Percentage Inhibition Efficiency Research Articles

Response surface methodology and experimental evaluation of the inhibitory properties of corn leaf extract for aluminum corrosion in acid media

Purpose This study aims to develop eco-friendly corrosion inhibitors for aluminum in acidic media by evaluating the corrosion inhibition properties of corn leaf extract (CLE) using response surface methodology (RSM) and experiments. Design/methodology/approach The RSM was combined with experiments to evaluate the corrosion inhibition properties of CLE on aluminum in acid media. Findings The effectiveness of the inhibition increased with increasing inhibitor concentration and time but decreased with increasing temperature. The corrosion inhibition mechanism revealed the corrosion process is spontaneous exothermic physical adsorption. Thermodynamic parameters revealed an activation energy between 32.1 and 24.7 kJ/mol, energy of adsorption between −14.53 and −65.07 and Gibbs free energy of −10.12 kJ/mol which indicated the CLE exothermically spontaneously physisorbed. A model was generated to estimate the effect of the process parameters (inhibitor concentration, reaction time and temperature) using the RSM. Optimization of the process factors was also carried out using the RSM. The percentage inhibition efficiency obtained experimentally (85.61%) was closely comparable to 84.89% obtained by the theoretical technique (RSM). The SEM observations of the inhibited and uninhibited Al samples demonstrated that CLE is an effective corrosion inhibitor for aluminum in acid media. Originality/value Results herein provide novel information on the possible application of CLEs as effective eco-friendly corrosion inhibitors.

Efficiency of some inhibitors on alpha amylase of the peach fruit fly larvae Bactrocera zonata (Saunders) (Diptera: Tephritidae)

Alpha amylase inhibitor (α-AI) extracted from wheat grains (Triticum sp.) as possible new agent in pest control, and some other organic inhibitors are evaluated against α-amylase of the fourth larval instar of the peach fruit fly (PFF) larvae; Bactrocera zonata (Saund.). 4.2 mg protein ml−1 of the inhibitor extracted by 70 % ammonium sulphate inhibited, in vitro, 97.9 % of amylolytic activity of the larvae. Percent inhibition efficiency (Ei%) of the crude inhibitor was directly proportional with its concentration in the range from 4.2 to 0.21 mg protein ml-1. The calculated IC50 was 1 mg protein ml-1. Increasing of the surrounding temperature from 10 to 35 °C not enhanced inhibitor efficiency, and the inhibitor could inhibit the enzyme efficiently at a relatively low temperature (10 °C). On the other hand, wheat extract showed quick binding affinity to α-amylase of PFF larvae. Incubation of the inhibitor with the enzyme for 10 min was sufficient for wheat α- AI to exert its maximum inhibition. Screening of other possible organic compounds act as α-AI such as citric, gallic and acetic acids showed that gallic acid was the most potent inhibitor, and it was able to inhibit α-amylase of the larvae, at a relatively, low concentration (10−4M). It could be concluded that there are natural potent inhibitors of PFF α-amylase which act as a key enzyme for carbohydrates digestion. This might be useful as an alternative method for controlling B. zonata population. Additional experiments are necessary to make these alternative compounds applicable in the field.

Unravelling adsorption potential of expired clindamycin as corrosion inhibitor at mild Steel/HCl interface via response surface methodology, artificial neural network, electrochemical, and computational strategies

