Plant Extracts as Green Corrosion Inhibitors for Different Metal Surfaces and Corrosive Media: A Review

Citrullus colocynthis fruit extract as effective eco-friendly corrosion inhibitor in a hydrochloric acid pickling medium for carbon steel by using both experimental and theoretical studies

The present study focuses on an environmental approach based on the use of an eco-friendly corrosion inhibitor from the Citrullus colocynthis fruit extract for enhancement corrosion resistance of carbon steel (C-S) in acid medium as an alternative to various organic and non-organic chemical inhibitors. The evaluation of the inhibition properties of the fruit methanolic extract of Citrullus colocynthis (CCE) were performed in molar hydrochloric acid (1 M HCl) medium using gravimetric and electrochemical (potentiodynamic polarization and AC impedance) techniques as well as surface analyses. CCE is rich in amino acids, mainly citrulline and β-(pyrazo-1-yl)-L-analine molecules. Based on the weight loss evaluation, the results demonstrated that this plant extract acts as an effective corrosion inhibitor and a protection level of 93.6% was attained at 500 ppm of CCE after 6 h of metal exposure at 303 K. According to polarization curves, CCE functions as a mixed-type inhibitor. In addition, AC impedance analyses have shown that the incorporation of CCE into the corrosive solution leads to a decrease in load capacity, while improving the charge/discharge function at the interface. This suggests the possibility of the formation of an adsorbed layer on the C-S surface. In addition, scanning electron microscope (SEM) observation, contact angle measurements, and Fourier-transform infrared spectroscopy (FTIR) analyses supported the development of a protective film over CS substrate surface afterwards addition of CCE. Langmuir and/or Temkin isotherms can be used to characterize the adsorption of this organic inhibitor on the C-S surface. X-ray photoelectron spectroscopy (XPS) has revealed that the inhibiting effect of CCE on the corrosion of C-S in 1 M HCl solution is mainly controlled by a chemisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where CCE molecules are incorporated. In order to understand the relationship between the molecular structure and anti-corrosion effectiveness of these inhibitor molecules, quantum chemical studies were carried out using density functional theory (DFT) and molecular dynamics (MD) simulation.

Unveiling green corrosion inhibitor of Aloe vera extracts for API 5L steel in seawater environment

This study evaluated Aloe vera extract as a green inhibitor to prevent corrosion in seawater environments. A. vera extract was produced by maceration with methanol-water at room temperature. Electrochemical techniques were used to evaluate the corrosion inhibitor effectiveness of the A. vera extract. The morphology of the corrosion products was analyzed by FE-SEM equipped with EDS and AFM. FT-IR and LCMS characterized the functional and structural groups in this extract. The electrochemical measurements show that A. vera extract could effectively reduce the corrosion of API 5L steel in seawater environments. Inhibition efficiency (IE) increases with increasing concentration. Optimal corrosion inhibition efficiency of around 83.75% (PDP) and 88.60% (EIS) was obtained by adding 300 mg L-1 of extract at 310 K. Furthermore, the higher the concentration of A. vera extract, the greater the activation energy (Ea), with the highest activation energy being 48.24 kJ mol-1 for the concentration of 300 mg L-1. Conversely, increasing the temperature and exposure duration reduces the corrosion inhibition efficiency (IE) values; the best exposure period was 30 min with 88.34% IE by a concentration of 300 mg L-1 at 300 K. This corrosion inhibition is achieved by the adsorption process of A. vera bioactive on metal surfaces with a mixed inhibitor through a physisorption-chemisorption mechanism. This finding was confirmed by the smoother surface morphology of the steel treated with A. vera extract than without. This unveiling investigation found that A. vera extract has the potential to be an environmentally friendly corrosion inhibitor in the seawater environment.

Corrosion inhibition of mild steel by Praecitrullus fistulosus (tinda fruit and peel) extracts

