Mixed-type Inhibitor Research Articles

Experimental insights into the adsorption of newly synthesized Gemini ethoxylated surfactant on C-steel in different acidic media accompanied by DFT and MCs studies

Abstract Bis ethoxylated cationic surfactant (BOECS) is synthesized. The prepared surfactant’s structure configuration was verified through a variety of spectral and physicochemical techniques, including FT-IR, MS,1HNMR, and surface activity evaluations. BOECS applications as a C-steel corrosion inhibitor in 1.0 N HCl and 1.0 N H2SO4 and sulfate reducing bacteria (SRB) mitigations have been investigated thoroughly. Physical properties of the BOECS indicate its potential adsorption affinity at the air/water interface. The electrical conductivity determines the CMC value in accordance with the surface tension value. Electrochemical kinetic parameters indicate the BOECS is sorted as a mixed-type inhibitor and has an inhibition efficacy of 91.22 % and 81.26% for HCl and H2SO4, respectively. Active centers of BOECS structure enhance its adsorption at the electrolyte/C-steel. Calculated adsorption energy change (∆G ads) and theoretical adsorption energy (E ads) values suggest strong and spontaneous BOECS adsorption. The cytotoxic performance of the synthesized BOECS exhibited a potent inhibitory potential against the SRB. The outcomes of this research exhibit that the BOECS can lower SRB growth from 106 to 102 cell/mL.

Design, synthesis, in vitro, and in vivo evaluation of novel phthalazinone-based derivatives as promising acetylcholinesterase inhibitors for treatment of Alzheimer's disease.

Twenty novel phthalazinone-based compounds were designed as acetylcholinesterase (hAChE) inhibitors. Compounds 7e and 17c demonstrated comparable or superior activity compared to donepezil, respectively, in in vitro enzyme assay. Moreover, both compounds 7e and 17c possess minimal toxicity on hepatic and neuroblastoma cell lines. Besides, it was proved that compounds 7e and 17c have percentage alternations and a transfer latency time comparable to donepezil and can alleviate the cognitive impairment caused by the scopolamine-induced model in mice. The kinetic analysis for compound 17c suggested this compound as a mixed-type inhibitor that could bind to both the peripheral (PAS) and the catalytic site (CAS) of the hAChE enzyme. The synthesized molecules were subjected to in silico analyses, including molecular docking studies, and the outcomes were consistent with the in vitro findings.

Review on anti-corrosion properties of expired antihypertensive drugs as benign corrosion inhibitors for metallic materials in various environments

Discovering new classes of organic corrosion inhibitors, such as expired drugs, can provide cheaper, low-toxic, and highly efficient alternatives to the toxic organic counterparts that serve as an efficient recycling or disposal strategy. Antihypertensive drugs constitute one of the cheapest classes of drugs, globally, and have been reported as highly effective corrosion inhibitors for a variety of metallic materials in various corrosion environments. The corrosion inhibition mechanism of these drugs, generally, involves the adsorption on the metallic surfaces and the formation of a protective organic film that retards the attack of substrates by corrosive entities in the media. The drug molecular structure usually contains π-bonds, phenyl rings, and polar functional groups (such as –NH2, –OH, –CN, and −Cl) which influence the electron density within the inhibitor framework and also facilitate adsorption of the drug on the metal surface. Generally, most antihypertensive drugs act as mixed-type inhibitors and usually obey Langmuir adsorption isotherm revealing physisorption adsorption mechanisms except telmisartan, losartan potassium, and atenolol when used in nitric acid. The reported inhibition efficiency of the drugs is generally above 90% with spironolactone having the highest efficiency of 98.1% at 30 °C.