Corrosion has produced unprecedented disintegration of metals, constituting an imminent danger to mankind and triggering catastrophic global economic losses. The effectiveness of expired clindamycin (ECLI) as a low-cost corrosion control agent for mild steel was investigated utilising response surface methodology (RSM), artificial neural network (ANN), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), quantum chemical computation (QCC), and molecular dynamic simulation (MDS) studies in conjunction with thermometric and gasometric protocols at different HCl concentrations. The RSM model demonstrated an outstanding level of accuracy in predicting the mild steel corrosion inhibition efficiency (IE), the volume of hydrogen gas (VHG), reaction number (RN), and corrosion rate (CR). The model was significantly influenced by the operational parameters that were investigated, such as temperature (299–333 K), ECLI concentrations (100–500 mg/L), immersion time (1–6 h), and acid concentration (0.5–2.5 M). It was observed that as ECLI concentration increases, the VHG, RN, and CR decreased per time as well as % IE increased. The thermometric, gasometric, PDP, and EIS results showed percentage inhibition efficiency of 69.10, 69.49, 83.17, and 77.87 %, respectively. PDP revealed that ECLI operates as a mixed type of inhibitor, and EIS indicated that the inhibition process involves charge transfer. The Langmuir isotherm suits better and accurately describes the ECLI adsorption process on mild steel. The electron transfer propensity of the ECLI on the metal surface is measured by QCC using the DFT approach. MDS was implemented to establish the optimal adsorption orientation between ECLI and Fe (110). The inspection of surface morphology by SEM displayed the formation of a blanket-like layer on the steel by ECLI. To validate the experimental results, RSM and ANN prediction models were utilised, which were evaluated using a normal plot of residual, predicted versus actual, and residual versus run, and were found to be effective modelling tools. This study illustrates that ECLI can be utilised as a potent and affordable mild steel inhibitor, even at high acid concentrations.

Insights into the corrosion resistance of Thaumatococcus daniellii on carbon steel in simulated sea water: Experimental and machine learning prediction

The present work compared the predictive abilities of response surface methodology (RSM) and adaptive neuro fuzzy inference systems (ANFIS) in modeling of carbon steel corrosion inhibition by Thaumatococcus daniellii leaf extract (TDE). Thaumatococcus daniellii leaf extract was examined using Fourier Transform Infrared Spectroscopy (FTIR) methods which revealed that the phytochemical components present in TDE has high-value flavonoids, tannins, and dominating functional groups needed to support long-term corrosion inhibition. Error indices revealed the superiority of ANFIS (R2 = 0.99443) and RSM (R2 = 0.98932) in predicting the inhibition efficiency of carbon steel corrosion, while statistical metrics confirmed the application of RSM and ANFIS techniques in modeling the corrosion inhibition of carbon steel. Weight loss and electrochemical, methods were used to validate the predictive abilities of RSM and ANFIS. In addition, the carbon steel surface was examined post immersion using fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and atomic force microscopy (AFM). According to the results, the optimal values of the percentage inhibition efficiencies (IE%) of TDE from weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) were found to be in close relationship as 88 %, 86 %, and 81 %, respectively, at a concentration of 2.0 g/L. TDE was confirmed to function as a mixed-type corrosion inhibitor according to potentiodynamic polarization results. The results of the machine learning are in line with the experimental findings.

Construction, Characterization, DFT Computational Study, and Evaluation the Performance of Some New N-Amino Pyridinone Schiff Base Catalyzed with Ceric(IV) Ammonium Nitrate (CAN) as Corrosion Inhibitors in Some Petroleum Applications

In this paper, two novel organic inhibitors, TAP-TPP and TAP-CEQ, were prepared via Schiff base condensation as a green chemistry methodology using an eco-friendly catalyst, ceric ammonium nitrate, with a high yield (87% and 91%), and characterized via elemental analysis, FTIR, 1H, and 13C NMR spectroscopic analysis tools. Weight loss assessment was utilized as a chemical testing method, and the maximum inhibition efficiency of TAP-TPP and TAP-CEQ is 89.4% and 91.8%, respectively. PDP and EIS were electrochemical measures to determine the efficacy of both inhibitors as anticorrosion for carbon steel alloys in 2 M HCl aggressive media. The collected electrochemical results demonstrated that both inhibitors behaved as excellent anticorrosion agents for metallic constructions. According to the potentiodynamic polarization (PDP) analysis, these organic inhibitors worked as mixed-type inhibitors. The adsorption isotherm revealed that undertaken compounds obeyed Langmuir adsorption isotherm with the free energies of adsorption of ranged from ΔG = − 34.29 to − 34.63 kJ Mol−1. Also, electrochemical impedance spectroscopy (EIS) data confirmed that the values charge transfer resistance (Rct) was increased by increasing the concentration of the injected inhibitor molecules. In contrast, the electrochemical double layer (Cdl) was dramatically decreased. The work was supported by two-surface analysis methods such as SEM and EDX. For more details, the values of percentage inhibition efficiency can be ordered as follows: TAP-CEQ > TAP-TPP. Finally, a suitable inhibition mechanism and theoretical studies including EHOMO, ELUMO, diploe moment (µ), and electrophilicity index (ω) were assumed and discussed in detailed.