Metal corrosion has recently emerged as a growing concern, impacting both local and industrial operations and disrupting conventional production methods. The utilization of green inhibitors to mitigate the metal degradation has garnered extensive attention from researchers and industrial professionals due to their prominent advantages: high efficiency, cost-effectiveness, and eco-friendliness. A novel ecofriendly inhibitor was prepared from Praecitrullus fistulosus (tinda fruit and peel) for mild steel (MS) corrosion in 1 M HCl. The presence of phenol, 3,5-bis (1,1-dimethyl ethyl)-, 9-octadecenoic acid, methyl ester, hexadecanoic acid 15-methyl-, methyl ester, 9, 12-octadecadienoic acid, methyl ester, 9, 12, 15-octadecatrienoic acid, methyl ester, (Z,Z,Z-), ascorbic acid, and phytol were identified as major constituent through LC/MS analysis of tinda extracts. The existence of these compounds was further confirmed through FTIR analysis, which shows the presence of various functional groups, such as -OH, CO, C-O-C, CC, and aromatic rings in the tinda extracts. Electrochemical and gravimetric analyses were used to investigate the inhibitory effect of tinda extracts. Outcomes of Tafel analysis revealed that both tinda extracts significantly reduced the corrosion current as compared to blank and achieved 83.73 % and 87.59 % inhibition efficiencies at 200 mg L-1 of tinda peel extract (TPE) and tinda fruit extract (TFE), respectively. The change in corrosion potential (Ecorr) was within an ±85 mV range compared to that of the uninhibited system, indicating that both tinda extracts demonstrated a mixed-type inhibition behavior. During adsorption studies, the best fit was obtained for the Langmuir adsorption model. The obtained values of standard Gibbs free energy (ΔG°ads) for TPE and TFE lie between -20 and - 40 kJ mol-1 but close to -20 kJ mol-1, which reveals preferential physical adsorption of the extracts on the metal surface. Thermodynamic parameters, including activation energy, enthalpy, and entropy, were computed across the temperature range of 303 to 323 K, suggesting that corrosion occurs spontaneously by the endothermic process. FESEM analysis depicted that inhibited systems exhibited smooth and crack-free surfaces as compared to blank system. AFM images demonstrated that surface roughness was significantly reduced for the inhibited system. In EDX analysis, the weight percentage of Cl was reduced in the presence of tinda extracts as compared to blank, and in XRD analysis, iron chloride (FeCl2) peak did not appear in the presence of inhibitor but it was in the uninhibited system. All surface-related findings signify that tinda extracts are adsorbed on the MS surface and form a protective layer that separates the metal from the corrosive solution.

Ultrasound assisted extraction of phytochemicals from Piper betel L

Piper betel contains phytochemicals with diverse pharmacological effects. The objective of this study was to enhance the extraction efficiency of phytochemicals and the chlorophyll content using ultrasonication. The Box-Behnken design was employed to optimize the time (10, 20, 30 min), temperature (20, 30, and 40 °C), and solid-solvent ratio (1:10, 1:20, 1:30) by utilizing response surface methods with three independent variables. Multiple parameters, including extract yield, total phenol, total flavonoid, antioxidant activity, and chlorophyll content were used to optimize the conditions. The linear relationship between power intensity and responses was determined to be statistically significant, with a p-value less than 0.01. The interaction effect of temperature, time, and ratio of solid solvent was shown to be statistically significant (p < 0.05) for all the obtained results. The optimal parameters for achieving the highest extract yield were as follows: a temperature of 40 °C, a sonication time of 30 min, and a solid solvent ratio of 1:10. These conditions result in an extract yield of 21.99 %, a total flavonoid content of 44.97 mg/GAE, a total phenolic content of 185.05 mg/GAE, a DPPH scavenging activity of 99.1 %, and a chlorophyll content of 49.95 mg/ml. This study highlights the significance of customized extraction methodologies for optimizing the bioactive capacity of phytochemicals derived from betel leaves. The elucidation of extraction parameters and the resultant phytochemical profiles serves as a fundamental framework for the advancement of innovative pharmaceuticals and nutraceuticals, capitalizing on the therapeutic attributes of this traditional medicinal botanical.

Antibacterial, antidiabetic, acute toxicity, antioxidant, and nephroproductive competence of extracts of Lannea coromandelica fruit through in-vitro and in-vivo animal model investigation