Electrochemical and DFT theoretical evaluation of the Randia monantha Benth extract as an eco-friendly corrosion inhibitor for mild steel in 1 M HCl solution

BackgroundDue to the growing concern about environmental pollution caused by commercial corrosion inhibitors, the anticorrosive properties of several natural products have been studied. MethodsThe present work assessed the inhibition performance of Randia monantha pulp and seed (RMPS) extract on corrosion of A36 mild steel in 1M HCl solution through weight loss and electrochemical measurements such as potentiodynamic polarization curves (PPC) and electrochemical impedance spectroscopy (EIS). Surface analysis was carried out using scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). Chemical characterization of RMPS extract and theoretical studies of its chief compounds were performed by spectroscopic studies and density functional theory (DFT) calculations, respectively. Significant findingsElectrochemical measurements results showed that corrosion inhibition increased as inhibitor concentration increased, achieving an acceptable inhibition efficiency of 91% at 1000 ppm. Polarization curves indicated that molecules of RMPS acted as a mixed-type inhibitor and their adsorption process obey the Langmuir isotherm manly by physisorption mechanism. Examination of corroded steel surface by SEM and EDS confirmed the adsorption of compounds presented in the extract. The chemical quantum calculations allowed to obtain electronic properties of the chief compounds of the natural extract and explained the inhibitor/metal surface interactions and adsorptions modes.

A comprehensive assessment of carbon steel corrosion inhibition by 1,10-phenanthroline in the acidic environment: insights from experimental and computational studies.

1,10-Phenanthroline (PHN) is a nitrogen-containing heterocyclic organic compound that is widely used in a variety of applications, including chemosensors, biological studies, and pharmaceuticals, which promotes its use as an organic inhibitor to reduce corrosion of steel in acidic solution. In this regard, the inhibition ability of PHN was examined for carbon steel (C48) in a 1.0M HCl environment by performing electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), mass loss, and thermometric/kinetic. Additionally, scanning electron microscopy (SEM) was used to examine the surface morphology of C48 immersed in 1.0M HCl protected with our inhibitor. According to the PDP tests, increasing the PHN concentration resulted in an improvement in corrosion inhibition efficiency. Besides, the maximum corrosion inhibition efficiency is about 90% at 328K. Furthermore, the PDP assessments demonstrated that PHN functions as a mixed-type inhibitor. The adsorption analysis reveals that our title molecule mechanism is due to physical-chemical adsorption, as predicted by the Frumkin, Temkin, Freundlich, and Langmuir isotherms. The SEM technique exhibited that the corrosion barrier occurs due to the adsorption of the PHN compound through the metal/1.0M HCl interface. In addition, the computational investigations based on a quantum calculation using density functional theory (DFT), reactivity (QTAIM, ELF, and LOL), and molecular-scale by Monte Carlo (MC) simulations confirmed the experimental results by providing further insight into the mode of adsorption of PHN on the metal surface, thus forming a protective film against corrosion on the C48 surface.

Inhibition Effect of Okanin Toward Human Cytochrome P450 3A4 and 2D6 with Multi-spectroscopic Studies and Molecular Docking.

Okanin, a major flavonoid of a popular herb tea, Coreopsis tinctoria Nutt., showed strong inhibition on CYP3A4 and CYP2D6. The strong interaction between okanin and CYPs were determined by enzyme kinetics, multispectral technique and molecular docking. The inhibition type of two enzymes, CYP3A4 and CYP2D6, by okanin are mixed and non-competitive inhibition type, respectively. The IC50 values and the binding constant of okanin to CYP3A4 can be deduced that the interaction was stronger than that of CYP2D6. The Conformations of CYP3A4 and CYP2D6 were changed by okanin. The evidence from fluorescence measurement along with molecular docking verified that these two CYPs were bound with okanin by hydrogen bonds and hydrophobic forces. Our investigation suggested that okanin may lead to interactions between herb and drug by inhibiting CYP3A4 and CYP2D6 activities, thus its consumption should be taken with caution.

