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Corrosion inhibition of carbon steel in hydrochloric acid solution by fruit peel aqueous extracts
Abstract
The inhibitive action of the aqueous extracts of fruit peels against corrosion of carbon steel in a 1M HCl solution was investigated using electrochemical impedance spectroscopy, potentiodynamic polarization curves, weight loss measurements and surface analysis. We analyzed aqueous extracts of mango, orange, passion fruit and cashew peels in different concentrations and found that the extracts act as good corrosion inhibitors for the tested system. The inhibition efficiency increases with increasing extract concentration and decreases with temperature. The adsorption of components of the fruit peel extracts on the surface of the carbon steel follows the Langmuir adsorption isotherm.
... This rise in temperature leads to a shift in the inhibitor adsorption equilibrium, favoring a desorption process and consequently leading to a reduction in surface coverage [58,59]. As a result, the inhibitor surface conformation order decreases and the corrosive ion mobility increases [60]. At 323 K, the CHBI has a significant corrosion inhibition efficiency (38.88%) when compared to a blank, as shown in Table 6. ...
... equilibrium, favoring a desorption process and consequently leading to a reduction surface coverage [58,59]. As a result, the inhibitor surface conformation order decreas and the corrosive ion mobility increases [60]. At 323 K, the CHBI has a significant corr sion inhibition efficiency (38.88%) when compared to a blank, as shown in Table 6. ...
... This rise in temperature leads to a shift in the inhibitor adsorption equilibrium, favoring a desorption process and consequently leading to a reduction in surface coverage [58,59]. As a result, the inhibitor surface conformation order decreases and the corrosive ion mobility increases [60]. At 323 K, the CHBI has a significant corrosion inhibition efficiency (38.88%) when compared to a blank, as shown in Table 6. ...
... equilibrium, favoring a desorption process and consequently leading to a reduction surface coverage [58,59]. As a result, the inhibitor surface conformation order decreas and the corrosive ion mobility increases [60]. At 323 K, the CHBI has a significant corr sion inhibition efficiency (38.88%) when compared to a blank, as shown in Table 6. ...
Citation: Adardour, M.; Lasri, M.; Ait Lahcen, M.; Maatallah, M.; Idouhli, R.; Alanazi, M.M.; Lahmidi, S.; Abouelfida, A.; Mague, J.T.; Baouid, A. Exploring the Efficacy of Benzimidazolone Derivative as Corrosion Inhibitors for Copper in a 3.5 wt.% NaCl Solution: A Comprehensive Experimental and Theoretical Investigation. Molecules 2023, 28, 6948. https://doi. Abstract: This study focuses on the synthesis, theoretical analysis, and application of the corrosion inhibitor known as benzimidazolone, specifically 1-(cyclohex-1-enyl)-1,3-dihydro-2H-benzimiazol-2-one (CHBI). The structure of CHBI was determined by X-ray diffraction (XRD). The inhibitory properties of CHBI were investigated in a 3.5 wt.% NaCl solution on pure copper using various electrochemical techniques such as potentiodynamic polarization curves (PDPs) and electrochemical impedance spectroscopy (EIS), as well as scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), UV-visible spectroscopy, and theoretical calculations. The obtained results indicate that CHBI is an excellent inhibitor, exhibiting remarkable effectiveness with an inhibition rate of 86.49% at 10 −3 M. To further confirm the extent of adsorption of the inhibitory molecule on the copper surface, density functional theory (DFT) and Monte Carlo (MC) simulation studies were conducted. The results of this study demonstrate the synthesis and characterization of CHBI as a corrosion inhibitor. The experimental and theoretical analyses provide valuable insights into the inhibitory performance of CHBI, indicating its strong adsorption on the copper surface.
... Some chemical products, as scale resistant in addition to corrosion-resistant, are applied to this fluid before injection to deter both scale deposition as well as corrosion in oil pipelines. [6][7][8] Due to high performance, economic advantages, and extensive implementation in various technological sectors, inhibitors are considered the most effective tool. Inhibitors' efficiency depends heavily on the inhibitor's physical properties as well as its chemical structure including polar groups, heteroatoms, aromatic rings, or/and π "pi" electrons. ...
... This results in a decline in C-steel's active area as a result of OPE's adsorption, subsequently, obstacle the corrosion cycle. 7 In the presence of orange peel extract [OPE], the kinetic of C-steel oxidation is minified slightly, as noticed conclusively in Figure 5 through the anodic branch. In a devastating medium as FW, the OPE's anti-corrosion characteristics on C-steel are significant. ...
The ongoing research aims to examine the influence of orange peel extract "OPE" as environmentally benign carbon steel's corrosion resistance in the formation water "FW". The research was implemented at various concentrations "0.5-2.5 percent (v/v)" of peel extract "100-500 ppm" at ambient temperature [25 o C] as well as "2.5 percent (v/v)" concentration at (25-55 o C) temperature range utilizing various technique. Such techniques include weight loss quantification, potentiodynamic polarization as well as open circuit potential in addition to dielectric spectroscopy [EIS]. The efficiency of inhibition has been estimated utilizing those techniques and then checked with energy dispersive radiation "EDS" in addition to FTIR analyses. The upshot divulged that OPE worked on as an efficient C-steel's corrosion inhibitor through adsorbing its active component on the C-steel's surface. The approach of adsorption was of physical type and it obeys Langmuir isotherm.
... Recently, trend has been deviated towards the nontoxic, cost effective, easily available, and eco-friendly natural inhibitors. This encourage researchers to extended the fundamental understanding towards corrosion inhibition efficiency (Ƞ%) of natural products such as plant extracts, seeds, oils, gums, etc., [5]- [8]. ...
... Bare HCl environment has vigorous attack on coupon's surface and created wide pits due to oxidation of metal atoms. In contrast, the addition of inhibitor considerably decreases the surface deterioration, and smoother surface can be seen with increasing the GG concentration [5]. Further, by examining the images, it is observed that that at optimum concentration of GG there is no oxidation film or pits on steel surface. ...
Steel is considered as a versatile material due to intrinsic mechanical properties and potential technological applications. However, environmental exposure inevitably oxidize and cause catastrophic industrial failures. To mitigate the oxidation of steel, various prevention methods are adopted, which are toxic and expensive. Herein, an eco-friendly and inexpensive approach is studied to prevent carbon steel from oxidation in the HCl environment. Biodegradable, non-ionic and water-soluble green inhibitor containing hetero polysaccharides is prepared by using guar seeds. Electrochemical measurement studies reveal that guar gum creates a non-conductive adhesive layer between the metal and corrosive media by adsorbing on the metallic surface. Fourier transform infrared and surface analysis confirms the adsorption of guar gum molecules on the metal surface. Industrially viable Gravimetric analysis results provided a weight loss efficiency of 91% for 24 hours, which decreases with exposure time. Lastly, Temkin adsorption model is used to validate adsorption and resulting inhibition.
... One of the huge impacts of failures in the pipeline of gas and oil manufacturing systems due to corrosion is that it influences about one-quarter to two-thirds of the overall breakdown of service in the industry [25] (Da Rocha et al., 2010;Eduok et al., 2012). A massive amount of money is consumed each year on diverse categories of corrosion regulation to sustain pipeline integrity. ...
... Different modern green capacity oil-based inhibitors have been applied in the past years. Some discoveries entail red pepper seed oil, Nigella sativa L. seed oil, palm oil, and Artemisia mesatlantica essential oil (Da Rocha et al., 2010;Machado et al., 2019). These inhibitors have depicted exceptional efficiency in acidic media with above 90%, hence revealing their capacity for industrial use. ...
Infrastructure upgrades in the energy sector are encouraged to satisfy the expanding world’s energy needs, including innovation, consumption, production, and transportation. Thus, steel has been an extensively used construction material, particularly for pipelines and oil wells. However, in their application, every step of the production cycle results in the corrosion of metal parts. One of the simplest and most active ways to inhibit steel from corroding, especially in acidic situations, is to use a corrosion inhibitor. Synthetic organic compounds have been used successfully as corrosion inhibitors in the gas and oil industry. However, their use is today restricted and controlled due to their toxicity, environmental harm, and growing concern about the preservation of ecosystems. This has necessitated the present trend of searching for and developing green inhibitors that are environmentally benign, non-toxic, biodegradable, and low in cost. Corrosion inhibitor develops a shielding layer on the metal surface. Corrosion is avoided by a thin coating that has been adsorbed on the metal surface, which keeps the metal isolated from its surroundings. Several researchers have reported on the success of green inhibitors for steel corrosion protection, particularly in acidic environments. However, the use of green inhibitors still leaves several questions about inhibitor formulation, content, and adsorption mechanisms to be answered. Therefore, based on provided experimental results and an explanation of their inhibitory action, the use of green inhibitors (especially organic inhibitors) for the prevention of pipeline steel corrosion in various grades is studied in this review. Both the identified drawback and the projected future trend have also been highlighted.
... 4 In this context, the employment of inhibitors emerges as an indispensable and widely adopted strategy to prevent the corrosion-induced dissolution of mild steel and other metals. [5][6][7] Although many synthetic compounds have proven effectiveness in providing anti-corrosion properties, a major drawback is their negative impact on human health and the environment. 8,9 The global concern regarding safety and sustainability issues associated with corrosion inhibitors in various industries has been a persistent issue. ...