The anti-dermatophytic (Proteus vulgaris, Klebsiella pneumoniae, Enterobacter aerogenes, Propionibacterium acnes, Staphylococcus aureus, and Streptococcus pyogenes) and nephroprotective activities of methanol and aqueous extracts obtained from Lannea coromandelica fruit were investigated through in-vitro (agar well diffusion method) and in-vivo (animal model) study. The methanol extract showed considerable antibacterial activity against selective bacterial pathogens at increased concentration (15.0 mg mL-1) in the following order P. vulgaris (35.2 ± 1.6 mm) > E. aerogenes (32.1 ± 2.1 mm) > K. pneumoniae (29.3±2 mm) > P. acnes (28.2 ± 2.4 mm) > S. aureus (25.5 ± 2.4 mm) > S. pyogenes (24.3 ± 2.1 mm) than aqueous extract. The MIC values of this methanol and aqueous extract was found as 2.5-7.5 mg mL-1 and 5.0 to 1.0 mg mL-1 respectively. Different treatment sets (A-E) on a rat-based animal model study revealed that the methanol extract has excellent antioxidant and nephroprotective activity, as well as favorable effects on essential biochemical substances involved in active metabolic activities. As demonstrated by histopathological and microscopic examination, the biologically active chemical present in methanol extract had a positive effect on serum markers, enzyme, and non-enzyme-based antioxidant activities, as well as lowering the toxicity caused by EG in the rat (as nephroprotective activity) renal cells.

Analysis of natural okra extracts as corrosion inhibitors for mild steel in acidic medium

Plant extracts have been shown to effectively inhibit metal corrosion. Using the Box-Behnken design, gravimetric, and electrochemical techniques, analyses were designed to investigate the anti-corrosion potential of okra in a 1M HCl medium. The inhibition performances derived from the various methods were in good agreement, demonstrating that physio-chemisorption was effective and adhered to the Langmuir isotherm model. The efficiency of okra mucilage extract was 96% at a much lower concentration compared to 91.2% and 88.4% for the unsieved extract and gelly-okra filtrate, respectively. FTIR results showed the presence of several functional groups in the okra mucilage extract that are associated with adsorption, and TGA analysis revealed that the extract has high thermal stability. FESEM analysis also supported evidence of adsorption. It was determined that corrosion inhibition by okra mucilage extract was primarily influenced by temperature, followed by extract concentration, with immersion time having the least effect. From the model optimization, it was observed that okra mucilage extract at 200 ppm, 60°C, and 24 h gave an inhibition efficiency of 89.98% and high desirability. These results demonstrate the high capacity of natural okra as an efficient biodegradable corrosion inhibitor.

Combination of practical and theoretical measurements of albumin egg as an eco-friendly inhibitor for copper corrosion in alkaline solutions

Utilizing environmentally acceptable substances as inhibitors of metal corrosion is one of the most important strategies to reduce corrosion. In alkaline solutions (1.0 M KOH), the influence of albumin egg as a green corrosion inhibitor for copper was studied via a mix of experimental and theoretical investigations. Cyclic voltammetry (CV), open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), AFM, and SEM/EDX methods were all utilized to examine the inhibitory effect of albumin egg. By increasing the amount of albumin egg in the corrosive solution, the inhibition efficiency is increased. The albumin egg is a highly effective cathodic type inhibitor, according to electrochemical tests, with an inhibition efficiency of up to 94%. It also follows the Langmuir isotherm during adsorption. Investigations using SEM/EDX and AFM show that the albumin egg can create an adsorption layer on the surface enabling the shielding of the copper surface from harmful ions. In order to better understand the molecular structure of the albumin egg and its inhibitory action against corrosion, computational and molecular dynamics simulation techniques were also employed for calculating the electronic characteristics of inhibitor molecules. Calculations were made for total energy (TE), change in total energy (DET), energy gap (ΔE), ELUMO, EHOMO, dipole moment (D), and softness (δ). Utilizing the Monte Carlo simulation, the mechanism of albumin egg adsorption on the surface of Cu was investigated. The theoretical outcomes were found to confirm the empirical results.

Synthesis, characterization, and evaluation of polymeric surfactants derived from PET plastic waste as green corrosion inhibitor of steel surfaces in marine environment for heavy industry