Corrosion resistance of Aluminium steel in 1N Sodium Hydroxide solution by an aqueous extract of Thespesia populnea plant leaves

Corrosion resistance effect of aluminium steel in 1N sodium hydroxide by an aqueous extract of Thespesia populnea plant leaves has been investigated by mass loss method. It is observed that as the concentration of the inhibitor increases, the inhibition efficiency increases. The mechanistic aspects of corrosion resistance have been studied by potentiodynamic polarization technique and electrochemical impedance spectroscopy. A maximum inhibition efficiency of 78.70% is achieved by this inhibitor system. Potentiodynamic polarization technique reveals that the inhibitor system functions as a mixed type of inhibitor, controlling anodic and cathodic reactions. It is noted that in the presence of inhibitor, linear polarization resistance value increases and corrosion current decreases. Electrochemical impedance studies reveal that a protective film is formed on the Al steel surface, since in the presence of inhibitor system, the charge transfer resistance value increases and double layer capacitance value decreases. This is due to adsorption of the molecules of the active ingredients of the extract on the Al steel surface. The inhibition efficiency increases due to adsorption of hetero atoms present in TP plant leaves extract on the Al steel surface. The maximum inhibition efficiency and the lower corrosion rate are obtained at high concentration 1200 ppm for TP plant leaves extract. By further increase in inhibitor concentration above 1200 ppm, the inhibition efficiency and corrosion rate almost remained constant. So, the 1200 ppm concentration is fixed as the maximum inhibition for the investigative aqueous extract of plant leaves as corrosion inhibitor. This concentration corresponds to the attainment of a saturation value in surface coverage of Al steel. The protective film formed over the Al steel surface has been characterized by Fourier Transform infra-red spectroscopy. The surface morphology of the protective film of carbon steel immersed in sodium hydroxide in the absence and presence of inhibitor has been studied by Scanning electron microscopy. The outcome of the study can be used in pickling industry wherein sodium hydroxide is used to remove the rust on the Al steel surface.

Synthesis, Characterization, and Evaluation of Co-MOF Based ZIF-67 for CO2 Corrosion Inhibition of X65 Steel: Insights from Electrochemical Studies and a Machine Learning Algorithm

Co-MOF based metal organic framework was synthesized by reacting a metal ion (cobalt nitrate hexahydrate) with an organic ligand (2-methylimidazole) via a wet chemical method. The resulting material was characterized using detailed analytical methods and further was used as a self-assembly corrosion inhibitor in sweet corrosive environment. The empirical data set via electrochemical studies was modeled using adaptive neuro fuzzy inference system (ANFIS). The observed results showed that Co-MOF could significantly impede the corrosion rate of X65 steel and protect it from CO2 corrosion. Increasing the concentration of Co-MOF in the test solution increased the inhibition efficiency up to 97% at 0.1 wt % Co-MOF with a mixed-type inhibition mechanism. In addition, the DFT/MD-simulation approach evidenced the adsorption disposition of Co-MOF in aqueous and gas phase which complement with the empirical findings. Also, the prognostic capability of the proposed algorithm based on the statistical parameters such as root-mean-square error (RMSE), chi square (χ2), model predictive error (MPE) and coefficient of determination (R2) were appraised. From the viewpoint of statistics, the explanatory model aligned credibly with the ANFIS algorithm. The overall findings confirmed a dense hybrid coating of the synthesized Co-MOF on X65 steel as responsible for the inhibition of the sweet corrosion.

Corrosion protection of mild-steel in 1M HCl using nanocomposite from Triumfetta rhomboidei

Titanium nanocomposite (TiTR) was synthesised from Triumfetta rhomboidea leaf extract and used as corrosion protection of mild steel (MS) in 1 M hydrochloric acid. The corrosion inhibition process of the nanocomposite was explored using weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP). The corrosion inhibition performance of TiTR is a function of concentration and temperature. The results revealed that TiTR was 84.27% efficient in limiting MS corrosion at 1.0 g L−1 and 3 h. The TiTR acted as a mixed-type corrosion inhibitor and Langmuir isotherm indicated that TiTR was adsorbed on mild steel through physisorption by forming a monolayer of film. Surface morphology study of MS visually confirmed the protection of MS by TiTR through film formation.