The corrosion of metals is still a huge challenge for various industries, and the pursuit of effective treatments ensures environmental sustainability. In this study, we utilized Chiquita banana sap-water extract (BSWE) to prevent mild steel from electrochemical corrosion in a 0.1 M HCl at room temperature. Corrosion resistance was assessed using various electrochemical methodologies, combining with surface characterization techniques. The results showed a high level of effectiveness when the corrosion current density decreased from 3292.67 μA cm⁻² (for the sample immerged in the blank solution) to 187.33 μA cm⁻² after 24 hours of immersion in the solution containing BSWE at a 2000 ppm concentration, equivalent to corrosion efficiency of 94.32%. Surface characterization revealed diminished corrosion on the inhibited steel surface due to the formation of a protective layer. X-ray photoelectron spectroscopy results demonstrated the presence of BSWE ingredients combining with iron oxides and hydroxides to form a smooth protective layer. Furthermore, theoretical calculations also indicated that the addition of BSWE can reduce steel surface damage when exposing to corrosive environment. The inhibitor based on banana sap extract can be referred to as a sustainable protective coating since it is biodegradable, abundantly available in banana plants and free of other harmful substances.
... Compared to conventional corrosion inhibitors, there are many environmentally friendly, edible, and non-toxic alternatives that provide similar characteristics while remaining safe to handle. Environmentally friendly corrosion inhibitor compounds can be derived from a variety of plant parts such as seeds, stems, leaves, flowers, fruits, and roots [61][62][63][64][65][66][67]. Some examples include inhibitors made from cinnamon, garlic, thyme, rosemary, mint, and turmeric. ...
The focus of this chapter will be on corrosion during downhole oil and gas treatments such as matrix acidizing, inorganic scale removal, and mud filter cake removal. The chapter will start by introducing the nature of oil and gas treatments, defining the types of corrosion, sharing the type of metallurgy, and the effect of alloying for tubulars used in the oilfield. After that, corrosive elements such as gases will be discussed. Common corrosion mechanisms and prevention methods that include the use of corrosion inhibitors and intensifiers will be shared. Additionally, the chapter will mention the passing criteria in the industry and the most notable chemical incompatibilities encountered. Moreover, the toxicity of these corrosion inhibitors will be touched on briefly and the chapter will end with environmentally friendly options for corrosion inhibition in the oilfield.
... Therefore, the study of non-toxic or environmentally friendly corrosion inhibitors is important to overcome this challenge. Recent literatures highlighting the use of plant extract from Carica papaya, Rosmarinus Officinalis, Damsissa, Murrayakoenigii, cashew, mango, Uncaria gambir, Fiscusycomorus, Gum Arabic, Raphia hookeri, Ipomoea invulcrata, Vigna unguiculata, Pachylobus edulis, Ginseng root, Dacroydes edulis and Zenthoxylum alatum had been investigated and [16][17][18][19][20][21][22] Ogunleye et al., 2018; [23][24][25][26][27][28][29][30] to mention but a few have been found to exhibit anticorrosion inhibiting effect for metal in acidic/alkaline media. In our continuous quest to explore, verify and validate more natural products of plant origin as corrosion inhibitors, the present study is on Stachytarpheta mutabilis leaf extract. ...
The anticorrosive potential of Stachytarpheta mutabilis leaf extract (SMLE) as a corrosion inhibitor for corrosion of mild steel (MS) in 1 M HCl was investigated using weight loss measurement as well as gasometric techniques at 30 and 60 oc. Relevant thermodynamic equations were employed to estimate the activation energy, enthalpy change and entropy change. The adsorption isotherms were used to determine the Gibbs free energy change. Results obtained showed that SMLE functioned as an excellent corrosion inhibitor for mild steel in the acidic environment. Temperature studies revealed a decrease in inhibition efficiency with increase in temperature and activation energies increased in the presence of the extract. The adsorption of SMLE on mild steel was approximated using Freundlich, Flory-Huggins, Frumkin, El-Awary’s and Temkin isotherms but Langmuir gave the best fit. Both kinetic and thermodynamic parameters governing the adsorption process were calculated and discussed. The adsorption followed a first order kinetics. As concluded from the results, the adsorption of S. mutabilis on mild steel in 1M HCl medium is feasible, spontaneous and it occurred by physical adsorption. From the experimental results obtained, it can be concluded that SMLE inhibit corrosion effectively when compared well with many reported green inhibitors for MS corrosion.
... Some organic compounds are known to be potent as corrosion inhibitors for different grades of steel in acidic and alkaline media (Dafali et al., 2002;Oguzie et al., 2005;Oguzie, 2005;Mihit et al. 2006;Oguzie, 2006). Other research scholars (Satapathy et al., 2009;da Rocha et al., 2010) have also reported that many materials of plant origin have been successfully used to reduce metal corrosion in the past. The extracts from seeds, barks, leaves, and root of these plant materials contain an array of natural products and have been tested for their corrosion inhibitory properties and some have been reported to successfully inhibit metal corrosion in acidic media Raja et al., 2008;Abboud et al., 2009;Okafor et al., 2010;Hmamou et al., 2012Hmamou et al., & 2015. ...
Methanol leaf extract of Datura discolor Bernh (DD) was investigated for its anticorrosion effect on low-carbon steel corroding in 0.5 M solutions of H2SO4, HCl and HNO3 by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. Three inhibitor packages were prepared by extracting the DD leaves using the respective acid solutions (0.5 M solutions of H2SO4, HCl and HNO3) as solvent following the procedure of hot extraction under reflux for 2 hours at room temperature. Open circuit potential (OCP) was first measured against elapsed time of immersion of coupons and recorded for the three systems for 30 min using 150 ml of the test acid solution. DD leaf extract was found to retard the corrosion of low-carbon steel in the hostile acidic environments by the adsorbed film of organic molecules interacting at the substrate-acid solution interface. Inhibitor efficiency (η%) was found to be a function of both extract (inhibitor) concentration and corrosive medium. With 150 mg/L of extract, inhibitor efficiency (η%) of >77 % in H2SO4, >60 % in HCl, and >35 % in HNO3 were recorded via electrochemical impedance spectroscopy, while >75 % in H2SO4, >65 % in HCl, and >34 % in HNO3 were recorded via potentiodynamic polarization measurements. These results are quite consistent and indicate that the inhibitor exhibited the best efficacy in sulfuric acid medium and the least efficacy in nitric acid. The impedance responses in the three acidic media suggests that the corrosion reaction occurred under charge transfer control. Values of the corrosion potential (𝐸𝑐𝑜𝑟𝑟) did not change significantly. The maximum change in corrosion potential recorded in all the experiments is < 85 mV and this suggests that DDL-extract functioned as a mixed-type inhibitor. The results of this study affirms that Datura discolor leaf extract could be harnessed as a sustainable inhibitor for protecting low-carbon steel from acid-induced corrosion.
... (In Ef (s), Ef means final potential and "s" refers to seconds. Quiet time (s) refers to quiescent time before potential scan) [15][16][17][18][19]. AC impedance spectra AC impedance spectra have been used to investigate the formation of a protective film during corrosion protection process [20][21][22][23][24][25][26][27][28][29][30][31][32]. ...
The corrosion resistance of SS 18/8 orthodontic wire in artificial saliva has been evaluated in the absence and presence of an aqueous extract of Spillanthus acemella plant leaves. Electrochemical studies such as polarization technique and AC impedance spectra have been employed. The protective film has been analyzed by FTIR and AFM. Polarization technique reveals that in the presence of extract, the corrosion potential of SS 18/8 orthodontic wire is shifted to cathodic side. The LPR value increases and corrosion current decreases. This implies that in the presence of extract the corrosion resistance of SS 18/8 orthodontic wire increases. Similar observation is made in the AC impedance spectra results also. There is increase in charge transfer resistance value, increase in impedance value and decrease in double layer capacitance value. FTIR spectral study reveals that the increase in corrosion resistance is due to adsorption of the active principles present in the extract of the leaves onto the metal surface. The AFM parameters of the AFM images [the average roughness (Ra) value, root mean square (RMS) roughness (Rq) and maximum peak to valley (P-V) height] were derived. These values increased when SS 18/8 orthodontic wire was immersed in artificial saliva whereas these values decreased when SS 18/8 orthodontic wire was immersed in artificial saliva+extract system. The outcome of the study is that the patients those who use these metal alloys for orthodontic purpose can chew and place the leaves of Spillanthes acmella in the teeth cavities to get relive from pain of toothache without any hesitation and fear.
... The other studies in this review that dedicated to researching these species obtained the same result concerning maximum efficiencies and, when investigating other aspects, reached the following common conclusions: the adsorption data followed the Langmuir isotherm and the inhibition efficiency increased with the increase of concentration and time, in the range of 1-24 h, in MLTI assays. ROCHA et al. [48] observed that the inhibition efficiency decreases with increasing temperature, in the range of 25-60 ºC, indicating a physical adsorption process. ROCHA et al. [51] studied orange and mango peels and pointed out an adsorption mechanism involving hydrogen bonds and substitution of water molecules on the metal surface. ...
Inhibitors are one of the oldest methods of mitigating corrosion, which is still a current challenging and costly problem. However, traditional inhibitors are toxic and non-biodegradable, which goes against the principles of Green Chemistry, so named for valuing the use of biodegradable and environmentally friendly products. They can be obtained from plants and their residues that, when subjected to some type of processing, generate extracts or oils with important inhibitory potential. In most cases, green inhibitors are organic compounds classified relating to the mechanism as mixed, having polar functional groups that act as adsorption centers on the metallic surface. This study aimed to carry out a systematic review of the literature on inhibitors from species of Brazilian flora and used in an acid environment to prevent corrosion in carbon steel in a specific medium. Brazil presents a rich biodiversity of flora, with more than 46,200 species cataloged in 2020, which provides a wide field of research in this area. The review included 28 different plant species. The results found were promising, with emphasis on the use of parts of vegetables that are normally discarded and show the potential for development and improvement of green inhibitors for future application on an industrial scale.
