Steel In Acidic Environment Research Articles

Interactions and corrosion mitigation prospective of pyrazole derivative on mild steel in HCl environment

The effectiveness of 1H˗pyrazole˗3,5˗dicarboxylic acid 5˗benzyl ester 3˗phenyl ester (PCBPE) as a preventer for deterioration of IS 513 Gr. D steel in 1 M HCl medium is evaluated via weight loss, electrochemical impedance, and polarization techniques. Kinetic and thermodynamic parameters assessed the feasibility of the adsorption process at diverse temperatures. The inhibition action on mild steel has been enhanced with increasing PCBPE concentration. It is found from the polarization studies that PCBPE behaves as mixed type inhibitor in HCl medium. The adsorption process of PCBPE on mild steel surface from acid environment is favoured Langmuir adsorption isotherm. The shielding efficiency of PCBPE has been enhanced at elevated concentrations, and it has been diminished at amplified temperatures. The Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrum (EDS) were used to establish a surface characterization of metal specimens. A quantum chemical analysis of electron density distributions in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) demonstrated how the inhibitor undergoes adsorption on mild steel in 1 M HCl. All experimental findings substantiate the corrosion mitigation performance of PCBPE on mild steel in acidic environments.

Benzothiazolylhydrazine azomethine derivatives for efficient corrosion inhibition of mild steel in acidic environment: Integrated experimental and density functional theory cum molecular dynamics simulation approach

Synthesis of challenging corrosion inhibitors is of prime importance to inhibit hydrogen-induced and localised metallic corrosion occur in the corrosive acidic solution. In this regard, the present research has been focused on the development of functionalised Schiff bases, namely, 1-(benzo[d]thiazol-2-yl)-2-((furan-2-yl)methylene)hydrazine (BTFMH), 1-(benzo[d]thiazol-2-yl)-2-((thiophen-2-yl)methylene)hydrazine (BTTMH), 1-(benzo[d]thiazol-2-yl)-2-((5-methylthiophen-2-yl)methylene)hydrazine (BTMMH) with an aim of effectively curtailing the issues associated to hydrogen-induced cracking and subsequent inhibition of metallic corrosion taking place in the corrosive acidic solution. The corrosion inhibiting performances of the synthesized inhibitors have been assessed for mild steel surfaces exposed in 1 M HCl medium using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization study revealed that the synthesized inhibitor molecules retarded the cathodic hydrogen evolution reaction at cathodic site and subsequently minimized the oxidation of metals at anode; thereby, these Schiff bases acted as the mixed type inhibitors. The EIS study revealed that the corrosion inhibition phenomenon is being controlled through charge transfer processes. All of these three synthesized inhibitor molecules showed approximately 96–98 % corrosion inhibiting efficiency at exceedingly low concentration (0.5 mM). The inhibition efficacy obtained for these synthesized inhibitor molecules follows the order: BTMMH > BTTMH > BTFMH. The adsorption nature of these inhibitor molecules on mild steel surfaces have been revealed through surface morphology, topography and water contact angle studies. Thereafter, the insight of corrosion inhibition mechanism at atomic level have been explored by density functional theory (DFT). The optimized geometrical structure, electron density distribution of frontier molecular orbitals and their corresponding energy parameters obtained from DFT as well as Fukui indices analysis have been explored to unveil the plausible modes of adsorption or the reactive sites present within the inhibitor molecules which facilitate their interactions with surface atoms of metals. The non-covalent interaction based on reduced density gradient have been explored to study intrinsic feeble interaction acting with the molecules. Afterwards, molecular dynamics simulation has been employed to validate the spontaneity along with the nature of interaction at the metal inhibitor interface. Furthermore, the equilibrium adsorption configuration of the synthesized inhibitor molecules on the targeted metal surface atoms have been envisaged and the interfacial phenomenon has been explained.