Experimental assessment and molecular-level exploration of the mechanism of action of Nettle (Urtica dioica L.) plant extract as an eco-friendly corrosion inhibitor for X38 mild steel in sulfuric acidic medium

The development of green corrosion inhibitors has gained considerable importance in recent years due to their minimal environmental impact and sustainable nature. As industries increasingly seek eco-friendly alternatives to conventional corrosion inhibitors, research focused on identifying effective and renewable corrosion protection solutions becomes imperative. The main purpose of this study is to evaluate the inhibition action of Nettle extract (NE) (Urtica dioica L.) as a promising green corrosion inhibitor for mild steel in a 0.5 mol/L H2SO4 medium. In this work, the corrosion protection performance of NE was assessed using weight loss, electrochemical, surface characterization, and computational chemistry methods. The results indicated that NE acted as an effective corrosion inhibitor, with inhibition efficiency reaching a maximum of 90% at a concentration of 4 g L-1. Polarization studies revealed that NE functions as a mixed-type inhibitor, while electrochemical impedance spectroscopy (EIS) results showed an increase in charge transfer resistance and a decrease in double layer capacitance values in the presence of NE. Surface characterization analysis confirmed the formation of a protective NE layer on the steel surface. Furthermore, Density-functional tight-binding (DFTB) simulations identified Quercetin, Kaempferol, and Serotonin as having stronger chemical bonding with the Fe(110) surface, while Histamine molecules exhibited physical interactions with iron atoms. This comprehensive evaluation of NE's inhibition action not only supports its potential as an eco-friendly inhibitor for mild steel corrosion protection but also contributes to the development of sustainable corrosion control strategies.

Azole derivatives inhibit wildtype butyrylcholinesterase and its common mutants.

Azoles, which have been used for antifungal chemotherapy for decades, have recently been of interest for their efficacy against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). There is little known about the potential of azoles against BChE, however there is none regarding their inhibitory effects against mutants of BChE. In the current study, an azole library of 1-aryl-2-(1H-imidazol-1-yl)ethanol/ethanone oxime esters were tested against AChE and BChE, which yielded derivates more potent than the positive control, galantamine, against both isoforms. Kinetic analyses were performed for wildtype and mutant (A328F and A328Y) inhibition for the two most potent BChE inhibitors, pivalic and 3-bezoylpropanoic acid esters of 2-(1H-imidazol-1-yl)-1-(2-naphthyl)ethanol, which were found to have great affinity to the wildtype and mutant BChE types with Ki values as low as 0.173 ± 0.012 µM. The compounds were identified to show linear competitive or mixed type inhibition. Molecular modeling confirmed these kinetic data and provided further insights regarding molecular basis of BChE inhibition by the active derivatives. Thus, current study suggests new azole derivatives with promising cholinesterase inhibitory effects and reveals the first set of information to promote our understanding for the inhibitory behavior of this class against the mutant BChE forms.

Xanthine oxidase inhibitory kinetics and mechanism of ellagic acid: In vitro, in silico and in vivo studies.

Ellagic acid (EA), which is widely distributed in many foods, has been found to possess inhibitory activity against xanthine oxidase (XO). However, there is ongoing debate about the difference in XO inhibitory activity between EA and allopurinol. Additionally, the inhibitory kinetics and mechanism of EA on XO are still unclear. Herein, the authors systematically studied the inhibitory effects of EA on XO. The authors' findings showed that EA is a reversible inhibitor with mixed-type inhibition, and its inhibitory activity is weaker than allopurinol. Fluorescence quenching experiments suggested that the generation of EA-XO complex was exothermic and spontaneous. In silico analysis further confirmed that EA entered the XO catalytic centre. Furthermore, the authors verified the anti-hyperuricemia effect of EA in vivo. This study elucidates the inhibition kinetics and mechanism of EA on XO, and lays a theoretical foundation for the further development of drugs and functional foods containing EA for the treatment of hyperuricemia.

Naturally-Occurring Tyrosinase Inhibitors Classified by Enzyme Kinetics and Copper Chelation.