Keywords
green inhibitors; Brazilian flora; mild steel; acidic medium
... The corrosion inhibition efficiency of steel API 5L grade B by mango peel extract at 25 ºC was 81.77 % [36]. A study on corrosion of carbon steel inhibited in 400 ppm in 1 M HCl was given an inhibition of 80 % for 4-hour immersion [37]. The efficiency was reported to decrease as the temperature was increased from 25 to 60 ºC. ...
Nowadays, researchers are interested in exploring the possibility of replacing harmful inorganic chemicals with green organic substances derived from natural sources. This study focuses on accessing the potential of a green corrosion inhibitor for mild steel, using plant extracts from local mango peel. The Harumanis mango peel leftover was extracted using solvent extraction techniques and the chemical compounds were characterized through Fourier Transform Infra-Red (FTIR) and UV-visible spectroscopy. The analysis showed that the crude extract of Harumanis mango peel (HMPE) contained active functional groups for corrosion inhibitory properties such as -OH, -COOH, -C=O and aromatic ring structure. The presence of mangiferin and other flavonols, likely acid gallic, was also detected. The efficiency of HMPE as a corrosion inhibitor for mild steel was investigated through a conventional corrosion test. The immersion test was carried out in different temperatures at 30, 40, 50 and 60 ⁰C with and without the addition of the 50 to 350 ppm HMPE inhibitor in 1 M hydrochloric acid, HCl. The result showed that the corrosion inhibition efficiency for mild steel in acidic medium increased as the concentration of the Harumanis mango peel increased. The maximum inhibition efficiency of 85 % was obtained at 30 ⁰C for 300 ppm. The adsorption of the Harumanis mango peel corrosion inhibitor obeys Langmuir isotherm model. The adsorption of HMPE on mild steel showed comprehensive (mixed) types as revealed by thermodynamic studies. Favourable adsorption was more dominant for 30 and 40 ºC inhibitors system, whereas at high temperatures the adsorption showed weak and unfavourable interaction between HMPE and the mild steel surface. Surface analysis showed the mild steel surface was free from pits and uniform corrosion as it was inhibited by the HMPE in low temperature solution.
... The figure clearly shows a depressed semicircular shape for all the impedance spectra. Slight deviations of the shape from a perfectly circle suggest interfacial impedance frequency dispersion (Da- Rocha et al. 2010;Pavithra et al. 2010). The equivalent circuit used in modeling the N80 steel/HCl solution interface is depicted as an insert in Fig. 3, where R s denotes solution resistance, R ct stands for charge transfer resistance and CPE is the constant phase element used to replace double layer capacitance (C dl ). ...
An investigation of the performance of recently synthesized pyridine-2-amine derivative namely, N-(5-methoxy-2-hydroxybenzylidene) pyridine-2-amine (N5MHP) as inhibitor of N80 steel corrosion in 1 M HCl environment was carried out using surface analysis, electrochemical impedance, polarization and weight loss method. Results obtained reveal that N5MHP performed well in protecting the steel surface, achieving an inhibition efficiency of 97.0% at 303 K with 1.0 mM concentration from weight loss method. Increasing temperature depreciated the corrosion inhibition efficiency of N5MHP but increase in concentration enhanced the protection performance of the inhibitor. Electrochemical tests results agreed with weight loss results. Langmuir isotherm was obeyed by N5MHP in its adsorption on the steel surface. Polarization studies revealed that N5MHP acted as mixed-type inhibitor. Surface morphology characterized using scanning electron microscopy (SEM) displayed a more protected surface of the X60 steel in the presence of N5MHP in the acid media. Theoretical calculations were performed by employing Density Functional Theory (DFT).
... Corrosion inhibition effect of Justicia gendarussa extract on mild steel in 1 M HCl medium was also studied (Satapathy et al., 2009). Rocha and coworkers (da Rocha & da Cunha Ponciano Gomes, 2010) reported the effect of aqueous extracts of mango, orange, passion fruit and cashew peels as corrosion inhibitors for carbon steel in 1 M hydrochloric acid. They showed that the inhibition efficiencies obtained in the presence of extracts followed the trend cashew < mango < passion fruit < orange. ...
Metal corrosion is a major global concern in many economic sectors. Specifically, in the food and pharmaceutical industry, stainless steel is exposed to heat, water, and harsh cleaning chemicals. Through those exposures, food grade stainless steel must remain durable, corrosion free, and be easy to sanitize. These features are crucial because produced foodstuffs and drugs must comply with high purity and quality standards. Just a proper selection of stainless-steel grade can prevent corrosion phenomena that can be detrimental to the whole manufacturing process. In this book chapter, the corrosion and biocorrosion inhibition of stainless steel was investigated under harsh cleaning chemicals condition (10% HCl). For that, Chitin and Chitosan are extracted successively from the pink shrimp shells of Parapenaeus longirostris collected from the local market of Mehdia. Their corrosion and biocorrosion inhibition potential was evaluated via standard weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopymeasurement.
... The corrosion rate increased and the inhibition efficiency of the MS decreased with increasing temperature in the presence of the ethanolic extract of ECPE in 1 N HCl electrolyte after immersion for 1 h. This is because high temperatures may cause several changes to the MS surface, such as severe etching and the desorption or degradation of inhibitor molecules [37]. ...
... Syringic and vanillic acids as well as some phenolic compounds (such as 4-hydroxy-3-methoxybenzoic acid, 3,4-dihydroxybenzoic acid and 3-acetyl-4-hydroxy-5-methoxybenzoic acid) which have also been found in the extract and are essential contributors to the corrosion inhibition effect of the mango peel extract [59]. Other studies with good maximum inhibition efficiencies (%IE) have also been reported for mango peel extract including 87.77% [60], 97% [61], 91% [62], etc. In Table 3, we summarised some fruit peels that are active as corrosion inhibitors. ...
Current successes recorded in the use of plant leaves as corrosion inhibitors have been globally admitted as one of the best options. Little attention is paid to the future implication or risks concerning food insecurity, economic challenges and competition in various sectors that employ plants as their raw materials. This study reviewed the potential of plant wastes (such as peels, rinds and other components) as alternative sources of sustainable corrosion inhibitors. The review reveals that through the considerations of experimental and quantum chemical data as well as their chemical constituents, most plant wastes have excellent corrosion inhibition capacity. Those tested and confirmed as good corrosion inhibitors have also been reviewed. Computational chemistry has been implemented to demonstrate how some challenges confronting the understanding of their inhibition mechanism can be resolved.
... The considerably low scan rate is usually applied and presented in the adopted literature to clearly observe reactions stages 17,18 . The inhibiting efficiencies obtained from EIS and polarization curves were calculated according to Equations 3 and 4, respectively. ...
Strong acids used in industrial applications as cleaning, descaling, among others, can severely damage metallic structures, requiring corrosion inhibitors to diminish or avoid these issues. Since many conventional compounds used for this purpose may result in environmental and human health issues, eco-friendly compounds such as Schiff bases have been recently investigated. The synthesis of three novel Schiff bases (SBs) was confirmed by infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (1H-NMR). Weight loss measurements were carried out in 1 M HCl over 303K-333K. Furthermore, the combination of these compounds with a surfactant improved the efficiencies, reaching an efficiency of 93%. Optical and scanning electron microscopies confirmed the reduced roughness and pit depths of carbon steel samples. Density-functional theory calculations for neutral forms of SBs revealed that the geometrical and the energetical parameters are similar for the three studied SBs. The geometrical results exhibited more planar structures of protonated species, improving the chemical and physical interactions between aromatic rings and metallic atoms.
... This concern emphasizes the need for sustainable and environmentally friendly compounds as replacement for application as corrosion inhibitors. Non-toxic and biodegradable compounds sourced from plants have been proven recently to possess some attractive corrosion inhibition properties [5]. Plant extracts are sustainable, renewable, economical, easily produced and non-toxic [6]. ...
Analysis and description of inhibition efficiency results for tea tree and grapefruit essential oil extracts (TTGP) on mild steel (MS) and alloy steel 3310 (AS3310) in 0.5 M H2SO4 solution was done. The results show TTGP performed effectively on MS at 2% to 3.5% TTGP concentration with final inhibition values of 71.70%, 79.25%, 83.58% and 92.45% at 240 h of exposure. Inhibition efficiency generally increased with TTGP concentration and exposure time, although inhibition efficiency at 2.5% 3% TTGP concentration decreased with exposure time. Effective TTGP inhibition performance on AS3310 occurred at 3% and 3.5% TTGP concentration only with final values of 72.50% and 73.25%. Inhibition efficiency of TTGP on AS3310 varied non-proportionately with its concentration. With respect to exposure time, inhibition efficiency of TTGP on AS3310 at all concentrations decreased. Results from ANOVA analysis shows TTGP concentration significantly influenced the performance output of TTGP extract with statistically significant factor of 85.73% and 84.78% (MS and AS3310). The corresponding values for exposure time, though determined to be statistically relevant is overwhelmingly far below the influence of exposure time at values of 4.63 and 14.27. Standard deviation data shows inhibition efficiency of TTGP on MS varied minimally from mean values at all concentrations (excluding 1.5% and 2% TTGP concentration). The corresponding values for TTGP on AS3310 were also generally low at all concentrations signifying stable inhibition performance. Data showed 48% and 18% of MS and AS3310 inhibition efficiency results are greater than 80% effective inhibition performance threshold at margins of error of 12.64% and 10%
... [267] 5Orange peel 400 mg/L -95 6Passion fruit peel 500 mg/L -90 7Cashew peel 800 mg/L -80 8Azadirachta indica (Neem leaves) 2 g/L HCl 1 M Physisorption 86.84 - [268] 9Psidium guajava 10 % HCl 5 % Mixed Physisorption 97.54 - [269] Vietnam Journal of Chemistry Aarti P. More et al. ...