The aim of this work was to prepare a nonionic polymeric surfactant from a recycled product of poly(ethylene terephthalate) plastic waste, PET. In this respect, PET waste was subjected to reverse polymerization (depolymerization) via reaction with both ethylene diamine (EDA) in the presence of a catalyst and propylene glycol (PG) in the presence of a transesterification catalyst. The corresponding products obtained were poly amino amide (PETAA) and poly glycol ester (PETPG), respectively. The obtained materials reacted with oleic acid to produce N1,N4-bis(2-((E)-octadec-9-enamido)ethyl)terephthalamide (PETAA-OL) and 2-(2-(((E)-octadec-8-enoyl)oxy)propoxy)ethyl (2-(2-(((E)-octadec-9-enoyl)oxy)propoxy)ethyl) terephthalate (PETPG-OL). The prepared materials were characterized by FT-IR, 1HNMR, and elemental analysis. It was evaluated as a corrosion inhibitor for carbon steel used in the petroleum industry in the marine environment. Chemical, analytical, and electrochemical techniques were used for the evaluation of the corrosion inhibition efficiency of the prepared polymeric surfactants. The effects of the polymeric surfactant concentration and reaction temperature were studied. The inhibition efficiency was found to increase with increasing concentration and decrease with rising temperature. The inhibition due to the adhesion and adsorption of the polymeric material on the steel surface agrees with the Langmuir adsorption isotherm model. The amount of dissolved iron in the corrosive medium due to the corrosion process was estimated using atomic absorption spectroscopy (AAS). It was found that the dissolution of iron was decreased by adding the prepared nonionic surfactants. Potentiodynamic polarization data indicate the mixed-type nature of surfactant inhibitors. According to the potentiodynamic polarization data, the prepared surfactant boosts polarization resistance and inhibition performance by adsorbing on the metal/electrolyte interface. The addition of inhibitor molecules to the aggressive medium produces a negative shift in the open-circuit potential due to the retardation of the cathodic reaction. The surface morphology of steel was examined using SEM. A protective coating of inhibitor molecules forms on the steel surface, according to the SEM measurements of the surface. The data obtained from different techniques are in good agreement, indicating good inhibition efficiency of the prepared nonionic surfactants derived from plastic waste in a marine environment.

Eco-Friendly Methanolic Myrrh Extract Corrosion Inhibitor for Aluminum in 1 M HCl

Aluminum corrosion was inhibited by myrrh extract when it was placed in a solution of 1 M HCl. Several procedures were used for these tests, including weight loss WL, potential dynamic polarization PL, and electrochemical impedance EIS in addition to theoretical calculations like density functional theory (DFT), Fukui functions, and Monte Carlo simulation. Fourier transform infrared spectroscopy was used to analyze the compositional surface of Al. Scanning electron microscopy was used to determine the shape of the Al surface. The inhibition rate of Al corrosion in HCl with varying myrrh extract contents at 25-45 °C was studied. An analysis of the PL curves indicates that myrrh extract is an inhibitor of mixed type. Upon increasing the concentration of myrrh, the inhibition efficiency increased. Moreover, rising temperatures decrease inhibition efficiency. It was discovered that the inhibition process follows the Langmuir isotherm, demonstrating that a monolayer has formed on the surface of aluminum. Theoretical and practical studies proved the validity of the conclusions.

Influence of blackberry leaf extract on the copper corrosion behaviour in 0.5 M NaCl

The research presented in this paper is focused on blackberry leaf extract (BLE) as a environmentally friendly corrosion inhibitor for copper in 0.5 M NaCl. The caffeic acid, quercetin-3-O-glucoside and kaempferol-3-O-glucoside were identified in BLE by using high-performance liquid chromatography (HPLC-DAD). The BLE functional groups were identified (ATR-FTIR). The electrochemical methods (potentiodynamic polarization, electrochemical frequency modulation and electrochemical impedance spectroscopy) show that BLE acts as a mixed type of inhibitor (max. IE is 97.19 %). The corrosion process is controlled by diffusion (BLE lower than 15 g/L) and charge transfer (15 g/L BLE).

Green tea and tulsi extracts as efficient green corrosion inhibitor for aluminum alloy in alkaline medium

Corrosion is a major issue in every industrial system. As a result of its widespread application, aluminum suffers enormous annual losses due to corrosion. Scientists are continually on the lookout for effective anti-corrosion strategies. Corrosion may be reduced in a number of ways, but many of them are harmful to the environment, so it's important to find a green alternative. Corrosion inhibitors in aluminum alloys can be found in green tea and tulsi extract. In this research, we found that aluminum alloy 1100 (Al-1100) ina 10% NaOH solution was inhibited by both green tea and Tulsi extract. Samples of AL alloy are submerged in 10% NaOH solutions with and without an inhibitor for a total of 25 days. The weight-loss technique is used to determine the effectiveness of an inhibitor, with tulsi extract far outperforming green tea with the best efficiency of 83.93% compared to the greatest efficiency of 14.29% for green tea. After being submerged in an inhibitory solution, an aluminum alloy surface developed an adsorbed protective layer, which is chemical adsorption, as seen by FTIR (Fourier-Transform Infrared Spectroscopy) spectroscopy. Green inhibitors those are present on the surface of the aluminum alloys are less corrosive confirmed by the SEM (Scanning Electron Microscopy) analysis. The chemical particles were found to be present as a coating over AL alloy surfaces, as determined by EDS (Energy Dispersion Spectroscopy) testing. In a10% NaOH solution, Al-1100 is inhibited more effectively by tulsi extracts than by green tea extracts.