Currently, there are three major assaying methods used to validate in vitro whitening activity from natural products: methods using mushroom tyrosinase, human tyrosinase, and dopachrome tautomerase (or tyrosinase-related protein-2, TRP-2). Whitening agent development consists of two ways, melanin synthesis inhibition in melanocytes and downregulation of melanocyte stimulation. For melanin levels, the melanocyte cell line has been used to examine melanin synthesis with the expression levels of TRP-1 and TRP-2. The proliferation of epidermal surfaced cells and melanocytes is stimulated by cellular signaling receptors, factors, or mediators including endothelin-1, α-melanocyte-stimulating hormone, nitric oxide, histamine, paired box 3, microphthalmia-associated transcription factor, pyrimidine dimer, ceramide, stem cell factors, melanocortin-1 receptor, and cAMP. In addition, the promoter region of melanin synthetic genes including tyrosinase is upregulated by melanocyte-specific transcription factors. Thus, the inhibition of growth and melanin synthesis in gene expression levels represents a whitening research method that serves as an alternative to tyrosinase inhibition. Many researchers have recently presented the bioactivity-guided fractionation, discovery, purification, and identification of whitening agents. Melanogenesis inhibition can be obtained using three different methods: tyrosinase inhibition, copper chelation, and melanin-related protein downregulation. There are currently four different types of inhibitors characterized based on their enzyme inhibition mechanisms: competitive, uncompetitive, competitive/uncompetitive mixed-type, and noncompetitive inhibitors. Reversible inhibitor types act as suicide substrates, where traditional inhibitors are classified as inactivators and reversible inhibitors based on the molecule-recognizing properties of the enzyme. In a minor role, transcription factors can also be downregulated by inhibitors. Currently, the active site copper iron-binding inhibitors such as kojic acid and chalcone exhibit tyrosinase inhibitory activity. Because the tyrosinase catalysis site structure is important for the mechanism determination of tyrosinase inhibitors, understanding the enzyme recognition and inhibitory mechanism of inhibitors is essential for the new development of tyrosinase inhibitors. The present review intends to classify current natural products identified by means of enzyme kinetics and copper chelation to exhibit tyrosinase enzyme inhibition.

Evaluation of 2,3-Dihydro-1,5-benzothiazepine Derivatives as Potential Tyrosinase Inhibitors: In Vitro and In Silico Studies.

Benzothiazepines are pharmacologically active compounds, frequently utilized as a precursor for acquiring versatile molecules with several bioactivities including anti-inflammatory, anti-human immunodeficiency virus (anti-HIV), analgesic, antitumor, antimicrobial, and antitubercular. In this study, the 2,4-diphenyl-2,3-dihydro-1,5-benzothiazepine scaffold was selected for their in vitro, docking, and druglikeness studies to evaluate their inhibitory potential against mushroom tyrosinase. All synthesized analogues, 1-14, exhibited moderate to good IC50 values ranging from 1.21 to 70.65 μM. The synthesized benzothiazepine derivatives were potent tyrosinase inhibitors, which outperformed the reference kojic acid (IC50 = 16.69 μM). The kinetic analysis revealed that compound 2 (2-(3,4-dimethoxyphenyl)-4-(p-tolyl)-2,3-dihydrobenzo[b][1,4]thiazepine) was a mixed-type tyrosinase inhibitor with a Ki value of 1.01 μM. Molecular modeling studies against tyrosinase protein (PDB ID: 2Y9X) were conducted to recognize the binding modes of these analogues. The utilization of molecular dynamic (MD) simulations enabled the assessment of the protein-ligand complex's dynamic behavior, stability, and binding affinity for the compounds. These simulations ultimately led to the identification of compound 2 as a potential inhibitor of tyrosinase. Additionally, a druglikeness study was conducted, which supported the promising potential of the new analogues as novel antityrosinase agents. The in silico studies were consistent with the in vitro results, showing that these ligands had good binding scores against tyrosinase and interacted with the core residues of the target protein. Gaussian 09 was used for the geometry optimization of all complexes.