Corrosion inhibitors are one of the practical and cost-effective way of preventing and inhibiting corrosion. An inhibitor's primary function includes creating a barrier by forming one or more molecular layers to protect against corrosive attacks. Organic molecules are one of the most popular, efficient, and practical corrosion inhibitors, and all studies demonstrate that organic compounds, preferentially those containing nitrogen (N), sulphur (S), and oxygen (O), have high inhibitory efficiency. Also, corrosion inhibitors include inorganic compounds. Since inorganic and organic inhibitors are both toxic and expensive; emphasis is being placed on developing green corrosion inhibitors as well as on modification of inhibitors. We are focusing on carbon steel (CS) substrate in this review as it is the first-line material and is widely employed in various industrial applications. Whereas corrosion resistance of CSs in acidic environments is a constantly evolving topic, working on better performance of CSs as more cost-effective alternatives to other alloys.
... Previous research has revealed that plant extracts have excellent compounds for suppressing metal electrolyte reactions (El-Etre, 1998, 2003Ebenso et al., 2004;Ibrahim et al., 2012;Zhang et al., 2012;Mourya et al., 2014). Several plant extracts, including Carica papaya, Rosmarinus officinalis, Damsissa, Murrayakoenigii, cashew, mango, Uncariagambir, and Fiscusycomorus extracts, have been studied (Ebenso and Ekpe, 1996;Kliskic et al., 2000;Abdel-Graber et al., 2006;Ashish and Quraishi, 2010;Da Rocha et al., 2010;Hussain and Kassim, 2011;Ogwo et al., 2017;Ogunleye et al., 2018;Okuma and Onyekwere, 2022). According to Helen et al. (2014), these plants have sufficient cyclic organic phytochemicals, nitrogen, sulfur, and oxygen atoms, which are responsible for their inhibitory characteristics. ...
The use of inorganic and synthetic organic compounds as corrosion inhibitors is becoming less prevalent due to environmental concerns. The use of environmentally friendly compounds is currently the focus of the majority of corrosion mitigation research. In this study a weight loss gravimetric technique was used to analyse the inhibitive effect of leaf extract from Lasienthera africanum against mild steel corrosion in hydrochloric acid solution. The inhibitor concentrations used were 20, 40, 60, 80 and 100 ppm in hydrochloric acid concentration of 0.5 M. The extract was shown to have a 98.6% inhibitory effectiveness in inhibiting the corrosion of mild steel coupons in acid environments, making it an excellent corrosion inhibitor against steel dissolution. It was revealed that the inhibitor efficiency increased as the inhibitor concentration increased, It was also shown that the weight loss decreased with an increase in inhibitor concentration. Scanning electron microscopy showed that as the concentration of Lasienthera africanum extract increased, the corroding system maintained a surface morphology generally devoid of micro-cracks on the test materials. Therefore, Lasienthera africanum leaf extract, with an inhibition efficiency of 98.6% on mild steel can be recommended for use in high acidic environment.
... where Y0 and α are ZCPE fit parameters, w is the angular frequency and i = √−1. Table 4 shows that the α values for the double layer capacitance exhibit a negligible decrease as inhibitor concentration increases at room temperature but, at higher temperatures, remain invariant [33,15,46]. For the pseudo-capacitance α values are essentially always equal to 1, indicating a non-distributed capacitance. ...
In the present work, the inhibitory effect of Ilex paraguariensis (Yerba Mate) extract on the corrosion of aluminum in 0.1 M HCl solution, in the temperature range of 298–323 K, was studied by using weight loss tests, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). The extract of Ilex paraguariensis exhibits improved inhibitory action as its concentration increases while its performance is maintained despite an increase in temperature. EIS theoretical data according to a suitable proposed equivalent circuit were successfully fitted to the experimental data. The adsorption of organic compounds followed a modified Langmuir isotherm behaviour. Derived thermodynamic parameters indicate the occurrence of both chemical and physical adsorption.
... The LPR curves were obtained in quadruplicate, at a scan rate of 0.333 mV s -1 and within a range of 15 mV around E corr (E = E corr ± 15 mV). This very low scan rate is typically applied and widely reported in the literature, and was adopted in order to clearly observe the reaction stages 39,40 . The inhibiting efficiencies obtained from PDP and LPR were calculated according to Equations 3 and 4, respectively. ...
... However, Plumeria rubra flower petal extract performed better than the leaf counterpart. It is pertinent to state that discussing the adsorption characteristics of these extracts in terms of thermodynamic parameters such as standard free energy of adsorption, heat of adsorption as well as activation energy would not be wise given the fact that the studied extracts contained infinite number of secondary metabolites whose molecular masses are not determined [23,32,36,37]. ...
The extracts of Plumeria rubra was used to control the corrosive nature of mild steel using 0.5M H2SO4 acod medium. Results of the investigation showed that this extract has high corrosive inhibition tendency and the mechanism of adsorption was that of physi-sorption as it fits well with Langmuir isothermic relationship.
... This behavior may have been caused by reduction in the local dielectric constant and/or by an increase in the thickness of the electrical double-layer. These results showed that the presence of (B) and (B insitu ) modified the electric double-layer structure, suggesting that these molecules act by adsorption at the metal/solution interface [43]. ...
Corrosion of metals and alloys is a significant issue in many industries, leading to significant economic losses and environmental concerns. Traditional corrosion inhibitors are generally expensive and involve toxic chemicals that pose a threat to human health and the environment. In recent years, there has been a growing interest in finding abundant, readily available, low-cost, eco-friendly, and sustainable alternatives to these inhibitors. Plant wastes, rich in bioactive compounds, can offer a sustainable and cost-effective solution for mitigating corrosion while minimizing environmental impact. This chapter discusses the potential of utilizing plant wastes as corrosion inhibitors to reduce waste in the environment and the harmful effects of corrosion and contribute to the circular economy. In the chapter, the importance of sustainable corrosion mitigation, the need for new green corrosion inhibitors, the potential of plant wastes as corrosion inhibitors, the types of plant wastes, their components, extraction methods, and their effectiveness as corrosion inhibitors were discussed. Recent developments; their environmental, health, and economic benefits; challenges and limitations; sustainability; and future prospects of utilizing plant wastes as potential corrosion inhibitors were also presented. Overall, by harnessing the potential of plant residues, we can contribute to a circular economy, reduce harmful waste released into the environment, and establish a sustainable, healthier and greener corrosion mitigation process.
The corrosion problem poses significant risks to a wide range of industrial sectors, including oil and gas, automotive, and maritime, which can lead to financial losses and safety risks as a result of this issue. To overcome this issue, there is a growing interest in developing environmentally friendly corrosion inhibitors. This chapter explores the use of plant and fruit extracts as green inhibitors, offering efficient corrosion protection while maintaining environmental balance. These inhibitors, which are sourced from biodegradable and eco-compatible materials, demonstrate high anticorrosion effectiveness, ease of application, cost-effectiveness, and recyclability. Moreover, utilizing fruit and vegetable waste as corrosion inhibitors presents advantages such as availability, renewability, cost-effectiveness, low environmental risks, and the ability to form protective layers on the metal substances' surface. This approach not only addresses corrosion control, but also contributes to waste reduction and the principles of a circular economy. This chapter investigates various waste materials, extraction techniques, and inhibitory properties, providing valuable insights for industries seeking sustainable corrosion protection solutions. By establishing a connection between waste management and corrosion control, this chapter aims to demonstrate the feasibility of using fruit and vegetable waste as a corrosion inhibitor that is both efficient and environmentally friendly.
Morus nigra (Mulberry leaves) was tested as a green inhibitor for mild steel (MS) in 0.5 M HCl by theoretical, surface study, and experimental techniques. The impedance, polarization, microscopy, Langmuir, and DFT (computational) techniques were used for the adsorption and corrosion inhibition study. The experimental and theoretical study supports each other results. Adsorption parameters were observed by Langmuir, Gaussian09W (DFT), and BIOVIA Materials Studio softwares. The surface study was carried out by metallurgical microscopy technique. The theoretical study includes chemical potential, electron‐donating power, chemical hardness, HOMO, LUMO, metal inhibitor interaction energy, adsorption energy, etc. UV‐visible, NMR, and FTIR studies show that aspartic acid is the major constituent present in the mulberry leaves extract. A 91.62% corrosion protection was provided by the Morus nigra at 1000 ppm. Polarization study proved mixed inhibition. The green inhibitor follows both physical and chemical modes of adsorption. The biochemical and chemical oxygen demand of unused acid left after the gravimetric study was found in an acceptable range.
In daily life, corrosion is an inevitable problem. Metal corrosion control is crucial for technical, financial, health, and environmental reasons. One of the finest methods for preventing corrosion in metals and metal alloys involves the application of inhibitors. Toxicity of the environment caused by synthetic inhibitors has increased the use of green corrosion inhibitors which are biodegradable, are nontoxic, and do not include heavy metals. In addition, these are affordable, easily accessible, and renewable. The majority of the natural products have the required components for their use as a good source of green corrosion inhibitors. These components help with the adsorption of these substances on metals or alloys to produce a coating that protects the surface and prevents corrosion. The numerous forms of green corrosion inhibitors are briefly covered in this chapter, with a focus on the discussion of the various characteristics of the green corrosion inhibitors documented in the literature.