Multidimensional analysis for corrosion inhibition by new pyrazoles on mild steel in acidic environment: Experimental and computational approach

Inhibition of mild steel (M.S) corrosion by some pyrazole-2-acetohydrazide derivatives, namely; ((E)-2-(3,5-dimethyl-1H-pyrazol-1-yl)-N'-(4-hydroxy-3-methoxybenzylidene)acetohydrazide (DHA) and (E)-2-(3,5-dimethyl-1H-pyrazol-1-yl)-N'-(furan-2-ylmethylene)acetohydrazide (DFA)) in 1 M HCl was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) measurements and Scanning Electron Microscopy (SEM) allowed M.S surface analysis. On the other hand, computational investigations (DFT and Monte-Carlo simulation (MCs), and Molecular dynamic simulations (MDs)) have been apprehended. The efficiency of inhibition increases as the concentration of inhibitor increases, and it also increases as the temperature increases. At a concentration of 10−3 M, the anti-corrosion performance of DHA was 97.6% and 85.9% for DFA, respectively, according to polarization measurements. PDP were used to obtain both anodic and cathodic inhibitions. The Langmuir isotherm was followed in the adsorption of DFA & DHA onto steel surfaces. Furthermore, when the inhibitor was present, SEM pictures exhibited better surface protection, which was matched with a molecular dynamic simulation that confirmed perfect surface alignment between the inhibitor and the M.S-surface. Experiments, DFT computations, MCs, and MDs are all in agreement.

Experimental, DFT and MC simulation analysis of Vicia Sativa weed aerial extract as sustainable and eco-benign corrosion inhibitor for mild steel in acidic environment

In the current investigation, the corrosion inhibition efficacy of a weed, Vicia Sativa has been investigated on the mild steel corrosion in 0.5 M HCl using weight-loss (WL) method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP) and scanning electron microscope (SEM) techniques, in addition to surface examination analysis. This investigation revealed Vicia Sativa extract (VSE) as a green and eco-benign corrosion inhibitor for mild steel in 0.5 M HCl corrosive solution demonstrated an inhibition efficiency (IE%) of 91.24% at 298K in presence of 1000 ppm of VSE. The results attained from EIS investigations indicated an enhancement in polarization resistance (Rp) from 55.78 Ω at 50ppm to 191.05 Ω at 1000ppm, affirming the inhibitive potential of the investigated inhibitor. Additionally, on increasing the concentration of VSE from 50ppm to 1000ppm, the values of icorr and corrosion rate (CR) decreased from 554.05 μA to 122 μA and 6.438mmy−1 to 1.4176mmy−1, demonstrating the excellent inhibition potential of VSE on the mild steel corrosion. Additionally, the cathode Tafel slope (βc) (from −142.76 to −153.24mV/dec) and anode Tafel slope (βa) (from 127.79 to 134.71mV/dec) values rarely altered when the inhibitor was introduced with increasing concentration from 50ppm to 1000ppm, showing that the process of hydrogen evolution stayed intact, revealing the inhibitor molecule adhesion on the metallic substrate which lessened the degree of active spots available for the reaction while sustaining the charge transfer process of hydrogen generation. Furthermore, integrated computational investigations, such as density functional theory (DFT) and Monte Carlo (MC) simulations confirms the potent inhibitory efficacy of VSE.

Green synthesis of zinc sulfide nanoparticles-organic heterocyclic polyol system as eco-friendly anti corrosion and anti-bacterial corrosion inhibitor for steel in acidic environment

ABSTRACT Green synthesis, characterization and evaluation of nanoscale zinc sulfide (ZnS) by precipitation chemical method. The zinc sulfide nanoparticles were prepared by chemical precipitation method using heterocyclic polyvinyl alcohol, PVA as a sensitizer. The prepared heterocyclic compounds system ZnS nanoparticles, PVA, EG were used as anti-bacterial corrosion towards sulfate-reducing bacteria (SRB) and anti-corrosion for carbon steel substrate in sulfuric acid and hydrogen sulfide bacterial corrosive environment using chemical, analytical, and electrochemical techniques. Effect of adding PVA, and ethylene glycol, EG to ZnS nanoparticles were studied. Effect of ZnS nanoparticles concentrations and the reaction temperature on the corrosion inhibition efficiency were studied. The inhibition due to adsorption of nanoparticles on steel surface, the adsorption agree well with Langmuir isotherm with suggested chemical adsorption mechanism. Potentiodynamic polarization (PD) and Electrochemical impedance spectroscopy (EIS) data explain that the used inhibitor is mixed-type and improves polarization resistance and inhibition performance by adhering to metal/electrolyte interface. The cathodic and anodic reactions are delayed when inhibitor molecules are added to an aggressive medium, which results in a negative shift in the open circuit potential. Addition of both PVA, and EG as organic polyol materials enhance the adsorption and inhibition properties of zinc sulfide nanoparticles on steel surface.

Newly Synthesized Morpholinyl Mannich Bases as Corrosion Inhibitors for N80 Steel in Acid Environment.