Electrochemical and computational studies of an expired vilazodone Drug as environmentally safe corrosion inhibitor for aluminum in chloride medium

Through using chemical and electrochemical methods, the theoretical and experimental investigation of the expired vilazodone drug's ability to prevent corrosion on aluminium (Al) in a corrosive medium of HCl (1 M) has been examined. Weighing tests (WL), electrochemical (impedance spectroscopy (EIS), potentiodynamic polarization (PDP)), atomic force microscopy (AFM), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) tests at 25 °C have all been used to investigate Vilazodone's capability to prevent corrosion of Al in 1 M HCl in the concentration in the range of 25–150 ppm. The corrosion inhibition effect of the investigate Vilazodone's against Al in acid environment was investigated weight loss and electrochemical methods. The highest % inhibition efficiency (%IE) was 95% resulted from weight loss technique at the highest concentration for inhibitor. According to the PDP data, this examined vilazodone function as a mixed-type inhibitor, impacting both the anodic and cathodic reactions. The inhibitors covered the active points of the metal surface, according to electrochemical impedance spectroscopy (EIS), to prevent corrosion. It was discovered that the inhibitor adsorption on the Al surface obeyed the Langmuir adsorption isothermal model. AFM, SEM, and FTIR surface examinations proved the inhibitor had a significant protective effect against Al dissolution in 1 M HCl. The outcomes from chemical and electrochemical methods are relatively consistent. Vilazodone acted as an effective corrosion inhibitor, according to all of the experimental data.

Novel Polyepoxysuccinic Acid-Grafted Polyacrylamide as a Green Corrosion Inhibitor for Carbon Steel in Acidic Solution.

Utilizing green corrosion inhibitors has been classified among the most efficient and economical mitigation practices against metallic degradation and failure. This study aims to integrate the features of green and complementary properties of polyepoxysuccinic acid (PESA) and polyacrylamide (PAM) for steel corrosion inhibition. A novel PESA-grafted-PAM (PESAPAM) has been first-ever synthesized in this research study and deployed as a corrosion inhibitor for C-steel in 1.0 M HCl solution. Eco-toxicity prediction confirmed the environmentally friendly properties acquired by the synthesized inhibitor. Electrochemical, kinetics, and surface microscopic studies were carried out to gain a holistic view of C-steel corrosion behavior with the PESAPAM. Furthermore, the performance of PESAPAM was compared with that of the pure PESA under the same testing conditions. Results revealed predominant inhibitive properties of PESAPAM with an inhibition efficiency (IE) reaching 90% at 500 mg·L-1 at 25 °C. Grafting PAM onto the PESA chain showed an overall performance improvement of 109% from IE% of 43 to 90%. Electrochemical measurements revealed a charge transfer-controlled corrosion mechanism and the formation of a thick double layer on the steel surface. The potentiodynamic study classified PESAPAM as a mixed-type inhibitor. Furthermore, the investigation of C-steel corrosion kinetics with the presence of PESAPAM predicted an activation energy of 85 kJ·mol-1, correlated with a physical adsorption behavior. Finally, performed scanning electron microscopy and energy-dispersive X-ray analyses confirmed the adsorption of PESA and PESAPAM, with superior coverage of PESAPAM onto the steel surface.

Corrosion inhibiting properties of polysaccharide extracted from Lepidium meyenii root for mild steel in acidic medium: Experimental, density functional theory, and Monte Carlo simulation studies

A polysaccharide obtained from maca (Lepidium meyenii) root extract (MREP) was evaluated as a novel, inexpensive, biocompatible corrosion inhibitor for mild steel (MS) in 1 M HCl. Fourier transform infrared (FTIR) and nuclear magnetic resonance studies were conducted to characterize the inhibitor. Gravimetric, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques were applied to assess the corrosion inhibition potential of the inhibitor. Gravimetric studies were conducted over the temperature range of 30–60 °C. The inhibition efficiency of MREP increased with the concentration and temperature. The maximum inhibition efficiency of MREP was 94.78% at 700 ppm and 60 °C. EIS analysis showed that as the MREP concentration increased, the Rp value obtained from the Nyquist plot increased due to the formation of MREP barrier film at the MS/solution interface. PDP analysis showed that MREP had a mixed type inhibition mechanism. The inhibition efficiencies calculated based on gravimetric, EIS, and PDP analyses were similar. Ultraviolet–visible, FTIR, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDAX) analyses demonstrated the formation of a protective film on the MS surface. MREP adsorbed on MS according to the Langmuir adsorption isotherm. The calculated density functional theory parameters indicated the formation of a strong bond between MREP and the unoccupied d-orbital of iron atoms in MS. By contrast, Monte Carlo simulations indicated the adsorption of the MREP inhibitor on the MS surface at the atomic level.