The use of food additives as green and environmental-friendly anti-corrosion inhibitors for protection of metals and alloys: a review

Corrosion inhibitors have offered new opportunities to bring positive impacts on our society, especially when it has helped in protecting metals against corrosion in an aqueous solution. Unfortunately, the commonly known corrosion inhibitors used to protect metals or alloys against corrosion are invariably related to one or more drawbacks such as the employment of hazardous anti-corrosion agents, leakage of anti-corrosion agents in aqueous solution, and high solubility of anti-corrosion agents in water. Over the years, using food additives as anti-corrosion agents have drawn interest as it offers biocompatibility, less toxic, and promising applications. In general, food additives are considered safe for human consumption worldwide, and it was rigorously tested and approved by the US Food and Drug Administration. Nowadays, researchers are more interested in innovating and using green, less toxic, and economical corrosion inhibitors in metal and alloy protection. As such, we have reviewed the use of food additives to protect metals and alloys against corrosion. The current review is significant and differs from the previous review articles made on corrosion inhibitors, in which the new role of food additives is highlighted as green and environmental-friendly substances in the protection of metals and alloys against corrosion. It is anticipated that the next generation will be utilizing non-toxic and sustainable anti-corrosion agents, in which food additives might be the potential to fulfill the green chemistry goals.

Evaluating Biofilm Inhibitory Potential in Fish Pathogen, Aeromonas hydrophila by Agricultural Waste Extracts and Assessment of Aerolysin Inhibitors Using In Silico Approach

Aeromonas hydrophila, an opportunistic bacteria, causes several devastating diseases in humans and animals, particularly aquatic species. Antibiotics have been constrained by the rise of antibiotic resistance caused by drug overuse. Therefore, new strategies are required to prevent appropriate antibiotic inability from antibiotic-resistant strains. Aerolysin is essential for A. hydrophila pathogenesis and has been proposed as a potential target for inventing drugs with anti-virulence properties. It is a unique method of disease prevention in fish to block the quorum-sensing mechanism of A. hydrophila. In SEM analysis, the crude solvent extracts of both groundnut shells and black gram pods exhibited a reduction of aerolysin formation and biofilm matrix formation by blocking the QS in A. hydrophila. Morphological changes were identified in the extracts treated bacterial cells. Furthermore, in previous studies, 34 ligands were identified with potential antibacterial metabolites from agricultural wastes, groundnut shells, and black gram pods using a literature survey. Twelve potent metabolites showed interactions between aerolysin and metabolites during molecular docking analysis, in that H-Pyran-4-one-2,3 dihydro-3,5 dihydroxy-6-methyl (-5.3 kcal/mol) and 2-Hexyldecanoic acid (-5.2 kcal/mol) showed promising results with potential hydrogen bond interactions with aerolysin. These metabolites showed a better binding affinity with aerolysin for 100 ns in molecular simulation dynamics. These findings point to a novel strategy for developing drugs using metabolites from agricultural wastes that may be feasible pharmacological solutions for treating A. hydrophila infections for the betterment of aquaculture.

Influence of Henna Extracts on Static and Dynamic Adsorption of Sodium Dodecyl Sulfate and Residual Oil Recovery from Quartz Sand