New Mannich bases, 3-morpholino-1-phenylpropan-1-one (MPO) and 3-morpholino-1-phenyl-3-(pyridin-4-yl) propan-1-one (MPPO), were synthesized, characterized, and studied as corrosion inhibitors for N80 steel in 1 M hydrochloric acid (HCl) solution using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and FT-IR spectroscopy. The inhibition efficiency increases with increasing inhibitor concentrations, and the corrosion inhibition efficiency of the MPO and MPPO could reach 90.3% and 91.4%, respectively, at a concentration of 300 ppm at 305 K. The effect of the temperature on the corrosion inhibition behavior of inhibitors was discussed. Electrochemical tests showed that the synthesized inhibitors are mixed. The EIS test results showed that the presence of MPO and MPPO reduced the double-layer capacitance in the corrosion process, thereby reducing the charge transfer resistance. The SEM and EDX results showed that the MPO and MPPO formed a uniform adsorption film on the surface of the N80 steel. The adsorption mechanism of the inhibitors was simulated with different adsorption models and the results showed that the inhibitors were the chemisorbed type. The results of the FT-IR spectroscopy proved that the inhibitor interacted with metal atoms on the steel surface.

Expired Dulcolax Drug as Corrosion Inhibitor for Low Carbon Steel in Acidic Environment

Expired Dulcolax Drug as Corrosion Inhibitor for Low Carbon Steel in Acidic Environment

A Brief Review on Fruit and Vegetable Extracts as Corrosion Inhibitors in Acidic Environments.

The corrosion of metals, i.e., the initiation and acceleration of the surface deterioration of metals through an electrochemical reaction with the surrounding intrusive environment, is a global concern because of the economic and environmental impacts. Corrosion inhibitors are considered the most practical choice among the available corrosion protection techniques due to their effectiveness in terms of functionality and cost. The use of traditional and toxic corrosion inhibitors has led to environmental issues, arousing the need for green counterparts that are environmentally friendly, easily accessible, biodegradable, and cost-effective. In this review, the utilization of green corrosion inhibitors purely acquired from renewable sources is explored, with an in-depth focus on the recent advancements in the use of fruit and vegetable extracts as green corrosion inhibitors. In particular, fruits and vegetables are natural sources of various phytochemicals that exhibit key potential in corrosion inhibition. To shed light on the true potential of such extracts in the protection of steel in acidic environments, the experimental techniques involved in corrosion inhibition and the mechanism of corrosion inhibition are discussed in detail. The study highlights the potential of fruit and vegetable extracts as non-toxic, economical, and effective corrosion inhibitors in the pursuit of green chemistry. In addition to discussing and outlining the current status and opportunities for employing fruit and vegetable extracts as corrosion inhibitors, the current review outlines the challenges involved in the utilization of such extracts in corrosion inhibition.

Multidimensional analysis for corrosion inhibition by Isoxsuprine on mild steel in acidic environment: Experimental and computational approach

This study investigates the impact of Isoxsuprine hydrochloride drug on mild steel corrosion in a 1.0 M HCl solution by employing weight loss, electrochemical methods, surface morphological techniques, and finally validated with theoretical studies like quantum calculation and MD simulation. Inhibitory efficacy of Isoxsuprine hydrochloride came out to be ∼ 97 % at 2000 ppm concentration. The analysis demonstrated the increase in the inhibition efficiency with the rising concentration of inhibitor and decreasing effectiveness with increased temperature. Thermodynamic parameters were also investigated by utilizing the data obtained from temperature. Potentiodynamic polarization validated that the Isoxsuprine hydrochloride retarded the cathodic as well as anodic reactions. During the adsorption process, the Isoxsuprine hydrochloride molecules followed the Langmuir adsorption isotherm. Theoretical calculations like quantum chemical calculation and molecular dynamics simulation also confirms excellent adsorption of Isoxsuprine hydrochloride on the metallic sample. The results from all of the different methods were consistent.