Inhibition of zinc corrosion by glycerol stearate in 1.0M hydrochloric acid medium with experimental, theoretical, and electrochemical techniques

Glycerol Stearate (GS) was investigated as a corrosion inhibitor via weight loss on zinc (Zn) metal inside 1.0M hydrochloric acids (HCl). Different electrochemical techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and characterization methods were used in the study. Weight loss measurements and inhibition efficiency (IE) were used to calculate the amount of weight loss and to scrutinize the effect of inhibition concentration on the metal in HCl, and it demonstrated that weight loss decreased as the inhibition concentration increased, and percentage inhibition efficiency increased with increasing inhibition concentration. The Corrosion rate () was calculated, and it was observed that it decreased with the increasing inhibition concentration but increased with an increase in temperature. The compound of inhibitor effectively prevented corrosion by becoming adsorbed to the metal surface and was confirmed by Fourier transform infrared spectroscopy (FTIR). Free Gibbs energy (FGE) demonstrated a spontaneous corrosion process at the metal surface of zinc and the scanning electron microscope (SEM) was used to investigate the surface morphology of the protective layer and confirmed that the adsorption of glycerol stearate was via physisorption adsorption. The adsorption of glycerol stearate on the metal surface was found to follow the Langmuir adsorption isotherm model.

Investigation of synthesized ethyl-(2-(5-arylidine-2,4-dioxothiazolidin-3-yl) acetyl) butanoate as an effective corrosion inhibitor for mild steel in 1 M HCl: A gravimetric, electrochemical, and spectroscopic study

The corrosion inhibition effects of five concentrations (5E-5 M to 9E-5 M) of ethyl-(2-(5-arylidine-2,4-dioxothiazolidin-3-yl) acetyl) butanoate, a novel thiazolidinedione derivative code named B1, were investigated on mild steel in 1 M HCl using gravimetric analysis, electrochemical analysis and Fourier transform infrared spectroscopy. After synthesis and purification, B1 was characterized using nuclear magnetic resonance spectroscopy. All gravimetric analysis experiments were carried out at four different temperatures: 303.15 K, 313.15 K, 323.15 K and 333.15 K, achieving a maximum percentage inhibition efficiency of 92% at 303.15 K. The maximum percentage inhibition efficiency obtained from electrochemical analysis, conducted at 303.15 K, was 83%. Thermodynamic parameters such as ΔG°ads showed that B1 adsorbs onto the MS surface via a mixed type of action at lower temperatures, transitioning to exclusively chemisorption at higher temperatures.

Ionic liquid as an effective green inhibitor for acid corrosion of aluminum composite: experimental and theoretical considerations

Results of anticorrosive performance of ionic liquid 1-methyl-1-propyl-piperidinium bromide (MPPB) on corrosion of 6061Al-10vol% SiC composite (Al-MMC) in 0.05 M HCl solution. Electrochemical techniques were adopted to study corrosion and corrosion inhibition rates. Experiments were conducted in the temperature range of 308–323 K by varying concentrations of MPPB. Conditions were standardized to accomplish maximum inhibition efficiency. Kinetic parameters were evaluated. Results were fitted into various adsorption isotherm models and they fitted best into the Langmuir adsorption isotherm. Using data from adsorption isotherms, thermodynamic parameters were calculated. The surface morphology was examined by energy-dispersive X-ray spectroscopy (EDAX), atomic force microscope (AFM), and scanning electron microscope (SEM). FTIR–spectra and X-ray diffraction (XRD) studies were performed to reaffirm the adsorption of MPPB. Adsorption of the inhibitor and mechanistic aspects of corrosion inhibition were supported and supplemented by quantum chemical calculations using density functional theory (DFT). The investigation revealed that percentage inhibition efficiency (% IE) improved with the increase in the concentration of MPPB, while it decreased with a rise in temperature. Maximum efficiency of 60% was observed with 400 ppm MPPB at 308 K. MPPB acted as a mixed inhibitor, obeyed the Langmuir adsorption model, and the mode of adsorption was physisorption. Quantum chemical calculations validated the results of the adsorption study.Graphical abstract