Over the last decade, the effectiveness of phytochemicals as corrosion inhibitors in acid environments has been confirmed. The study shows that using plants could be a cost-effective and environmentally friendly alternative to synthetic inhibitors that can be expensive and dangerous. In particular, the inhibitory properties and the adsorption behavior of genistein, a chemical compound extracted from the flower extract of Retama monosperma (L.) Boiss, were investigated for their durable application in protecting carbon steel in 1 M HCl medium. The results showed that, genistein had an exceptional performance in inhibiting corrosion with a significant inhibition efficiency of 78% at 5 × 10−4 M. Furthermore, scanning electron microscopy revealed that a protective layer had formed on the surface of the carbon steel, helping to improve corrosion resistance. A study on the effects of temperature revealed that the inhibitory efficacy of genistein decreased with increasing temperature. To further analyze the adsorption mechanism, a theoretical analysis based on density functional theory (DFT) method and molecular dynamic (MD) simulations was carried out, which demonstrated the interaction of the adsorbed molecules with the steel surface.
The goal of the ongoing study is to determine how orange peel extract (OPE), an environmentally benign additive, affects the corrosion resistance of carbon steel in formation water (FW). The study utilized diverse techniques to investigate the effects of different peel extract concentrations, ranging from 0.5 to 2.5 percent (v/v), and concentrations of 100 to 500 ppm at room temperature (25 °C). Subsequently, the optimal concentration of 2.5 percent (v/v) was identified, and the temperature range was expanded to 25–55 °C for further examination. These techniques include dielectric spectroscopy (EIS), potentiodynamic polarisation, open circuit potential, and weight loss quantification. The inhibitory efficiency was assessed using the aforementioned techniques, and the results were further verified through the utilization of energy-dispersive radiation (EDS) and FTIR analyses. The outcomes of electrochemical testing demonstrated that orange peel extract (OPE) displayed significant effectiveness in preventing corrosion, with an inhibition rate of 90.13% when used at a concentration of 2.5% and a temperature of 25 °C. The findings suggested that orange peel extract (OPE) acts as a corrosion inhibitor with both inhibitory mechanisms. Its performance improves as the concentration of the inhibitor increases, conforming to the Langmuir adsorption isotherm model, and it adsorbed to the steel surface through physical adsorption. The findings revealed that orange peel extract (OPE) effectively served as a corrosion inhibitor for carbon steel by adsorbing its active components onto the surface of the steel. This adsorption process was primarily physical and followed the Langmuir isotherm.
In this research, the mild steel corrosion inhibition effect of three extracts from soybean meal and
a soybean protein commercial sample was examined using mass loss tests, electrochemical impedance
spectroscopy (EIS) and potentiodynamic polarization (PDP). The anti-corrosive properties
of soybean meal extracts were investigated normalizing the peptide/protein amount. The inhibitors
were chemically characterized by spectroscopic studies and HPLC. The morphological
characterization of the mild steel surface was performed by SEM. Our results demonstrated that
all inhibitors showed the same inhibition efficiency if the normalization in peptide/protein
amount was performed, indicating proteins/peptides as the class of molecules responsible for inhibiting
corrosion. For example, for 100 mg L−1 in protein content, the inhibition efficiency was
84 and 82%, respectively, from electrochemical impedance and polarization curves results, and
89 and 93–94% after 2 and 24 h immersion time, respectively, from mass loss measurements. Polarization
curves indicated that all inhibitors behave as a mixed-type inhibitor, more explicit for
the cathodic branch. The SEM results suggest that all extracts promoted a protective action
against corrosion of the mild steel in H2SO4 solution.
This study examined earlier research on using papaya and neem extracts as inhibitors to minimize the corrosion of mild steel in a variety of corrosive situations. The potential inhibitory characteristics of plant extracts to potentially replace the hitherto used, well-known inhibitors that are harmful to the people handling them as well as the environment, inspired several scholars to conduct corrosion inhibition tests on metals using plant extracts. The findings of earlier research demonstrated that the maximal inhibitory efficiency provided by neem leaf extract to prevent the degradation of carbon steel in a hydrochloric acid (1 M) medium was 97%, while 86% was observed for the protection in H2SO4 (1 M) solution. The extract from Carica papaya leaves was shown to have up to 83% maximum inhibitory efficacy for preventing mild steel corrosion in HCl (1 M). It has been revealed that when extract concentration increased, the rate of steel corrosion reduced. Additionally, papaya leaves' corrosion-inhibiting mechanism was said to occur mostly in the cathodic area. Both plant-leaf extracts (Papaya and Neem) have been reported to have adsorption qualities that, for the most part, agreed with the Langmuir adsorption isotherm model.
The corrosion inhibition of orthodontic wire made of SS 18/8 alloy in artificial saliva, with and without the presence of tablet esomeprazole − 40 mg has been investigated by electrochemical analysis. Polarisation study indicates that in the presence of the mentioned tablet, polarisation resistance (Rp) value increases and corrosion current (Icorr) decreases. That is, the corrosion resistance of SS 18/8 alloy in artificial saliva increases. AC impedance spectroscopy reveals that charge transfer resistance value (Rct) value increases and double layer capacitance value (Cdl) decreases. The open circuit potential (OCP) values for the inhibited system are more negative than that of the uninhibited blank system. The vibration peaks obtained from the FTIR spectra indicates the presence of functional group in esomeprazole pill and these characteristic peaks are slightly shifted in the analyzed scratched film from the surface of the orthodontic wire after immersion. AFM micrograph image of the polished specimen sample immersed in artificial saliva (AS) with esomeprazole tablet solution shows lesser degree of surface deterioration than those for SS 18/8 specimen immersed only in artificial saliva. From the present work, it is reported that people clipped with orthodontic wire made of SS 18/8 alloy need not worry about orthodontic corrosion for taking esomeprazole tablet for the treatment of gastro esophageal reflux disease and other medicinal purpose.
Abstract Artemisia capillaris leaf extract (ACLE) for corrosion inhibition of Q235 steel at 25–65 °C in 1 m HCl was analyzed by weight loss measurements, electrochemical tests, and quantum chemical calculations. Ultra‐high‐resolution electro‐spray time‐of‐flight mass spectrometry was used to determine the major components in ACLE. The results show that ACLE has an obvious corrosion inhibition effect. At 10 g L−1 of ACLE, the corrosion inhibition efficiency can reach 99 % at 25 °C, but the inhibition efficiency decreases with the increase of temperature. Caffeic acid (0.55 wt % in ACLE) is speculated to be a major effective corrosion inhibition component in ACLE. The adsorption of active molecules in ACLE on the Fe surface may involve both physisorption and chemisorption, and however it may incline to physisorption. The adsorption of ACLE on the Q235 steel surface is a spontaneous process and conforms to the Langmuir adsorption isotherm model. The presence of ACLE can obviously increase the apparent activation energy of the dissolution reaction of iron. The combination of ACLE and L‐cysteine has a preferable synergistic inhibition effect, with the optimal mass ratio of ACLE and L‐cysteine of 7 : 3 at 25 °C. This work may provide an alternative strategy for the corrosion inhibition of metals via the synergistic effect of plant extracts with other inhibitors.
In this paper, Solanum lyratum leaves were prepared into a corrosion inhibitor by a pure water extraction method. As a natural plant, S. lyratum leaf extract as a corrosion inhibitor has green features. S. lyratum leaf extract (SLLE) can effectively inhibit the corrosion of Cu in H2SO4 solution. The protective effect on copper in 0.5 mol/L H2SO4 solution was studied by electrochemical measurement, Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and theoretical calculation. These results showed that the maximum corrosion inhibition efficiency (η) of SLLE for copper obtained in the electrochemical measurement at different temperatures is more than 90%. The adsorption of SLLE on copper surfaces conforms to the Langmuir isotherm adsorption model. FTIR and XPS showed the bonding information. SEM and AFM proved that the SLLE can protect the copper from corrosion media. The interaction and inhibition mechanism between the SLLE and copper surface was further revealed at the molecular level by theoretical calculation.
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.
Review Article:
Abstract:
Iron is a widely used metal due to its low cost and availability, but it is susceptible to corrosion in many circumstances. This corrosion can result in economic and environmental losses, and negatively affect the physical and chemical properties of the metal. This chapter provides a background on iron corrosion in archaeology and introduces various inhibitors used for its protection. It starts with a general overview of corrosion and metallurgy of iron, followed by an in-depth explanation of the mechanisms of iron corrosion in water and air. The chapter concludes with a review of different corrosion inhibitors, focusing on those made from natural plant extracts.
Keywords: archeological iron; corrosion; mechanism; green inhibitors; protection
The integrity of mild steel affects its performance in many areas of modern manufacturing. On the other hand, corrosion remains an important concern with mild steel because it reverts mild steel to its most stable oxide state. This has led to an increased search for sustainable alternatives to conventional inorganic corrosion inhibitors. Plant-based inhibitors are fast gaining more attention among researchers due to their relative advantages. To holistically address corrosion in mild steel, the sustainability perspective which cuts across the economics, safety, and environmental impacts of plant-based inhibitors from plant-based extracts must be considered. Furthermore, a clear understanding of the current trends in the deployment of environment-friendly inhibitors is necessary to operate in different environments. This study examines adsorption mechanisms, characterization techniques, as well as several factors affecting the inhibition efficiency of plant-based corrosion inhibitors in relation to economic, safety, and environmental considerations. Additionally, it outlines a plan that allows for a structured reflection on the existing literature on corrosion control and management based on a sustainability perspective. Finally, it has been identified in this review that although researchers have made a tremendous effort for corrosion inhibition in mild steel using other techniques, more research is still needed to develop sustainable technologies that could assist in isolating bioactive compounds responsible for inhibition, which could further minimize the incidence of wastage attributable to the inability to ascertain the exact amount of plant extracts for certain corrosion inhibition processes.