The application of surfactant flooding for enhanced oil recovery (EOR) promotes hydrocarbon recovery through reduction of oil-water interfacial tension and alteration of oil-wet rock wettability into the water-wet state. Unfortunately, surfactant depletion in porous media, due to surfactant molecule adsorption and retention, adversely affects oil recovery, thus increasing the cost of the surfactant flooding process. Chemical-based materials are normally used as inhibitors or sacrificial agents to minimize surfactant adsorption, but they are quite expensive and not environmentally friendly. Plant-based materials (henna extracts) are far more sustainable because they are obtained from natural sources. However, there is limited research on the application of henna extracts as inhibitors to reduce dynamic adsorption of the surfactant in porous media and improve oil recovery from such media. Thus, henna extracts were introduced as an eco-friendly and low-cost sacrificial agent for minimizing the static and dynamic adsorption of sodium dodecyl sulfate (SDS) onto quartz sand in this study. Results showed that the extent of surfactant adsorption was inversely proportional to the henna extract concentration, and the adsorption of the henna extract onto the quartz surface was a multilayer adsorption that followed the Freundlich isotherm model. Precisely, the henna extract adsorption on quartz sand is in the range of 3.12-4.48 mg/g (for static adsorption) and 5.49-6.73 mg/g (for dynamic adsorption), whereas the SDS adsorption on quartz sand was obtained as 2.11 and 4.79 mg/g at static and dynamic conditions, respectively. In the presence of 8000 mg/L henna extract, SDS static and dynamic adsorption was significantly reduced by 64 and 82%, respectively. At the same conditions, the residual oil recovery increased by 9.2% over normal surfactant flooding. The study suggests that the use of henna extracts as a sacrificial agent during SDS flooding could result in the reduction of static and dynamic adsorption of surfactant molecules on quartz sand, thus promoting hydrocarbon recovery from sandstone formations.

Application of Biomass Corrosion Inhibitors in Metal Corrosion Control: A Review

Corrosion is the process of damaging materials, and corrosion of metallic materials frequently results in serious consequences. The addition of corrosion inhibitors is the most effective means of preventing metal corrosion. Until now, researchers have made unremitting efforts in the research of high-efficiency green corrosion inhibitors, and research on biomass corrosion inhibitors in a class of environmentally friendly corrosion inhibitors is currently quite promising. This work presents the classification of green biomass corrosion inhibitors in detail, including plant-based corrosion inhibitors, amino acid corrosion inhibitors, and biosurfactant corrosion inhibitors, based on the advantages of easy preparation, environmental friendliness, high corrosion inhibition efficiency, and a wide application range of biomass corrosion inhibitors. This work also introduces the preparation methods of biomass corrosion inhibitors, including hydrolysis, enzymatic digestion, the heating reflux method, and microwave extraction. In addition, the corrosion inhibition mechanisms of green biomass corrosion inhibitors, including physical adsorption, chemisorption, and film-forming adsorption, and evaluation methods of biomass corrosion inhibitors are also explicitly described. This study provides valuable insights into the development of green corrosion inhibitors.

Chitosan with Natural Additives as a Potential Food Packaging

Recently, the development of materials based on natural polymers have been observed. This is the result of increasing environmental degradation, as well as increased awareness and consumer expectations. Many industries, especially the packaging industry, face challenges resulting from legal regulations. Chitin is the most common biopolymer right after cellulose and is used to produce chitosan. Due to the properties of chitosan, such as non-toxicity, biocompatibility, as well as antimicrobial properties, chitosan-based materials are used in many industries. Many studies have been conducted to determine the suitability of chitosan materials as food packaging, and their advantages and limitations have been identified. Thanks to the possibility of modifying the chitosan matrix by using natural additives, it is possible to strengthen the antioxidant and antimicrobial activity of chitosan films, which means that, in the near future, chitosan-based materials will be a more environmentally friendly alternative to the plastic packaging used so far. The article presents literature data on the most commonly used natural additives, such as essential oils, plant extracts, or polysaccharides, and their effects on antimicrobial, antioxidant, mechanical, barrier, and optical properties. The application of chitosan as a natural biopolymer in food packaging extends the shelf-life of various food products while simultaneously reducing the use of synthetic plastics, which in turn will have a positive impact on the natural environment. However, further research on chitosan and its combinations with various materials is still needed to extent the application of chitosan in food packaging and bring its application to industrial levels.

Green surfactants for corrosion control: Design, performance and applications

Surfactants enjoy an augmented share of hydrophilicity and hydrophobicity and are well-known for their anticorrosive potential. The use of non-toxic surfactants is gaining growing interest because of the scaling demands of green chemistry. Green surfactants have successfully replaced traditional toxic surfactant-based corrosion inhibitors. Recently, many reports described the corrosion inhibition potential of green surfactants. The present article aims to describe the recent advancements in using green surfactants in corrosion mitigation. They create a charge transfer barrier through their adsorption at the interface of the metal and the environment. Their adsorption is well explained by the Langmuir adsorption isotherm. In the adsorbed layer, their hydrophilic polar heads orient toward the metal side and their hydrophobic tails orient toward the solution side. They block the active sites and retard the anodic and cathodic and act as mixed-type inhibitors. Their adsorption and bonding nature are fruitfully supported by surface analyses. They can form mono- or multilayers depending upon the nature of the metal, electrolyte and experimental conditions. The challenges and opportunities of using green surfactants as corrosion inhibitors have also been described.

