The influence of the concentration of inhibitor, immersion time, temperature, activation energy, enthalpy and entropy has been reported. The mitigation efficiency of biotin obtained by all methods was in good correlation with each other. Polarization studies revealed that biotin acted as a mixed inhibitor. The adsorption of biotin was found to obey the Langmuir adsorption isotherm. Surface studies showed the hydrophobic nature of the steel with inhibitor and vindicated the formation of a film on the metal surface that reduced the corrosion rate.

Heterocyclic Corrosion Inhibitors for J55 Steel in a Sweet Corrosive Medium

The inhibitory effect of two heterocyclic porphyrin compounds, specifically 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin palladium(II) (PF-1) and 4,4',4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (PF-2), was studied in a sweet corrosion environment (3.5 wt % NaCl + CO₂) on J55 steel by means of weight loss and electrochemical methods. Surface changes were studied using contact angle, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM) techniques. It was established that PF-2 showed the superlative inhibition efficiency of average of about 93% at 400 ppm concentration. The inductive behavior of the J55 steel surface in the presence of inhibitors was confirmed by SECM. The AFM further confirmed that the surface roughness was considerably decreased in the presence of porphyrins. The surface wettability of the steel was also investigated, and the results established the formation of a water-repellant layer on the surface when porphyrins are absorbed and layer became more hydrophobic with PF-2. Thermodynamics studies showed that the inhibition efficiencies of two compounds evaluated by all measurements follow the Langmuir adsorption isotherm.

Adsorption and corrosion inhibition properties of N-{n-[1-R-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-3-yl]phenyl}methanesulfonamides on mild steel in 1 M HCl: experimental and theoretical studies

The experimental corrosion inhibition properties were supported by detailed theoretical studies that revealed the dependence of protection efficiency on proton affinity.

Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO₂ by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (HPTB), 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin (T4PP), 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrakis(benzoic acid) (THP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) was studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM) techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR) were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their E_HOMO, E_LUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

Corrosion Inhibition of Carbon Steel in HCl Solution by Some Plant Extracts

The strict environmental legislations and increasing ecological awareness among scientists have led to the development of “green” alternatives to mitigate corrosion. In the present work, literature on green corrosion inhibitors has been reviewed, and the salient features of our work on green corrosion inhibitors have been highlighted. Among the studied leaves, extractAndrographis paniculatashowed better inhibition performance (98%) than the other leaves extract.Strychnos nuxvomicashowed better inhibition (98%) than the other seed extracts.Moringa oleiferais reflected as a good corrosion inhibitor of mild steel in 1 M HCl with 98% inhibition efficiency among the studied fruits extract.Bacopa monnierishowed its maximum inhibition performance to be 95% at 600 ppm among the investigated stem extracts. All the reported plant extracts were found to inhibit the corrosion of mild steel in acid media.