Ptychostomum schleicheri (Bryophyta) Ekstraktının Yumuşak Çeliğin Korozyonu Üzerine Yeşil Önleyici Etkisi

In present study, the inhibitive impact of Ptychostomum schleicheri extract, a moss species of Bryaceae family, on the mild steel corrosion in 1 M HCl at ambient temperature was firstly analysed by Tafel extrapolation method, electrochemical impedance spectroscopy (EIS) and linear polarization (LPR) techniques. Electrochemical tests were conducted by 1 h immersing mild steels in HCl solutions containing four various concentrations of moss extract. At a concentration of 0.200% (w/v), the moss extract displayed around 90 percent inhibition efficiency by three electrochemical methods, and it was also observed that its protective effect increased depending on the upsurge in the concentration of Ptychostomum schleicheri extract. The morphologies of mild steels surface in 1 M HCl with and without P. schleicheri extract at the end of 1 h immersion time were visualized by a metal microscope. Finally, according to the electrochemical data and surface morphology results, it can be said that the extract molecules adsorbed on the mild steel surface to achieve almost maximal coverage and contact.

Evaluation of Adansonia Digitata (Baobab) Leaf and Root Extracts as Inhibitor on Dual Phase Steel (DPS) in 0.3M H2SO4

Purpose: In this work, the effect of indigenously sourced baobab leaf and root was experimented on the substrate of inter-critically developed dual phase steel in 0.3M H2SO4.
 Methodology: Standard techniques were adopted in carrying out the development and the corrosion experiments. Weight loss method was adopted and the corrosion rate eventually estimated following a standard route.
 Findings: From the results, it was observed that inter-critical heat treatment technique can be used to develop dual phase steel with a competing properties with the conventional dual phase steel. The use of baobab leaf and root extracts was also observed to serve as an organic inhibitor for dual phase steel having observed that the percentage inhibition efficiency (% IE) increases with increase in the soaking temperature of the developed DPS.
 Recommendation: The use of baobab leaf and root is thus recommended as alternative organic inhibitor to impede corrosion rate in DPS.

Corrosion inhibitory potential of selected flavonoid derivatives: Electrochemical, molecular⋅⋅⋅Zn surface interactions and quantum chemical approaches

Zinc metal corrosion inhibitor potential of some flavonoid derivatives, namely, naringenin (NRNG), morin hydrate (MNHD), and 6-hydroxyflavone (6-HFN), was investigated by measuring their inhibitory activities, determining their thermodynamic and kinetic adsorption mechanistic properties as well as comparing their molecular⋅⋅⋅Zn metal surface interaction strengths. The inhibition efficiencies were evaluated in 1.5 M hydrochloric acid (HCl) environment and different concentrations of the inhibitors (from 2.0 × 10−4 – 1.8 × 10−3 M) using gravimetric and various electrochemical methods at 30–60 °C. The molecular···metal surface interactions were determined using the density functional theory method by using the GGA/RPBE/DNP approach. Electrochemical studies show that 6-HFN and NRNG are the most and least effective corrosion inhibitors, with 77.54 and 70.46 maximum percentage inhibition efficiency, respectively. Atomic Absorption Spectroscopy technique was used to compare the concentration of the zinc ions that remained in the solution after gravimetric analysis in the absence and presence of the inhibitors at 30 °C; it was found that the inhibited solution contained less concentrations of zinc ions as compared to the uninhibited solution. Surface morphology techniques (e.g., 3D microscope) suggest that a localised type of corrosion took place on the metals, and the corrosion damage was minimal in the presence of the inhibitors. FT-IR showed a strong adsorption of the functional groups found in the inhibitor compounds, with CC functional group being strongly retained by all three inhibitors. The flavonoid inhibitor compounds were found to absorb chemically at low temperatures and physically at high temperatures. Langmuir adsorption isotherm was obeyed. The trend for molecular···metal surface interaction strengths follows the trend obtained from experimental findings on inhibition efficiency. Overall, the results suggest that all the molecules investigated are good corrosion inhibitors with a preference for those compounds in which there exists extended electron delocalization through the aromatic rings and in which there are minimal electron-withdrawing groups on the aromatic rings.