Performance evaluation of newly synthetized bi-pyrazole derivatives as corrosion inhibitors for mild steel in acid environment

Two new synthesized bi-pyrazole-carbohydrazides, namely 1,1′-(propane-1,3-diyl)bis (5-methyl-1H-pyrazole-3-carbohydrazide) (P2PZ) and 1,1′-(oxy bis (ethane -2,1-diyl)) bis (5-methyl-1H-pyrazole-3- Carbohydrazide) (O2PZ) were evaluated as corrosion inhibitors for mild steel (MS) in 1.0 M HCl media. Comparative study of inhibitory action of P2PZ and O2PZ was conducted first using mass loss and electrochemical measurements (potentiodynamic polarization curves, PPC, and electrochemical impedance spectroscopy, EIS) and it had shown that P2PZ outperforms O2PZ. The electrochemical studies showed a corrosion inhibition efficiency of 95% and 84% at 308 K and 10−3 mol/L of P2PZ and O2PZ, respectively. Their efficiency augmented with augmentation of concentration and decreased with augmentation of temperature. Electrochemical impedance spectroscopy showed that the corrosion inhibition followed a charge transfer process. Polarization curves suggested that the P2PZ and O2PZ acted as mixed-type inhibitors and followed the Langmuir adsorption isotherm. The free energy of adsorption (ΔGads) values, which lie within the range of -39.94 to -37.36 KJ mol−1, confirmed a physicochemical adsorption process. Scanning electron microscope (SEM) images indicated the formation of a protective layer on the surface of the metal in the presence of both inhibitors. Density Functional Theory (DFT) and molecular dynamics (MD) simulation have been introduced to carry out a theoretical investigation of the inhibitors’ reactivity and interaction with the iron surface, respectively. The comparative study based on experimental and theoretical results showed that the trend of inhibition potentials of tested inhibitors depends on their electron-donating/accepting abilities. The trend of reactivity of molecules P2PZ and O2PZ matched well with experimental results.

Protoporphyrin Extracted from Biomass Waste as Sustainable Corrosion Inhibitors of T22 Carbon Steel in Acidic Environments

Carbon steel is one of the most employed materials in many industrial sectors due to its unique physical and mechanical properties. However, within a certain period of time, carbon steel-based materials are susceptible to corrosion under operating conditions and corrosion inhibitors are important to extending the limit of use of carbon steel. In this study, the influence of protoporphyrin from animal blood hemin as an eco-friendly corrosion inhibitor for T22 carbon steel in an acidic environment (0.5 M HCl) was conducted. The hemin isolated from animal blood extracts was modified to obtain the protoporphyrin. The dosage of protoporphyrin was varied between 40 and 200 ppm and the temperature influence were studied in the range of 298–318 K. The inhibition efficiency of protoporphyrin in 0.5 M hydrochloric acid reached up to 46.2% at a dose of 160 ppm at a temperature of 298 K. The inhibition efficiency (IE) value further decreases with increasing temperature, thereby showing the process exothermic in nature and the weakening of the inhibitor molecules to adsorb on the surface of the T22 carbon steel. The potentiodynamic polarization measurements indicate that protoporphyrin acts as a mixed-type inhibitor. The adsorption of protoporphyrin on the surface of T22 carbon steel obeys the Langmuir adsorption isotherm. The thermodynamic parameter of adsorption allows us to suggest the adsorption process was dominated by physical adsorption. Thus, these current results present a case study using protoporphyrin as a promising green inhibitor for carbon steel T22 in hydrochloric acid prepared from livestock waste.

Evaluation of the anticorrosion performance of Tamsulosin as corrosion inhibitor for pipeline steel in acidic environment: experimental and theoretical study

The inhibition performance of expired Tamsulosin (TAM) was studied on St52 pipeline steel in 1 M HCl by gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopic analysis. It was seen that the presence of the studied expired drug decreased the corrosion rate of the pipeline steel. TAM’s efficiency as an inhibitor increased as its concentration increased but decrease with temperature rise. The expired drug showed maximal inhibition efficiency of 98.1% from weight loss measurement at 2.0 × 10−3 M TAM concentration and 303 K. PDP results showed that TAM acted as a mixed-type inhibitor. The adsorption study revealed that Langmuir isotherms gave the best fit. The surface morphological study revealed that TAM formed an adsorbed protective layer on the St52 steel surface in the acid medium. The theoretical study performed using the density functional theory (DFT) allowed correlation with an experimental study.