Quantitative and qualitative analyses of grafted okra for corrosion inhibition of mild steel in acidic medium

Introduction: Natural plant polymers demonstrate effective corrosion inhibition abilities, because of their numerous binding sites and excellent adsorption abilities. Methodology: In this study, the Box-Behnken method, gravimetric and electrochemical analyses were used to design and investigate the corrosion inhibition potential of a modified graft polymer of okra for mild steel in a 1M HCl medium. The influence of inhibitor concentration, temperature, and time were also investigated. Qualitatively, the Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), and Field emission scanning electron microscopy (FESEM) were used to characterize the extracts and evaluate the metal's surface morphology. Results and discussion: The quantitative analyses showed that the modified natural polymer's inhibition efficiency (IE) increased with concentration and reached 73.5% at 800 ppm, with a mixed-type mode of inhibition. From the response surface methodology, it was revealed that temperature influences the IE more than concentration and immersion time. The optimized IE using the desirability function showed the possibility of attaining 88.2% inhibition with inhibitor concentration at 142.3 ppm, temperature at 60.4°C, and an immersion time of 22.4 h. The new functional groups in the hybrid polymer revealed by FTIR analysis shows that grafting improved the inhibitor's adsorption abilities. TGA analysis confirmed the extract's high thermal stability, which highlights the inhibitor's strong adsorption and efficiency for high temperatures. FESEM analysis indicated evidence of inhibitor adsorption onto the metal surface. Conclusion: These findings suggest that the grafting of okra with acrylamide enhances its inhibition properties and contributes to its functionality as a cost-effective plant-based alternative inhibitor against corrosion for mild steel facilities.

A General Use QSAR-ARX Model to Predict the Corrosion Inhibition Efficiency of Drugs in Terms of Quantum Mechanical Descriptors and Experimental Comparison for Lidocaine

A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and ΔN values. The most efficient drugs are found with pK_a ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.

The co-adsorption of thymohydroquinone dimethyl ether (THQ) and coumarin present in the aqueous extract of Ayapana triplinervis on mild steel and its protection in hydrochloric acid up to 323 K: computational and physicochemical studies

This study evaluates the corrosion inhibition property of the aqueous and alcoholic leaf extracts of the medicinal plant Ayapana triplinervis. The major components in the extracts are thymohydroquinone dimethyl ether (THQ) and coumarin. It is clear from the weight-loss studies that the water extract of the leaves (AYW) is superior to the alcoholic extract (AYA) in terms of offering corrosion inhibition. The 96% efficiency of 4% (v/v) AYW in 0.5 N HCl at room temperature changes to 84.62% at 323 K. The mixed-type inhibition behaviour of AYW shows slight dominance in the anodic direction. Studies suggest the multilayer adsorption of phytochemicals on the metal surface and that the adsorption follows the Temkin model. Theoretical studies using DFT and BIOVIA Materials Studio investigations establish THQ as a good inhibitor with high adsorption characteristics. Even though the concentration of coumarin in the extract is low, its presence in the extract facilitates the adsorption of THQ on the metal surface, which is evident from the MD simulation study. The changes in the surface topography and elemental composition of the metal specimen in the inhibited and uninhibited solution are monitored by SEM and EDX spectral studies. XPS data support the presence of both THQ and coumarin on the metal surface and the existence of co-ordinate bonding between the metal's d orbital and the O atoms of THQ. Theoretical and experimental studies support the mixed mode of adsorption of THQ as physisorption followed by chemisorption.

This study evaluates the corrosion inhibition property of the aqueous and alcoholic leaf extracts of the medicinal plant Ayapana triplinervis.