Effect of expired doxofylline drug on corrosion protection of soft steel in 1 M HCl: Electrochemical, quantum chemical and synergistic effect studies

The corrosion inhibition property of expired Doxofylline (DF) was tested for soft steel in 1 M hydrochloric acid solution by adopting mass change and electrochemical measurement techniques. At 200 ppm concentration of DF, maximum of 72.84% inhibition efficiency was noticed. However with addition of 50 ppm of KI, it enhances the percentage inhibition efficiency up to 88.48%. DF resists both anodic and cathodic reactions and functioned as mixed-inhibition mechanism. At higher temperatures, electrochemical impedance response noticed that, the diameter of the semicircle decreases as solution temperature increases As a result, in both absence and presence of the inhibitor the Rp values were decreased. Quantum chemical studies revealed about structural and electronic effects in relation to the inhibition efficiencies. Surface morphology of both inhibited and corroded soft steel was assessed by means of scanning electron microscopy (SEM)) and atomic force microscope (AFM). The SEM images of soft steel reflect the inhibitive property of the DF at optimized concentration and a significant decrease in the surface roughness was observed (surface roughness was reduced from 606 nm to 294 nm as measured by AFM)). UV-Visible absorption peaks signifies that CC and CO groups from the inhibitor were interacted with iron cations, which is the evidence for the formation protective film over the soft steel surface.

Electrochemical approach to interfacial adsorption and inhibitory performance of (2E)-2- [(IH-Imidazole 2yl) methylidene] Hydrazine1-carbothioamide for corrosion mitigation

This work features the synthesis and use of (2E)-2- [(IH-Imidazole 2yl) methylidene] Hydrazine1-carbothioamide (IMHC) as anticorrosion agent for mild steel (MS)corrosion in 0.5 M sulfuric acid (H 2 SO 4 ). Electrochemical studies were conducted at different temperatures. Conditions were optimized to achieve maximum inhibition efficiency. Kinetic parameters were evaluated. Results were fitted into various adsorption isotherms. Thermodynamic parameters were calculated by using suitable equations and graph. The surface morphology study was done by scanning electron microscope (SEM) and energy dispersive X-beam (EDX). The inhibition efficiency was found to decrease with rise in temperature. Maximum percentage inhibition efficiency (%IE) observed was around 79 with 1 × 10 −3 M IMHC at 303 K. IMHC functioned as mixed inhibitor. Results obtained suggested that physical adsorption of IMHC occurred onto the MS surface and obeyed Langmuir model. Mechanism is discussed in detail. IMHC can be considered as good inhibitor for corrosion of MS in H 2 SO 4 medium. .

A STUDY OF CORROSION INHIBITON EFFECT OF THIOSEMICARBAZIDE BASED SCHIFF BASE ON ALUMINIUM METAL IN ACIDIC MEDIUM

Corrosion is the destruction of metal surface by the reaction with its environment (humidity, gases, acid, alkaline etc.). In this process metal convert in to the more stable form such as sulphide oxide etc. Corrosion of materials and structures is a hindrance to the development of society as it causes significant loss to the economy, leads to pollution, and leads to serious disasters, hence its prevention and control is of great benefit for the humanity. Addition of corrosion inhibitors is one of the practical and easy methods to protect metals and alloys against attack of corrosion in many industrial environments. In this chapter thiosemicarbazide based Schiff base 2-[(3,4-dihydroxy-5-nitrophenyl)methylidene]hydrazine-1-carbothioamide (DHNPMHC) was synthesized and characterized using elemental analysis, FT-IR and UV–Vis methods. The inhibition efficiency of Schiff base DHNPMHC against aluminium corrosion in 0.5 M HCl was examined using mass loss measurement and scanning electron microscopy (SEM). Results showed that DHNPMHC is an effective inhibitor for aluminium corrosion in 0.5 M HCl solution. The inhibition efficiency also increased with concentration of inhibitor increased. Maximum percentage inhibition efficiency 92.6 % (at 4-hour immersion time) is shown at highest concentration of inhibitor 5% (5X10-5M). Adsorption of the inhibitor on the aluminium surface followed Langmuir adsorption isotherm. SEM study of aluminium surface in presence of inhibitor and in absence of inhibitor also supports the inhibition of corrosion in acidic medium. All results show that the Schiff base of thiosemicarbazide (DHNPMHC) is excellent corrosion inhibitor for aluminium in 0.5 M HCl.