Amide Compounds as Corrosion Inhibitors for Carbon Steel in Acidic Environment

Amide Compounds as Corrosion Inhibitors for Carbon Steel in Acidic Environment

2-(2,4-Dimethoxybenzylidene)-N-Phenylhydrazinecarbothioamide as an Efficient Corrosion Inhibitor for Mild Steel in Acidic Environment

In this work, a new Schiff base, namely 2-(2,4-dimethoxybenzylidene)-N-phenylhydrazinecarbothioamide (DP), was synthesized and fully characterized by some spectroscopical techniques (Fourier Transform Infrared (FT-IR), and Nuclear Magnetic Resonance (1H-NMR and 13C-NMR) in addition to micro elemental analysis-CHN. The newly synthesized corrosion inhibitor was evaluated for its corrosion inhibition performance on mild steel coupons in 1 M hydrochloric acid solution by using gravimetric techniques. The experimental findings of weight loss measurements revealed that the inhibition efficiency increased with the DP concentration and reached a maximum value of 94.8% at the 0.005 M concentration but decreased with reducing temperature (at temperatures ranging from 303 to 333 K). Moreover, the significant inhibition efficiency and the value of ΔGo indicated that DP participates in Chemisorption and Physisorption on the mild steel surface. The adsorption process of the synthesized inhibitor on a mild steel surface follows Langmuir adsorption isotherm. The uninhibited and inhibited surface morphology of the mild steel coupons was investigated using scanning electron microscopy (SEM).

Anticorrosion activity of 2-thiоhуdantoin-Shiff base derivatives for mild steel in 0.5 M HCl

Several 2-thiohyd?nt?in?Shiff base derivatives were prepared as ecofriendly corrosion inhibitors for mild steel in acid environment. Their anticorrosion properties were studied on mild steel in 0.5 M HCl solution as corrosion electrolyte by using usu?l gr?vim?tri? and different el??tr??hemic?l techniques (w?ight l?ss m??sur?m?nt, p?t?nti?dyn?mi? p?l?riz?ti?n and p?t?nti?st?ti? ?l??tr??h?mic?l imp?d?n?? s???tr?sc???). Mild steel surface was characterized using two analytical techniques, scanning electron microscopy for surface morphology and elemental composition and atomic force microscopy. The study has shown that the inhibiting action of these environmentally benign inhibitors synthesized from inexpensive commercially available starting materials could be attributed to adsorption on the metal surface.

Corrosion mitigation for steel in acid environment using novel p-phenylenediamine and benzidine coumarin derivatives: synthesis, electrochemical, computational and SRB biological resistivity.

Three novel p-phenylenediamine and benzidine coumarin derivatives were synthetized, namely: 4,4'-((((1,4-phenylenebis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-diyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (PhODB), 4,4'-(((-([1,1'-biphenyl]-4,4'-diylbis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-diyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (BODB) and 4,4'-(((-((3,3'-dimethoxy-[1,1'-biphenyl]-4,4'-diyl)bis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-iyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (DODB). Their chemical structures were proved by performing Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance and mass spectrometry analysis. The synthesized p-phenylenediamine and benzidine coumarin derivatives were tested as corrosion inhibitors for mild steel (MS) in 1 M HCl solution using weight loss, electrochemical, morphological, and theoretical studies. The compound 3,3'-dimethoxy benzidine coumarin derivative (DODB) was proved to give the highest efficiency with 94.98% obtained from weight loss measurements. These compounds are mixed inhibitors, as seen by the polarization curves. Impedance diagrams showed that when the concentration of these derivatives rose, the double-layer capacitance fell and the charge transfer resistance increased. Calculated thermodynamic parameters were computed and the mechanism of adsorption was also studied for the synthesized p-phenylenediamine and benzidine coumarin derivatives. The ability of the synthesized derivatives to protect the surface against corrosion was investigated by scanning electron microscope (SEM), UV-visible spectroscopy and energy dispersive X-ray spectroscopy (EDX). Theoretical chemical calculations (DFT) and biological resistivity (SRB) were investigated.

Corrosion inhibition, adsorption behaviour, and thermodynamic studies of red dragon fruit (Selenicereus costaricensis) waste peel extracts on mild steel in acidic environment

Metal corrosion is brought about by the oxidation of atoms on the surface resulting in irreversible damage to structures at staggering costs. Hence, the search for efficient and cost-effective corrosion inhibitors is relevant. In this study, the ethanolic extract of Red Dragon Fruit (Selenicereus costaricensis) waste peels (RDF) has been tested for its anti-corrosion property using the weight loss method at different temperatures (303-343 K). The calculated inhibition efficiency of 2% RDF is 97%. Thermodynamic studies reveal that increasing inhibitor concentration raises the activation parameters of mild steel in acidic media such as activation energy (Ea) and changes in enthalpy (Ho) and entropy (So). Moreover, increased immersion time, inhibitor concentration, and temperature led to increased inhibition efficiency. The spontaneous process (Go ads = -23.47 kJ/mol) of adsorption of RDF on mild steel surfaces obeys the Langmuir isotherm model. Lastly, optical microscopy of the inhibited and uninhibited systems confirms the potential of the RDF against pitting corrosion.