Environmentally benign Prosopis juliflora extract for corrosion protection by sorption - Gravimetric, mechanistic and thermodynamic studies

Environmentally benign plant extract compounds have gained significant attention in the corrosion prevention applications due to their biodegradability and eco-friendliness. The adsorptive corrosion control action of Prosopis juliflora plant extract was investigated using differential mass change experiments and the mechanism was validated using Tafel and Nyquist plots. The effect of green corrosion inhibitor concentration (0-800 ppm) on corrosion rate at different solution temperatures (305.15, 310.15 and 315.15 K) in 1 M HCl was studied. The corrosion inhibitor exhibited monolayer surface coverage and confirmed by Langmuir isotherm (R² > 0.970). The negative values of Gibbs free energy (<20 kJ/mol) proved the electrostatic interaction between the inhibitor and metal surface. The enhanced energy barrier for the corrosion process was confirmed by changes in E_a in the presence of biomass-based inhibitor on the mild steel surface. Electrochemical impedance study proved that the double layer capacitance (C_dl) decreased and the resistance increased with increase in corrosion inhibitor concentration. The surface modifications on the metal were observed using scanning electroscope imaging. ATR studies were conducted for functional group identification of the corrosion inhibitor.

Structured Thin Films Based on Synergistic Effects of MnTa2O6 Oxide and bis-Carboxy-phenyl-substituted Porphyrins, Capable to Inhibit Steel Corrosion

Covering steel surfaces with suitable materials with the capacity to protect against corrosion represents a challenge for both research and industry, as steel, due to its paramount utility, is the most recycled material. This study presents the realization of new sandwich type materials based on 5,10-(4-carboxy-phenyl)-15,20-(4-phenoxy-phenyl)-porphyrin or 5,15-(4-carboxy-phenyl)-10,20-diphenylporphyrin and MnTa2O6 designed to improve corrosion inhibition of steel in aggressive media. The thin films, designed as single- or sandwich-type structures were obtained on carbon steel through the drop-casting technique. Morphological investigations of thin films were carried out by field emission-scanning electron microscopy (SEM) and atomic force microscopy (AFM). The inhibition of a steel corrosion process was evaluated in an aggressive environment of 0.1 M HCl by performing electrochemical investigations such as open circuit potential (OCP) and the potentiodynamic polarization technique. The influence of variations in the cathodic Tafel slopes βc and anodic Tafel slopes βa over the corrosion rates was discussed. The best corrosion inhibition efficiency of 91.76% was realized by the steel electrode covered with sandwich-type layers of 5,15-(4-carboxy-phenyl)-10,20-diphenylporphyrin on the bottom layer and MnTa2O6 on the top. The effect of location of the COOH groups in the cis or trans position on the tetrapyrrolic ring was also discussed to understand the corrosion inhibition mechanism.

Green corrosion inhibitor: Cymbopogon schoenanthus extract in an acid cleaning solution for aluminum brass

The purpose of this study was to see if Cymbopogon schoenanthus aerial extract (CSA extract) could reduce the corrosion of aluminum brass in acid cleaning solutions in the distillation plant. For this assessment, measurements of weight loss and polarization technique have all been used. We discovered that at 250 ppm, the efficiency of CSA extract was excellent (97%). Polarization assessments confirmed that the organic compounds in CSA extract were effective mixed-type corrosion inhibitors. HPLC and FTIR analysis were used to explore the key chemical components of CSA extract. CSA extract caused the corrosion process to have a higher energy barrier. Observations of SEM and FT-IR spectra confirmed that CSA extract prevents corrosion attacks at the aluminum brass’s surface.

Date palm leaves extract as a green and sustainable corrosion inhibitor for low carbon steel in 15 wt.% HCl solution: the role of extraction solvent on inhibition effect

Date palm leaves (DPL) was extracted using acetone (ACE), ethanol (ETH), aqueous (AE), butanol (BUT), methanol (METH), isopropanol (ISO), and ethyl acetate (EHY ACT). The extracts were characterized using Fourier-transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) spectroscopy. The various solvent DPL extracts were screened for anticorrosion property against low carbon steel in 15 wt.% HCl solution at 25 °C. ACE, AE, and ETH DPL extracts are found to promote the corrosion of the low carbon steel while BUT, ISO, METH, and EHY ACT DPL extracts exhibit anticorrosion property. However, BUT DPL extract shows the best anticorrosion property with 400 ppm protecting the low carbon steel by 82%. Based on the results from the screening experiments, BUT extract was selected for a comprehensive corrosion inhibition study. Inhibition effectiveness of BUT DPL extract is found to increase with increasing concentration with 1000 ppm affording 97% protection at 25 °C. The inhibition performance increases up to 40 °C but slightly decreases as the temperature was raised to 50 °C and 60 °C. However, BUT DPL extract could afford 86% protection at 60 °C. Scanning electron microscope and atomic force spectroscopy results confirm that BUT DPL extract is indeed an effective inhibitor for X60 carbon steel in 15 wt.% HCl solution.