Electrochemical and quantum chemical study to assess the role of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide as inhibitor for acid corrosion of mild steel

Synthesis and inhibition effectiveness of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide (FMHC) as an inhibitor for corrosion of mild steel in 0.5 M H2SO4 is reported. Experiments were conducted at various temperatures (303–323 K) by adopting potentiodynamic polarization and electrochemical impedance spectroscopy. Readings obtained demonstrated that percentage inhibition efficiency (% IE) improved with the upsurge in the concentration of FMHC, while it decreased with a rise in temperature. The highest % IE observed was 60% for 2.5 × 10–4 M FMHC at 303 K. FMHC worked moderately as a mixed inhibitor. FMHC obeyed the Langmuir model of adsorption and the mode of adsorption was physisorption on the mild steel surface which was further endorsed by examining the surface using the scanning electron microscope. A clear insight into the mechanistic features of corrosion inhibition by using FMHC was acquired. Calculation of activation parameters helped to suggest an appropriate mechanism for the adsorption of FMHC on mild steel through quantum chemical calculations using density functional theory (DFT).Graphical abstract

Naturally Occurring Exudates Gums as Ecofriendly Inhibitors for Mild Steel Corrosion in Acidic Medium

The corrosion inhibition potentials of gum exudates from Daniella oliveri (DO) and Commiphora Africana (CA) for the corrosion of mild steel in H2 SO4 have been studied using weight loss and thermometric methods at 303 and 333K. Results show that the exudates gum actually reduced the rates of corrosion of mild steel. Increase in the concentrations of the exudate’s gums increased their percentage inhibition efficiencies. Corrosion rate was found to increase with increase in temperature in the presence and absence of the gum exudates, though the corrosion rate was slower in the presence of the exudates gums. Both DO and CA exudates gums were found to obey Temkin and Langmuir adsorption models at all concentrations and temperatures studied. Physical adsorption mechanism was proposed from the adsorption parameters. Kinetic and thermodynamic parameters revealed that the adsorption process is spontaneous, exothermic and no significant difference was found between the inhibition efficiencies of DO and CA.

INHIBITING ALUMINIUM ACID CORROSION USING LEAVES EXTRACT OF GUIERA SENEGALENSIS

The effects of Guiera senegalensis leaves extract as a potential green corrosion inhibitor for Aluminum (Al) in HCl acid solution was investigated using weight loss, LPR, FT-IR, and scanning electron microscope techniques at varying experimental conditions. The result indicates that the percentage inhibition efficiency increases with increase in concentration of the inhibitor and decreased with increase in temperature and immersion period. SEM images showed that the Al metal is protected by the inhibitor molecules, while FT-IR spectra indicates the mechanism of physical adsorption of inhibitors onto Al surface. LPR result showed that the inhibition efficiency of the inhibitor was moderate and act as mixed-type inhibitor. The data obtained from the thermodynamic parameters were fitted into various adsorption isotherms, Freundlich adsorption isotherm was observed to be the best fitted isotherm.