Failure analysis in API X70 pipeline steel in sour environment with an emphasis on fracture surfaces and crack propagation

The aim of this study is to investigate the fracture surfaces and crack propagation in an API X70 pipeline steel in acidic environment. To this purpose, as-received and electrochemically hydrogen-charged tensile specimens are subjected to tensile testing. Moreover, EBSD measurements were carried out on the cross section (RD-ND plane) in as-received and hydrogen-charged specimens. The results showed that hydrogen charging and strain rate of tensile testing were considered as two effective parameters in determining the type of fracture. Moreover, the fracture of the uncharged specimens was quite ductile and the strain rate had little effect on the fracture type. A direct correlation was found between type of fracture and the strain rate in hydrogen-charged specimens. With increasing strain rate, the fracture in hydrogen-charged specimens did not have enough time to initiate from inclusions and precipitates and connect to the main fracture surface. <001>∥ND oriented grains have the highest hydrogen atoms due to the largest interatomic space and the distortion energy accumulated at grain boundaries due to the lack of sufficient activated slip system. The variation of KAM distribution to higher values of hydrogen-charged specimen could be effectively associated to the formation of dislocation walls and dislocation tangles especially in the vicinity of bcc grain boundaries. The higher volume fraction of the grains with high Taylor factor data formed in the hydrogen-charged specimen were highly susceptible to plastic instability, enhancing the crack propagation.

Synthesis, characterization of novel coumarin dyes as corrosion inhibitors for mild steel in acidic environment: Experimental, theoretical, and biological studies

The new azo acetyl coumarin derivatives were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and mass spectral studies. The ability for these three dyes to act as corrosion inhibitors for mild steel in 1.0 M HCl was confirmed by potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). The state of mixed adsorption with the PP effect is shown. The azo acetyl coumarin derivatives showed the strongest corrosion inhibition of 85.29–93.01% at a corrosion of 7.5 × 10−4 M. Adsorption of the inhibitory molecules on the mild steel surface followed Langmuir adsorption isotherm. The adsorption phenomenon was verified using UV–Vis, scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) technique, whereas FTIR confirmed the presence of several functional groups containing heteroatoms. Also, quantum chemical parameters, inductively coupled plasma atomic emission spectroscopy, and the anti-bacterial effect of these new derivatives against sulfate reducing bacteria (SRB) were studied. All obtained results ensure that these derivatives can form an effective blocking layer and control the corrosion process.

Dispersive interactions in the adsorption and corrosion inhibition effects of Alstonia boonei on mild steel in acidic environments

PurposeThe purpose of this paper is to study the adsorption properties of a proven traditional medicine of West Africa origin, Alstonia boonei with an attempt to evaluate its application in the corrosion protection of mild steel in 5 M H2SO4 and 5 M HCl.Design/methodology/approachPhytochemical screening and Fourier transform infrared spectroscopy analysis were used to characterize the methanolic extract of the plant. Gravimetry, gasometry and electrochemical techniques were used in the corrosion inhibition studies of the extract and computational studies were used to describe the electronic and adsorption properties of eugenol, the most abundant phytochemical in Alstonia boonei.FindingsThe extract acted as a mixed-type inhibitor in both acidic solutions, with improved inhibition efficiency achieved with increasing concentration. While the efficiency increased with temperature for the HCl system, it decreased for the H2SO4 system. The mechanism of adsorption proposed for Alstonia boonei was chemisorption in the HCl system and physisorption in the H2SO4 system, and the adsorptions obeyed Langmuir isotherm at low temperatures. Computational parameters showed that eugenol, being a representative of Alstonia boonei, possesses excellent adsorption properties and has the potential to compete with other established plant-based corrosion inhibitors.Research limitations/implicationsAs opposed to pure compounds with distinctive corrosion effects, plant extracts are generally composed of a myriad of phytoconstituents that competitively promote or inhibit the corrosion process and their net effect is evident as inhibition efficiencies. This is, therefore, the main research limitation associated with the corrosion inhibition study of Alstonia boonei.Originality/valueBeing very rich in antioxidant properties by its proven curative and preventive effects for diseases, the interest was stimulated towards the attractive results that abound from its corrosion protection of metals via its anti-oxidation route.