Carbohydrate polymers (polysaccharides) and their derivatives are widely utilized in sustainable corrosion inhibition (SCI) because of their various fascinating properties including multiple adsorption sites, high solubility and high efficiency. Contrary to traditional synthetic polymer-based corrosion inhibitors, polysaccharides are related to the 4E dimension, which stands for Energy, Economy, Ecology, and Effectivity. Furthermore, they are relatively more environmentally benign, biodegradable, and non-bioaccumulative. The current review describes the SCI features of various heteropolysaccharides, including gum Arabic (GA), glycosaminoglycans (chondroitin-4-sulfate (CS), hyaluronic acid (HA), heparin, etc.), pectin, alginates, and agar for the first time. They demonstrate impressive anticorrosive activity for different metals and alloys in a variety of corrosive electrolytes. Through their adsorption at the metal/electrolyte interface, heteropolysaccharides function by producing a corrosion-protective film. In general, their adsorption follows the Langmuir isotherm model. In their molecular structures, heteropolysaccharides contain several polar functional groups like -OH, -NH2, -COCH3, -CH2OH, cyclic and bridging O, -CH2SO3H, -SO3OH, -COOH, -NHCOCH3, -OHOR, etc. that serve as adsorption centers when they bind to metallic surfaces.
The present study focuses on the corrosion inhibition property of Swietenia macrophylla fruit shell extract on mild steel (MS) in 0.5 M HCl solution with the help of weight loss (WL), electrochemical (potentiodynamic polarization and AC impedance spectroscopy) and scanning electron microscopy (SEM) techniques. Weight loss results suggest that, the protection efficiency enhances with a rise in the amount of Swietenia macrophylla fruit shell extract and decreases with an increase in the corrosive solution temperature. Tafel plots signify that, mixed corrosion inhibition property of green extract (Swietenia macrophylla fruit shell extract) over the MS surface in 0.5 M HCl solution system. According to impedance spectroscopy results, the charge transfer plays vital role in the prevention of the dissolution process. Theoretical study by quantum chemical method signifies the electron donation property of chemical component of Swietenia macrophylla fruit shell extract. SEM results fully support the chemical (weight loss) and electrochemical (Tafel plot and AC impedance spectroscopy) results.
This study aimed to determine the antioxidant capacity of cashew apple pulp and raw concentrated extract. The antioxidant potential of aqueous (EAq) and alcoholic (EAlc) extracts and of free phenolic acids (FPA) and esterified (soluble - SPA and insoluble - IPA) fractions of the by-products of the cashew apple clone CCP-76 were evaluated in a beta-carotene-linoleate system by the free radical [2,2-diphenyl-1-picrylhydrazyl (DPPH)] scavenging assay and the Rancimat test. In addition, the total phenolic content and phenolic acid profile were determined using Folin-Ciocateau reagent and gas chromatography, respectively. The EAq and the FPA fraction of the by-products showed the highest phenolic content. The phenolic acid fractions generally displayed stronger antioxidant activity than the extracts tested with the beta-carotene-linoleate and DPPH systems. However, in the Rancimat test, the extracts showed higher antioxidant activity than the fractions and BHT. Nine phenolic acids (gallic, ferulic, caffeic, protocatechuic, quinic, cinnamic, gentisic, p-coumaric and salicylic acids), which give the fractions their antioxidant potential, were identified and quantified (both free and esterified forms). These results characterized the in vitro antioxidant capacity of the pulp and raw concentrated extract of the cashew apple clone CCP-76.
The inhibitive action of leaves (LV), seeds (SD) and a combination of leaves and seeds (LVSD) extracts of Phyllanthus amarus on mild steel corrosion in HCl and H2SO4 solutions was studied using weight loss and gasometric techniques. The results indicate that the extracts functioned as a good inhibitor in both environments and inhibition efficiency increased with extracts concentration. Temperature studies revealed an increase in inhibition efficiency with rise in temperature and activation energies decreased in the presence of the extract. A mechanism of chemical adsorption of the plants components on the surface of the metal is proposed for the inhibition behaviour. The adsorption characteristics of the inhibitor were approximated by Temkin isotherm.
Exudate gum from Raphia hookeri (RH) was tested as corrosion inhibitor for mild steel in H2SO4 using weight loss and hydrogen evolution techniques at 30–60°C. Results obtained revealed that RH act as corrosion inhibitor
for mild steel in sulfuric acid medium. The corrosion rates in all concentrations studied increased with rise in temperature.
The inhibition efficiency was observed to increase with increase in RH concentration but decreased with rise in temperature,
which is suggestive of physical adsorption mechanism. The inhibitive action of RH is discussed in view of the adsorption of
its phytochemical components onto steel surface, which protects the metal surface and thus do not permit the corrosion process
to take place. The adsorption of the exudate gum onto the steel surface was found to follow the Langmuir adsorption isotherm.
The free energies for the adsorption process and the apparent activation energies, enthalpies and entropies of the dissolution
process were determined. The fundamental thermodynamic functions were used to glean important information about the RH inhibitory
behavior. The results were explained in terms of chemical thermodynamics.
Methanolic extract powders of acerola, passion fruit and pineapple industrial residues, including pulp, seeds and peel, altogether (except for acerola) devoid of seeds, were screened for antioxidant capacity. The total phenolic contents (TPCs) of the extract powders were compared with their radical-scavenging activities (RSA) against both DPPH• and superoxide anion () radicals, and their protective effect against liposome peroxidation, triggered by peroxyl radical. Lipid peroxidation was followed by the fluorescence decay of the probe, 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid (C11-BODIPY581/591). The TPCs of acerola, passion fruit and pineapple extract powders were (94.6 ± 7.4); (41.2 ± 4.2) and (9.1 ± 1.3) mg of gallic acid equivalents g−1 of dry extract, respectively. Acerola showed the best RSA-DPPH• scores, whereas passion fruit was more protective on the RSA- system. Together with the protective effects against lipid peroxidation (rate of BODIPY decay), which were similar for acerola and passion fruit extracts, these data suggest that the methanolic extracts of acerola and passion fruit residues may be useful as antioxidant supplements, particularly the acerola extract, due to its high phenolic content.
THE INHIBITION of juice extracts of cashews (Anacardium Occidentale) on the corrosion of mild steel test specimens immersed in 0.5M H2SO4 at ambient temperature was evaluated. The weight-loss method and potential-measurement technique were used for the experimental work. The juice was obtained from the bark, apples, and nuts of the tree: the bark juice extract provided a fairly good inhibition performance at a concentration of only 0.5ml juice per 100ml of acid; the nut juice extract, at all concentrations used, provided very minimal corrosion inhibition of the test specimen in the acid; the cashew apple juice gave more-than-average performance of inhibition of the test specimen at all the concentrations used.
The performance of bark and leaf solution extracts of mango (Mangifera Indica) on the corrosion inhibition of mild steel test specimen immersed in 0.2M dilute sulphuric acid at ambient temperature was investigated. The experimental work was performed by using the weight-loss method and potential measurement technique. Solution extracts were made from the bark and leaves of the tree. The results obtained showed that the bark and the leaves, separately used, will provide very little inhibition. The combination of the two, however, at a concentration of 1.0ml/100ml of 0.2M dilute sulphuric acid, gave very good results that could make it a very useful inhibitor at the ambient temperature.
The flavonoid, carotenoid and pectin composition in peels of eight varieties of citrus {Ponkan (Citrus reticulata Blanco), Tonkan (C. tankan Hayata), Murcott (C. reticulate×C. sinensis), Wendun (C. grandis Osbeck), Peiyou (C. grandis Osbeck CV), Kumquat (C. microcarpa), Liucheng [C. sinensis (L.) Osbeck], and Lemon [C. limon (L.) Bur]} cultivated in Taiwan was determined. The total flavonoid content exceeded the total carotenoid content. Ponkan (C. reticulata Blanco) peel had the highest total carotenoid content (2.04±0.036mg/gdb) and Wendun (C. grandis Osbeck) and Peiyou (C. grandis Osbeck CV) peels, the lowest (0.036±0.0006 and 0.021±0.0004mg/gdb, respectively). Naringin was abundant in Peiyou (C. grandis Osbeck CV) and Wendun (C. grandis Osbeck) peels (29.8±0.20 and 23.9±0.32mg/gdb, respectively) and hesperidin was aboundant in Ponkan (C. reticulata Blanco), Tonkan (C. tankan Hayata), and Liucheng [C. sinensis (L.) Osbeck] peels (29.5±0.32, 23.4±0.25, 20.7±0.38mg/gdb, respectively). Kumquat (C. microcarpa) peel contained the most diosmin (1.12±0.03mg/gdb) and quercetin (0.78±0.003mg/gdb). Levels of caffeic acid (3.06±0.03–80.8±3.72μg/gdb) were much lower than that of chlorgenic acid, ferulic acid, sinapic acid and ρ-coumaric acid. Ponkan (C. reticulata Blanco), Kumquat (C. microcarpa) and Liucheng [C. sinensis (L.) Osbeck] peels contained the most total amounts of lutein, zeaxanthin, β-cryptoxanthin, and β-carotene (114, 113, and 108mg/gdb, respectively). The total pectin content ranged from 36.0±1.46 to 86.4±3.36mg/gdb.
Seven different extracts, fractions and residues of Navel sweet orange (Citrus sinensis) peel were evaluated for their radical scavenging activity by the DPPH and luminol induced chemiluminescence methods. Also, the Folin–Ciocalteu method was used to determine the total phenolic content. High phenolic content and radical scavenging activities were found for the ethyl acetate fraction. Comparison was made with reference compounds, Trolox, ascorbic acid, quercetin, which are already known for their good antioxidant activity. The radical scavenging activity of the ethyl acetate fraction approached the activity of the standards.Total phenolic content showed a small relation with radical scavenging activity. The radical scavenging activity examined with the DPPH method correlated well to values obtained by chemiluminescence.The antioxidant activity found in the fractions of Citrus sinensis, should be attributed to the presence of flavonoids and other phenolic compounds. Among the various classes of flavonoids: flavanone glycosides, flavones and flavonols seem to prevail as indicated by two dimensional thin layer chromatography and color reactions. This information shows that ethyl acetate fraction of navel sweet orange peel can be used as antioxidant in food and medicinal preparations.