Corrosion Protection of Carbon Steel in 2M HCl Using Aizoon canariense Extract

The corrosion inhibition effectiveness of Aizoon canariense for carbon steel (CS) in 2 M HCl (the corrosive medium) has been examined by employing chemical and electrochemical methods. The inhibition efficiency was found to improve with a rise in the environment's extract and temperature concentration. The inhibitive effect of this extract was explained on the basis of adsorption on the metal surface; the adsorption effect follows Langmuir adsorption isotherm. The percent inhibition efficiency (IE%) reached 90.23% at 45oC, and activation energy (E*a) has been determined in the presence and absence of Aizoon canariense extract. The corrosion rate was calculated and revealed that Aizoon canariense has a good inhibition effect on CS. The surface morphology of CS was examined by employing various techniques. The polarization results indicated that this extract acts as a mixed kind inhibitor. The parameters for the corrosion procedure have also been determined and discussed.

Corrosion Inhibitive Potentials Of (E)-5-((4-Benzoylphenyl)Diazenyl)-2-Hydroxybenzoic Acid On Mild Steel Surface In 0.5 M HCl- Experimental And DFT Calculations

One of the ways of reducing metal corrosion and its devastating effects is by using organic corrosion inhibitors. This is because of the π-conjugation in their moieties, their ability to donate electrons to the metal’s vacant d-orbitals, and their low lying LUMO orbitals for accepting electrons as well from the metal, all these improve their adsorption on the metal surface. (E)-5-((4-benzoylphenyl)diazenyl)-2-hydroxybenzoic acid (AD4) was synthesized via the coupling reaction of p-aminobenzonephenone and Salicylic acid, characterized via FTIR, UV/Vis, 1H-NMR, and 13C-NMR spectroscopy. The melting point of AD4 is 103oC–106oC indicating that it is thermally stable and pure. Gravimetric and potentiodynamic polarization techniques were employed to obtain the corrosion rates (Cr) and percentage inhibition efficiency (%IE) at different concentrations of the inhibitor and at different temperatures. The thermodynamic parameters like Enthalpy, ∆Hoads, Entropy, ∆Soads and free energy of adsorption (∆Gads) of Adsorption were calculated. The Langmuir adsorption isotherm was used to describe the adsorption of AD4 molecules on mild steel. Quantum mechanical calculations were employed to calculate the electronic properties and global reactivity descriptors of AD4. The theoretical results are broadly consistent with experimental results. From the results obtained AD4 could be used as a corrosion inhibition agent in the oil and gas industries.

Electrochemical evaluation of inhibition efficiency of some nonionic surfactants based on tolyltriazole derivatives on the corrosion of Cu-Zn alloy in seawater

Two nonionic surfactants based on tolyltriazole derivatives namely: 5-methyl-1 Decaethoxide-benzotriazole, TTA (12) and 5-methyl-1 Tetracosaethoxide-benzotriazole, TTA (24) were synthesized and evaluated as corrosion inhibitors for 65Cu-35Zn alloy dissolution in aerated seawater. The corrosion inhibition capability of these nonionic surfactants has been investigated in seawater solution using potentiodynamic polarization, electrochemical impedance spectroscopy, EIS, and scanning electron microscopic SEM/EDX measurements. According to both potentiodynamic polarization and EIS measurements, it has been found that the investigated tolyltriazoles compounds, TTAs, work as efficient inhibitors for 65Cu-35Zn corrosion and the protection aptitude raised by increasing the concentration of inhibitors. EIS measurements indicated that the charge-transfer resistances increase upon increasing the TTAs concentration. It was found that the percentage inhibition efficiency (η%) increases by increasing the inhibitor concentration. Also, the results showed enhancement in inhibition efficiencies with decreasing the molecular size of the surfactant or the degree of ethoxylation at low concentration. At high concentration, the inhibition efficiency of the different inhibitors independent on the degree of ethoxylation. Potentiodynamic polarization curves indicated that the inhibitors under investigation act as mixed type. Finally, the surface characterization of the protective film formed on 65Cu-35Zn surface was examined by using SEM and energy dispersive X-ray, EDX, techniques. Adsorption of TTA, TTA(12), TTA(24) on the surface of Cu-35Zn in seawater, follows the Langmuir adsorption isotherm. The adsorption free energy of inhibitors on 65Cu-35Zn alloy reveals a strong physical adsorption of the inhibitor on the metal surface.