Experimental and theoretical approaches to the inhibition of carbon steel corrosion by thiophene derivative in 1 M HCl

Via electrochemical approach, the effect of [4-(4-chloro-phenylazo)-3-hydroxy-5-phenylamino-thiophen-2-yl]-phenyl-methanone (TD) as a corrosion inhibitor for the corrosion of carbon steel (CS) in 1.0 M HCl solution has been demonstrated. Electrochemical examination, surface analysis, and theoretical studies (quantum chemistry and molecular dynamic) were used to examine the efficiency of the inhibitor. Both inhibitor concentration and temperature were found to induce inhibitory responses. According to the findings, this compound acts as a mixed-type inhibitor. It also behaves according to the Langmuir and Henry adsorption isotherms. Thermodynamic parameters were calculated and discussed. Polarization data showed that the examined compounds significantly adsorbed on the steel surface, which rises the inhibition efficiency up to 95 % in the presence of 5 × 10−5 M at 25°C. The predicted molecular dynamics (MD) simulation and quantum chemistry results revealed good consistency with the experimental work.

Corrosion inhibition of mild steel in hydrochloric acid solution by the expired Ampicillin drug

This study examines the utilization of the expired drug, namely ampicillin, as a mild steel corrosion inhibitor in an acidic environment. The inhibitor was evaluated using weight loss and electrochemical measurement accompanied with surface analytical techniques. The drug showed a potential inhibitory efficiency of > 95% at 55 °C. The inclusion of the inhibitor increased the charge transfer resistance at the steel-solution interface, according to impedance analyses. According to potentiodynamic polarisation measurements, expired ampicillin drug significantly decreased the corrosion current density and worked as a mixed-type corrosion inhibitor. The Langmuir adsorption isotherm was followed by the adsorption of ampicillin drug on the steel substrate, exhibiting an association of physical and chemical adsorption mechanisms. The surface study performed using contact angle and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) measurements supported the inhibitor adsorption on the steel substrate.

Corrosion Inhibition of Mild Steel and Aluminum in Hydrochloric Acid Solutions by Gum Exudates from Erythrophleum Africanum

The corrosion inhibition potentials of gum exudates extracted from Erthrophleum Africanum on mild steel and aluminium in acidic media were studied using gravimetric, Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) and potentiodynamic methods. The results range for gravimetric showed (30.30-80.0 %) and potentiodynamic polarization (66.50-86.74 %) which shows that the inhibition efficiency of the inhibitor increases with increase in concentration of gum exudate but decreases with increasing temperature. The addition of the gum exudate affects both the cathodic and anodic partial reaction, thereby reducing the cathodic and anodic current densities and the corresponding corrosion densities, which makes the gum act as a mixed type of inhibitor. The inhibitor was found to be an adsorption inhibitor that best fits the Temkim adsorption model; because the data have high degrees of linearity and the parameters were positive. The activation energy values ranges from 10 - 20 J/mol which indicates that the adsorption of the inhibitors favors the mechanism of physical adsorption, free energy of absorption ranges from -10.51 to -11.69 J/mol which indicate that the reaction is spontaneous and it’s an exothermic reaction. FTIR spectra of the inhibitors and the corrosion products of mild steel and Aluminum (in the presence of the inhibitors) revealed that there were shifts in frequencies of adsorption (821,925,1620,1730,1990) suggesting that some functional groups were used in adsorption and some new bonds were formed. (CH Rocking, = CH ‘oop’, C=O symmetric stretch) Examinations of the morphology of the mild steel and Aluminum (using SEM) before and after inhibition revealed the formation of protective coverage over the surface of the metal