The corrosion inhibitive effect of the extract of black pepper on mild steel (MS) in 1 M H2SO4 media was evaluated by conventional weight loss studies (303–323 K), electrochemical studies viz., Tafel polarization, ac impedance and scanning electron microscope (SEM) studies. Results of weight loss study reveal that black pepper extract acts as a good inhibitor even at high temperatures also. The inhibition is through adsorption which is found to follow Temkin adsorption isotherm. Tafel polarization method revealed the mixed mode inhibition of black pepper extract. Analysis of impedance data has been made with equivalent circuit with constant phase angle element for calculation of double layer capacitance value. SEM studies provide the confirmatory evidence for the protection of MS by the green inhibitor.
Azadirachta indica leaves extract (AI) was investigated as a copper corrosion inhibitor in 0.5 M sulphuric acid. Inhibition efficiency of AI was compared to that of the already proven good inhibitors 2-acetamino-5-mercapto-1,3,4-thiadiazole (AAMTDA) and 1,2,3-benzotriazole (BTAH). The inhibition properties were studied using electrochemical polarization and weight loss techniques. In the region of active copper dissolution, the highest inhibition efficiency was exhibited by AAMTDA (92.7%). AI exhibited somewhat higher efficiency (86.4%) than the widely used BTAH (85.5%), showing that the extract could serve as a effective substitute for currently preferred copper corrosion inhibitors in sulphuric acid. The weight loss results were interpreted by means of the Frumkin isotherm of adsorption on the metal surface. The values of ΔGads equal to −41.96 kJ mol−1 for AAMTDA and −35.22 kJ mol−1 for BTAH indicate strong spontaneous adsorption while the surface coverage dependence on the log c following the Frumkin isotherm is suggestive of chemisorption in case of all three tested inhibitors.
The inhibitive action of the aqueous extract of the root of shirsh el zallouh (Ferula harmonis) toward the corrosion of C-steel in HCl solution was investigated. The inhibition efficiency was measured using weight loss and potentiostatic polarization techniques. The electrochemical behavior of the extract was investigated using cyclic voltammetry. It was found that the addition of the extract reduces the corrosion rate of C-steel. The inhibition efficiency increases with increasing extract concentration. The inhibitive effect of the tested extract was discussed in view of adsorption of its components on the steel surface. The adsorption of the extract components on the C-steel surface follows Langmuir adsorption isotherm. The inhibition efficiency decreases as the temperature is increased. The presence of extract increases the activation energy of the corrosion process of C-steel. The curves of cyclic voltammetry technique showed that the adsorbed molecules reduce the charge density on the steel surface.
The corrosion inhibition properties of Gossypium hirsutum L. leave extracts (GLE) and seed extracts (GSE) in 2M sodium hydroxide (NaOH) solutions were studied using chemical technique. Gossypium extracts inhibited the corrosion of aluminium in NaOH solution. The inhibition efficiency increased with increasing concentration of the extracts. The leave extract (GLE) was found to be more effective than the seed extract (GSE). The GLE gave 97% inhibition efficiency while the GSE gave 94% at the highest concentration.
The inhibitor effect of the naturally occurring biological molecule caffeic acid on the corrosion of mild steel in 0.1M H2SO4 was investigated by weight loss, potentiodynamic polarization, electrochemical impedance and Raman spectroscopy. The different techniques confirmed the adsorption of caffeic acid onto the mild steel surface and consequently the inhibition of the corrosion process. Caffeic acid acts by decreasing the available cathodic reaction area and modifying the activation energy of the anodic reaction. A mechanism is proposed to explain the inhibitory action of the corrosion inhibitor.
The inhibitive effect of the extract of khillah (Ammi visnaga) seeds, on the corrosion of SX 316 steel in HCl solution was determined using weight loss measurements as well as potentiostatic technique. It was found that the presence of the extract reduces markedly the corrosion rate of steel in the acid solution. The inhibition efficiency increases as the extract concentration is increased. The inhibitive effect of khillah extract was discussed on the basis of adsorption of its components on the metal surface. Negative values were calculated for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of insoluble complexes as a result of interaction between iron cations and khellin, which present in the extract, was also discussed.
The performance of an open-recirculating cooling system, an important component in most industries, is affected by corrosion and scale formation. Numerous additives have been used in the past for the control of corrosion and scale formation. Effects of the naturally occurring compounds azadirachta indica (leaves), punica granatum (shell), and momordica charantia (fruits), on corrosion of mild steel in 3% sodium chloride (NaCl) were assessed using weight loss, electrochemical polarization, and impedance techniques. Extracts of the compounds exhibited excellent inhibition efficiencies comparable to that of hydroxyethylidine diphosphonic acid (HEDP), the most preferred cooling water inhibitor. The compounds were found effective under static and flowing conditions. Extracts were quite effective in retarding formation of scales, and the maximum antiscaling efficiency was exhibited by the extract of azadirachta indica (98%). The blowdown of the cooling system possessed color and chemical oxygen demand (COD). Concentrations of these parameters were reduced by an adsorption process using activated carbon as an adsorbent.
The effect of extracts of Chamomile (Chamaemelum mixtum L.), Halfabar (Cymbopogon proximus), Black cumin (Nigella sativa L.), and Kidney bean (Phaseolus vulgaris L.) plants on the corrosion of steel in aqueous 1M sulphuric acid were investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. EIS measurements showed that the dissolution process of steel occurs under activation control. Potentiodynamic polarization curves indicated that the plant extracts behave as mixed-type inhibitors. The corrosion rates of steel and the inhibition efficiencies of the extracts were calculated. The results obtained show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of steel in sulphuric acid media. Inhibition was found to increase with increasing concentration of the plant extract up to a critical concentration. The inhibitive actions of plant extracts are discussed on the basis of adsorption of stable complex at the steel surface. Theoretical fitting of different isotherms, Langmuir, Flory–Huggins, and the kinetic–thermodynamic model, were tested to clarify the nature of adsorption.
The inhibitive effect of lupine (Lupinous albus L.) extract on the corrosion of steel in aqueous solution of 1M sulphuric and 2M hydrochloric acids was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization curves indicated that the lupine extract acts as a mixed-type inhibitor. EIS measurements showed that the dissolution process is under activation control. The inhibition efficiency of the extract obtained from impedance and polarization measurements was in a good agreement and was found to increase with increasing concentration of the extract. The obtained results showed that, the lupine extract could serve as an effective inhibitor for the corrosion of steel in acid media and the extract was more effective in case of hydrochloric acid. Theoretical fitting of the corrosion data to the kinetic–thermodynamic model was tested to show the nature of adsorption.
The inhibitive effects of aqueous extracts of Opuntia ficus indica and Aloe eru (leaves) and of Orange, Mango and Pomegranate (fruit-peels) on the corrosion of mild steel, aluminium, zinc and copper in HCl and H2SO4 solutions have been investigated by means of weight loss and polarisation measurements. The extracts retard the dissolution reactions to an extent dependent on the metal used, the concentration of the additive and the type, concentration and temperature of the attacking acid. The additives provide adequate protection to steel in 5% HCl at 25°c and in 10% HCl at 25° and 40°c. In the presence of a sufficient concentration of the extracts in 5% HCl at 25°c, the inhibitive efficiency towards steel decreases in the order: Mango (82%), Orange and Aloe eru (80%), Opuntia f.i. (75%), Pomegranate (65%). The order of effiCiency differs for the different metals, but extract of Mango peels is still the most effectivefor Al (82%) and Zn (80%). The most effective extract for Cu is that of Pomegranate fruit-shells (73%). The extracts are generally more effective in HCl than in H2SO4Polarisation measurements indicate that all the extracts increase the polarisation of the cathodic reaction of all the four metals tested and the anodic polarisation of steel and Zn, while Orange and Aloe have no effect on the anodic reaction of Al and only Pomegranate has any effect on the anodic polarisation of Cu. The results suggest that the extracts generally act as mixed inhibitors. The mechanism of inhibition has been discussed.
Monomeric phenols were extracted by acetone/water (60:40) from the skin and flesh of four cashew apple genotypes from Brazil and Bénin (West Africa), purified by absorption chromatography and subjected to HPLC-DAD/ESI-MS analysis. Skins were found much richer than fleshes in simple phenolics. Flavonol glycosides were dominant with myricetin and quercetin hexosides (2 of each), pentosides (3 of each), and rhamnosides as major compounds. Anthocyanidin glycosides were detected in skins from the two scarlet and orange pigmented genotypes as peonidin, petunidin and cyanidin 3-O-hexosides, and were absent from fleshes.
Natural oil extracted from Pennyroyal Mint (Mentha pulegium, PM) was evaluated as corrosion inhibitor of steel in molar hydrochloric using weight loss measurements, electrochemical polarisation and EIS methods. The naturally oil was found to retard the corrosion rate of steel. The inhibition efficiency was found to increase with oil content to attain 80% at 2.76 g/L. PM oil acts as a cathodic inhibitor. The increase in temperature leads to an increase in the inhibition efficiency of the natural substance. The adsorption isotherm of natural product on the steel has been determined.
The inhibition effect of Zenthoxylum alatum plant extract on the corrosion of mild steel in 5% and 15% aqueous hydrochloric acid solution has been investigated by weight loss and electrochemical impedance spectroscopy (EIS). The corrosion inhibition efficiency increases on increasing plant extract concentration till 2400 ppm. The effect of temperature on the corrosion behaviour of mild steel in 5% and 15% HCl with addition of plant extract was studied in the temperature range 50–80 °C. Surface analysis (SEM, XPS and FT-IR) was also carried out to establish the corrosion inhibitive property of this plant extract in HCl solution. Plant extract is able to reduce the corrosion of steel more effectively in 5% HCl than in 15% HCl. The adsorption of this plant extract on the mild steel surface obeys the Langmuir adsorption isotherm.
The adsorption and inhibition effect of 6-benzylaminopurine (BAP) on cold rolled steel (CRS) in 1.0 M HCl at 25–50 °C was studied by weight loss and potentiodynamic polarization methods. The results showed that BAP was a good inhibitor in 1.0 M HCl, and the inhibition efficiency (IE) increased with the inhibitor concentration. The adsorption of BAP on the CRS surface obeyed the Langmuir adsorption isotherm equation. Both thermodynamic parameters (adsorption heat ΔH0, adsorption free energy ΔG0 and adsorption entropy ΔS0) and kinetic parameters (apparent activation energy Ea and pre-exponential factor A) were calculated and discussed. Polarization curves showed that BAP acted as a mixed-type inhibitor in hydrochloric acid. Good agreement between weight loss and polarization methods was obtained. The adsorbed film on CRS surface containing optimum dose of BAP was investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscope (AFM). Quantum chemical calculation was applied to elucidate the adsorption mode of the inhibitor molecule onto steel surface. Depending on the results, the inhibitive mechanism was proposed from the viewpoint of adsorption theory.
The effect of the extract of Aloe vera leaves on the corrosion of zinc in 2 M HCl solution was studied using weight loss technique. A. vera extract inhibited the corrosion of zinc in 2 M HCl solution and the inhibition efficiency increased with increasing concentration of the extract but decreased with increasing temperature. The adsorption of the inhibitor molecules on zinc surface was in accordance with Langmuir adsorption isotherm. A first-order kinetics relationship with respect to zinc was obtained with and without the extract from the kinetics treatment of the data.
The inhibitive action of henna extract (Lawsonia inermis) and its main constituents (lawsone, gallic acid, α-d-Glucose and tannic acid) on corrosion of mild steel in 1 M HCl solution was investigated through electrochemical techniques and surface analysis (SEM/EDS). Polarization measurements indicate that all the examined compounds act as a mixed inhibitor and inhibition efficiency increases with inhibitor concentration. Maximum inhibition efficiency (92.06%) is obtained at 1.2 g/l henna extract. Inhibition efficiency increases in the order: lawsone > henna extract > gallic acid > α-d-Glucose > tannic acid. Also, inhibition mechanism and thermodynamic parameters are discussed.
The aqueous extract of the leaves of henna (lawsonia) is tested as corrosion inhibitor of C-steel, nickel and zinc in acidic, neutral and alkaline solutions, using the polarization technique. It was found that the extract acts as a good corrosion inhibitor for the three tested electrodes in all tested media. The inhibition efficiency increases as the added concentration of extract is increased. The degree of inhibition depends on the nature of metal and the type of the medium. For C-steel and nickel, the inhibition efficiency increases in the order: alkaline < neutral < acid, while in the case of zinc it increases in the order: acid < alkaline < neutral. The extract acts as a mixed inhibitor. The inhibitive action of the extract is discussed in view of adsorption of lawsonia molecules on the metal surface. It was found that this adsorption follows Langmuir adsorption isotherm in all tested systems. The formation of complex between metal cations and lawsone is also proposed as additional inhibition mechanism of C-steel and nickel corrosion.
Corrosion inhibition effect of Justicia gendarussa extract (JGPE) on mild steel in 1 M HCl medium has been investigated by weight loss and electrochemical techniques. Inhibition efficiency of 93% was achieved with 150 ppm JGPE at 25 °C. The polarization studies showed that JGPE acts as mixed-type inhibitor. The Nyquist plots showed that on increasing JGPE concentration, increases charge transfer resistance and decreases double layer capacitance. JGPE obeys the Langmuir adsorption isotherm. AFM and ESCA confirmed the adsorption of JGPE on mild steel surface. Finally, JGPE inhibition efficiency was discussed in terms of adsorption and protective film formation.
Corrosion inhibition of mild steel in 2 M HCl and 1 M H2SO4 by extracts of selected plants was investigated using a gasometric technique at temperatures of 30 and 60 °C. The studied plants materials include leaf extracts Occimum viridis (OV), Telferia occidentalis (TO), Azadirachta indica (AI) and Hibiscus sabdariffa (HS) as well as extracts from the seeds of Garcinia kola (GK). The results indicate that all the extracts inhibited the corrosion process in both acid media by virtue of adsorption and inhibition efficiency improved with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms were deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. Comparative analysis of the inhibitor adsorption behaviour in 2 M HCl and 1 M H2SO4 as well as the effects of temperature and halide additives suggest that both protonated and molecular species could be responsible for the inhibiting action of the extracts.
Berberine was abstracted from coptis chinensis and its inhibition efficiency on corrosion of mild steel in 1 M H2SO4 was investigated through weight loss experiment, electrochemical techniques and scanning electronic microscope (SEM) with energy disperse spectrometer (EDS). The weight loss results showed that berberine is an excellent corrosion inhibitor for mild steel immersed in 1 M H2SO4. Potentiodynamic curves suggested that berberine suppressed both cathodic and anodic processes for its concentrations higher than 1.0 × 10−4 M and mainly cathodic reaction was suppressed for lower concentrations. The Nyquist diagrams of impedance for mild steel in 1 M H2SO4 containing berberine with different concentrations showed one capacitive loop, and the polarization resistance increased with the inhibitor concentration rising. A good fit to Flory–Huggins isotherm was obtained between surface coverage degree and inhibitor concentration. The surface morphology and EDS analysis for mild steel specimens in sulfuric acid in the absence and presence of the inhibitor also proved the results obtained by the weight loss and electrochemical experiments. The correlation of inhibition effect and molecular structure of berberine was then discussed by quantum chemistry study.
The inhibitive action of leaf extracts of Sansevieria trifasciata on aluminium corrosion in 2 M HCl and 2 M KOH solutions was studied using the gasometric technique. The results indicate that the extract functioned as a good inhibitor in both environments and inhibition efficiency increased with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the extract. A mechanism of physical adsorption is proposed for the inhibition behaviour. The adsorption characteristics of the inhibitor were approximated by Freundlich isotherm.
The effect of the extract of Phyllanthus amarus leaves on the corrosion of aluminum in 2 M NaOH solution was studied using chemical technique. The extract acts as corrosion inhibitor, with 76% efficiency at the highest concentration in the alkaline environment and the inhibition efficiency increased with increasing concentration of the extract. The adsorption of the inhibitor on aluminum surface was in accordance with the Langmuir adsorption isotherm. A zero-order kinetics relationship with respect to aluminum was obtained with and without the extract from the kinetics treatment of the data.
Bioactive compounds such as polyphenols, carotenoids and anthocyanins present in fruits and vegetables are receiving increased attention because of their potential antioxidant activity. Consumption of such antioxidants offers health benefits including protection against cardiovascular diseases and cancer. Mango peel is a major byproduct obtained during the processing of mango products such as mango pulp and amchur. In the present study, the antioxidant activity of mango peel extracts was examined. Polyphenol, anthocyanin and carotenoid contents in acetone extract of peels were determined. Ripe peels contained higher amount of anthocyanins and carotenoids compared to raw peels while raw mango peel had high polyphenol content. Antioxidant activity of ripe and raw mango peels extracted in acetone was determined using different antioxidant systems such as reducing power activity, DPPH free radical scavenging activity, iron induced lipid peroxidation of liver microsomes and soybean lipoxygenase inhibition. The IC50 values were found to be in the range of 1.39–5.24 μg of gallic acid equivalents. Thus, the mango peel extract exhibited good antioxidant activity in different systems and thus may be used in nutraceutical and functional foods.
The inhibitive action of the aqueous extract of olive (Olea europaea L.) leaves toward the corrosion of C-steel in 2 M HCl solution was investigated using weight loss measurements, Tafel polarization, and cyclic voltammetry. It was found that the extract acts as a good corrosion inhibitor for the tested system. The inhibition efficiency increases with increasing extract concentration. The inhibitive action of the extract is discussed with a view to adsorption of its components onto the steel surface, making a barrier to mass and charge transfer. The adsorption of extract components onto the steel surface was found to be a spontaneous process and to follow the Langmuir adsorption isotherm. It was found also that such adsorption increases the activation energy of the corrosion process. The results of cyclic voltammetry showed that the presence of olive extract decreases the charge density in the transpassive region. The inhibition efficiency is greatly reduced as the temperature is increased.
Phytochemicals such as polyphenols and carotenoids are gaining importance because of their contribution to human health and their multiple biological effects such as antioxidant, antimutagenic, anticarcinogenic and cytoprotective activities and other therapeutic properties. Mango peel is a major by-product in pulp industry and it contains various bioactive compounds like polyphenols, carotenoids and others. In the present study, the protective effect of peel extracts of unripe and ripe mango fruits of two varieties namely, Raspuri and Badami on hydrogen peroxide induced hemolysis, lipid peroxidation, degradation of membrane proteins and its morphological changes are reported. The oxidative hemolysis of rat erythrocytes by hydrogen peroxide was inhibited by mango peel extract in a dose dependent manner. The IC(50) value for lipid peroxidation inhibition on erythrocyte ghost membrane was found to be in the range of 4.5-19.3 microg gallic acid equivalents. The mango peel extract showed protection against membrane protein degradation caused by hydrogen peroxide. Morphological changes to erythrocyte membrane caused by hydrogen peroxide were protected by mango peel extract. The results demonstrated that mango peel extracts protected erythrocytes against oxidative stress and may impart health benefits and it could be used as a valuable food ingredient or a nutraceutical product.